mirror of
https://github.com/libfuse/libfuse.git
synced 2026-07-07 14:47:41 +08:00
Replace fork by posix_spawn in mount_util.c
This completes commit bb9cecbf67
("Use posix_spawn instead of fork+exec") and replaces remaining
fork by posix_spawn.
Not modified is mount_bsd.d as I cannot test it.
Signed-off-by: Bernd Schubert <bernd@bsbernd.com>
This commit is contained in:
Bernd Schubert
committed by
Bernd Schubert
Bernd Schubert
parent
4230b91081
commit
6806ad4e1c
+120
-67
@@ -8,6 +8,8 @@
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See the file LGPL2.txt.
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*/
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#define _GNU_SOURCE
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#include "fuse_config.h"
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#include "mount_util.h"
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#ifdef __linux__
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@@ -35,6 +37,7 @@
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#include "fuse_mount_compat.h"
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#include <sys/param.h>
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#include <spawn.h>
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/* Environment variable for FUSE kernel device */
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#define FUSE_KERN_DEVICE_ENV "FUSE_KERN_DEVICE"
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@@ -184,13 +187,88 @@ static int mtab_needs_update(const char *mnt)
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}
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#endif /* IGNORE_MTAB */
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/*
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* @brief Spawn @cmd with a clean environment and the given signal mask.
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*
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* @param[out] pid Child pid on success.
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* @param[in] cmd Absolute path of the executable.
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* @param[in] argv NULL-terminated argument vector.
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* @param[in] mask Signal mask to install in the child.
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* @return 0 on success, positive errno on failure.
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*/
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static int fuse_mount_spawn(pid_t *pid, const char *cmd, char *const argv[],
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sigset_t *mask)
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{
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posix_spawnattr_t attr;
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char *const envp[] = { NULL };
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uid_t ruid = getuid();
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uid_t euid = geteuid();
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int res;
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res = posix_spawnattr_init(&attr);
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if (res) {
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fprintf(stderr, "Failed to init posix_spawn attr for cmd %s: %s\n",
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cmd, strerror(res));
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return res;
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}
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res = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGMASK);
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if (res) {
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fprintf(stderr, "Failed to set posix_spawn flags for cmd %s: %s\n",
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cmd, strerror(res));
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goto out_destroy;
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}
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res = posix_spawnattr_setsigmask(&attr, mask);
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if (res) {
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fprintf(stderr, "Failed to set posix_spawn sigmask for cmd %s: %s\n",
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cmd, strerror(res));
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goto out_destroy;
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}
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/*
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* Reached via setuid-root fusermount (ruid != euid, euid 0) or via
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* lib/mount.c in a privileged daemon after a direct mount (ruid ==
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* euid). /bin/mount keys "restricted" mode off the real uid, so raise
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* it to euid for the fusermount case; ruid == euid needs no change.
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* Done in this single-threaded parent as posix_spawn cannot do it.
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*/
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if (ruid != euid && setreuid(euid, -1) == -1) {
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res = errno;
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fprintf(stderr, "Failed to set real uid for cmd %s: %s\n",
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cmd, strerror(res));
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goto out_destroy;
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}
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res = posix_spawn(pid, cmd, NULL, &attr, argv, envp);
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/*
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* A failed restore would leave this process with the raised real uid;
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* refuse to continue rather than run on privileged.
