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https://github.com/amadvance/snapraid.git
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Sanitize shell execution
This commit is contained in:
Andrea Mazzoleni
parent
033ce93d5b
commit
60316a5eda
1 changed files with 197 additions and 15 deletions
212
cmdline/unix.c
212
cmdline/unix.c
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@ -21,6 +21,115 @@ int eaccess(const char* pathname, int mode)
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}
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#endif
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/****************************************************************************/
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/* exec */
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#if HAVE_LINUX_DEVICE
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/**
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* Validates a string for shell metacharacters.
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* Returns -1 if dangerous characters are detected, 0 otherwise.
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*/
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static int validate_shell_input(const char* str)
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{
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/*
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* Define characters that can be used to inject commands or alter logic
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* Includes: ; | & $ > < ` ' " ( ) [ * ? \ ~ and whitespace
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*/
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const char* danger_chars = ";|&$><`'\"()[]*?\\~\r\n ";
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/* check for any of the forbidden characters */
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if (strpbrk(str, danger_chars) != 0)
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return -1;
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/* check if the string starts with a hyphen to prevent flag injection */
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if (str[0] == '-')
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return -1;
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return 0;
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}
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/**
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* Validates a string for exec.
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* Returns -1 if dangerous characters are detected, 0 otherwise.
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*/
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static int validate_exec_input(const char* str)
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{
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/* reject paths trying to go up levels */
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if (strstr(str, "..") != 0)
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return -1;
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/* reject inputs starting with '-' to prevent Flag Injection */
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if (str[0] == '-')
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return -1;
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return 0;
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}
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/*
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* Scrubbed environment
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* Only provide the bare essentials.
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*/
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static char* const envp_scrubbed[] = {
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"PATH="
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#ifdef __APPLE__
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"/opt/homebrew/bin:"
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#endif
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"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
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"TERM=dumb",
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"LANG=C",
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"IFS= \t\n",
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NULL
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};
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/**
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* Executes a command with arguments.
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* @param args A NULL-terminated array of strings. args[0] is the executable.
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* @return The exit status of the command, or -1 on fork/wait failure.
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*/
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static int systemv(const char* args[])
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{
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pid_t pid = fork();
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if (pid < 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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if (pid == 0) {
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#if defined(CLOSE_RANGE_CLOEXEC) && defined(HAVE_CLOSE_RANGE)
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/* set all fd to be closed on exec as extra safety measure */
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close_range(3, ~0U, CLOSE_RANGE_CLOEXEC);
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#endif
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/* child process */
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execve(args[0], (char* const*)args, envp_scrubbed);
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_exit(EXIT_FAILURE);
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}
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/* parent process */
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int status;
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pid_t ret;
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do {
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ret = waitpid(pid, &status, 0);
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} while (ret == -1 && errno == EINTR);
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if (ret == -1) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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if (WIFEXITED(status)) {
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return WEXITSTATUS(status);
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} else if (WIFSIGNALED(status)) {
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return -WTERMSIG(status);
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}
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return -1;
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}
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#endif
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/**
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* Exit codes.
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*/
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@ -777,6 +886,12 @@ static int devdereference_zfs(uint64_t device, const char* dir, tommy_list* devl
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if (slash)
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*slash = 0;
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if (validate_shell_input(pool) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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snprintf(cmd, sizeof(cmd), "%s status -P %s 2>/dev/null", zpool, pool);
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FILE* fp = popen(cmd, "r");
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@ -2139,7 +2254,6 @@ int fssnapshot_btrfs_create(const struct fssnapshot_struct* fss, const char* nam
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static int fssnapshot_bcachefs_create(const struct fssnapshot_struct* fss, const char* name)
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{
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char target_path[PATH_MAX];
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char cmd[PATH_MAX * 3 + 64];
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int ret;
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const char* bcachefs = find_bcachefs();
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@ -2152,9 +2266,23 @@ static int fssnapshot_bcachefs_create(const struct fssnapshot_struct* fss, const
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pathcpy(target_path, sizeof(target_path), fss->snapshot_dir);
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pathcat(target_path, sizeof(target_path), name);
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snprintf(cmd, sizeof(cmd), "%s subvolume snapshot -r %s %s", bcachefs, fss->root_dir, target_path);
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if (validate_exec_input(fss->root_dir) != 0 || validate_exec_input(target_path) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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ret = system(cmd);
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const char* argv[] = {
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bcachefs,
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"subvolume",
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"snapshot",
