findmnt: improve reliability of match testing

The "match" is defined if a string or void data is defined for the
matching function. It is necessary to test both variants instead of
relying solely on get_match(), which only returns string data.

This patch introduces the is_defined_match() macro to hide this detail
in the code and make it more readable.

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

diff --git a/misc-utils/findmnt.c b/misc-utils/findmnt.c
index 4256789053a6aaec7b3af3655ed61641244a64af..51324841129bc66cdd4f970b1cee41e72763d3fe 100644 (file)
--- a/misc-utils/findmnt.c
+++ b/misc-utils/findmnt.c
@@ -225,6 +225,8 @@ static void *get_match_data(int id)
        return infos[id].match_data;
 }
 
+#define is_defined_match(x)    (get_match(x) || get_match_data(x))
+
 static void set_match(int id, const char *match)
 {
        assert((size_t) id < ARRAY_SIZE(infos));
@@ -314,11 +316,11 @@ int is_listall_mode(unsigned int flags)
        if ((flags & FL_DF || flags & FL_REAL || flags & FL_PSEUDO) && !(flags & FL_ALL))
                return 0;
 
-       return (!get_match(COL_SOURCE) &&
-               !get_match(COL_TARGET) &&
-               !get_match(COL_FSTYPE) &&
-               !get_match(COL_OPTIONS) &&
-               !get_match(COL_MAJMIN));
+       return (!is_defined_match(COL_SOURCE) &&
+               !is_defined_match(COL_TARGET) &&
+               !is_defined_match(COL_FSTYPE) &&
+               !is_defined_match(COL_OPTIONS) &&
+               !is_defined_match(COL_MAJMIN));
 }
 
 /*
@@ -361,9 +363,9 @@ static int poll_action_name_to_id(const char *name, size_t namesz)
  */
 static int is_mount_compatible_mode(unsigned int flags)
 {
-       if (!get_match(COL_SOURCE))
+       if (!is_defined_match(COL_SOURCE))
               return 0;                /* <devname|TAG=|mountpoint> is required */
-       if (get_match(COL_FSTYPE) || get_match(COL_OPTIONS))
+       if (is_defined_match(COL_FSTYPE) || is_defined_match(COL_OPTIONS))
                return 0;               /* cannot be restricted by -t or -O */
        if (!(flags & FL_FIRSTONLY))
                return 0;               /* we have to return the first entry only */
@@ -1265,7 +1267,7 @@ again:
 
                if (!fs &&
                    !(findmnt->flags & FL_NOSWAPMATCH) &&
-                   !get_match(COL_TARGET) && get_match(COL_SOURCE)) {
+                   !is_defined_match(COL_TARGET) && is_defined_match(COL_SOURCE)) {
 
                        /* swap 'spec' and target. */
                        set_match(COL_TARGET, get_match(COL_SOURCE));
@@ -1327,7 +1329,7 @@ static int poll_match(struct libmnt_fs *fs, struct findmnt *findmnt)
        int rc = match_func(fs, findmnt);
 
        if (rc == 0 && !(findmnt->flags & FL_NOSWAPMATCH) &&
-           get_match(COL_SOURCE) && !get_match(COL_TARGET)) {
+           is_defined_match(COL_SOURCE) && !is_defined_match(COL_TARGET)) {
                /*
                 * findmnt --poll /foo
                 * The '/foo' maybe source as well as target.
@@ -2050,7 +2052,7 @@ int main(int argc, char *argv[])
                errx(EXIT_FAILURE, _(
                        "options --kernel=listmount and --tab-file or --task can't be used together"));
 
-       if (optind < argc && (get_match(COL_SOURCE) || get_match(COL_TARGET)))
+       if (optind < argc && (is_defined_match(COL_SOURCE) || is_defined_match(COL_TARGET)))
                errx(EXIT_FAILURE, _(
                        "options --target and --source can't be used together "
                        "with command line element that is not an option"));
@@ -2065,13 +2067,13 @@ int main(int argc, char *argv[])
                findmnt.flags &= ~FL_SUBMOUNTS;
 
        if (!(findmnt.flags & FL_SUBMOUNTS) && ((findmnt.flags & FL_FIRSTONLY)
-           || get_match(COL_TARGET)
-           || get_match(COL_SOURCE)
-           || get_match(COL_MAJMIN)))
+           || is_defined_match(COL_TARGET)
+           || is_defined_match(COL_SOURCE)
+           || is_defined_match(COL_MAJMIN)))
                findmnt.flags &= ~FL_TREE;
 
        if (!(findmnt.flags & FL_NOSWAPMATCH) &&
-           !get_match(COL_TARGET) && get_match(COL_SOURCE)) {
+           !is_defined_match(COL_TARGET) && is_defined_match(COL_SOURCE)) {
                /*
                 * Check if we can swap source and target; it's
                 * not possible if the source is LABEL=/UUID=
@@ -2155,7 +2157,7 @@ int main(int argc, char *argv[])
                    && tabtype == TABTYPE_KERNEL_MOUNTINFO
                    && (findmnt.flags & FL_NOSWAPMATCH)
                    && !(findmnt.flags & FL_STRICTTARGET)
-                   && get_match(COL_TARGET)) {
+                   && is_defined_match(COL_TARGET)) {
                        /*
                         * Found nothing, maybe the --target is regular file,
                         * try it again with extra functionality for target