fuse: reorganize mounting code

Macro-driven conditional compilation was a chaos.

New scheme is:

contrib/fuse-lib/mount-common.c:
  libfuse routines used both by glusterfs and fusermount
contrib/fuse-lib/mount.c:
  libfuse-derived but customized mounting code for glusterfs
contrib/fuse-util/mount_util.c:
  libfuse routines used only by fusermount

Change-Id: I3e0ba7f74e36556b78244cd7676eb4d379939602
BUG: 762389
Signed-off-by: Csaba Henk <csaba@redhat.com>
Reviewed-on: http://review.gluster.com/3342
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 247 insertions, 0 deletions

diff --git a/contrib/fuse-lib/mount-common.c b/contrib/fuse-lib/mount-common.c
new file mode 100644
index 00000000000..7411e56c89b
--- /dev/null
+++ b/contrib/fuse-lib/mount-common.c
@@ -0,0 +1,247 @@
+/*
+  FUSE: Filesystem in Userspace
+  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
+  Copyright (c) 2010 Gluster, Inc. <http://www.gluster.com>
+
+  This program can be distributed under the terms of the GNU LGPLv2.
+  See the file COPYING.LIB.
+*/
+
+#include "mount-gluster-compat.h"
+
+/*
+ * These functions (and gf_fuse_umount() in mount.c)
+ * were originally taken from libfuse as of commit 7960e99e
+ * (http://fuse.git.sourceforge.net/git/gitweb.cgi?p=fuse/fuse;a=commit;h=7960e99e)
+ * almost verbatim. What has been changed upon adoption:
+ * - style adopted to that of glusterfs
+ * - s/fprintf/gf_log/
+ * - s/free/FREE/, s/malloc/MALLOC/
+ * - there are some other minor things
+ *
+ * For changes that were made later and syncs with upstream,
+ * see the commit log.
+ */
+
+#ifndef __NetBSD__
+static int
+mtab_needs_update (const char *mnt)
+{
+        int res;
+        struct stat stbuf;
+
+        /* If mtab is within new mount, don't touch it */
+        if (strncmp (mnt, _PATH_MOUNTED, strlen (mnt)) == 0 &&
+            _PATH_MOUNTED[strlen (mnt)] == '/')
+                return 0;
+
+        /*
+         * Skip mtab update if /etc/mtab:
+         *
+         *  - doesn't exist,
+         *  - is a symlink,
+         *  - is on a read-only filesystem.
+         */
+        res = lstat (_PATH_MOUNTED, &stbuf);
+        if (res == -1) {
+                if (errno == ENOENT)
+                        return 0;
+        } else {
+                if (S_ISLNK (stbuf.st_mode))
+                        return 0;
+
+                res = access (_PATH_MOUNTED, W_OK);
+                if (res == -1 && errno == EROFS)
+                        return 0;
+        }
+
+        return 1;
+}
+#else /* __NetBSD__ */
+#define mtab_needs_update(x) 1
+#endif /* __NetBSD__ */
+
+int
+fuse_mnt_add_mount (const char *progname, const char *fsname,
+                    const char *mnt, const char *type, const char *opts)
+{
+        int res;
+        int status;
+        sigset_t blockmask;
+        sigset_t oldmask;
+
+        if (!mtab_needs_update (mnt))
+                return 0;
+
+        sigemptyset (&blockmask);
+        sigaddset (&blockmask, SIGCHLD);
+        res = sigprocmask (SIG_BLOCK, &blockmask, &oldmask);
+        if (res == -1) {
+                GFFUSE_LOGERR ("%s: sigprocmask: %s",
+                               progname, strerror (errno));
+                return -1;
+        }
+
+        res = fork ();
+        if (res == -1) {
+                GFFUSE_LOGERR ("%s: fork: %s", progname, strerror (errno));
+                goto out_restore;
+        }
+        if (res == 0) {
+                char templ[] = "/tmp/fusermountXXXXXX";
+                char *tmp;
+
+                sigprocmask (SIG_SETMASK, &oldmask, NULL);
+                setuid (geteuid ());
+
+                /*
+                 * hide in a directory, where mount isn't able to resolve
+                 * fsname as a valid path
+                 */
+                tmp = mkdtemp (templ);
+                if (!tmp) {
+                        GFFUSE_LOGERR ("%s: failed to create temporary directory",
+                                       progname);
+                        exit (1);
+                }
+                if (chdir (tmp)) {
+                        GFFUSE_LOGERR ("%s: failed to chdir to %s: %s",
+                                       progname, tmp, strerror (errno));
+                        exit (1);
+                }
+                rmdir (tmp);
+                execl (_PATH_MOUNT, _PATH_MOUNT, "-i", "-f", "-t", type,
+                       "-o", opts, fsname, mnt, NULL);
+                GFFUSE_LOGERR ("%s: failed to execute %s: %s",
