libmount: block signals when update utab

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/shlibs/mount/src/tab_update.c b/shlibs/mount/src/tab_update.c
index e2c196c542dc5184fa02d28bc5a1743216019ff5..4822dffc5e8589aa3704a31d18d353707ed3ef90 100644 (file)
--- a/shlibs/mount/src/tab_update.c
+++ b/shlibs/mount/src/tab_update.c
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
+#include <signal.h>
 
 #include "c.h"
 #include "mountP.h"
@@ -40,6 +41,9 @@ struct libmnt_update {
        unsigned long   mountflags;
        int             userspace_only;
        int             ready;
+
+       sigset_t        oldsigmask;
+       int             utab_lock;
 };
 
 static int utab_new_entry(struct libmnt_fs *fs, unsigned long mountflags, struct libmnt_fs **ent);
@@ -58,8 +62,8 @@ struct libmnt_update *mnt_new_update(void)
        if (!upd)
                return NULL;
 
+       upd->utab_lock = -1;
        DBG(UPDATE, mnt_debug_h(upd, "allocate"));
-
        return upd;
 }
 
@@ -630,58 +634,79 @@ leave:
        return rc;
 }
 
-static int utab_lock(const char *filename)
+static int utab_lock(struct libmnt_update *upd)
 {
        char *lfile;
-       int fd;
+       int rc;
+       sigset_t sigs;
 
-       assert(filename);
+       assert(upd);
+       assert(upd->filename);
+       assert(upd->userspace_only);
 
-       if (asprintf(&lfile, "%s.lock", filename) == -1)
+       if (asprintf(&lfile, "%s.lock", upd->filename) == -1)
                return -1;
 
        DBG(UPDATE, mnt_debug("%s: locking", lfile));
 
-       fd = open(lfile, O_RDONLY|O_CREAT|O_CLOEXEC, S_IWUSR|
-                                                    S_IRUSR|S_IRGRP|S_IROTH);
+       sigemptyset(&upd->oldsigmask);
+       sigfillset(&sigs);
+       sigprocmask(SIG_BLOCK, &sigs, &upd->oldsigmask);
+
+       upd->utab_lock = open(lfile, O_RDONLY|O_CREAT|O_CLOEXEC, S_IWUSR|
+                                    S_IRUSR|S_IRGRP|S_IROTH);
        free(lfile);
 
-       if (fd < 0)
-               return -errno;
+       if (upd->utab_lock < 0) {
+               rc = -errno;
+               goto err;
+       }
 
-       while (flock(fd, LOCK_EX) < 0) {
+       while (flock(upd->utab_lock, LOCK_EX) < 0) {
                int errsv;
                if ((errno == EAGAIN) || (errno == EINTR))
                        continue;
                errsv = errno;
-               close(fd);
-               return -errsv;
+               close(upd->utab_lock);
+               upd->utab_lock = -1;
+               rc = -errsv;
+               goto err;
        }
-       return fd;
+       return 0;
+err:
+       sigprocmask(SIG_SETMASK, &upd->oldsigmask, NULL);
+       return rc;
 }
 
-static void utab_unlock(int fd)
+static void utab_unlock(struct libmnt_update *upd)
 {
-       if (fd >= 0) {
+       assert(upd);
+       assert(upd->userspace_only);
+
+       if (upd->utab_lock >= 0) {
                DBG(UPDATE, mnt_debug("unlocking utab"));
-               close(fd);
+               close(upd->utab_lock);
+               upd->utab_lock = -1;
+               sigprocmask(SIG_SETMASK, &upd->oldsigmask, NULL);
        }
 }
 
 static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 {
        struct libmnt_table *tb;
-       int rc = 0, u_lc = -1;
+       int rc = 0;
 
        assert(upd);
        assert(upd->fs);
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: add entry", upd->filename));
 
-       if (lc)
-               mnt_lock_file(lc);
-       else if (upd->userspace_only)
-               u_lc = utab_lock(upd->filename);
+       if (upd->userspace_only)
+               rc = utab_lock(upd);
+       else if (lc)
+               rc = mnt_lock_file(lc);
+       if (rc)
+               return rc;
 
        tb = __mnt_new_table_from_file(upd->filename,
                        upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -695,10 +720,10 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
                }
        }
 
-       if (lc)
+       if (upd->userspace_only)
+               utab_unlock(upd);
+       else if (lc)
                mnt_unlock_file(lc);
-       else if (u_lc != -1)
-               utab_unlock(u_lc);
 
        mnt_free_table(tb);
        return rc;
@@ -707,17 +732,19 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
 {
        struct libmnt_table *tb;
-       int rc = 0, u_lc = -1;
+       int rc = 0;
 
        assert(upd);
        assert(upd->target);
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: remove entry", upd->filename));
 
-       if (lc)
-               mnt_lock_file(lc);
-       else if (upd->userspace_only)
-               u_lc = utab_lock(upd->filename);
+       if (upd->userspace_only)
+               rc = utab_lock(upd);
+       else if (lc)
+               rc = mnt_lock_file(lc);
+       if (rc)
+               return rc;
 
        tb = __mnt_new_table_from_file(upd->filename,
                        upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -729,10 +756,11 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
                        mnt_free_fs(rem);
                }
        }
-       if (lc)
+
+       if (upd->userspace_only)
+               utab_unlock(upd);
+       else if (lc)
                mnt_unlock_file(lc);
-       else if (u_lc != -1)
-               utab_unlock(u_lc);
 
        mnt_free_table(tb);
        return rc;
@@ -741,14 +769,16 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
 static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *lc)
 {
        struct libmnt_table *tb = NULL;
-       int rc = 0, u_lc = -1;
+       int rc = 0;
 
        DBG(UPDATE, mnt_debug_h(upd, "%s: modify target", upd->filename));
 
-       if (lc)
-               mnt_lock_file(lc);
-       else if (upd->userspace_only)
-               u_lc = utab_lock(upd->filename);
+       if (upd->userspace_only)
+               rc = utab_lock(upd);
+       else if (lc)
+               rc = mnt_lock_file(lc);
+       if (rc)
+               return rc;
 
        tb = __mnt_new_table_from_file(upd->filename,
                        upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -761,10 +791,11 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
                                rc = update_table(upd, tb);
                }
        }
-       if (lc)
+
+       if (upd->userspace_only)
+               utab_unlock(upd);
+       else if (lc)
                mnt_unlock_file(lc);
-       else if (u_lc != -1)
-               utab_unlock(u_lc);
 
        mnt_free_table(tb);
        return rc;
@@ -773,7 +804,7 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
 static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *lc)
 {
        struct libmnt_table *tb = NULL;
-       int rc = 0, u_lc = -1;
+       int rc = 0;
        struct libmnt_fs *fs;
 
        assert(upd);
@@ -783,10 +814,12 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
 
        fs = upd->fs;
 
-       if (lc)
-               mnt_lock_file(lc);
-       else if (upd->userspace_only)
-               u_lc = utab_lock(upd->filename);
+       if (upd->userspace_only)
+               rc = utab_lock(upd);
+       else if (lc)
+               rc = mnt_lock_file(lc);
+       if (rc)
+               return rc;
 
        tb = __mnt_new_table_from_file(upd->filename,
                        upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
@@ -804,10 +837,10 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
                }
        }
 
-       if (lc)
+       if (upd->userspace_only)
+               utab_unlock(upd);
+       else if (lc)
                mnt_unlock_file(lc);
-       else if (u_lc != -1)
-               utab_unlock(u_lc);
 
        mnt_free_table(tb);
        return rc;