aboutsummaryrefslogtreecommitdiff
path: root/util-linux/mount.c
diff options
context:
space:
mode:
Diffstat (limited to 'util-linux/mount.c')
-rw-r--r--util-linux/mount.c62
1 files changed, 61 insertions, 1 deletions
diff --git a/util-linux/mount.c b/util-linux/mount.c
index b92e2c297..19ac13930 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -1886,6 +1886,58 @@ static int nfsmount(struct mntent *mp, unsigned long vfsflags, char *filteropts)
#endif // !ENABLE_FEATURE_MOUNT_NFS
+// Find "...,NAME=NUM,..." in the option string, remove "NAME=NUM" option
+// and return NUM.
+// Return 0 if not found.
+// All instances must be parsed and removed (for example, since kernel 5.4
+// squashfs: Unknown parameter 'sizelimit'
+// will result if loopback mount option "sizelimit=NNN" is not removed
+// and squashfs sees it in option string).
+static unsigned long long cut_out_ull_opt(char *opts, const char *name_eq)
+{
+ unsigned long long ret = 0;
+
+ if (!opts) // allow NULL opts (simplifies callers' work)
+ return ret;
+
+ for (;;) {
+ char *end;
+ char *opt;
+
+ // Find comma-delimited "NAME="
+ for (;;) {
+ opt = strstr(opts, name_eq);
+ if (!opt)
+ return ret;
+ if (opt == opts)
+ break; // found it (it's first opt)
+ if (opt[-1] == ',') {
+ opts = opt - 1;
+ break; // found it (it's not a first opt)
+ }
+ // False positive like "VNAME=", we are at "N".
+ // - skip it, loop back to searching
+ opts = opt + 1;
+ }
+
+ ret = bb_strtoull(opt + strlen(name_eq), &end, 0);
+ if (errno && errno != EINVAL) {
+ err:
+ bb_error_msg_and_die("bad option '%s'", opt);
+ }
+ if (*end == '\0') {
+ // It is "[,]NAME=NUM\0" - truncate it and return
+ *opts = '\0';
+ return ret;
+ }
+ if (*end != ',')
+ goto err;
+ // We are at trailing comma
+ // Remove "NAME=NUM," and loop back to check for duplicate opts
+ overlapping_strcpy(opt, end + 1);
+ }
+}
+
// Mount one directory. Handles CIFS, NFS, loopback, autobind, and filesystem
// type detection. Returns 0 for success, nonzero for failure.
// NB: mp->xxx fields may be trashed on exit
@@ -2029,9 +2081,16 @@ static int singlemount(struct mntent *mp, int ignore_busy)
) {
// Do we need to allocate a loopback device for it?
if (ENABLE_FEATURE_MOUNT_LOOP && S_ISREG(st.st_mode)) {
+ unsigned long long offset;
+ unsigned long long sizelimit;
+
loopFile = bb_simplify_path(mp->mnt_fsname);
mp->mnt_fsname = NULL; // will receive malloced loop dev name
+ // Parse and remove loopback options
+ offset = cut_out_ull_opt(filteropts, "offset=");
+ sizelimit = cut_out_ull_opt(filteropts, "sizelimit=");
+
// mount always creates AUTOCLEARed loopdevs, so that umounting
// drops them without any code in the userspace.
// This happens since circa linux-2.6.25:
@@ -2040,7 +2099,8 @@ static int singlemount(struct mntent *mp, int ignore_busy)
// Subject: Allow auto-destruction of loop devices
loopfd = set_loop(&mp->mnt_fsname,
loopFile,
- 0,
+ offset,
+ sizelimit,
((vfsflags & MS_RDONLY) ? BB_LO_FLAGS_READ_ONLY : 0)
| BB_LO_FLAGS_AUTOCLEAR
);