/* This file is part of GNUnet Copyright (C) 2012 GNUnet e.V. GNUnet is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. */ /** * @file src/regex/regex_internal.c * @brief library to create Deterministic Finite Automatons (DFAs) from regular * expressions (regexes). * @author Maximilian Szengel */ #include "platform.h" #include "gnunet_util_lib.h" #include "gnunet_regex_service.h" #include "regex_internal_lib.h" #include "regex_internal.h" /** * Set this to #GNUNET_YES to enable state naming. Used to debug NFA->DFA * creation. Disabled by default for better performance. */ #define REGEX_DEBUG_DFA GNUNET_NO /** * Set of states using MDLL API. */ struct REGEX_INTERNAL_StateSet_MDLL { /** * MDLL of states. */ struct REGEX_INTERNAL_State *head; /** * MDLL of states. */ struct REGEX_INTERNAL_State *tail; /** * Length of the MDLL. */ unsigned int len; }; /** * Append state to the given StateSet. * * @param set set to be modified * @param state state to be appended */ static void state_set_append (struct REGEX_INTERNAL_StateSet *set, struct REGEX_INTERNAL_State *state) { if (set->off == set->size) GNUNET_array_grow (set->states, set->size, set->size * 2 + 4); set->states[set->off++] = state; } /** * Compare two strings for equality. If either is NULL they are not equal. * * @param str1 first string for comparison. * @param str2 second string for comparison. * * @return 0 if the strings are the same or both NULL, 1 or -1 if not. */ static int nullstrcmp (const char *str1, const char *str2) { if ((NULL == str1) != (NULL == str2)) return -1; if ((NULL == str1) && (NULL == str2)) return 0; return strcmp (str1, str2); } /** * Adds a transition from one state to another on @a label. Does not add * duplicate states. * * @param ctx context * @param from_state starting state for the transition * @param label transition label * @param to_state state to where the transition should point to */ static void state_add_transition (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_State *from_state, const char *label, struct REGEX_INTERNAL_State *to_state) { struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_Transition *oth; if (NULL == from_state) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n"); return; } /* Do not add duplicate state transitions */ for (t = from_state->transitions_head; NULL != t; t = t->next) { if (t->to_state == to_state && 0 == nullstrcmp (t->label, label) && t->from_state == from_state) return; } /* sort transitions by label */ for (oth = from_state->transitions_head; NULL != oth; oth = oth->next) { if (0 < nullstrcmp (oth->label, label)) break; } t = GNUNET_new (struct REGEX_INTERNAL_Transition); if (NULL != ctx) t->id = ctx->transition_id++; if (NULL != label) t->label = GNUNET_strdup (label); else t->label = NULL; t->to_state = to_state; t->from_state = from_state; /* Add outgoing transition to 'from_state' */ from_state->transition_count++; GNUNET_CONTAINER_DLL_insert_before (from_state->transitions_head, from_state->transitions_tail, oth, t); } /** * Remove a 'transition' from 'state'. * * @param state state from which the to-be-removed transition originates. * @param transition transition that should be removed from state 'state'. */ static void state_remove_transition (struct REGEX_INTERNAL_State *state, struct REGEX_INTERNAL_Transition *transition) { if (NULL == state || NULL == transition) return; if (transition->from_state != state) return; GNUNET_free_non_null (transition->label); state->transition_count--; GNUNET_CONTAINER_DLL_remove (state->transitions_head, state->transitions_tail, transition); GNUNET_free (transition); } /** * Compare two states. Used for sorting. * * @param a first state * @param b second state * * @return an integer less than, equal to, or greater than zero * if the first argument is considered to be respectively * less than, equal to, or greater than the second. */ static int state_compare (const void *a, const void *b) { struct REGEX_INTERNAL_State **s1 = (struct REGEX_INTERNAL_State **) a; struct REGEX_INTERNAL_State **s2 = (struct REGEX_INTERNAL_State **) b; return (*s1)->id - (*s2)->id; } /** * Get all edges leaving state @a s. * * @param s state. * @param edges all edges leaving @a s, expected to be allocated and have enough * space for `s->transitions_count` elements. * * @return number of edges. */ static unsigned int state_get_edges (struct REGEX_INTERNAL_State *s, struct REGEX_BLOCK_Edge *edges) { struct REGEX_INTERNAL_Transition *t; unsigned int count; if (NULL == s) return 0; count = 0; for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL != t->to_state) { edges[count].label = t->label; edges[count].destination = t->to_state->hash; count++; } } return count; } /** * Compare to state sets by comparing the id's of the states that are contained * in each set. Both sets are expected to be sorted by id! * * @param sset1 first state set * @param sset2 second state set * @return 0 if the sets are equal, otherwise non-zero */ static int state_set_compare (struct REGEX_INTERNAL_StateSet *sset1, struct REGEX_INTERNAL_StateSet *sset2) { int result; unsigned int i; if (NULL == sset1 || NULL == sset2) return 1; result = sset1->off - sset2->off; if (result < 0) return -1; if (result > 0) return 1; for (i = 0; i < sset1->off; i++) if (0 != (result = state_compare (&sset1->states[i], &sset2->states[i]))) break; return result; } /** * Clears the given StateSet 'set' * * @param set set to be cleared */ static void state_set_clear (struct REGEX_INTERNAL_StateSet *set) { GNUNET_array_grow (set->states, set->size, 0); set->off = 0; } /** * Clears an automaton fragment. Does not destroy the states inside the * automaton. * * @param a automaton to be cleared */ static void automaton_fragment_clear (struct REGEX_INTERNAL_Automaton *a) { if (NULL == a) return; a->start = NULL; a->end = NULL; a->states_head = NULL; a->states_tail = NULL; a->state_count = 0; GNUNET_free (a); } /** * Frees the memory used by State @a s * * @param s state that should be destroyed */ static void automaton_destroy_state (struct REGEX_INTERNAL_State *s) { struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_Transition *next_t; if (NULL == s) return; GNUNET_free_non_null (s->name); GNUNET_free_non_null (s->proof); state_set_clear (&s->nfa_set); for (t = s->transitions_head; NULL != t; t = next_t) { next_t = t->next; state_remove_transition (s, t); } GNUNET_free (s); } /** * Remove a state from the given automaton 'a'. Always use this function when * altering the states of an automaton. Will also remove all transitions leading * to this state, before destroying it. * * @param a automaton * @param s state to remove */ static void automaton_remove_state (struct REGEX_INTERNAL_Automaton *a, struct REGEX_INTERNAL_State *s) { struct REGEX_INTERNAL_State *s_check; struct REGEX_INTERNAL_Transition *t_check; struct REGEX_INTERNAL_Transition *t_check_next; if (NULL == a || NULL == s) return; /* remove all transitions leading to this state */ for (s_check = a->states_head; NULL != s_check; s_check = s_check->next) { for (t_check = s_check->transitions_head; NULL != t_check; t_check = t_check_next) { t_check_next = t_check->next; if (t_check->to_state == s) state_remove_transition (s_check, t_check); } } /* remove state */ GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s); a->state_count--; automaton_destroy_state (s); } /** * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy * 's2'. 's1' will contain all (non-duplicate) outgoing transitions of 's2'. * * @param ctx context * @param a automaton * @param s1 first state * @param s2 second state, will be destroyed */ static void automaton_merge_states (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_Automaton *a, struct REGEX_INTERNAL_State *s1, struct REGEX_INTERNAL_State *s2) { struct REGEX_INTERNAL_State *s_check; struct REGEX_INTERNAL_Transition *t_check; struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_Transition *t_next; int is_dup; if (s1 == s2) return; /* 1. Make all transitions pointing to s2 point to s1, unless this transition * does not already exists, if it already exists remove transition. */ for (s_check = a->states_head; NULL != s_check; s_check = s_check->next) { for (t_check = s_check->transitions_head; NULL != t_check; t_check = t_next) { t_next = t_check->next; if (s2 == t_check->to_state) { is_dup = GNUNET_NO; for (t = t_check->from_state->transitions_head; NULL != t; t = t->next) { if (t->to_state == s1 && 0 == strcmp (t_check->label, t->label)) is_dup = GNUNET_YES; } if (GNUNET_NO == is_dup) t_check->to_state = s1; else state_remove_transition (t_check->from_state, t_check); } } } /* 2. Add all transitions from s2 to sX to s1 */ for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next) { if (t_check->to_state != s1) state_add_transition (ctx, s1, t_check->label, t_check->to_state); } /* 3. Rename s1 to {s1,s2} */ #if REGEX_DEBUG_DFA char *new_name; new_name = s1->name; GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name); GNUNET_free (new_name); #endif /* remove state */ GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2); a->state_count--; automaton_destroy_state (s2); } /** * Add a state to the automaton 'a', always use this function to alter the * states DLL of the automaton. * * @param a automaton to add the state to * @param s state that should be added */ static void automaton_add_state (struct REGEX_INTERNAL_Automaton *a, struct REGEX_INTERNAL_State *s) { GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s); a->state_count++; } /** * Depth-first traversal (DFS) of all states that are reachable from state * 's'. Performs 'action' on each visited state. * * @param s start state. * @param marks an array of size a->state_count to remember which state was * already visited. * @param count current count of the state. * @param check function that is checked before advancing on each transition * in the DFS. * @param check_cls closure for check. * @param action action to be performed on each state. * @param action_cls closure for action. */ static void automaton_state_traverse (struct REGEX_INTERNAL_State *s, int *marks, unsigned int *count, REGEX_INTERNAL_traverse_check check, void *check_cls, REGEX_INTERNAL_traverse_action action, void *action_cls) { struct REGEX_INTERNAL_Transition *t; if (GNUNET_YES == marks[s->traversal_id]) return; marks[s->traversal_id] = GNUNET_YES; if (NULL != action) action (action_cls, *count, s); (*count)++; for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL == check || (NULL != check && GNUNET_YES == check (check_cls, s, t))) { automaton_state_traverse (t->to_state, marks, count, check, check_cls, action, action_cls); } } } /** * Traverses the given automaton