1 files changed, 146 insertions, 87 deletions

diff --git a/arch/um/os-Linux/umid.c b/arch/um/os-Linux/umid.c
index ecf107ae5ac..c1dc89261f6 100644
--- a/arch/um/os-Linux/umid.c
+++ b/arch/um/os-Linux/umid.c
@@ -1,24 +1,26 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
 #include <stdio.h>
-#include <unistd.h>
 #include <stdlib.h>
-#include <string.h>
+#include <dirent.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <signal.h>
-#include <dirent.h>
-#include <sys/fcntl.h>
+#include <string.h>
+#include <unistd.h>
 #include <sys/stat.h>
-#include <sys/param.h>
-#include "init.h"
-#include "os.h"
-#include "user.h"
-#include "mode.h"
+#include <init.h>
+#include <os.h>
 
 #define UML_DIR "~/.uml/"
 
 #define UMID_LEN 64
 
 /* Changed by set_umid, which is run early in boot */
-char umid[UMID_LEN] = { 0 };
+static char umid[UMID_LEN] = { 0 };
 
 /* Changed by set_uml_dir and make_uml_dir, which are run early in boot */
 static char *uml_dir = UML_DIR;
@@ -28,13 +30,13 @@ static int __init make_uml_dir(void)
 	char dir[512] = { '\0' };
 	int len, err;
 
-	if(*uml_dir == '~'){
+	if (*uml_dir == '~') {
 		char *home = getenv("HOME");
 
 		err = -ENOENT;
-		if(home == NULL){
-			printk("make_uml_dir : no value in environment for "
-			       "$HOME\n");
+		if (home == NULL) {
+			printk(UM_KERN_ERR "make_uml_dir : no value in "
+			       "environment for $HOME\n");
 			goto err;
 		}
 		strlcpy(dir, home, sizeof(dir));
@@ -53,7 +55,7 @@ static int __init make_uml_dir(void)
 	}
 	strcpy(uml_dir, dir);
 
-	if((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)){
+	if ((mkdir(uml_dir, 0777) < 0) && (errno != EEXIST)) {
 	        printf("Failed to mkdir '%s': %s\n", uml_dir, strerror(errno));
 		err = -errno;
 		goto err_free;
@@ -67,35 +69,57 @@ err:
 	return err;
 }
 
-static int actually_do_remove(char *dir)
+/*
+ * Unlinks the files contained in @dir and then removes @dir.
+ * Doesn't handle directory trees, so it's not like rm -rf, but almost such. We
+ * ignore ENOENT errors for anything (they happen, strangely enough - possibly
+ * due to races between multiple dying UML threads).
+ */
+static int remove_files_and_dir(char *dir)
 {
 	DIR *directory;
 	struct dirent *ent;
 	int len;
 	char file[256];
+	int ret;
 
 	directory = opendir(dir);
-	if(directory == NULL)
-		return -errno;
+	if (directory == NULL) {
+		if (errno != ENOENT)
+			return -errno;
+		else
+			return 0;
+	}
 
-	while((ent = readdir(directory)) != NULL){
-		if(!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
+	while ((ent = readdir(directory)) != NULL) {
+		if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
 			continue;
 		len = strlen(dir) + sizeof("/") + strlen(ent->d_name) + 1;
-		if(len > sizeof(file))
-			return -E2BIG;
+		if (len > sizeof(file)) {
+			ret = -E2BIG;
+			goto out;
+		}
 
 		sprintf(file, "%s/%s", dir, ent->d_name);
-		if(unlink(file) < 0)
-			return -errno;
+		if (unlink(file) < 0 && errno != ENOENT) {
+			ret = -errno;
+			goto out;
+		}
 	}
-	if(rmdir(dir) < 0)
-		return -errno;
 
-	return 0;
+	if (rmdir(dir) < 0 && errno != ENOENT) {
+		ret = -errno;
+		goto out;
+	}
+
+	ret = 0;
+out:
+	closedir(directory);
+	return ret;
 }
 
-/* This says that there isn't already a user of the specified directory even if
+/*
+ * This says that there isn't already a user of the specified directory even if
  * there are errors during the checking.  This is because if these errors
  * happen, the directory is unusable by the pre-existing UML, so we might as
  * well take it over.  This could happen either by
@@ -103,89 +127,112 @@ static int actually_do_remove(char *dir)
  * 	something other than UML sticking stuff in the directory
  *	this boot racing with a shutdown of the other UML
  * In any of these cases, the directory isn't useful for anything else.
+ *
+ * Boolean return: 1 if in use, 0 otherwise.
  */
-
-static int not_dead_yet(char *dir)
+static inline int is_umdir_used(char *dir)
 {
 	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
 	char pid[sizeof("nnnnn\0")], *end;
 	int dead, fd, p, n, err;
 
