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/*
This file is part of GNUnet.
Copyright (C) 2001-2013 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero 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 util/crypto_hash_file.c
* @brief incremental hashing of files
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet_util_lib.h"
#include <gcrypt.h>
#define LOG(kind,...) GNUNET_log_from (kind, "util-crypto-hash-file", __VA_ARGS__)
#define LOG_STRERROR_FILE(kind,syscall,filename) GNUNET_log_from_strerror_file (kind, "util-crypto-hash-file", syscall, filename)
/**
* Context used when hashing a file.
*/
struct GNUNET_CRYPTO_FileHashContext
{
/**
* Function to call upon completion.
*/
GNUNET_CRYPTO_HashCompletedCallback callback;
/**
* Closure for callback.
*/
void *callback_cls;
/**
* IO buffer.
*/
unsigned char *buffer;
/**
* Name of the file we are hashing.
*/
char *filename;
/**
* File descriptor.
*/
struct GNUNET_DISK_FileHandle *fh;
/**
* Cummulated hash.
*/
gcry_md_hd_t md;
/**
* Size of the file.
*/
uint64_t fsize;
/**
* Current offset.
*/
uint64_t offset;
/**
* Current task for hashing.
*/
struct GNUNET_SCHEDULER_Task * task;
/**
* Priority we use.
*/
enum GNUNET_SCHEDULER_Priority priority;
/**
* Blocksize.
*/
size_t bsize;
};
/**
* Report result of hash computation to callback
* and free associated resources.
*/
static void
file_hash_finish (struct GNUNET_CRYPTO_FileHashContext *fhc,
const struct GNUNET_HashCode * res)
{
fhc->callback (fhc->callback_cls, res);
GNUNET_free (fhc->filename);
if (!GNUNET_DISK_handle_invalid (fhc->fh))
GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fhc->fh));
gcry_md_close (fhc->md);
GNUNET_free (fhc); /* also frees fhc->buffer */
}
/**
* File hashing task.
*
* @param cls closure
*/
static void
file_hash_task (void *cls)
{
struct GNUNET_CRYPTO_FileHashContext *fhc = cls;
struct GNUNET_HashCode *res;
size_t delta;
ssize_t sret;
fhc->task = NULL;
GNUNET_assert (fhc->offset <= fhc->fsize);
delta = fhc->bsize;
if (fhc->fsize - fhc->offset < delta)
delta = fhc->fsize - fhc->offset;
sret = GNUNET_DISK_file_read (fhc->fh,
fhc->buffer,
delta);
if ( (sret < 0) ||
(delta != (size_t) sret) )
{
LOG_STRERROR_FILE (GNUNET_ERROR_TYPE_WARNING,
"read",
fhc->filename);
file_hash_finish (fhc,
NULL);
return;
}
gcry_md_write (fhc->md,
fhc->buffer,
delta);
fhc->offset += delta;
if (fhc->offset == fhc->fsize)
{
res = (struct GNUNET_HashCode *) gcry_md_read (fhc->md,
GCRY_MD_SHA512);
file_hash_finish (fhc, res);
return;
}
fhc->task = GNUNET_SCHEDULER_add_with_priority (fhc->priority,
&file_hash_task,
fhc);
}
/**
* Compute the hash of an entire file.
*
* @param priority scheduling priority to use
* @param filename name of file to hash
* @param blocksize number of bytes to process in one task
* @param callback function to call upon completion
* @param callback_cls closure for @a callback
* @return NULL on (immediate) errror
*/
struct GNUNET_CRYPTO_FileHashContext *
GNUNET_CRYPTO_hash_file (enum GNUNET_SCHEDULER_Priority priority,
const char *filename,
size_t blocksize,
GNUNET_CRYPTO_HashCompletedCallback callback,
void *callback_cls)
{
struct GNUNET_CRYPTO_FileHashContext *fhc;
GNUNET_assert (blocksize > 0);
fhc =
GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_FileHashContext) + blocksize);
fhc->callback = callback;
fhc->callback_cls = callback_cls;
fhc->buffer = (unsigned char *) &fhc[1];
fhc->filename = GNUNET_strdup (filename);
if (GPG_ERR_NO_ERROR != gcry_md_open (&fhc->md, GCRY_MD_SHA512, 0))
{
GNUNET_break (0);
GNUNET_free (fhc);
return NULL;
}
fhc->bsize = blocksize;
if (GNUNET_OK !=
GNUNET_DISK_file_size (filename,
&fhc->fsize,
GNUNET_NO,
GNUNET_YES))
{
GNUNET_free (fhc->filename);
GNUNET_free (fhc);
return NULL;
}
fhc->fh = GNUNET_DISK_file_open (filename,
GNUNET_DISK_OPEN_READ,
GNUNET_DISK_PERM_NONE);
if (! fhc->fh)
{
GNUNET_free (fhc->filename);
GNUNET_free (fhc);
return NULL;
}
fhc->priority = priority;
fhc->task = GNUNET_SCHEDULER_add_with_priority (priority,
&file_hash_task,
fhc);
return fhc;
}
/**
* Cancel a file hashing operation.
*
* @param fhc operation to cancel (callback must not yet have been invoked)
*/
void
GNUNET_CRYPTO_hash_file_cancel (struct GNUNET_CRYPTO_FileHashContext *fhc)
{
GNUNET_SCHEDULER_cancel (fhc->task);
GNUNET_free (fhc->filename);
GNUNET_break (GNUNET_OK ==
GNUNET_DISK_file_close (fhc->fh));
GNUNET_free (fhc);
}
/* end of crypto_hash_file.c */
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