using depth-first-search (DFS) from it's start * state, visiting all reachable states and calling 'action' on each one of * them. * * @param a automaton to be traversed. * @param start start state, pass a->start or NULL to traverse the whole automaton. * @param check function that is checked before advancing on each transition * in the DFS. * @param check_cls closure for @a check. * @param action action to be performed on each state. * @param action_cls closure for @a action */ void REGEX_INTERNAL_automaton_traverse (const struct REGEX_INTERNAL_Automaton *a, struct REGEX_INTERNAL_State *start, REGEX_INTERNAL_traverse_check check, void *check_cls, REGEX_INTERNAL_traverse_action action, void *action_cls) { unsigned int count; struct REGEX_INTERNAL_State *s; if (NULL == a || 0 == a->state_count) return; int marks[a->state_count]; for (count = 0, s = a->states_head; NULL != s && count < a->state_count; s = s->next, count++) { s->traversal_id = count; marks[s->traversal_id] = GNUNET_NO; } count = 0; if (NULL == start) s = a->start; else s = start; automaton_state_traverse (s, marks, &count, check, check_cls, action, action_cls); } /** * String container for faster string operations. */ struct StringBuffer { /** * Buffer holding the string (may start in the middle!); * NOT 0-terminated! */ char *sbuf; /** * Allocated buffer. */ char *abuf; /** * Length of the string in the buffer. */ size_t slen; /** * Number of bytes allocated for @e sbuf */ unsigned int blen; /** * Buffer currently represents "NULL" (not the empty string!) */ int16_t null_flag; /** * If this entry is part of the last/current generation array, * this flag is #GNUNET_YES if the last and current generation are * identical (and thus copying is unnecessary if the value didn't * change). This is used in an optimization that improves * performance by about 1% --- if we use int16_t here. With just * "int" for both flags, performance drops (on my system) significantly, * most likely due to increased cache misses. */ int16_t synced; }; /** * Compare two strings for equality. If either is NULL they are not equal. * * @param s1 first string for comparison. * @param s2 second string for comparison. * * @return 0 if the strings are the same or both NULL, 1 or -1 if not. */ static int sb_nullstrcmp (const struct StringBuffer *s1, const struct StringBuffer *s2) { if ( (GNUNET_YES == s1->null_flag) && (GNUNET_YES == s2->null_flag) ) return 0; if ( (GNUNET_YES == s1->null_flag) || (GNUNET_YES == s2->null_flag) ) return -1; if (s1->slen != s2->slen) return -1; if (0 == s1->slen) return 0; return memcmp (s1->sbuf, s2->sbuf, s1->slen); } /** * Compare two strings for equality. * * @param s1 first string for comparison. * @param s2 second string for comparison. * * @return 0 if the strings are the same, 1 or -1 if not. */ static int sb_strcmp (const struct StringBuffer *s1, const struct StringBuffer *s2) { if (s1->slen != s2->slen) return -1; if (0 == s1->slen) return 0; return memcmp (s1->sbuf, s2->sbuf, s1->slen); } /** * Reallocate the buffer of 'ret' to fit 'nlen' characters; * move the existing string to the beginning of the new buffer. * * @param ret current buffer, to be updated * @param nlen target length for the buffer, must be at least ret->slen */ static void sb_realloc (struct StringBuffer *ret, size_t nlen) { char *old; GNUNET_assert (nlen >= ret->slen); old = ret->abuf; ret->abuf = GNUNET_malloc (nlen); ret->blen = nlen; GNUNET_memcpy (ret->abuf, ret->sbuf, ret->slen); ret->sbuf = ret->abuf; GNUNET_free_non_null (old); } /** * Append a string. * * @param ret where to write the result * @param sarg string to append */ static void sb_append (struct StringBuffer *ret, const struct StringBuffer *sarg) { if (GNUNET_YES == ret->null_flag) ret->slen = 0; ret->null_flag = GNUNET_NO; if (ret->blen < sarg->slen + ret->slen) sb_realloc (ret, ret->blen + sarg->slen + 128); GNUNET_memcpy (&ret->sbuf[ret->slen], sarg->sbuf, sarg->slen); ret->slen += sarg->slen; } /** * Append a C string. * * @param ret where to write the result * @param cstr string to append */ static void sb_append_cstr (struct StringBuffer *ret, const char *cstr) { size_t cstr_len = strlen (cstr); if (GNUNET_YES == ret->null_flag) ret->slen = 0; ret->null_flag = GNUNET_NO; if (ret->blen < cstr_len + ret->slen) sb_realloc (ret, ret->blen + cstr_len + 128); GNUNET_memcpy (&ret->sbuf[ret->slen], cstr, cstr_len); ret->slen += cstr_len; } /** * Wrap a string buffer, that is, set ret to the format string * which contains an "%s" which is to be replaced with the original * content of 'ret'. Note that optimizing this function is not * really worth it, it is rarely called. * * @param ret where to write the result and take the input for %.*s from * @param format format string, fprintf-style, with exactly one "%.*s" * @param extra_chars how long will the result be, in addition to 'sarg' length */ static void sb_wrap (struct StringBuffer *ret, const char *format, size_t extra_chars) { char *temp; if (GNUNET_YES == ret->null_flag) ret->slen = 0; ret->null_flag = GNUNET_NO; temp = GNUNET_malloc (ret->slen + extra_chars + 1); GNUNET_snprintf (temp, ret->slen + extra_chars + 1, format, (int) ret->slen, ret->sbuf); GNUNET_free_non_null (ret->abuf); ret->abuf = temp; ret->sbuf = temp; ret->blen = ret->slen + extra_chars + 1; ret->slen = ret->slen + extra_chars; } /** * Format a string buffer. Note that optimizing this function is not * really worth it, it is rarely called. * * @param ret where to write the result * @param format format string, fprintf-style, with exactly one "%.*s" * @param extra_chars how long will the result be, in addition to 'sarg' length * @param sarg string to print into the format */ static void sb_printf1 (struct StringBuffer *ret, const char *format, size_t extra_chars, const struct StringBuffer *sarg) { if (ret->blen < sarg->slen + extra_chars + 1) sb_realloc (ret, sarg->slen + extra_chars + 1); ret->null_flag = GNUNET_NO; ret->sbuf = ret->abuf; ret->slen = sarg->slen + extra_chars; GNUNET_snprintf (ret->sbuf, ret->blen, format, (int) sarg->slen, sarg->sbuf); } /** * Format a string buffer. * * @param ret where to write the result * @param format format string, fprintf-style, with exactly two "%.*s" * @param extra_chars how long will the result be, in addition to 'sarg1/2' length * @param sarg1 first string to print into the format * @param sarg2 second string to print into the format */ static void sb_printf2 (struct StringBuffer *ret, const char *format, size_t extra_chars, const struct StringBuffer *sarg1, const struct StringBuffer *sarg2) { if (ret->blen < sarg1->slen + sarg2->slen + extra_chars + 1) sb_realloc (ret, sarg1->slen + sarg2->slen + extra_chars + 1); ret->null_flag = GNUNET_NO; ret->slen = sarg1->slen + sarg2->slen + extra_chars; ret->sbuf = ret->abuf; GNUNET_snprintf (ret->sbuf, ret->blen, format, (int) sarg1->slen, sarg1->sbuf, (int) sarg2->slen, sarg2->sbuf); } /** * Format a string buffer. Note that optimizing this function is not * really worth it, it is rarely called. * * @param ret where to write the result * @param format format string, fprintf-style, with exactly three "%.*s" * @param extra_chars how long will the result be, in addition to 'sarg1/2/3' length * @param sarg1 first string to print into the format * @param sarg2 second string to print into the format * @param sarg3 third string to print into the format */ static void sb_printf3 (struct StringBuffer *ret, const char *format, size_t extra_chars, const struct StringBuffer *sarg1, const struct StringBuffer *sarg2, const struct StringBuffer *sarg3) { if (ret->blen < sarg1->slen + sarg2->slen + sarg3->slen + extra_chars + 1) sb_realloc (ret, sarg1->slen + sarg2->slen + sarg3->slen + extra_chars + 1); ret->null_flag = GNUNET_NO; ret->slen = sarg1->slen + sarg2->slen + sarg3->slen + extra_chars; ret->sbuf = ret->abuf; GNUNET_snprintf (ret->sbuf, ret->blen, format, (int) sarg1->slen, sarg1->sbuf, (int) sarg2->slen, sarg2->sbuf, (int) sarg3->slen, sarg3->sbuf); } /** * Free resources of the given string buffer. * * @param sb buffer to free (actual pointer is not freed, as they * should not be individually allocated) */ static void sb_free (struct StringBuffer *sb) { GNUNET_array_grow (sb->abuf, sb->blen, 0); sb->slen = 0; sb->sbuf = NULL; sb->null_flag= GNUNET_YES; } /** * Copy the given string buffer from 'in' to 'out'. * * @param in input string * @param out output string */ static void sb_strdup (struct StringBuffer *out, const struct StringBuffer *in) { out->null_flag = in->null_flag; if (GNUNET_YES == out->null_flag) return; if (out->blen < in->slen) { GNUNET_array_grow (out->abuf, out->blen, in->slen); } out->sbuf = out->abuf; out->slen = in->slen; GNUNET_memcpy (out->sbuf, in->sbuf, out->slen); } /** * Copy the given string buffer from 'in' to 'out'. * * @param cstr input string * @param out output string */ static void sb_strdup_cstr (struct StringBuffer *out, const char *cstr) { if (NULL == cstr) { out->null_flag = GNUNET_YES; return; } out->null_flag = GNUNET_NO; out->slen = strlen (cstr); if (out->blen < out->slen) { GNUNET_array_grow (out->abuf, out->blen, out->slen); } out->sbuf = out->abuf; GNUNET_memcpy (out->sbuf, cstr, out->slen); } /** * Check if the given string @a str needs parentheses around it when * using it to generate a regex. * * @param str string * * @return #GNUNET_YES if parentheses are needed, #GNUNET_NO otherwise */ static int needs_parentheses (const struct StringBuffer *str) { size_t slen; const char *op; const char *cl; const char *pos; const char *end; unsigned int cnt; if ((GNUNET_YES == str->null_flag) || ((slen = str->slen) < 2)) return GNUNET_NO; pos = str->sbuf; if ('(' != pos[0]) return GNUNET_YES; end = str->sbuf + slen; cnt = 1; pos++; while (cnt > 0) { cl = memchr (pos, ')', end - pos); if (NULL == cl) { GNUNET_break (0); return GNUNET_YES; } /* while '(' before ')', count opening parens */ while ( (NULL != (op = memchr (pos, '(', end - pos))) && (op < cl) ) { cnt++; pos = op + 1; } /* got ')' first */ cnt--; pos = cl + 1; } return (*pos == '\0') ? GNUNET_NO : GNUNET_YES; } /** * Remove parentheses surrounding string @a str. * Example: "(a)" becomes "a", "(a|b)|(a|c)" stays the same. * You need to #GNUNET_free() the returned string. * * @param str string, modified to contain a * @return string without surrounding parentheses, string 'str' if no preceding * epsilon could be found, NULL if 'str' was NULL */ static void remove_parentheses (struct StringBuffer *str) { size_t slen; const char *pos; const char *end; const char *sbuf; const char *op; const char *cp; unsigned int cnt; if (0) return; sbuf = str->sbuf; if ( (GNUNET_YES == str->null_flag) || (1 >= (slen = str->slen)) || ('(' != str->sbuf[0]) || (')' != str->sbuf[slen - 1]) ) return; cnt = 0; pos = &sbuf[1]; end = &sbuf[slen - 1]; op = memchr (pos, '(', end - pos); cp = memchr (pos, ')', end - pos); while (NULL != cp) { while ( (NULL != op) && (op < cp) ) { cnt++; pos = op + 1; op = memchr (pos, '(', end - pos); } while ( (NULL != cp) && ( (NULL == op) || (cp < op) ) ) { if (0 == cnt) return; /* can't strip parens */ cnt--; pos = cp + 1; cp = memchr (pos, ')', end - pos); } } if (0 != cnt) { GNUNET_break (0); return; } str->sbuf++; str->slen -= 2; } /** * Check if the string 'str' starts with an epsilon (empty string). * Example: "(|a)" is starting with an epsilon. * * @param str string to test * * @return 0 if str has no epsilon, 1 if str starts with '(|' and ends with ')' */ static int has_epsilon (const struct StringBuffer *str) { return (GNUNET_YES != str->null_flag) && (0 < str->slen) && ('(' == str->sbuf[0]) && ('|' == str->sbuf[1]) && (')' == str->sbuf[str->slen - 1]); } /** * Remove an epsilon from the string str. Where epsilon is an empty string * Example: str = "(|a|b|c)", result: "a|b|c" * The returned string needs to be freed. * * @param str original string * @param ret where to return string without preceding epsilon, string 'str' if no preceding * epsilon could be found, NULL if 'str' was NULL */ static void remove_epsilon (const struct StringBuffer *str, struct StringBuffer *ret) { if (GNUNET_YES == str->null_flag) { ret->null_flag = GNUNET_YES; return; } if ( (str->slen > 1) && ('(' == str->sbuf[0]) && ('|' == str->sbuf[1]) && (')' == str->sbuf[str->slen - 1]) ) { /* remove epsilon */ if (ret->blen < str->slen - 3) { GNUNET_array_grow (ret->abuf, ret->blen, str->slen - 3); } ret->sbuf = ret->abuf; ret->slen = str->slen - 3; GNUNET_memcpy (ret->sbuf, &str->sbuf[2], ret->slen); return; } sb_strdup (ret, str); } /** * Compare n bytes of 'str1' and 'str2' * * @param str1 first string to compare * @param str2 second string for comparison * @param n number of bytes to compare * * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise */ static int sb_strncmp (const struct StringBuffer *str1, const struct StringBuffer *str2, size_t n) { size_t max; if ( (str1->slen != str2->slen) && ( (str1->slen < n) || (str2->slen < n) ) ) return -1; max = GNUNET_MAX (str1->slen, str2->slen); if (max > n) max = n; return memcmp (str1->sbuf, str2->sbuf, max); } /** * Compare n bytes of 'str1' and 'str2' * * @param str1 first string to compare * @param str2 second C string for comparison * @param n number of bytes to compare (and length of str2) * * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise */ static int sb_strncmp_cstr (const struct StringBuffer *str1, const char *str2, size_t n) { if (str1->slen < n) return -1; return memcmp (str1->sbuf, str2, n); } /** * Initialize string buffer for storing strings of up to n * characters. * * @param sb buffer to initialize * @param n desired target length */ static void sb_init (struct StringBuffer *sb, size_t n) { sb->null_flag = GNUNET_NO; sb->abuf = sb->sbuf = (0 == n) ? NULL : GNUNET_malloc (n); sb->blen = n; sb->slen = 0; } /** * Compare 'str1', starting from position 'k', with whole 'str2' * * @param str1 first string to compare, starting from position 'k' * @param str2 second string for comparison * @param k starting position in 'str1' * * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise */ static int sb_strkcmp (const struct StringBuffer *str1, const struct StringBuffer *str2, size_t k) { if ( (GNUNET_YES == str1->null_flag) || (GNUNET_YES == str2->null_flag) || (k > str1->slen) || (str1->slen - k != str2->slen) ) return -1; return memcmp (&str1->sbuf[k], str2->sbuf, str2->slen); } /** * Helper function used as 'action' in 'REGEX_INTERNAL_automaton_traverse' * function to create the depth-first numbering of the states. * * @param cls states array. * @param count current state counter. * @param s current state. */ static void number_states (void *cls, const unsigned int count, struct REGEX_INTERNAL_State *s) { struct REGEX_INTERNAL_State **states = cls; s->dfs_id = count; if (NULL != states) states[count] = s; } #define PRIS(a) \ ((GNUNET_YES == a.null_flag) ? 6 : (int) a.slen), \ ((GNUNET_YES == a.null_flag) ? "(null)" : a.sbuf) /** * Construct the regular expression given the inductive step, * $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* * R^{(k-1)}_{kj}, and simplify the resulting expression saved in R_cur_ij. * * @param R_last_ij value of $R^{(k-1)_{ij}. * @param R_last_ik value of $R^{(k-1)_{ik}. * @param R_last_kk value of $R^{(k-1)_{kk}. * @param R_last_kj value of $R^{(k-1)_{kj}. * @param R_cur_ij result for this inductive step is saved in R_cur_ij, R_cur_ij * is expected to be NULL when called! * @param R_cur_l optimization -- kept between iterations to avoid realloc * @param R_cur_r optimization -- kept between iterations to avoid realloc */ static void automaton_create_proofs_simplify (const struct StringBuffer *R_last_ij, const struct StringBuffer *R_last_ik, const struct StringBuffer *R_last_kk, const struct StringBuffer *R_last_kj, struct StringBuffer *R_cur_ij, struct StringBuffer *R_cur_l, struct StringBuffer *R_cur_r) { struct StringBuffer R_temp_ij; struct StringBuffer R_temp_ik; struct StringBuffer R_temp_kj; struct StringBuffer R_temp_kk; int eps_check; int ij_ik_cmp; int ij_kj_cmp; int ik_kk_cmp; int kk_kj_cmp; int clean_ik_kk_cmp; int clean_kk_kj_cmp; size_t length; size_t length_l; size_t length_r; /* * $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} * R_last == R^{(k-1)}, R_cur == R^{(k)} * R_cur_ij = R_cur_l | R_cur_r * R_cur_l == R^{(k-1)}_{ij} * R_cur_r == R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} */ if ( (GNUNET_YES == R_last_ij->null_flag) && ( (GNUNET_YES == R_last_ik->null_flag) || (GNUNET_YES == R_last_kj->null_flag))) { /* R^{(k)}_{ij} = N | N */ R_cur_ij->null_flag = GNUNET_YES; R_cur_ij->synced = GNUNET_NO; return; } if ( (GNUNET_YES == R_last_ik->null_flag) || (GNUNET_YES == R_last_kj->null_flag) ) { /* R^{(k)}_{ij} = R^{(k-1)}_{ij} | N */ if (GNUNET_YES == R_last_ij->synced) { R_cur_ij->synced = GNUNET_YES; R_cur_ij->null_flag = GNUNET_NO; return; } R_cur_ij->synced = GNUNET_YES; sb_strdup (R_cur_ij, R_last_ij); return; } R_cur_ij->synced = GNUNET_NO; /* $R^{(k)}_{ij} = N | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} OR * $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} */ R_cur_r->null_flag = GNUNET_YES; R_cur_r->slen = 0; R_cur_l->null_flag = GNUNET_YES; R_cur_l->slen = 0; /* cache results from strcmp, we might need these many times */ ij_kj_cmp = sb_nullstrcmp (R_last_ij, R_last_kj); ij_ik_cmp = sb_nullstrcmp (R_last_ij, R_last_ik); ik_kk_cmp = sb_nullstrcmp (R_last_ik, R_last_kk); kk_kj_cmp = sb_nullstrcmp (R_last_kk, R_last_kj); /* Assign R_temp_(ik|kk|kj) to R_last[][] and remove epsilon as well * as parentheses, so we can better compare the contents */ memset (&R_temp_ij, 0, sizeof (struct StringBuffer)); memset (&R_temp_ik, 0, sizeof (struct StringBuffer)); memset (&R_temp_kk, 0, sizeof (struct StringBuffer)); memset (&R_temp_kj, 0, sizeof (struct StringBuffer)); remove_epsilon (R_last_ik, &R_temp_ik); remove_epsilon (R_last_kk, &R_temp_kk); remove_epsilon (R_last_kj, &R_temp_kj); remove_parentheses (&R_temp_ik); remove_parentheses (&R_temp_kk); remove_parentheses (&R_temp_kj); clean_ik_kk_cmp = sb_nullstrcmp (R_last_ik, &R_temp_kk); clean_kk_kj_cmp = sb_nullstrcmp (&R_temp_kk, R_last_kj); /* construct R_cur_l (and, if necessary R_cur_r) */ if (GNUNET_YES != R_last_ij->null_flag) { /* Assign R_temp_ij to R_last_ij and remove epsilon as well * as parentheses, so we can better compare the contents */ remove_epsilon (R_last_ij, &R_temp_ij); remove_parentheses (&R_temp_ij); if ( (0 == sb_strcmp (&R_temp_ij, &R_temp_ik)) && (0 == sb_strcmp (&R_temp_ik, &R_temp_kk)) && (0 == sb_strcmp (&R_temp_kk, &R_temp_kj)) ) { if (0 == R_temp_ij.slen) { R_cur_r->null_flag = GNUNET_NO; } else if ((0 == sb_strncmp_cstr (R_last_ij, "(|", 2)) || (0 == sb_strncmp_cstr (R_last_ik, "(|", 2) && 0 == sb_strncmp_cstr (R_last_kj, "(|", 2))) { /* * a|(e|a)a*(e|a) = a* * a|(e|a)(e|a)*(e|a) = a* * (e|a)|aa*a = a* * (e|a)|aa*(e|a) = a* * (e|a)|(e|a)a*a = a* * (e|a)|(e|a)a*(e|a) = a* * (e|a)|(e|a)(e|a)*(e|a) = a* */ if (GNUNET_YES == needs_parentheses (&R_temp_ij)) sb_printf1 (R_cur_r, "(%.*s)*", 3, &R_temp_ij); else sb_printf1 (R_cur_r, "%.*s*", 1, &R_temp_ij); } else { /* * a|aa*a = a+ * a|(e|a)a*a = a+ * a|aa*(e|a) = a+ * a|(e|a)(e|a)*a = a+ * a|a(e|a)*(e|a) = a+ */ if (GNUNET_YES == needs_parentheses (&R_temp_ij)) sb_printf1 (R_cur_r, "(%.*s)+", 3, &R_temp_ij); else sb_printf1 (R_cur_r, "%.*s+", 1, &R_temp_ij); } } else if ( (0 == ij_ik_cmp) && (0 == clean_kk_kj_cmp) && (0 != clean_ik_kk_cmp) ) { /* a|ab*b = ab* */ if (0 == R_last_kk->slen) sb_strdup (R_cur_r, R_last_ij); else if (GNUNET_YES == needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "%.*s(%.*s)*", 3, R_last_ij, &R_temp_kk); else sb_printf2 (R_cur_r, "%.*s%.*s*", 1, R_last_ij, R_last_kk); R_cur_l->null_flag = GNUNET_YES; } else if ( (0 == ij_kj_cmp) && (0 == clean_ik_kk_cmp) && (0 != clean_kk_kj_cmp)) { /* a|bb*a = b*a */ if (R_last_kk->slen < 1) { sb_strdup (R_cur_r, R_last_kj); } else if (GNUNET_YES == needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)*%.*s", 3, &R_temp_kk, R_last_kj); else sb_printf2 (R_cur_r, "%.*s*%.*s", 1, &R_temp_kk, R_last_kj); R_cur_l->null_flag = GNUNET_YES; } else if ( (0 == ij_ik_cmp) && (0 == kk_kj_cmp) && (! has_epsilon (R_last_ij)) && has_epsilon (R_last_kk)) { /* a|a(e|b)*(e|b) = a|ab* = a|a|ab|abb|abbb|... = ab* */ if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "%.*s(%.*s)*", 3, R_last_ij, &R_temp_kk); else sb_printf2 (R_cur_r, "%.*s%.*s*", 1, R_last_ij, &R_temp_kk); R_cur_l->null_flag = GNUNET_YES; } else if ( (0 == ij_kj_cmp) && (0 == ik_kk_cmp) && (! has_epsilon (R_last_ij)) && has_epsilon (R_last_kk)) { /* a|(e|b)(e|b)*a = a|b*a = a|a|ba|bba|bbba|... = b*a */ if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)*%.*s", 3, &R_temp_kk, R_last_ij); else sb_printf2 (R_cur_r, "%.*s*%.*s", 1, &R_temp_kk, R_last_ij); R_cur_l->null_flag = GNUNET_YES; } else { sb_strdup (R_cur_l, R_last_ij); remove_parentheses (R_cur_l); } } else { /* we have no left side */ R_cur_l->null_flag = GNUNET_YES; } /* construct R_cur_r, if not already constructed */ if (GNUNET_YES == R_cur_r->null_flag) { length = R_temp_kk.slen - R_last_ik->slen; /* a(ba)*bx = (ab)+x */ if ( (length > 0) && (GNUNET_YES != R_last_kk->null_flag) && (0 < R_last_kk->slen) && (GNUNET_YES != R_last_kj->null_flag) && (0 < R_last_kj->slen) && (GNUNET_YES != R_last_ik->null_flag) && (0 < R_last_ik->slen) && (0 == sb_strkcmp (&R_temp_kk, R_last_ik, length)) && (0 == sb_strncmp (&R_temp_kk, R_last_kj, length)) ) { struct StringBuffer temp_a; struct StringBuffer temp_b; sb_init (&temp_a, length); sb_init (&temp_b, R_last_kj->slen - length); length_l = length; temp_a.sbuf = temp_a.abuf; GNUNET_memcpy (temp_a.sbuf, R_last_kj->sbuf, length_l); temp_a.slen = length_l; length_r = R_last_kj->slen - length; temp_b.sbuf = temp_b.abuf; GNUNET_memcpy (temp_b.sbuf, &R_last_kj->sbuf[length], length_r); temp_b.slen = length_r; /* e|(ab)+ = (ab)* */ if ( (GNUNET_YES != R_cur_l->null_flag) && (0 == R_cur_l->slen) && (0 == temp_b.slen) ) { sb_printf2 (R_cur_r, "(%.