6561e0746
Steffen Trumtrar
2020-10-01
Subject
mount: support the sizelimit and offset option for loop devices
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include/libbb.h+2 -1
| @@ -1515,7 +1515,8 @@ int del_loop(const char *device) FAST_FUNC; | |
| * malloc and return it in *devname. | |
| * return value is the opened fd to the loop device, or < on error | |
| */ | |
| - | int set_loop(char **devname, const char *file, unsigned long long offset, unsigned flags) FAST_FUNC; |
| + | int set_loop(char **devname, const char *file, unsigned long long offset, |
| + | unsigned long long sizelimit, unsigned flags) FAST_FUNC; |
| /* These constants match linux/loop.h (without BB_ prefix): */ | |
| #define BB_LO_FLAGS_READ_ONLY 1 | |
| #define BB_LO_FLAGS_AUTOCLEAR 4 | |
libbb/loop.c+3 -1
| @@ -102,7 +102,8 @@ int FAST_FUNC get_free_loop(void) | |
| * search will re-use an existing loop device already bound to that | |
| * file/offset if it finds one. | |
| */ | |
| - | int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, unsigned flags) |
| + | int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, |
| + | unsigned long long sizelimit, unsigned flags) |
| { | |
| char dev[LOOP_NAMESIZE]; | |
| char *try; | |
| @@ -185,6 +186,7 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse | |
| memset(&loopinfo, 0, sizeof(loopinfo)); | |
| safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE); | |
| loopinfo.lo_offset = offset; | |
| + | loopinfo.lo_sizelimit = sizelimit; |
| /* | |
| * Used by mount to set LO_FLAGS_AUTOCLEAR. | |
| * LO_FLAGS_READ_ONLY is not set because RO is controlled by open type of the file. | |
util-linux/losetup.c+1 -1
| @@ -150,7 +150,7 @@ int losetup_main(int argc UNUSED_PARAM, char **argv) | |
| if (opt & OPT_P) { | |
| flags |= BB_LO_FLAGS_PARTSCAN; | |
| } | |
| - | if (set_loop(&d, argv[0], offset, flags) < 0) |
| + | if (set_loop(&d, argv[0], offset, 0, flags) < 0) |
| bb_simple_perror_msg_and_die(argv[0]); | |
| return EXIT_SUCCESS; | |
| } | |
util-linux/mount.c+61 -1
| @@ -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 | |
| ); | |