autofs-5.0.3 - check for mtab pointing to /proc/mounts

From: Ian Kent <raven@themaw.net>

autofs has problems if /etc/mtab points to /proc/mounts.

This patchs adds a check to see if this is the case. If it is then

autofs uses the mount(8) "-n" option which disables the normal mtab

update error checking.

---

 CHANGELOG      |    1 

 daemon/spawn.c |   66 +++++++++++++++++++++++++++++++++++++++++++++++++++------

 2 files changed, 61 insertions(+), 6 deletions(-)

--- autofs-5.0.3.orig/CHANGELOG

+++ autofs-5.0.3/CHANGELOG

@@ -31,6 +31,7 @@

 - add replicated server selection debug logging.

 - update replicated server selection documentation.

 - use /dev/urandom instead of /dev/random.

+- check for mtab pointing to /proc/mounts.

 14/01/2008 autofs-5.0.3

 -----------------------

--- autofs-5.0.3.orig/daemon/spawn.c

+++ autofs-5.0.3/daemon/spawn.c

@@ -305,11 +305,13 @@ int spawn_mount(unsigned logopt, ...)

 	char **argv, **p;

 	char prog[] = PATH_MOUNT;

 	char arg0[] = PATH_MOUNT;

+	char argn[] = "-n";

 	/* In case we need to use the fake option to mount */

 	char arg_fake[] = "-f";

 	unsigned int options;

 	unsigned int retries = MTAB_LOCK_RETRIES;

-	int ret, printed = 0;

+	int update_mtab = 1, ret, printed = 0;

+	char buf[PATH_MAX];

 	/* If we use mount locking we can't validate the location */

 #ifdef ENABLE_MOUNT_LOCKING

@@ -322,6 +324,17 @@ int spawn_mount(unsigned logopt, ...)

 	for (argc = 1; va_arg(arg, char *); argc++);

 	va_end(arg);

+	ret = readlink(_PATH_MOUNTED, buf, PATH_MAX);

+	if (ret != -1) {

+		buf[ret] = '\0';

+		if (!strcmp(buf, _PROC_MOUNTS)) {

+			debug(logopt,

+			      "mtab link detected, passing -n to mount");

+			argc++;

+			update_mtab = 0;

+		}

+	}

+

 	/* Alloc 1 extra slot in case we need to use the "-f" option */

 	if (!(argv = alloca(sizeof(char *) * argc + 2)))

 		return -1;

@@ -329,7 +342,12 @@ int spawn_mount(unsigned logopt, ...)

 	argv[0] = arg0;

 	va_start(arg, logopt);

-	p = argv + 1;

+	if (update_mtab)

+		p = argv + 1;

+	else {

+		argv[1] = argn;

+		p = argv + 2;

+	}

 	while ((*p = va_arg(arg, char *))) {

 		if (options == SPAWN_OPT_NONE && !strcmp(*p, "-o")) {

 			*(++p) = va_arg(arg, char *);

@@ -409,11 +427,13 @@ int spawn_bind_mount(unsigned logopt, ..

 	char prog[] = PATH_MOUNT;

 	char arg0[] = PATH_MOUNT;

 	char bind[] = "--bind";

+	char argn[] = "-n";

 	/* In case we need to use the fake option to mount */

 	char arg_fake[] = "-f";

 	unsigned int options;

 	unsigned int retries = MTAB_LOCK_RETRIES;

-	int ret, printed = 0;

+	int update_mtab = 0, ret, printed = 0;

+	char buf[PATH_MAX];

 	/* If we use mount locking we can't validate the location */

 #ifdef ENABLE_MOUNT_LOCKING

@@ -430,6 +450,17 @@ int spawn_bind_mount(unsigned logopt, ..

 	for (argc = 2; va_arg(arg, char *); argc++);

 	va_end(arg);

+	ret = readlink(_PATH_MOUNTED, buf, PATH_MAX);

+	if (ret != -1) {

+		buf[ret] = '\0';

+		if (!strcmp(buf, _PROC_MOUNTS)) {

+			debug(logopt,

+			      "mtab link detected, passing -n to mount");

+			argc++;

+			update_mtab = 0;

+		}

+	}

+

 	if (!(argv = alloca(sizeof(char *) * argc + 2)))

 		return -1;

@@ -437,7 +468,12 @@ int spawn_bind_mount(unsigned logopt, ..

 	argv[1] = bind;

 	va_start(arg, logopt);

-	p = argv + 2;

+	if (update_mtab)

+		p = argv + 2;

+	else {

+		argv[2] = argn;

+		p = argv + 3;

+	}

 	while ((*p++ = va_arg(arg, char *)));

 	va_end(arg);

@@ -499,10 +535,12 @@ int spawn_umount(unsigned logopt, ...)

 	char **argv, **p;

 	char prog[] = PATH_UMOUNT;

 	char arg0[] = PATH_UMOUNT;

+	char argn[] = "-n";

 	unsigned int options;

 	unsigned int retries = MTAB_LOCK_RETRIES;

-	int ret, printed = 0;

+	int update_mtab = 1, ret, printed = 0;

 	unsigned int wait = defaults_get_umount_wait();

+	char buf[PATH_MAX];

 #ifdef ENABLE_MOUNT_LOCKING

 	options = SPAWN_OPT_LOCK;

@@ -514,13 +552,29 @@ int spawn_umount(unsigned logopt, ...)

 	for (argc = 1; va_arg(arg, char *); argc++);

 	va_end(arg);

+	ret = readlink(_PATH_MOUNTED, buf, PATH_MAX);

+	if (ret != -1) {

+		buf[ret] = '\0';

+		if (!strcmp(buf, _PROC_MOUNTS)) {

+			debug(logopt,

+			      "mtab link detected, passing -n to mount");

+			argc++;

+			update_mtab = 0;

+		}

+	}

+

 	if (!(argv = alloca(sizeof(char *) * argc + 1)))

 		return -1;

 	argv[0] = arg0;

 	va_start(arg, logopt);

-	p = argv + 1;

+	if (update_mtab)

+		p = argv + 1;

+	else {

+		argv[1] = argn;

+		p = argv + 2;

+	}

 	while ((*p++ = va_arg(arg, char *)));

 	va_end(arg);