*s%.*s)*", 3, R_last_ik, &temp_a); sb_free (R_cur_l); R_cur_l->null_flag = GNUNET_YES; } else { sb_printf3 (R_cur_r, "(%.*s%.*s)+%.*s", 3, R_last_ik, &temp_a, &temp_b); } sb_free (&temp_a); sb_free (&temp_b); } else if (0 == sb_strcmp (&R_temp_ik, &R_temp_kk) && 0 == sb_strcmp (&R_temp_kk, &R_temp_kj)) { /* * (e|a)a*(e|a) = a* * (e|a)(e|a)*(e|a) = a* */ if (has_epsilon (R_last_ik) && has_epsilon (R_last_kj)) { if (needs_parentheses (&R_temp_kk)) sb_printf1 (R_cur_r, "(%.*s)*", 3, &R_temp_kk); else sb_printf1 (R_cur_r, "%.*s*", 1, &R_temp_kk); } /* aa*a = a+a */ else if ( (0 == clean_ik_kk_cmp) && (0 == clean_kk_kj_cmp) && (! has_epsilon (R_last_ik)) ) { if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)+%.*s", 3, &R_temp_kk, &R_temp_kk); else sb_printf2 (R_cur_r, "%.*s+%.*s", 1, &R_temp_kk, &R_temp_kk); } /* * (e|a)a*a = a+ * aa*(e|a) = a+ * a(e|a)*(e|a) = a+ * (e|a)a*a = a+ */ else { eps_check = (has_epsilon (R_last_ik) + has_epsilon (R_last_kk) + has_epsilon (R_last_kj)); if (1 == eps_check) { if (needs_parentheses (&R_temp_kk)) sb_printf1 (R_cur_r, "(%.*s)+", 3, &R_temp_kk); else sb_printf1 (R_cur_r, "%.*s+", 1, &R_temp_kk); } } } /* * aa*b = a+b * (e|a)(e|a)*b = a*b */ else if (0 == sb_strcmp (&R_temp_ik, &R_temp_kk)) { if (has_epsilon (R_last_ik)) { if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)*%.*s", 3, &R_temp_kk, R_last_kj); else sb_printf2 (R_cur_r, "%.*s*%.*s", 1, &R_temp_kk, R_last_kj); } else { if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)+%.*s", 3, &R_temp_kk, R_last_kj); else sb_printf2 (R_cur_r, "%.*s+%.*s", 1, &R_temp_kk, R_last_kj); } } /* * ba*a = ba+ * b(e|a)*(e|a) = ba* */ else if (0 == sb_strcmp (&R_temp_kk, &R_temp_kj)) { if (has_epsilon (R_last_kj)) { if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "%.*s(%.*s)*", 3, R_last_ik, &R_temp_kk); else sb_printf2 (R_cur_r, "%.*s%.*s*", 1, R_last_ik, &R_temp_kk); } else { if (needs_parentheses (&R_temp_kk)) sb_printf2 (R_cur_r, "(%.*s)+%.*s", 3, R_last_ik, &R_temp_kk); else sb_printf2 (R_cur_r, "%.*s+%.*s", 1, R_last_ik, &R_temp_kk); } } else { if (0 < R_temp_kk.slen) { if (needs_parentheses (&R_temp_kk)) { sb_printf3 (R_cur_r, "%.*s(%.*s)*%.*s", 3, R_last_ik, &R_temp_kk, R_last_kj); } else { sb_printf3 (R_cur_r, "%.*s%.*s*%.*s", 1, R_last_ik, &R_temp_kk, R_last_kj); } } else { sb_printf2 (R_cur_r, "%.*s%.*s", 0, R_last_ik, R_last_kj); } } } sb_free (&R_temp_ij); sb_free (&R_temp_ik); sb_free (&R_temp_kk); sb_free (&R_temp_kj); if ( (GNUNET_YES == R_cur_l->null_flag) && (GNUNET_YES == R_cur_r->null_flag) ) { R_cur_ij->null_flag = GNUNET_YES; return; } if ( (GNUNET_YES != R_cur_l->null_flag) && (GNUNET_YES == R_cur_r->null_flag) ) { struct StringBuffer tmp; tmp = *R_cur_ij; *R_cur_ij = *R_cur_l; *R_cur_l = tmp; return; } if ( (GNUNET_YES == R_cur_l->null_flag) && (GNUNET_YES != R_cur_r->null_flag) ) { struct StringBuffer tmp; tmp = *R_cur_ij; *R_cur_ij = *R_cur_r; *R_cur_r = tmp; return; } if (0 == sb_nullstrcmp (R_cur_l, R_cur_r)) { struct StringBuffer tmp; tmp = *R_cur_ij; *R_cur_ij = *R_cur_l; *R_cur_l = tmp; return; } sb_printf2 (R_cur_ij, "(%.*s|%.*s)", 3, R_cur_l, R_cur_r); } /** * Create proofs for all states in the given automaton. Implementation of the * algorithm descriped in chapter 3.2.1 of "Automata Theory, Languages, and * Computation 3rd Edition" by Hopcroft, Motwani and Ullman. * * Each state in the automaton gets assigned 'proof' and 'hash' (hash of the * proof) fields. The starting state will only have a valid proof/hash if it has * any incoming transitions. * * @param a automaton for which to assign proofs and hashes, must not be NULL */ static int automaton_create_proofs (struct REGEX_INTERNAL_Automaton *a) { unsigned int n = a->state_count; struct REGEX_INTERNAL_State *states[n]; struct StringBuffer *R_last; struct StringBuffer *R_cur; struct StringBuffer R_cur_r; struct StringBuffer R_cur_l; struct StringBuffer *R_swap; struct REGEX_INTERNAL_Transition *t; struct StringBuffer complete_regex; unsigned int i; unsigned int j; unsigned int k; R_last = GNUNET_malloc_large (sizeof (struct StringBuffer) * n * n); R_cur = GNUNET_malloc_large (sizeof (struct StringBuffer) * n * n); if ( (NULL == R_last) || (NULL == R_cur) ) { GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "malloc"); GNUNET_free_non_null (R_cur); GNUNET_free_non_null (R_last); return GNUNET_SYSERR; } /* create depth-first numbering of the states, initializes 'state' */ REGEX_INTERNAL_automaton_traverse (a, a->start, NULL, NULL, &number_states, states); for (i = 0; i < n; i++) GNUNET_assert (NULL != states[i]); for (i = 0; i < n; i++) for (j = 0; j < n; j++) R_last[i *n + j].null_flag = GNUNET_YES; /* Compute regular expressions of length "1" between each pair of states */ for (i = 0; i < n; i++) { for (t = states[i]->transitions_head; NULL != t; t = t->next) { j = t->to_state->dfs_id; if (GNUNET_YES == R_last[i * n + j].null_flag) { sb_strdup_cstr (&R_last[i * n + j], t->label); } else { sb_append_cstr (&R_last[i * n + j], "|"); sb_append_cstr (&R_last[i * n + j], t->label); } } /* add self-loop: i is reachable from i via epsilon-transition */ if (GNUNET_YES == R_last[i * n + i].null_flag) { R_last[i * n + i].slen = 0; R_last[i * n + i].null_flag = GNUNET_NO; } else { sb_wrap (&R_last[i * n + i], "(|%.*s)", 3); } } for (i = 0; i < n; i++) for (j = 0; j < n; j++) if (needs_parentheses (&R_last[i * n + j])) sb_wrap (&R_last[i * n + j], "(%.*s)", 2); /* Compute regular expressions of length "k" between each pair of states per * induction */ memset (&R_cur_l, 0, sizeof (struct StringBuffer)); memset (&R_cur_r, 0, sizeof (struct StringBuffer)); for (k = 0; k < n; k++) { for (i = 0; i < n; i++) { for (j = 0; j < n; j++) { /* Basis for the recursion: * $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} * R_last == R^{(k-1)}, R_cur == R^{(k)} */ /* Create R_cur[i][j] and simplify the expression */ automaton_create_proofs_simplify (&R_last[i * n + j], &R_last[i * n + k], &R_last[k * n + k], &R_last[k * n + j], &R_cur[i * n + j], &R_cur_l, &R_cur_r); } } /* set R_last = R_cur */ R_swap = R_last; R_last = R_cur; R_cur = R_swap; /* clear 'R_cur' for next iteration */ for (i = 0; i < n; i++) for (j = 0; j < n; j++) R_cur[i * n + j].null_flag = GNUNET_YES; } sb_free (&R_cur_l); sb_free (&R_cur_r); /* assign proofs and hashes */ for (i = 0; i < n; i++) { if (GNUNET_YES != R_last[a->start->dfs_id * n + i].null_flag) { states[i]->proof = GNUNET_strndup (R_last[a->start->dfs_id * n + i].sbuf, R_last[a->start->dfs_id * n + i].slen); GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof), &states[i]->hash); } } /* complete regex for whole DFA: union of all pairs (start state/accepting * state(s)). */ sb_init (&complete_regex, 16 * n); for (i = 0; i < n; i++) { if (states[i]->accepting) { if ( (0 == complete_regex.slen) && (0 < R_last[a->start->dfs_id * n + i].slen) ) { sb_append (&complete_regex, &R_last[a->start->dfs_id * n + i]); } else if ( (GNUNET_YES != R_last[a->start->dfs_id * n + i].null_flag) && (0 < R_last[a->start->dfs_id * n + i].slen) ) { sb_append_cstr (&complete_regex, "|"); sb_append (&complete_regex, &R_last[a->start->dfs_id * n + i]); } } } a->canonical_regex = GNUNET_strndup (complete_regex.sbuf, complete_regex.slen); /* cleanup */ sb_free (&complete_regex); for (i = 0; i < n; i++) for (j = 0; j < n; j++) { sb_free (&R_cur[i * n + j]); sb_free (&R_last[i * n + j]); } GNUNET_free (R_cur); GNUNET_free (R_last); return GNUNET_OK; } /** * Creates a new DFA state based on a set of NFA states. Needs to be freed using * automaton_destroy_state. * * @param ctx context * @param nfa_states set of NFA states on which the DFA should be based on * * @return new DFA state */ static struct REGEX_INTERNAL_State * dfa_state_create (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_StateSet *nfa_states) { struct REGEX_INTERNAL_State *s; char *pos; size_t len; struct REGEX_INTERNAL_State *cstate; struct REGEX_INTERNAL_Transition *ctran; unsigned int i; s = GNUNET_new (struct REGEX_INTERNAL_State); s->id = ctx->state_id++; s->index = -1; s->lowlink = -1; if (NULL == nfa_states) { GNUNET_asprintf (&s->name, "s%i", s->id); return s; } s->nfa_set = *nfa_states; if (nfa_states->off < 1) return s; /* Create a name based on 'nfa_states' */ len = nfa_states->off * 14 + 4; s->name = GNUNET_malloc (len); strcat (s->name, "{"); pos = s->name + 1; for (i = 0; i < nfa_states->off; i++) { cstate = nfa_states->states[i]; GNUNET_snprintf (pos, pos - s->name + len, "%i,", cstate->id); pos += strlen (pos); /* Add a transition for each distinct label to NULL state */ for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next) if (NULL != ctran->label) state_add_transition (ctx, s, ctran->label, NULL); /* If the nfa_states contain an accepting state, the new dfa state is also * accepting. */ if (cstate->accepting) s->accepting = 1; } pos[-1] = '}'; s->name = GNUNET_realloc (s->name, strlen (s->name) + 1); memset (nfa_states, 0, sizeof (struct REGEX_INTERNAL_StateSet)); return s; } /** * Move from the given state 's' to the next state on transition 'str'. Consumes * as much of the given 'str' as possible (usefull for strided DFAs). On return * 's' will point to the next state, and the length of the substring used for * this transition will be returned. If no transition possible 0 is returned and * 's' points to NULL. * * @param s starting state, will point to the next state or NULL (if no * transition possible) * @param str edge label to follow (will match longest common prefix) * * @return length of the substring comsumed from 'str' */ static unsigned int dfa_move (struct REGEX_INTERNAL_State **s, const char *str) { struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_State *new_s; unsigned int len; unsigned int max_len; if (NULL == s) return 0; new_s = NULL; max_len = 0; for (t = (*s)->transitions_head; NULL != t; t = t->next) { len = strlen (t->label); if (0 == strncmp (t->label, str, len)) { if (len >= max_len) { max_len = len; new_s = t->to_state; } } } *s = new_s; return max_len; } /** * Set the given state 'marked' to #GNUNET_YES. Used by the * #dfa_remove_unreachable_states() function to detect unreachable states in the * automaton. * * @param cls closure, not used. * @param count count, not used. * @param s state where the marked attribute will be set to #GNUNET_YES. */ static void mark_states (void *cls, const unsigned int count, struct REGEX_INTERNAL_State *s) { s->marked = GNUNET_YES; } /** * Remove all unreachable states from DFA 'a'. Unreachable states are those * states that are not reachable from the starting state. * * @param a DFA automaton */ static void dfa_remove_unreachable_states (struct REGEX_INTERNAL_Automaton *a) { struct REGEX_INTERNAL_State *s; struct REGEX_INTERNAL_State *s_next; /* 1. unmark all states */ for (s = a->states_head; NULL != s; s = s->next) s->marked = GNUNET_NO; /* 2. traverse dfa from start state and mark all visited states */ REGEX_INTERNAL_automaton_traverse (a, a->start, NULL, NULL, &mark_states, NULL); /* 3. delete all states that were not visited */ for (s = a->states_head; NULL != s; s = s_next) { s_next = s->next; if (GNUNET_NO == s->marked) automaton_remove_state (a, s); } } /** * Remove all dead states from the DFA 'a'. Dead states are those states that do * not transition to any other state but themselves. * * @param a DFA automaton */ static void dfa_remove_dead_states (struct REGEX_INTERNAL_Automaton *a) { struct REGEX_INTERNAL_State *s; struct REGEX_INTERNAL_State *s_next; struct REGEX_INTERNAL_Transition *t; int dead; GNUNET_assert (DFA == a->type); for (s = a->states_head; NULL != s; s = s_next) { s_next = s->next; if (s->accepting) continue; dead = 1; for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL != t->to_state && t->to_state != s) { dead = 0; break; } } if (0 == dead) continue; /* state s is dead, remove it */ automaton_remove_state (a, s); } } /** * Merge all non distinguishable states in the DFA 'a' * * @param ctx context * @param a DFA automaton * @return #GNUNET_OK on success */ static int dfa_merge_nondistinguishable_states (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_Automaton *a) { uint32_t *table; struct REGEX_INTERNAL_State *s1; struct REGEX_INTERNAL_State *s2; struct REGEX_INTERNAL_Transition *t1; struct REGEX_INTERNAL_Transition *t2; struct REGEX_INTERNAL_State *s1_next; struct REGEX_INTERNAL_State *s2_next; int change; unsigned int num_equal_edges; unsigned int i; unsigned int state_cnt; unsigned long long idx; unsigned long long idx1; if ( (NULL == a) || (0 == a->state_count) ) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not merge nondistinguishable states, automaton was NULL.\n"); return GNUNET_SYSERR; } state_cnt = a->state_count; table = GNUNET_malloc_large ((sizeof (uint32_t) * state_cnt * state_cnt / 32) + sizeof (uint32_t)); if (NULL == table) { GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "malloc"); return GNUNET_SYSERR; } for (i = 0, s1 = a->states_head; NULL != s1; s1 = s1->next) s1->marked = i++; /* Mark all pairs of accepting/!accepting states */ for (s1 = a->states_head; NULL != s1; s1 = s1->next) for (s2 = a->states_head; NULL != s2; s2 = s2->next) if ( (s1->accepting && !s2->accepting) || (!s1->accepting && s2->accepting) ) { idx = (unsigned long long) s1->marked * state_cnt + s2->marked; table[idx / 32] |= (1U << (idx % 32)); } /* Find all equal states */ change = 1; while (0 != change) { change = 0; for (s1 = a->states_head; NULL != s1; s1 = s1->next) { for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next) { idx = (unsigned long long) s1->marked * state_cnt + s2->marked; if (0 != (table[idx / 32] & (1U << (idx % 32)))) continue; num_equal_edges = 0; for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next) { for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next) { if (0 == strcmp (t1->label, t2->label)) { num_equal_edges++; /* same edge, but targets definitively different, so we're different as well */ if (t1->to_state->marked > t2->to_state->marked) idx1 = (unsigned long long) t1->to_state->marked * state_cnt + t2->to_state->marked; else idx1 = (unsigned long long) t2->to_state->marked * state_cnt + t1->to_state->marked; if (0 != (table[idx1 / 32] & (1U << (idx1 % 32)))) { table[idx / 32] |= (1U << (idx % 32)); change = 1; /* changed a marker, need to run again */ } } } } if ( (num_equal_edges != s1->transition_count) || (num_equal_edges != s2->transition_count) ) { /* Make sure ALL edges of possible equal states are the same */ table[idx / 32] |= (1U << (idx % 32)); change = 1; /* changed a marker, need to run again */ } } } } /* Merge states that are equal */ for (s1 = a->states_head; NULL != s1; s1 = s1_next) { s1_next = s1->next; for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next) { s2_next = s2->next; idx = (unsigned long long) s1->marked * state_cnt + s2->marked; if (0 == (table[idx / 32] & (1U << (idx % 32)))) automaton_merge_states (ctx, a, s1, s2); } } GNUNET_free (table); return GNUNET_OK; } /** * Minimize the given DFA 'a' by removing all unreachable states, removing all * dead states and merging all non distinguishable states * * @param ctx context * @param a DFA automaton * @return GNUNET_OK on success */ static int dfa_minimize (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_Automaton *a) { if (NULL == a) return GNUNET_SYSERR; GNUNET_assert (DFA == a->type); /* 1. remove unreachable states */ dfa_remove_unreachable_states (a); /* 2. remove dead states */ dfa_remove_dead_states (a); /* 3. Merge nondistinguishable states */ if (GNUNET_OK != dfa_merge_nondistinguishable_states (ctx, a)) return GNUNET_SYSERR; return GNUNET_OK; } /** * Context for adding strided transitions to a DFA. */ struct REGEX_INTERNAL_Strided_Context { /** * Length of the strides. */ const unsigned int stride; /** * Strided transitions DLL. New strided transitions will be stored in this DLL * and afterwards added to the DFA. */ struct REGEX_INTERNAL_Transition *transitions_head; /** * Strided transitions DLL. */ struct REGEX_INTERNAL_Transition *transitions_tail; }; /** * Recursive helper function to add strides to a DFA. * * @param cls context, contains stride length and strided transitions DLL. * @param depth current depth of the depth-first traversal of the graph. * @param label current label, string that contains all labels on the path from * 'start' to 's'. * @param start start state for the depth-first traversal of the graph. * @param s current state in the depth-first traversal */ static void dfa_add_multi_strides_helper (void *cls, const unsigned int depth, char *label, struct REGEX_INTERNAL_State *start, struct REGEX_INTERNAL_State *s) { struct REGEX_INTERNAL_Strided_Context *ctx = cls; struct REGEX_INTERNAL_Transition *t; char *new_label; if (depth == ctx->stride) { t = GNUNET_new (struct REGEX_INTERNAL_Transition); t->label = GNUNET_strdup (label); t->to_state = s; t->from_state = start; GNUNET_CONTAINER_DLL_insert (ctx->transitions_head, ctx->transitions_tail, t); } else { for (t = s->transitions_head; NULL != t; t = t->next) { /* Do not consider self-loops, because it end's up in too many * transitions */ if (t->to_state == t->from_state) continue; if (NULL != label) { GNUNET_asprintf (&new_label, "%s%s", label, t->label); } else new_label = GNUNET_strdup (t->label); dfa_add_multi_strides_helper (cls, (depth + 1), new_label, start, t->to_state); } } GNUNET_free_non_null (label); } /** * Function called for each state in the DFA. Starts a traversal of depth set in * context starting from state 's'. * * @param cls context. * @param count not used. * @param s current state. */ static void dfa_add_multi_strides (void *cls, const unsigned int count, struct REGEX_INTERNAL_State *s) { dfa_add_multi_strides_helper (cls, 0, NULL, s, s); } /** * Adds multi-strided transitions to the given 'dfa'. * * @param regex_ctx regex context needed to add transitions to the automaton. * @param dfa DFA to which the multi strided transitions should be added. * @param stride_len length of the strides. */ void REGEX_INTERNAL_dfa_add_multi_strides (struct REGEX_INTERNAL_Context *regex_ctx, struct REGEX_INTERNAL_Automaton *dfa, const unsigned int stride_len) { struct REGEX_INTERNAL_Strided_Context ctx = { stride_len, NULL, NULL }; struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_Transition *t_next; if (1 > stride_len || GNUNET_YES == dfa->is_multistrided) return; /* Compute the new transitions of given stride_len */ REGEX_INTERNAL_automaton_traverse (dfa, dfa->start, NULL, NULL, &dfa_add_multi_strides, &ctx); /* Add all the new transitions to the automaton. */ for (t = ctx.transitions_head; NULL != t; t = t_next) { t_next = t->next; state_add_transition (regex_ctx, t->from_state, t->label, t->to_state); GNUNET_CONTAINER_DLL_remove (ctx.transitions_head, ctx.transitions_tail, t); GNUNET_free_non_null (t->label); GNUNET_free (t); } /* Mark this automaton as multistrided */ dfa->is_multistrided = GNUNET_YES; } /** * Recursive Helper function for DFA path compression. Does DFS on the DFA graph * and adds new transitions to the given transitions DLL and marks states that * should be removed by setting state->contained to GNUNET_YES. * * @param dfa DFA for which the paths should be compressed. * @param start starting state for linear path search. * @param cur current state in the recursive DFS. * @param label current label (string of traversed labels). * @param max_len maximal path compression length. * @param transitions_head transitions DLL. * @param transitions_tail transitions DLL. */ void dfa_compress_paths_helper (struct REGEX_INTERNAL_Automaton *dfa, struct REGEX_INTERNAL_State *start, struct REGEX_INTERNAL_State *cur, char *label, unsigned int max_len, struct REGEX_INTERNAL_Transition **transitions_head, struct REGEX_INTERNAL_Transition **transitions_tail) { struct REGEX_INTERNAL_Transition *t; char *new_label; if (NULL != label && ((cur->incoming_transition_count > 1 || GNUNET_YES == cur->accepting || GNUNET_YES == cur->marked) || (start != dfa->start && max_len > 0 && max_len == strlen (label)) || (start == dfa->start && GNUNET_REGEX_INITIAL_BYTES == strlen (label)))) { t = GNUNET_new (struct REGEX_INTERNAL_Transition); t->label = GNUNET_strdup (label); t->to_state = cur; t->from_state = start; GNUNET_CONTAINER_DLL_insert (*transitions_head, *transitions_tail, t); if (GNUNET_NO == cur->marked) { dfa_compress_paths_helper (dfa, cur, cur, NULL, max_len, transitions_head, transitions_tail); } return; } else if (cur != start) cur->contained = GNUNET_YES; if (GNUNET_YES == cur->marked && cur != start) return; cur->marked = GNUNET_YES; for (t = cur->transitions_head; NULL != t; t = t->next) { if (NULL != label) GNUNET_asprintf (&new_label, "%s%s", label, t->label); else new_label = GNUNET_strdup (t->label); if (t->to_state != cur) { dfa_compress_paths_helper (dfa, start, t->to_state, new_label, max_len, transitions_head, transitions_tail); } GNUNET_free (new_label); } } /** * Compress paths in the given 'dfa'. Linear paths like 0->1->2->3 will be * compressed to 0->3 by combining transitions. * * @param regex_ctx context for adding new transitions. * @param dfa DFA representation, will directly modify the given DFA. * @param max_len maximal length of the compressed paths. */ static void dfa_compress_paths (struct REGEX_INTERNAL_Context *regex_ctx, struct REGEX_INTERNAL_Automaton *dfa, unsigned int max_len) { struct REGEX_INTERNAL_State *s; struct REGEX_INTERNAL_State *s_next; struct REGEX_INTERNAL_Transition *t; struct REGEX_INTERNAL_Transition *t_next; struct REGEX_INTERNAL_Transition *transitions_head = NULL; struct REGEX_INTERNAL_Transition *transitions_tail = NULL; if (NULL == dfa) return; /* Count the incoming transitions on each state. */ for (s = dfa->states_head; NULL != s; s = s->next) { for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL != t->to_state) t->to_state->incoming_transition_count++; } } /* Unmark all states. */ for (s = dfa->states_head; NULL != s; s = s->next) { s->marked = GNUNET_NO; s->contained = GNUNET_NO; } /* Add strides and mark states that can be deleted. */ dfa_compress_paths_helper (dfa, dfa->start, dfa->start, NULL, max_len, &transitions_head, &transitions_tail); /* Add all the new transitions to the automaton. */ for (t = transitions_head; NULL != t; t = t_next) { t_next = t->next; state_add_transition (regex_ctx, t->from_state, t->label, t->to_state); GNUNET_CONTAINER_DLL_remove (transitions_head, transitions_tail, t); GNUNET_free_non_null (t->label); GNUNET_free (t); } /* Remove marked states (including their incoming and outgoing transitions). */ for (s = dfa->states_head; NULL != s; s = s_next) { s_next = s->next; if (GNUNET_YES == s->contained) automaton_remove_state (dfa, s); } } /** * Creates a new NFA fragment. Needs to be cleared using * automaton_fragment_clear. * * @param start starting state * @param end end state * * @return new NFA fragment */ static struct REGEX_INTERNAL_Automaton * nfa_fragment_create (struct REGEX_INTERNAL_State *start, struct REGEX_INTERNAL_State *end) { struct REGEX_INTERNAL_Automaton *n; n = GNUNET_new (struct REGEX_INTERNAL_Automaton); n->type = NFA; n->start = NULL; n->end = NULL; n->state_count = 0; if (NULL == start || NULL == end) return n; automaton_add_state (n, end); automaton_add_state (n, start); n->state_count = 2; n->start = start; n->end = end; return n; } /** * Adds a list of states to the given automaton 'n'. * * @param n automaton to which the states should be added * @param states_head head of the DLL of states * @param states_tail tail of the DLL of states */ static void nfa_add_states (struct REGEX_INTERNAL_Automaton *n, struct REGEX_INTERNAL_State *states_head, struct REGEX_INTERNAL_State *states_tail) { struct REGEX_INTERNAL_State *s; if (NULL == n || NULL == states_head) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n"); return; } if (NULL == n->states_head) { n->states_head = states_head; n->states_tail = states_tail; return; } if (NULL != states_head) { n->states_tail->next = states_head; n->states_tail = states_tail; } for (s = states_head; NULL != s; s = s->next) n->state_count++; } /** * Creates a new NFA state. Needs to be freed using automaton_destroy_state. * * @param ctx context * @param accepting is it an accepting state or not * * @return new NFA state */ static struct REGEX_INTERNAL_State * nfa_state_create (struct REGEX_INTERNAL_Context *ctx, int accepting) { struct REGEX_INTERNAL_State *s; s = GNUNET_new (struct REGEX_INTERNAL_State); s->id = ctx->state_id++; s->accepting = accepting; s->marked = GNUNET_NO; s->contained = 0; s->index = -1; s->lowlink = -1; s->scc_id = 0; s->name = NULL; GNUNET_asprintf (&s->name, "s%i", s->id); return s; } /** * Calculates the closure set for the given set of states. * * @param ret set to sorted nfa closure on 'label' (epsilon closure if 'label' is NULL) * @param nfa the NFA containing 's' * @param states list of states on which to base the closure on * @param label transitioning label for which to base the closure on, * pass NULL for epsilon transition */ static void nfa_closure_set_create (struct REGEX_INTERNAL_StateSet *ret, struct REGEX_INTERNAL_Automaton *nfa, struct REGEX_INTERNAL_StateSet *states, const char *label) { struct REGEX_INTERNAL_State *s; unsigned int i; struct REGEX_INTERNAL_StateSet_MDLL cls_stack; struct REGEX_INTERNAL_State *clsstate; struct REGEX_INTERNAL_State *currentstate; struct REGEX_INTERNAL_Transition *ctran; memset (ret, 0, sizeof (struct REGEX_INTERNAL_StateSet)); if (NULL == states) return; for (i = 0; i < states->off; i++) { s = states->states[i]; /* Add start state to closure only for epsilon closure */ if (NULL == label) state_set_append (ret, s); /* initialize work stack */ cls_stack.head = NULL; cls_stack.tail = NULL; GNUNET_CONTAINER_MDLL_insert (ST, cls_stack.head, cls_stack.tail, s); cls_stack.len = 1; while (NULL != (currentstate = cls_stack.tail)) { GNUNET_CONTAINER_MDLL_remove (ST, cls_stack.head, cls_stack.tail, currentstate); cls_stack.len--; for (ctran = currentstate->transitions_head; NULL != ctran; ctran = ctran->next) { if (NULL == (clsstate = ctran->to_state)) continue; if (0 != clsstate->contained) continue; if (0 != nullstrcmp (label, ctran->label)) continue; state_set_append (ret, clsstate); GNUNET_CONTAINER_MDLL_insert_tail (ST, cls_stack.head, cls_stack.tail, clsstate); cls_stack.len++; clsstate->contained = 1; } } } for (i = 0; i < ret->off; i++) ret->states[i]->contained = 0; if (ret->off > 1) qsort (ret->states, ret->off, sizeof (struct REGEX_INTERNAL_State *), &state_compare); } /** * Pops two NFA fragments (a, b) from the stack and concatenates them (ab) * * @param ctx context */ static void nfa_add_concatenation (struct REGEX_INTERNAL_Context *ctx) { struct REGEX_INTERNAL_Automaton *a; struct REGEX_INTERNAL_Automaton *b; struct REGEX_INTERNAL_Automaton *new_nfa; b = ctx->stack_tail; GNUNET_assert (NULL != b); GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b); a = ctx->stack_tail; GNUNET_assert (NULL != a); GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); state_add_transition (ctx, a->end, NULL, b->start); a->end->accepting = 0; b->end->accepting = 1; new_nfa = nfa_fragment_create (NULL, NULL); nfa_add_states (new_nfa, a->states_head, a->states_tail); nfa_add_states (new_nfa, b->states_head, b->states_tail); new_nfa->start = a->start; new_nfa->end = b->end; new_nfa->state_count += a->state_count + b->state_count; automaton_fragment_clear (a); automaton_fragment_clear (b); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa); } /** * Pops a NFA fragment from the stack (a) and adds a new fragment (a*) * * @param ctx context */ static void nfa_add_star_op (struct REGEX_INTERNAL_Context *ctx) { struct REGEX_INTERNAL_Automaton *a; struct REGEX_INTERNAL_Automaton *new_nfa; struct REGEX_INTERNAL_State *start; struct REGEX_INTERNAL_State *end; a = ctx->stack_tail; if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "nfa_add_star_op failed, because there was no element on the stack"); return; } GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, NULL, a->start); state_add_transition (ctx, start, NULL, end); state_add_transition (ctx, a->end, NULL, a->start); state_add_transition (ctx, a->end, NULL, end); a->end->accepting = 0; end->accepting = 1; new_nfa = nfa_fragment_create (start, end); nfa_add_states (new_nfa, a->states_head, a->states_tail); automaton_fragment_clear (a); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa); } /** * Pops an NFA fragment (a) from the stack and adds a new fragment (a+) * * @param ctx context */ static void nfa_add_plus_op (struct REGEX_INTERNAL_Context *ctx) { struct REGEX_INTERNAL_Automaton *a; a = ctx->stack_tail; if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "nfa_add_plus_op failed, because there was no element on the stack"); return; } GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); state_add_transition (ctx, a->end, NULL, a->start); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a); } /** * Pops an NFA fragment (a) from the stack and adds a new fragment (a?) * * @param ctx context */ static void nfa_add_question_op (struct REGEX_INTERNAL_Context *ctx) { struct REGEX_INTERNAL_Automaton *a; struct REGEX_INTERNAL_Automaton *new_nfa; struct REGEX_INTERNAL_State *start; struct REGEX_INTERNAL_State *end; a = ctx->stack_tail; if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "nfa_add_question_op failed, because there was no element on the stack"); return; } GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, NULL, a->start); state_add_transition (ctx, start, NULL, end); state_add_transition (ctx, a->end, NULL, end); a->end->accepting = 0; new_nfa = nfa_fragment_create (start, end); nfa_add_states (new_nfa, a->states_head, a->states_tail); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa); automaton_fragment_clear (a); } /** * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that * alternates between a and b (a|b) * * @param ctx context */ static void nfa_add_alternation (struct REGEX_INTERNAL_Context *ctx) { struct REGEX_INTERNAL_Automaton *a; struct REGEX_INTERNAL_Automaton *b; struct REGEX_INTERNAL_Automaton *new_nfa; struct REGEX_INTERNAL_State *start; struct REGEX_INTERNAL_State *end; b = ctx->stack_tail; GNUNET_assert (NULL != b); GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b); a = ctx->stack_tail; GNUNET_assert (NULL != a); GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, NULL, a->start); state_add_transition (ctx, start, NULL, b->start); state_add_transition (ctx, a->end, NULL, end); state_add_transition (ctx, b->end, NULL, end); a->end->accepting = 0; b->end->accepting = 0; end->accepting = 1; new_nfa = nfa_fragment_create (start, end); nfa_add_states (new_nfa, a->states_head, a->states_tail); nfa_add_states (new_nfa, b->states_head, b->states_tail); automaton_fragment_clear (a); automaton_fragment_clear (b); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa); } /** * Adds a new nfa fragment to the stack * * @param ctx context * @param label label for nfa transition */ static void nfa_add_label (struct REGEX_INTERNAL_Context *ctx, const char *label) { struct REGEX_INTERNAL_Automaton *n; struct REGEX_INTERNAL_State *start; struct REGEX_INTERNAL_State *end; GNUNET_assert (NULL != ctx); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, label, end); n = nfa_fragment_create (start, end); GNUNET_assert (NULL != n); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n); } /** * Initialize a new context * * @param ctx context */ static void REGEX_INTERNAL_context_init (struct REGEX_INTERNAL_Context *ctx) { if (NULL == ctx) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!"); return; } ctx->state_id = 0; ctx->transition_id = 0; ctx->stack_head = NULL; ctx->stack_tail = NULL; } /** * Construct an NFA by parsing the regex string of length 'len'. * * @param regex regular expression string * @param len length of the string * * @return NFA, needs to be freed using REGEX_INTERNAL_destroy_automaton */ struct REGEX_INTERNAL_Automaton * REGEX_INTERNAL_construct_nfa (const char *regex, const size_t len) { struct REGEX_INTERNAL_Context ctx; struct REGEX_INTERNAL_Automaton *nfa; const char *regexp; char curlabel[2]; char *error_msg; unsigned int count; unsigned int altcount; unsigned int atomcount; unsigned int poff; unsigned int psize; struct { int altcount; int atomcount; } *p; if (NULL == regex || 0 == strlen (regex) || 0 == len) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex. Empty regex string provided.