 	n = snprintf(file, sizeof(file), "%s/pid", dir);
-	if(n >= sizeof(file)){
-		printk("not_dead_yet - pid filename too long\n");
+	if (n >= sizeof(file)) {
+		printk(UM_KERN_ERR "is_umdir_used - pid filename too long\n");
 		err = -E2BIG;
 		goto out;
 	}
 
 	dead = 0;
 	fd = open(file, O_RDONLY);
-	if(fd < 0){
-		if(fd != -ENOENT){
-			printk("not_dead_yet : couldn't open pid file '%s', "
-			       "err = %d\n", file, -fd);
+	if (fd < 0) {
+		fd = -errno;
+		if (fd != -ENOENT) {
+			printk(UM_KERN_ERR "is_umdir_used : couldn't open pid "
+			       "file '%s', err = %d\n", file, -fd);
 		}
 		goto out;
 	}
 
 	err = 0;
 	n = read(fd, pid, sizeof(pid));
-	if(n <= 0){
-		printk("not_dead_yet : couldn't read pid file '%s', "
-		       "err = %d\n", file, -n);
+	if (n < 0) {
+		printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
+		       "'%s', err = %d\n", file, errno);
+		goto out_close;
+	} else if (n == 0) {
+		printk(UM_KERN_ERR "is_umdir_used : couldn't read pid file "
+		       "'%s', 0-byte read\n", file);
 		goto out_close;
 	}
 
 	p = strtoul(pid, &end, 0);
-	if(end == pid){
-		printk("not_dead_yet : couldn't parse pid file '%s', "
-		       "errno = %d\n", file, errno);
+	if (end == pid) {
+		printk(UM_KERN_ERR "is_umdir_used : couldn't parse pid file "
+		       "'%s', errno = %d\n", file, errno);
 		goto out_close;
 	}
 
-	if((kill(p, 0) == 0) || (errno != ESRCH))
+	if ((kill(p, 0) == 0) || (errno != ESRCH)) {
+		printk(UM_KERN_ERR "umid \"%s\" is already in use by pid %d\n",
+		       umid, p);
 		return 1;
+	}
 
-	err = actually_do_remove(dir);
-	if(err)
-		printk("not_dead_yet - actually_do_remove failed with "
-		       "err = %d\n", err);
-
-	return err;
-
- out_close:
+out_close:
 	close(fd);
- out:
+out:
 	return 0;
 }
 
+/*
+ * Try to remove the directory @dir unless it's in use.
+ * Precondition: @dir exists.
+ * Returns 0 for success, < 0 for failure in removal or if the directory is in
+ * use.
+ */
+static int umdir_take_if_dead(char *dir)
+{
+	int ret;
+	if (is_umdir_used(dir))
+		return -EEXIST;
+
+	ret = remove_files_and_dir(dir);
+	if (ret) {
+		printk(UM_KERN_ERR "is_umdir_used - remove_files_and_dir "
+		       "failed with err = %d\n", ret);
+	}
+	return ret;
+}
+
 static void __init create_pid_file(void)
 {
 	char file[strlen(uml_dir) + UMID_LEN + sizeof("/pid\0")];
 	char pid[sizeof("nnnnn\0")];
 	int fd, n;
 
-	if(umid_file_name("pid", file, sizeof(file)))
+	if (umid_file_name("pid", file, sizeof(file)))
 		return;
 
 	fd = open(file, O_RDWR | O_CREAT | O_EXCL, 0644);
-	if(fd < 0){
-		printk("Open of machine pid file \"%s\" failed: %s\n",
-		       file, strerror(-fd));
+	if (fd < 0) {
+		printk(UM_KERN_ERR "Open of machine pid file \"%s\" failed: "
+		       "%s\n", file, strerror(errno));
 		return;
 	}
 
 	snprintf(pid, sizeof(pid), "%d\n", getpid());
 	n = write(fd, pid, strlen(pid));
-	if(n != strlen(pid))
-		printk("Write of pid file failed - err = %d\n", -n);
+	if (n != strlen(pid))
+		printk(UM_KERN_ERR "Write of pid file failed - err = %d\n",
+		       errno);
 
 	close(fd);
 }
 
 int __init set_umid(char *name)
 {
-	if(strlen(name) > UMID_LEN - 1)
+	if (strlen(name) > UMID_LEN - 1)
 		return -E2BIG;
 
 	strlcpy(umid, name, sizeof(umid));
@@ -193,25 +240,26 @@ int __init set_umid(char *name)
 	return 0;
 }
 
+/* Changed in make_umid, which is called during early boot */
 static int umid_setup = 0;
 
