libmount: don't use sscanf() for mountinfo parsing

Addresses: https://github.com/karelzak/util-linux/issues/780
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/include/pathnames.h b/include/pathnames.h
index ed8ea330ddf10a751af529c739bc75ecd2f374a4..2e877cf324be188fd70602ca1164312fd5735f16 100644 (file)
--- a/include/pathnames.h
+++ b/include/pathnames.h
@@ -15,7 +15,7 @@
 #endif
 
 /* used by kernel in /proc (e.g. /proc/swaps) for deleted files */
-#define PATH_DELETED_SUFFIX    "\\040(deleted)"
+#define PATH_DELETED_SUFFIX    " (deleted)"
 #define PATH_DELETED_SUFFIX_SZ (sizeof(PATH_DELETED_SUFFIX) - 1)
 
 /* DEFPATHs from <paths.h> don't include /usr/local */

diff --git a/libmount/src/tab_parse.c b/libmount/src/tab_parse.c
index 6eec8ba3536c41773074625d8985527ae0d93152..a4bef20790e1d93041d56a0ee0f12e207bf51f7b 100644 (file)
--- a/libmount/src/tab_parse.c
+++ b/libmount/src/tab_parse.c
@@ -47,8 +47,10 @@ static const char *next_number(const char *s, int *num, int *rc)
 {
        char *end = NULL;
 
+       if (!s || !*s)
+               return s;
+
        assert(num);
-       assert(s);
        assert(rc);
 
        *rc = -EINVAL;
@@ -70,6 +72,13 @@ static inline const char *skip_separator(const char *p)
        return p;
 }
 
+static inline const char *skip_nonspearator(const char *p)
+{
+       while (p && *p && !(*p == ' ' || *p == '\t'))
+               p++;
+       return p;
+}
+
 /*
  * Parses one line from {fs,m}tab
  */
@@ -82,7 +91,7 @@ static int mnt_parse_table_line(struct libmnt_fs *fs, const char *s)
 
        /* (1) source */
        p = unmangle(s, &s);
-               if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
+       if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
                DBG(TAB, ul_debug("tab parse error: [source]"));
                goto fail;
        }
@@ -153,29 +162,68 @@ fail:
  */
 static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, const char *s)
 {
-       int rc, end = 0;
+       int rc = 0;
        unsigned int maj, min;
-       char *fstype = NULL, *src = NULL;
-       const char *p;
-
-       rc = sscanf(s,  "%d "           /* (1) id */
-                       "%d "           /* (2) parent */
-                       "%u:%u "        /* (3) maj:min */
-                       UL_SCNsA" "     /* (4) mountroot */
-                       UL_SCNsA" "     /* (5) target */
-                       UL_SCNsA        /* (6) vfs options (fs-independent) */
-                       "%n",           /* number of read bytes */
-
-                       &fs->id,
-                       &fs->parent,
-                       &maj, &min,
-                       &fs->root,
-                       &fs->target,
-                       &fs->vfs_optstr,
-                       &end);
-
-       if (rc >= 7 && end > 0)
-               s += end;
+       char *p;
+
+       fs->flags |= MNT_FS_KERNEL;
+
+       /* (1) id */
+       s = next_number(s, &fs->id, &rc);
+       if (!s || !*s || rc) {
+               DBG(TAB, ul_debug("tab parse error: [id]"));
+               goto fail;
+       }
+
+       s = skip_separator(s);
+
+       /* (2) parent */
+       s = next_number(s, &fs->parent, &rc);
+       if (!s || !*s || rc) {
+               DBG(TAB, ul_debug("tab parse error: [parent]"));
+               goto fail;
+       }
+
+       s = skip_separator(s);
+
+       /* (3) maj:min */
+       if (sscanf(s, "%u:%u", &maj, &min) != 2) {
+               DBG(TAB, ul_debug("tab parse error: [maj:min]"));
+               goto fail;
+       }
+       fs->devno = makedev(maj, min);
+       s = skip_nonspearator(s);
+       s = skip_separator(s);
+
+       /* (4) mountroot */
+       fs->root = unmangle(s, &s);
+       if (!fs->root) {
+               DBG(TAB, ul_debug("tab parse error: [mountroot]"));
+               goto fail;
+       }
+
+       s = skip_separator(s);
+
+       /* (5) target */
+       fs->target = unmangle(s, &s);
+       if (!fs->target) {
+               DBG(TAB, ul_debug("tab parse error: [target]"));
+               goto fail;
+       }
+
+       /* remove "\040(deleted)" suffix */
+       p = (char *) endswith(fs->target, PATH_DELETED_SUFFIX);
+       if (p && *p)
+               *p = '\0';
+
+       s = skip_separator(s);
+
+       /* (6) vfs options (fs-independent) */
+       fs->vfs_optstr = unmangle(s, &s);
+       if (!fs->vfs_optstr) {
+               DBG(TAB, ul_debug("tab parse error: [VFS options]"));
+               goto fail;
+       }
 