\n"); return NULL; } REGEX_INTERNAL_context_init (&ctx); regexp = regex; curlabel[1] = '\0'; p = NULL; error_msg = NULL; altcount = 0; atomcount = 0; poff = 0; psize = 0; for (count = 0; count < len && *regexp; count++, regexp++) { switch (*regexp) { case '(': if (atomcount > 1) { --atomcount; nfa_add_concatenation (&ctx); } if (poff == psize) GNUNET_array_grow (p, psize, psize * 2 + 4); /* FIXME why *2 +4? */ p[poff].altcount = altcount; p[poff].atomcount = atomcount; poff++; altcount = 0; atomcount = 0; break; case '|': if (0 == atomcount) { error_msg = "Cannot append '|' to nothing"; goto error; } while (--atomcount > 0) nfa_add_concatenation (&ctx); altcount++; break; case ')': if (0 == poff) { error_msg = "Missing opening '('"; goto error; } if (0 == atomcount) { /* Ignore this: "()" */ poff--; altcount = p[poff].altcount; atomcount = p[poff].atomcount; break; } while (--atomcount > 0) nfa_add_concatenation (&ctx); for (; altcount > 0; altcount--) nfa_add_alternation (&ctx); poff--; altcount = p[poff].altcount; atomcount = p[poff].atomcount; atomcount++; break; case '*': if (atomcount == 0) { error_msg = "Cannot append '*' to nothing"; goto error; } nfa_add_star_op (&ctx); break; case '+': if (atomcount == 0) { error_msg = "Cannot append '+' to nothing"; goto error; } nfa_add_plus_op (&ctx); break; case '?': if (atomcount == 0) { error_msg = "Cannot append '?' to nothing"; goto error; } nfa_add_question_op (&ctx); break; default: if (atomcount > 1) { --atomcount; nfa_add_concatenation (&ctx); } curlabel[0] = *regexp; nfa_add_label (&ctx, curlabel); atomcount++; break; } } if (0 != poff) { error_msg = "Unbalanced parenthesis"; goto error; } while (--atomcount > 0) nfa_add_concatenation (&ctx); for (; altcount > 0; altcount--) nfa_add_alternation (&ctx); GNUNET_array_grow (p, psize, 0); nfa = ctx.stack_tail; GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa); if (NULL != ctx.stack_head) { error_msg = "Creating the NFA failed. NFA stack was not empty!"; goto error; } /* Remember the regex that was used to generate this NFA */ nfa->regex = GNUNET_strdup (regex); /* create depth-first numbering of the states for pretty printing */ REGEX_INTERNAL_automaton_traverse (nfa, NULL, NULL, NULL, &number_states, NULL); /* No multistriding added so far */ nfa->is_multistrided = GNUNET_NO; return nfa; error: GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex: `%s'\n", regex); if (NULL != error_msg) GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg); GNUNET_free_non_null (p); while (NULL != (nfa = ctx.stack_head)) { GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa); REGEX_INTERNAL_automaton_destroy (nfa); } return NULL; } /** * Create DFA states based on given 'nfa' and starting with 'dfa_state'. * * @param ctx context. * @param nfa NFA automaton. * @param dfa DFA automaton. * @param dfa_state current dfa state, pass epsilon closure of first nfa state * for starting. */ static void construct_dfa_states (struct REGEX_INTERNAL_Context *ctx, struct REGEX_INTERNAL_Automaton *nfa, struct REGEX_INTERNAL_Automaton *dfa, struct REGEX_INTERNAL_State *dfa_state) { struct REGEX_INTERNAL_Transition *ctran; struct REGEX_INTERNAL_State *new_dfa_state; struct REGEX_INTERNAL_State *state_contains; struct REGEX_INTERNAL_State *state_iter; struct REGEX_INTERNAL_StateSet tmp; struct REGEX_INTERNAL_StateSet nfa_set; for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next) { if (NULL == ctran->label || NULL != ctran->to_state) continue; nfa_closure_set_create (&tmp, nfa, &dfa_state->nfa_set, ctran->label); nfa_closure_set_create (&nfa_set, nfa, &tmp, NULL); state_set_clear (&tmp); state_contains = NULL; for (state_iter = dfa->states_head; NULL != state_iter; state_iter = state_iter->next) { if (0 == state_set_compare (&state_iter->nfa_set, &nfa_set)) { state_contains = state_iter; break; } } if (NULL == state_contains) { new_dfa_state = dfa_state_create (ctx, &nfa_set); automaton_add_state (dfa, new_dfa_state); ctran->to_state = new_dfa_state; construct_dfa_states (ctx, nfa, dfa, new_dfa_state); } else { ctran->to_state = state_contains; state_set_clear (&nfa_set); } } } /** * Construct DFA for the given 'regex' of length 'len'. * * Path compression means, that for example a DFA o -> a -> b -> c -> o will be * compressed to o -> abc -> o. Note that this parameter influences the * non-determinism of states of the resulting NFA in the DHT (number of outgoing * edges with the same label). For example for an application that stores IPv4 * addresses as bitstrings it could make sense to limit the path compression to * 4 or 8. * * @param regex regular expression string. * @param len length of the regular expression. * @param max_path_len limit the path compression length to the * given value. If set to 1, no path compression is applied. Set to 0 for * maximal possible path compression (generally not desireable). * @return DFA, needs to be freed using REGEX_INTERNAL_automaton_destroy. */ struct REGEX_INTERNAL_Automaton * REGEX_INTERNAL_construct_dfa (const char *regex, const size_t len, unsigned int max_path_len) { struct REGEX_INTERNAL_Context ctx; struct REGEX_INTERNAL_Automaton *dfa; struct REGEX_INTERNAL_Automaton *nfa; struct REGEX_INTERNAL_StateSet nfa_start_eps_cls; struct REGEX_INTERNAL_StateSet singleton_set; REGEX_INTERNAL_context_init (&ctx); /* Create NFA */ nfa = REGEX_INTERNAL_construct_nfa (regex, len); if (NULL == nfa) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create DFA, because NFA creation failed\n"); return NULL; } dfa = GNUNET_new (struct REGEX_INTERNAL_Automaton); dfa->type = DFA; dfa->regex = GNUNET_strdup (regex); /* Create DFA start state from epsilon closure */ memset (&singleton_set, 0, sizeof (struct REGEX_INTERNAL_StateSet)); state_set_append (&singleton_set, nfa->start); nfa_closure_set_create (&nfa_start_eps_cls, nfa, &singleton_set, NULL); state_set_clear (&singleton_set); dfa->start = dfa_state_create (&ctx, &nfa_start_eps_cls); automaton_add_state (dfa, dfa->start); construct_dfa_states (&ctx, nfa, dfa, dfa->start); REGEX_INTERNAL_automaton_destroy (nfa); /* Minimize DFA */ if (GNUNET_OK != dfa_minimize (&ctx, dfa)) { REGEX_INTERNAL_automaton_destroy (dfa); return NULL; } /* Create proofs and hashes for all states */ if (GNUNET_OK != automaton_create_proofs (dfa)) { REGEX_INTERNAL_automaton_destroy (dfa); return NULL; } /* Compress linear DFA paths */ if (1 != max_path_len) dfa_compress_paths (&ctx, dfa, max_path_len); return dfa; } /** * Free the memory allocated by constructing the REGEX_INTERNAL_Automaton data * structure. * * @param a automaton to be destroyed */ void REGEX_INTERNAL_automaton_destroy (struct REGEX_INTERNAL_Automaton *a) { struct REGEX_INTERNAL_State *s; struct REGEX_INTERNAL_State *next_state; if (NULL == a) return; GNUNET_free_non_null (a->regex); GNUNET_free_non_null (a->canonical_regex); for (s = a->states_head; NULL != s; s = next_state) { next_state = s->next; GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s); automaton_destroy_state (s); } GNUNET_free (a); } /** * Evaluates the given string using the given DFA automaton * * @param a automaton, type must be DFA * @param string string that should be evaluated * * @return 0 if string matches, non-0 otherwise */ static int evaluate_dfa (struct REGEX_INTERNAL_Automaton *a, const char *string) { const char *strp; struct REGEX_INTERNAL_State *s; unsigned int step_len; if (DFA != a->type) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Tried to evaluate DFA, but NFA automaton given"); return -1; } s = a->start; /* If the string is empty but the starting state is accepting, we accept. */ if ((NULL == string || 0 == strlen (string)) && s->accepting) return 0; for (strp = string; NULL != strp && *strp; strp += step_len) { step_len = dfa_move (&s, strp); if (NULL == s) break; } if (NULL != s && s->accepting) return 0; return 1; } /** * Evaluates the given string using the given NFA automaton * * @param a automaton, type must be NFA * @param string string that should be evaluated * @return 0 if string matches, non-0 otherwise */ static int evaluate_nfa (struct REGEX_INTERNAL_Automaton *a, const char *string) { const char *strp; char str[2]; struct REGEX_INTERNAL_State *s; struct REGEX_INTERNAL_StateSet sset; struct REGEX_INTERNAL_StateSet new_sset; struct REGEX_INTERNAL_StateSet singleton_set; unsigned int i; int result; if (NFA != a->type) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Tried to evaluate NFA, but DFA automaton given"); return -1; } /* If the string is empty but the starting state is accepting, we accept. */ if ((NULL == string || 0 == strlen (string)) && a->start->accepting) return 0; result = 1; memset (&singleton_set, 0, sizeof (struct REGEX_INTERNAL_StateSet)); state_set_append (&singleton_set, a->start); nfa_closure_set_create (&sset, a, &singleton_set, NULL); state_set_clear (&singleton_set); str[1] = '\0'; for (strp = string; NULL != strp && *strp; strp++) { str[0] = *strp; nfa_closure_set_create (&new_sset, a, &sset, str); state_set_clear (&sset); nfa_closure_set_create (&sset, a, &new_sset, 0); state_set_clear (&new_sset); } for (i = 0; i < sset.off; i++) { s = sset.states[i]; if ( (NULL != s) && (s->accepting) ) { result = 0; break; } } state_set_clear (&sset); return result; } /** * Evaluates the given @a string against the given compiled regex @a a * * @param a automaton * @param string string to check * @return 0 if string matches, non-0 otherwise */ int REGEX_INTERNAL_eval (struct REGEX_INTERNAL_Automaton *a, const char *string) { int result; switch (a->type) { case DFA: result = evaluate_dfa (a, string); break; case NFA: result = evaluate_nfa (a, string); break; default: GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Evaluating regex failed, automaton has no type!