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*/
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if (ruid != euid && setreuid(ruid, -1) == -1) {
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fprintf(stderr, "Failed to restore real uid for cmd %s: %s\n",
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cmd, strerror(errno));
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abort();
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}
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out_destroy:
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posix_spawnattr_destroy(&attr);
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return res;
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}
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/*
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* @return caller expects 0 or -1
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*/
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static int add_mount(const char *progname, const char *fsname,
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const char *mnt, const char *type, const char *opts)
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{
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int res;
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int status;
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pid_t pid;
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sigset_t blockmask;
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sigset_t oldmask;
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const char *cmd = "/bin/mount";
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sigemptyset(&blockmask);
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sigaddset(&blockmask, SIGCHLD);
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@@ -200,36 +278,28 @@ static int add_mount(const char *progname, const char *fsname,
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return -1;
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}
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res = fork();
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if (res == -1) {
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fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
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char const * const argv[] = {
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cmd, "--no-canonicalize", "-i", "-f", "-t", type, "-o", opts,
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fsname, mnt, NULL
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};
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res = fuse_mount_spawn(&pid, cmd, (char * const *) argv, &oldmask);
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if (res) {
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fprintf(stderr, "%s: failed to execute %s: %s\n",
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progname, cmd, strerror(res));
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res = -1;
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goto out_restore;
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}
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if (res == 0) {
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char *env = NULL;
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sigprocmask(SIG_SETMASK, &oldmask, NULL);
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if(setuid(geteuid()) == -1) {
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fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
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res = -1;
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goto out_restore;
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}
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execle("/bin/mount", "/bin/mount", "--no-canonicalize", "-i",
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"-f", "-t", type, "-o", opts, fsname, mnt, NULL, &env);
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fprintf(stderr, "%s: failed to execute /bin/mount: %s\n",
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progname, strerror(errno));
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exit(1);
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}
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res = waitpid(res, &status, 0);
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res = waitpid(pid, &status, 0);
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if (res == -1)
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fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
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fprintf(stderr, "%s: waitpid of %d: %s\n", progname,
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pid, strerror(errno));
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if (status != 0)
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res = -1;
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out_restore:
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out_restore:
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sigprocmask(SIG_SETMASK, &oldmask, NULL);
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return res;
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@@ -248,8 +318,10 @@ static int exec_umount(const char *progname, const char *rel_mnt, int lazy)
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{
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int res;
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int status;
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pid_t pid;
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sigset_t blockmask;
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sigset_t oldmask;
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const char *cmd = "/bin/umount";
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sigemptyset(&blockmask);
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sigaddset(&blockmask, SIGCHLD);
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@@ -259,34 +331,23 @@ static int exec_umount(const char *progname, const char *rel_mnt, int lazy)
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return -1;
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}
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res = fork();
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if (res == -1) {
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fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
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char const * const argv_lazy[] = {
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cmd, "-i", "-l", rel_mnt, NULL
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};
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char const * const argv_normal[] = {
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cmd, "-i", rel_mnt, NULL
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};
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char const * const *argv = lazy ? argv_lazy : argv_normal;
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res = fuse_mount_spawn(&pid, cmd, (char * const *) argv, &oldmask);
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if (res) {
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fprintf(stderr, "%s: failed to execute %s: %s\n",
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progname, cmd, strerror(res));
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res = -1;
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goto out_restore;
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}
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if (res == 0) {
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char *env = NULL;
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sigprocmask(SIG_SETMASK, &oldmask, NULL);
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if(setuid(geteuid()) == -1) {
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fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
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res = -1;
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goto out_restore;
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}
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if (lazy) {
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execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
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"-l", NULL, &env);
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} else {
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execle("/bin/umount", "/bin/umount", "-i", rel_mnt,
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NULL, &env);
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}
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fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
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progname, strerror(errno));
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exit(1);
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}
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res = waitpid(res, &status, 0);
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res = waitpid(pid, &status, 0);
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if (res == -1)
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fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
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@@ -318,8 +379,10 @@ static int remove_mount(const char *progname, const char *mnt)
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{
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int res;
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int status;
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pid_t pid;
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sigset_t blockmask;
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sigset_t oldmask;
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const char *cmd = "/bin/umount";
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sigemptyset(&blockmask);
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sigaddset(&blockmask, SIGCHLD);
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@@ -329,29 +392,19 @@ static int remove_mount(const char *progname, const char *mnt)
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return -1;
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}
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res = fork();
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if (res == -1) {
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fprintf(stderr, "%s: fork: %s\n", progname, strerror(errno));
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char const * const argv[] = {
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cmd, "--no-canonicalize", "-i", "--fake", mnt, NULL
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};
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res = fuse_mount_spawn(&pid, cmd, (char * const *) argv, &oldmask);
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if (res) {
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fprintf(stderr, "%s: failed to execute %s: %s\n",
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progname, cmd, strerror(res));
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res = -1;
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goto out_restore;
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}
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if (res == 0) {
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char *env = NULL;
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sigprocmask(SIG_SETMASK, &oldmask, NULL);
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if(setuid(geteuid()) == -1) {
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fprintf(stderr, "%s: setuid: %s\n", progname, strerror(errno));
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res = -1;
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goto out_restore;
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}
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execle("/bin/umount", "/bin/umount", "--no-canonicalize", "-i",
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"--fake", mnt, NULL, &env);
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fprintf(stderr, "%s: failed to execute /bin/umount: %s\n",
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progname, strerror(errno));
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exit(1);
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}
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res = waitpid(res, &status, 0);
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res = waitpid(pid, &status, 0);
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if (res == -1)
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fprintf(stderr, "%s: waitpid: %s\n", progname, strerror(errno));
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