        /* (7) optional fields, terminated by " - " */
        p = strstr(s, " - ");
@@ -185,82 +233,56 @@ static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, const char *s)
        }
        if (p > s + 1)
                fs->opt_fields = strndup(s + 1, p - s - 1);
-       s = p + 3;
-
-       end = 0;
-       rc += sscanf(s, UL_SCNsA"%n",   /* (8) FS type */
-
-                       &fstype,
-                       &end);
-
-       if (rc >= 8 && end > 0)
-               s += end;
-       if (s[0] == ' ')
-               s++;
-
-       /* (9) source can unfortunately be an empty string "" and scanf does
-        * not work well with empty string. Test with:
-        *     $ sudo mount -t tmpfs "" /tmp/bb
-        *     $ mountpoint /tmp/bb
-        * */
-       if (s[0] == ' ') {
-               src = strdup("");
-               s++;
-               rc++;
-               rc += sscanf(s, UL_SCNsA,       /* (10) fs options (fs specific) */
-
-                               &fs->fs_optstr);
-       } else {
-               rc += sscanf(s, UL_SCNsA" "     /* (9) source */
-                               UL_SCNsA,       /* (10) fs options (fs specific) */
 
-                               &src,
-                               &fs->fs_optstr);
-       }
-
-       if (rc >= 10) {
-               size_t sz;
+       s = skip_separator(p + 3);
 
-               fs->flags |= MNT_FS_KERNEL;
-               fs->devno = makedev(maj, min);
-
-               /* remove "\040(deleted)" suffix */
-               sz = strlen(fs->target);
-               if (sz > PATH_DELETED_SUFFIX_SZ) {
-                       char *ptr = fs->target + (sz - PATH_DELETED_SUFFIX_SZ);
+       /* (8) FS type */
+       p = unmangle(s, &s);
+       if (!p || (rc = __mnt_fs_set_fstype_ptr(fs, p))) {
+               DBG(TAB, ul_debug("tab parse error: [fstype]"));
+               goto fail;
+       }
 
-                       if (strcmp(ptr, PATH_DELETED_SUFFIX) == 0)
-                               *ptr = '\0';
+       /* (9) source -- maybe empty string */
+       if (!s || !*s) {
+               DBG(TAB, ul_debug("tab parse error: [source]"));
+               goto fail;
+       } else if (*s == ' ' && *(s+1) == ' ') {
+               if ((rc = mnt_fs_set_source(fs, ""))) {
+                       DBG(TAB, ul_debug("tab parse error: [empty source]"));
+                       goto fail;
                }
-
-               unmangle_string(fs->root);
-               unmangle_string(fs->target);
-               unmangle_string(fs->vfs_optstr);
-               unmangle_string(fstype);
-               unmangle_string(src);
-               unmangle_string(fs->fs_optstr);
-
-               rc = __mnt_fs_set_fstype_ptr(fs, fstype);
-               if (!rc) {
-                       fstype = NULL;
-                       rc = __mnt_fs_set_source_ptr(fs, src);
-                       if (!rc)
-                               src = NULL;
+       } else {
+               s = skip_separator(s);
+               p = unmangle(s, &s);
+               if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
+                       DBG(TAB, ul_debug("tab parse error: [regular source]"));
+                       goto fail;
                }
+       }
 
-               /* merge VFS and FS options to one string */
-               fs->optstr = mnt_fs_strdup_options(fs);
-               if (!fs->optstr)
-                       rc = -ENOMEM;
-       } else {
-               DBG(TAB, ul_debug(
-                       "mountinfo parse error [sscanf rc=%d]: '%s'", rc, s));
-               rc = -EINVAL;
+       s = skip_separator(s);
+
+       /* (10) fs options (fs specific) */
+       fs->fs_optstr = unmangle(s, &s);
+       if (!fs->fs_optstr) {
+               DBG(TAB, ul_debug("tab parse error: [FS options]"));
+               goto fail;
        }
 
-       free(fstype);
-       free(src);
+       /* merge VFS and FS options to one string */
+       fs->optstr = mnt_fs_strdup_options(fs);
+       if (!fs->optstr) {
+               rc = -ENOMEM;
+               DBG(TAB, ul_debug("tab parse error: [merge VFS and FS options]"));
+               goto fail;
+       }
 
+       return 0;
+fail:
+       if (rc == 0)
+               rc = -EINVAL;
+       DBG(TAB, ul_debug("tab parse error on: '%s' [rc=%d]", s, rc));
        return rc;
 }