-int __init make_umid(void)
+static int __init make_umid(void)
 {
 	int fd, err;
 	char tmp[256];
 
-	if(umid_setup)
+	if (umid_setup)
 		return 0;
 
 	make_uml_dir();
 
-	if(*umid == '\0'){
+	if (*umid == '\0') {
 		strlcpy(tmp, uml_dir, sizeof(tmp));
 		strlcat(tmp, "XXXXXX", sizeof(tmp));
 		fd = mkstemp(tmp);
-		if(fd < 0){
-			printk("make_umid - mkstemp(%s) failed: %s\n",
-			       tmp, strerror(errno));
+		if (fd < 0) {
+			printk(UM_KERN_ERR "make_umid - mkstemp(%s) failed: "
+			       "%s\n", tmp, strerror(errno));
 			err = -errno;
 			goto err;
 		}
@@ -220,11 +268,12 @@ int __init make_umid(void)
 
 		set_umid(&tmp[strlen(uml_dir)]);
 
-		/* There's a nice tiny little race between this unlink and
+		/*
+		 * There's a nice tiny little race between this unlink and
 		 * the mkdir below.  It'd be nice if there were a mkstemp
 		 * for directories.
 		 */
-		if(unlink(tmp)){
+		if (unlink(tmp)) {
 			err = -errno;
 			goto err;
 		}
@@ -232,35 +281,44 @@ int __init make_umid(void)
 
 	snprintf(tmp, sizeof(tmp), "%s%s", uml_dir, umid);
 	err = mkdir(tmp, 0777);
-	if(err < 0){
+	if (err < 0) {
 		err = -errno;
-		if(errno != EEXIST)
+		if (err != -EEXIST)
 			goto err;
 
-		if(not_dead_yet(tmp) < 0)
+		if (umdir_take_if_dead(tmp) < 0)
 			goto err;
 
 		err = mkdir(tmp, 0777);
 	}
-	if(err < 0){
-		printk("Failed to create '%s' - err = %d\n", umid, err);
-		goto err_rmdir;
+	if (err) {
+		err = -errno;
+		printk(UM_KERN_ERR "Failed to create '%s' - err = %d\n", umid,
+		       errno);
+		goto err;
 	}
 
 	umid_setup = 1;
 
 	create_pid_file();
 
-	return 0;
-
- err_rmdir:
-	rmdir(tmp);
+	err = 0;
  err:
 	return err;
 }
 
 static int __init make_umid_init(void)
 {
+	if (!make_umid())
+		return 0;
+
+	/*
+	 * If initializing with the given umid failed, then try again with
+	 * a random one.
+	 */
+	printk(UM_KERN_ERR "Failed to initialize umid \"%s\", trying with a "
+	       "random umid\n", umid);
+	*umid = '\0';
 	make_umid();
 
 	return 0;
@@ -273,12 +331,12 @@ int __init umid_file_name(char *name, char *buf, int len)
 	int n, err;
 
 	err = make_umid();
-	if(err)
+	if (err)
 		return err;
 
 	n = snprintf(buf, len, "%s%s/%s", uml_dir, umid, name);
-	if(n >= len){
-		printk("umid_file_name : buffer too short\n");
+	if (n >= len) {
+		printk(UM_KERN_ERR "umid_file_name : buffer too short\n");
 		return -E2BIG;
 	}
 
@@ -292,21 +350,22 @@ char *get_umid(void)
 
 static int __init set_uml_dir(char *name, int *add)
 {
-	if(*name == '\0'){
+	if (*name == '\0') {
 		printf("uml_dir can't be an empty string\n");
 		return 0;
 	}
 
-	if(name[strlen(name) - 1] == '/'){
+	if (name[strlen(name) - 1] == '/') {
 		uml_dir = name;
 		return 0;
 	}
 
 	uml_dir = malloc(strlen(name) + 2);
-	if(uml_dir == NULL){
+	if (uml_dir == NULL) {
 		printf("Failed to malloc uml_dir - error = %d\n", errno);
 
-		/* Return 0 here because do_initcalls doesn't look at
+		/*
+		 * Return 0 here because do_initcalls doesn't look at
 		 * the return value.
 		 */
 		return 0;
@@ -326,9 +385,9 @@ static void remove_umid_dir(void)
 	char dir[strlen(uml_dir) + UMID_LEN + 1], err;
 
 	sprintf(dir, "%s%s", uml_dir, umid);
-	err = actually_do_remove(dir);
-	if(err)
-		printf("remove_umid_dir - actually_do_remove failed with "
+	err = remove_files_and_dir(dir);
+	if (err)
+		printf("remove_umid_dir - remove_files_and_dir failed with "
 		       "err = %d\n", err);
 }