+                               progname, _PATH_MOUNT, strerror (errno));
+                exit (1);
+        }
+
+        res = waitpid (res, &status, 0);
+        if (res == -1)
+                GFFUSE_LOGERR ("%s: waitpid: %s", progname, strerror (errno));
+        res = (res != -1 && status == 0) ? 0 : -1;
+
+ out_restore:
+        sigprocmask (SIG_SETMASK, &oldmask, NULL);
+        return res;
+}
+
+char *
+fuse_mnt_resolve_path (const char *progname, const char *orig)
+{
+        char buf[PATH_MAX];
+        char *copy;
+        char *dst;
+        char *end;
+        char *lastcomp;
+        const char *toresolv;
+
+        if (!orig[0]) {
+                GFFUSE_LOGERR ("%s: invalid mountpoint '%s'", progname, orig);
+                return NULL;
+        }
+
+        copy = strdup (orig);
+        if (copy == NULL) {
+                GFFUSE_LOGERR ("%s: failed to allocate memory", progname);
+                return NULL;
+        }
+
+        toresolv = copy;
+        lastcomp = NULL;
+        for (end = copy + strlen (copy) - 1; end > copy && *end == '/'; end --);
+        if (end[0] != '/') {
+                char *tmp;
+                end[1] = '\0';
+                tmp = strrchr (copy, '/');
+                if (tmp == NULL) {
+                        lastcomp = copy;
+                        toresolv = ".";
+                } else {
+                        lastcomp = tmp + 1;
+                        if (tmp == copy)
+                                toresolv = "/";
+                }
+                if (strcmp (lastcomp, ".") == 0 || strcmp (lastcomp, "..") == 0) {
+                        lastcomp = NULL;
+                        toresolv = copy;
+                }
+                else if (tmp)
+                        tmp[0] = '\0';
+        }
+        if (realpath (toresolv, buf) == NULL) {
+                GFFUSE_LOGERR ("%s: bad mount point %s: %s", progname, orig,
+                               strerror (errno));
+                FREE (copy);
+                return NULL;
+        }
+        if (lastcomp == NULL)
+                dst = strdup (buf);
+        else {
+                dst = (char *) MALLOC (strlen (buf) + 1 + strlen (lastcomp) + 1);
+                if (dst) {
+                        unsigned buflen = strlen (buf);
+                        if (buflen && buf[buflen-1] == '/')
+                                sprintf (dst, "%s%s", buf, lastcomp);
+                        else
+                                sprintf (dst, "%s/%s", buf, lastcomp);
+                }
+        }
+        FREE (copy);
+        if (dst == NULL)
+                GFFUSE_LOGERR ("%s: failed to allocate memory", progname);
+        return dst;
+}
+
+int
+fuse_mnt_umount (const char *progname, const char *abs_mnt,
+                 const char *rel_mnt, int lazy)
+{
+        int res;
+        int status;
+        sigset_t blockmask;
+        sigset_t oldmask;
+
+        if (!mtab_needs_update (abs_mnt)) {
+                res = umount2 (rel_mnt, lazy ? 2 : 0);
+                if (res == -1)
+                        GFFUSE_LOGERR ("%s: failed to unmount %s: %s",
+                                       progname, abs_mnt, strerror (errno));
+                return res;
+        }
+
+        sigemptyset (&blockmask);
+        sigaddset (&blockmask, SIGCHLD);
+        res = sigprocmask (SIG_BLOCK, &blockmask, &oldmask);
+        if (res == -1) {
+                GFFUSE_LOGERR ("%s: sigprocmask: %s", progname,
+                               strerror (errno));
+                return -1;
+        }
+
+        res = fork ();
+        if (res == -1) {
+                GFFUSE_LOGERR ("%s: fork: %s", progname, strerror (errno));
+                goto out_restore;
+        }
+        if (res == 0) {
+                sigprocmask (SIG_SETMASK, &oldmask, NULL);
+                setuid (geteuid ());
+                execl ("/bin/umount", "/bin/umount", "-i", rel_mnt,
+                      lazy ? "-l" : NULL, NULL);
+                GFFUSE_LOGERR ("%s: failed to execute /bin/umount: %s",
+                               progname, strerror (errno));
+                exit (1);
+        }
+        res = waitpid (res, &status, 0);
+        if (res == -1)
+                GFFUSE_LOGERR ("%s: waitpid: %s", progname, strerror (errno));
+
+        if (status != 0)
+                res = -1;
+
+ out_restore:
+        sigprocmask (SIG_SETMASK, &oldmask, NULL);
+        return res;
+}