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Re: [Cluster-devel] [PATCH] gfs2: Fix handling of mount points with spaces



On Mon, Apr 26, 2010 at 04:09:25PM -0400, Lon Hohberger wrote:
> Mount points may contain spaces, tabs, newlines, and the
> backslash character according to getmntent(3).  Unfortunately,
> while scanning /proc/mounts, mount.gfs2 was not unescaping
> the escape sequences, causing mount.gfs2 to not update mtab.
> 
> Utilities relying on mtab (e.g. fuser) would consequently
> be unable to list processes holding references on the mount
> point.

Looks good.

> Resolves: rhbz#586100
> 
> Signed-off-by: Lon Hohberger <lhh redhat com>
> ---
>  gfs2/mount/util.c |   55 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 53 insertions(+), 2 deletions(-)
> 
> diff --git a/gfs2/mount/util.c b/gfs2/mount/util.c
> index 16fc382..bc26daf 100644
> --- a/gfs2/mount/util.c
> +++ b/gfs2/mount/util.c
> @@ -201,6 +201,48 @@ void parse_opts(struct mount_options *mo)
>  	log_debug("parse_opts: locktable = \"%s\"", mo->locktable);
>  }
>  
> +/* Remove escape sequences from mount path.  Per getmntent(3), there are
> +   only four escape sequences we need to handle.  Consequently, this does
> +   not need to be a general-purpose unescape function */
> +
> +static int mnt_unescape(char *dest, size_t len, const char *src)
> +{
> +	unsigned i = 0, j = 0;
> +	size_t srclen;
> +	int ret = -1;
> +
> +	srclen = strlen(src);
> +	while (i < srclen) {
> +		if (src[i] != '\\') {
> +			dest[j] = src[i];
> +			++i; ++j;
> +			continue;
> +		}
> +
> +		++i;
> +		if ((srclen - 3) < i)
> +			return -1;
> +
> +		if (!strncmp(&src[i], "040", 3)) {
> +			dest[j] = ' ';
> +		} else if (!strncmp(&src[i], "011", 3)) {
> +			dest[j] = '\t';
> +		} else if (!strncmp(&src[i], "012", 3)) {
> +			dest[j] = '\n';
> +		} else if (!strncmp(&src[i], "134", 3)) {
> +			dest[j] = '\\';
> +		} else {
> +			return -1;
> +		}
> +
> +		i+=3;
> +		j++;
> +	}
> +
> +	return 0;
> +}
> +
> +
>  /* - when unmounting, we don't know the dev and need this function to set it;
>     we also want to select the _last_ line with a matching dir since it will
>     be the top-most fs that the umount(2) will unmount
> @@ -212,6 +254,7 @@ void read_proc_mounts(struct mount_options *mo)
>  	FILE *file;
>  	char line[PATH_MAX];
>  	char path[PATH_MAX];
> +	char unescaped_path[PATH_MAX];
>  	char type[PATH_MAX];
>  	char opts[PATH_MAX];
>  	char device[PATH_MAX];
> @@ -234,8 +277,16 @@ void read_proc_mounts(struct mount_options *mo)
>  	while (fgets(line, PATH_MAX, file)) {
>  		if (sscanf(line, "%s %s %s %s", device, path, type, opts) != 4)
>  			continue;
> -		if (strcmp(path, mo->dir))
> -			continue;
> +		if (strcmp(path, mo->dir)) {
> +			if (!strchr(path, '\\'))
> +				continue;
> +			/* /proc/mounts entry may have escaped spaces */
> +			if (mnt_unescape(unescaped_path, sizeof(unescaped_path),
> +					 path) < 0)
> +				continue;
> +			if (strcmp(unescaped_path, mo->dir))
> +				continue;
> +		}
>  		if (mo->dev[0]) {
>  			if (stat(device, &st_mounts_dev))
>  				continue;
> -- 
> 1.6.2.5


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