\n"); result = GNUNET_SYSERR; break; } return result; } /** * Get the canonical regex of the given automaton. * When constructing the automaton a proof is computed for each state, * consisting of the regular expression leading to this state. A complete * regex for the automaton can be computed by combining these proofs. * As of now this function is only useful for testing. * * @param a automaton for which the canonical regex should be returned. * * @return */ const char * REGEX_INTERNAL_get_canonical_regex (struct REGEX_INTERNAL_Automaton *a) { if (NULL == a) return NULL; return a->canonical_regex; } /** * Get the number of transitions that are contained in the given automaton. * * @param a automaton for which the number of transitions should be returned. * * @return number of transitions in the given automaton. */ unsigned int REGEX_INTERNAL_get_transition_count (struct REGEX_INTERNAL_Automaton *a) { unsigned int t_count; struct REGEX_INTERNAL_State *s; if (NULL == a) return 0; t_count = 0; for (s = a->states_head; NULL != s; s = s->next) t_count += s->transition_count; return t_count; } /** * Get the first key for the given @a input_string. This hashes the first x bits * of the @a input_string. * * @param input_string string. * @param string_len length of the @a input_string. * @param key pointer to where to write the hash code. * @return number of bits of @a input_string that have been consumed * to construct the key */ size_t REGEX_INTERNAL_get_first_key (const char *input_string, size_t string_len, struct GNUNET_HashCode *key) { size_t size; size = string_len < GNUNET_REGEX_INITIAL_BYTES ? string_len : GNUNET_REGEX_INITIAL_BYTES; if (NULL == input_string) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n"); return 0; } GNUNET_CRYPTO_hash (input_string, size, key); return size; } /** * Recursive function that calls the iterator for each synthetic start state. * * @param min_len minimum length of the path in the graph. * @param max_len maximum length of the path in the graph. * @param consumed_string string consumed by traversing the graph till this state. * @param state current state of the automaton. * @param iterator iterator function called for each edge. * @param iterator_cls closure for the @a iterator function. */ static void iterate_initial_edge (unsigned int min_len, unsigned int max_len, char *consumed_string, struct REGEX_INTERNAL_State *state, REGEX_INTERNAL_KeyIterator iterator, void *iterator_cls) { char *temp; struct REGEX_INTERNAL_Transition *t; unsigned int num_edges = state->transition_count; struct REGEX_BLOCK_Edge edges[num_edges]; struct REGEX_BLOCK_Edge edge[1]; struct GNUNET_HashCode hash; struct GNUNET_HashCode hash_new; unsigned int cur_len; if (NULL != consumed_string) cur_len = strlen (consumed_string); else cur_len = 0; if ( ( (cur_len >= min_len) || (GNUNET_YES == state->accepting) ) && (cur_len > 0) && (NULL != consumed_string) ) { if (cur_len <= max_len) { if ( (NULL != state->proof) && (0 != strcmp (consumed_string, state->proof)) ) { (void) state_get_edges (state, edges); GNUNET_CRYPTO_hash (consumed_string, strlen (consumed_string), &hash); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Start state for string `%s' is %s\n", consumed_string, GNUNET_h2s (&hash)); iterator (iterator_cls, &hash, consumed_string, state->accepting, num_edges, edges); } if ( (GNUNET_YES == state->accepting) && (cur_len > 1) && (state->transition_count < 1) && (cur_len < max_len) ) { /* Special case for regex consisting of just a string that is shorter than * max_len */ edge[0].label = &consumed_string[cur_len - 1]; edge[0].destination = state->hash; temp = GNUNET_strdup (consumed_string); temp[cur_len - 1] = '\0'; GNUNET_CRYPTO_hash (temp, cur_len - 1, &hash_new); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Start state for short string `%s' is %s\n", temp, GNUNET_h2s (&hash_new)); iterator (iterator_cls, &hash_new, temp, GNUNET_NO, 1, edge); GNUNET_free (temp); } } else /* cur_len > max_len */ { /* Case where the concatenated labels are longer than max_len, then split. */ edge[0].label = &consumed_string[max_len]; edge[0].destination = state->hash; temp = GNUNET_strdup (consumed_string); temp[max_len] = '\0'; GNUNET_CRYPTO_hash (temp, max_len, &hash); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Start state at split edge `%s'-`%s` is %s\n", temp, edge[0].label, GNUNET_h2s (&hash_new)); iterator (iterator_cls, &hash, temp, GNUNET_NO, 1, edge); GNUNET_free (temp); } } if (cur_len < max_len) { for (t = state->transitions_head; NULL != t; t = t->next) { if (NULL != strchr (t->label, (int) '.')) { /* Wildcards not allowed during starting states */ GNUNET_break (0); continue; } if (NULL != consumed_string) GNUNET_asprintf (&temp, "%s%s", consumed_string, t->label); else GNUNET_asprintf (&temp, "%s", t->label); iterate_initial_edge (min_len, max_len, temp, t->to_state, iterator, iterator_cls); GNUNET_free (temp); } } } /** * Iterate over all edges starting from start state of automaton 'a'. Calling * iterator for each edge. * * @param a automaton. * @param iterator iterator called for each edge. * @param iterator_cls closure. */ void REGEX_INTERNAL_iterate_all_edges (struct REGEX_INTERNAL_Automaton *a, REGEX_INTERNAL_KeyIterator iterator, void *iterator_cls) { struct REGEX_INTERNAL_State *s; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Iterating over starting edges\n"); iterate_initial_edge (GNUNET_REGEX_INITIAL_BYTES, GNUNET_REGEX_INITIAL_BYTES, NULL, a->start, iterator, iterator_cls); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Iterating over DFA edges\n"); for (s = a->states_head; NULL != s; s = s->next) { struct REGEX_BLOCK_Edge edges[s->transition_count]; unsigned int num_edges; num_edges = state_get_edges (s, edges); if ( ( (NULL != s->proof) && (0 < strlen (s->proof)) ) || s->accepting) { GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Creating DFA edges at `%s' under key %s\n", s->proof, GNUNET_h2s (&s->hash)); iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges, edges); } s->marked = GNUNET_NO; } } /** * Struct to hold all the relevant state information in the HashMap. * * Contains the same info as the Regex Iterator parametes except the key, * which comes directly from the HashMap iterator. */ struct temporal_state_store { int reachable; char *proof; int accepting; int num_edges; struct REGEX_BLOCK_Edge *edges; }; /** * Store regex iterator and cls in one place to pass to the hashmap iterator. */ struct client_iterator { REGEX_INTERNAL_KeyIterator iterator; void *iterator_cls; }; /** * Iterator over all edges of a dfa. Stores all of them in a HashMap * for later reachability marking. * * @param cls Closure (HashMap) * @param key hash for current state. * @param proof proof for current state * @param accepting GNUNET_YES if this is an accepting state, GNUNET_NO if not. * @param num_edges number of edges leaving current state. * @param edges edges leaving current state. */ static void store_all_states (void *cls, const struct GNUNET_HashCode *key, const char *proof, int accepting, unsigned int num_edges, const struct REGEX_BLOCK_Edge *edges) { struct GNUNET_CONTAINER_MultiHashMap *hm = cls; struct temporal_state_store *tmp; size_t edges_size; tmp = GNUNET_new (struct temporal_state_store); tmp->reachable = GNUNET_NO; tmp->proof = GNUNET_strdup (proof); tmp->accepting = accepting; tmp->num_edges = num_edges; edges_size = sizeof (struct REGEX_BLOCK_Edge) * num_edges; tmp->edges = GNUNET_malloc (edges_size); GNUNET_memcpy(tmp->edges, edges, edges_size); GNUNET_CONTAINER_multihashmap_put (hm, key, tmp, GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST); } /** * Mark state as reachable and call recursively on all its edges. * * If already marked as reachable, do nothing. * * @param state State to mark as reachable. * @param hm HashMap which stores all the states indexed by key. */ static void mark_as_reachable (struct temporal_state_store *state, struct GNUNET_CONTAINER_MultiHashMap *hm) { struct temporal_state_store *child; unsigned int i; if (GNUNET_YES == state->reachable) /* visited */ return; state->reachable = GNUNET_YES; for (i = 0; i < state->num_edges; i++) { child = GNUNET_CONTAINER_multihashmap_get (hm, &state->edges[i].destination); if (NULL == child) { GNUNET_break (0); continue; } mark_as_reachable (child, hm); } } /** * Iterator over hash map entries to mark the ones that are reachable. * * @param cls closure * @param key current key code * @param value value in the hash map * @return #GNUNET_YES if we should continue to iterate, * #GNUNET_NO if not. */ static int reachability_iterator (void *cls, const struct GNUNET_HashCode *key, void *value) { struct GNUNET_CONTAINER_MultiHashMap *hm = cls; struct temporal_state_store *state = value; if (GNUNET_YES == state->reachable) /* already visited and marked */ return GNUNET_YES; if (GNUNET_REGEX_INITIAL_BYTES > strlen (state->proof) && GNUNET_NO == state->accepting) /* not directly reachable */ return GNUNET_YES; mark_as_reachable (state, hm); return GNUNET_YES; } /** * Iterator over hash map entries. * Calling the callback on the ones marked as reachables. * * @param cls closure * @param key current key code * @param value value in the hash map * @return #GNUNET_YES if we should continue to iterate, * #GNUNET_NO if not. */ static int iterate_reachables (void *cls, const struct GNUNET_HashCode *key, void *value) { struct client_iterator *ci = cls; struct temporal_state_store *state = value; if (GNUNET_YES == state->reachable) { ci->iterator (ci->iterator_cls, key, state->proof, state->accepting, state->num_edges, state->edges); } GNUNET_free (state->edges); GNUNET_free (state->proof); GNUNET_free (state); return GNUNET_YES; } /** * Iterate over all edges of automaton 'a' that are reachable from a state with * a proof of at least GNUNET_REGEX_INITIAL_BYTES characters. * * Call the iterator for each such edge. * * @param a automaton. * @param iterator iterator called for each reachable edge. * @param iterator_cls closure. */ void REGEX_INTERNAL_iterate_reachable_edges (struct REGEX_INTERNAL_Automaton *a, REGEX_INTERNAL_KeyIterator iterator, void *iterator_cls) { struct GNUNET_CONTAINER_MultiHashMap *hm; struct client_iterator ci; hm = GNUNET_CONTAINER_multihashmap_create (a->state_count * 2, GNUNET_NO); ci.iterator = iterator; ci.iterator_cls = iterator_cls; REGEX_INTERNAL_iterate_all_edges (a, &store_all_states, hm); GNUNET_CONTAINER_multihashmap_iterate (hm, &reachability_iterator, hm); GNUNET_CONTAINER_multihashmap_iterate (hm, &iterate_reachables, &ci); GNUNET_CONTAINER_multihashmap_destroy (hm); } /* end of regex_internal.c */