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"-r",
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fss->root_dir,
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target_path,
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0
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};
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ret = systemv(argv);
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if (ret != 0) {
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/* LCOV_EXCL_START */
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return -1;
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@ -2168,7 +2296,7 @@ static int fssnapshot_bcachefs_create(const struct fssnapshot_struct* fss, const
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#if HAVE_LINUX_DEVICE
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static int fssnapshot_zfs_create(const struct fssnapshot_struct* fss, const char* name)
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{
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char cmd[PATH_MAX * 2 + 64];
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char snapshot[PATH_MAX + 64];
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int ret;
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const char* zfs = find_zfs();
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@ -2178,9 +2306,22 @@ static int fssnapshot_zfs_create(const struct fssnapshot_struct* fss, const char
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/* LCOV_EXCL_STOP */
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}
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snprintf(cmd, sizeof(cmd), "%s snapshot %s@%s", zfs, fss->dataset, name);
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snprintf(snapshot, sizeof(snapshot), "%s@%s", fss->dataset, name);
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ret = system(cmd);
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if (validate_exec_input(snapshot) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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const char* argv[] = {
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zfs,
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"snapshot",
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snapshot,
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0
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};
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ret = systemv(argv);
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if (ret != 0) {
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/* LCOV_EXCL_START */
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return -1;
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@ -2244,7 +2385,6 @@ int fssnapshot_btrfs_delete(const struct fssnapshot_struct* fss, const char* nam
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static int fssnapshot_bcachefs_delete(const struct fssnapshot_struct* fss, const char* name)
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{
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char target_path[PATH_MAX];
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char cmd[PATH_MAX * 2 + 64];
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int ret;
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const char* bcachefs = find_bcachefs();
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@ -2257,9 +2397,21 @@ static int fssnapshot_bcachefs_delete(const struct fssnapshot_struct* fss, const
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pathcpy(target_path, sizeof(target_path), fss->snapshot_dir);
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pathcat(target_path, sizeof(target_path), name);
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snprintf(cmd, sizeof(cmd), "%s subvolume delete %s", bcachefs, target_path);
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if (validate_exec_input(target_path) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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ret = system(cmd);
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const char* argv[] = {
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bcachefs,
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"subvolume",
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"delete",
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target_path,
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0,
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};
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ret = systemv(argv);
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if (ret != 0) {
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/* LCOV_EXCL_START */
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return -1;
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@ -2273,7 +2425,7 @@ static int fssnapshot_bcachefs_delete(const struct fssnapshot_struct* fss, const
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#if HAVE_LINUX_DEVICE
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static int fssnapshot_zfs_delete(const struct fssnapshot_struct* fss, const char* name)
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{
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char cmd[PATH_MAX * 2 + 64];
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char snapshot[PATH_MAX + 64];
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int ret;
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const char* zfs = find_zfs();
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@ -2283,9 +2435,22 @@ static int fssnapshot_zfs_delete(const struct fssnapshot_struct* fss, const char
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/* LCOV_EXCL_STOP */
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}
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snprintf(cmd, sizeof(cmd), "%s destroy %s@%s", zfs, fss->dataset, name);
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snprintf(snapshot, sizeof(snapshot), "%s@%s", fss->dataset, name);
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ret = system(cmd);
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if (validate_exec_input(snapshot) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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const char* argv[] = {
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zfs,
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"destroy",
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snapshot,
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0
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};
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ret = systemv(argv);
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if (ret != 0) {
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/* LCOV_EXCL_START */
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return -1;
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@ -2358,7 +2523,8 @@ static int fssnapshot_bcachefs_rename(const struct fssnapshot_struct* fss, const
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#if HAVE_LINUX_DEVICE
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static int fssnapshot_zfs_rename(const struct fssnapshot_struct* fss, const char* old_name, const char* new_name)
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{
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char cmd[PATH_MAX * 2 + 64];
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char old_snapshot[PATH_MAX + 64];
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char new_snapshot[PATH_MAX + 64];
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int ret;
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const char* zfs = find_zfs();
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@ -2368,9 +2534,25 @@ static int fssnapshot_zfs_rename(const struct fssnapshot_struct* fss, const char
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/* LCOV_EXCL_STOP */
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}
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snprintf(cmd, sizeof(cmd), "%s rename %s@%s %s@%s", zfs, fss->dataset, old_name, fss->dataset, new_name);
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snprintf(old_snapshot, sizeof(old_snapshot), "%s@%s", fss->dataset, old_name);
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snprintf(new_snapshot, sizeof(new_snapshot), "%s@%s", fss->dataset, new_name);
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ret = system(cmd);
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if (validate_exec_input(old_snapshot) != 0 || validate_exec_input(new_snapshot) != 0) {
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/* LCOV_EXCL_START */
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return -1;
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/* LCOV_EXCL_STOP */
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}
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const char* argv[] = {
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zfs,
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"rename",
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old_snapshot,
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new_snapshot,
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0
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};
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ret = systemv(argv);
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if (ret != 0) {
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/* LCOV_EXCL_START */
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return -1;
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