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mount: pass NULL, not "", as "data" to mount syscall if we have no opts

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When mounting a filesystem without any additional options (data parameter
to the mount(2) syscall), pass NULL instead of an empty string like GNU
mount does. This fixes, for example mounting cgroup fs with bbox mount.

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Alexander Shishkin 2010-10-28 06:10:03 +02:00 committed by Denys Vlasenko
parent 78b286fea5
commit 7765095441
1 changed files with 22 additions and 12 deletions
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34
util-linux/mount.c
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@ -332,7 +332,7 @@ static void append_mount_options(char **oldopts, const char *newopts)
} }
// Use the mount_options list to parse options into flags. // Use the mount_options list to parse options into flags.
// Also return list of unrecognized options if unrecognized != NULL // Also update list of unrecognized options if unrecognized != NULL
static long parse_mount_options(char *options, char **unrecognized) static long parse_mount_options(char *options, char **unrecognized)
{ {
long flags = MS_SILENT; long flags = MS_SILENT;
@ -348,25 +348,35 @@ static long parse_mount_options(char *options, char **unrecognized)
// FIXME: use hasmntopt() // FIXME: use hasmntopt()
// Find this option in mount_options // Find this option in mount_options
for (i = 0; i < ARRAY_SIZE(mount_options); i++) { for (i = 0; i < ARRAY_SIZE(mount_options); i++) {
if (!strcasecmp(option_str, options)) { if (strcasecmp(option_str, options) == 0) {
long fl = mount_options[i]; long fl = mount_options[i];
if (fl < 0) flags &= fl; if (fl < 0)
else flags |= fl; flags &= fl;
break; else
flags |= fl;
goto found;
} }
option_str += strlen(option_str) + 1; option_str += strlen(option_str) + 1;
} }
// If unrecognized not NULL, append unrecognized mount options // We did not recognize this option.
if (unrecognized && i == ARRAY_SIZE(mount_options)) { // If "unrecognized" is not NULL, append option there.
// Note that we should not append *empty* option -
// in this case we want to pass NULL, not "", to "data"
// parameter of mount(2) syscall.
// This is crucial for filesystems that don't accept
// any arbitrary mount options, like cgroup fs:
// "mount -t cgroup none /mnt"
if (options[0] && unrecognized) {
// Add it to strflags, to pass on to kernel // Add it to strflags, to pass on to kernel
i = *unrecognized ? strlen(*unrecognized) : 0; char *p = *unrecognized;
*unrecognized = xrealloc(*unrecognized, i + strlen(options) + 2); unsigned len = p ? strlen(p) : 0;
*unrecognized = p = xrealloc(p, len + strlen(options) + 2);
// Comma separated if it's not the first one // Comma separated if it's not the first one
if (i) (*unrecognized)[i++] = ','; if (len) p[len++] = ',';
strcpy((*unrecognized)+i, options); strcpy(p + len, options);
} }
found:
if (!comma) if (!comma)
break; break;
// Advance to next option // Advance to next option