libmount: make mnt_match_options() more robust

* don't allocate and use a buffer for the pattern if the pattern is empty

* make it more obvious how empty pattern and empty optstr is evaluated

* add regression test

Reported-by: Sören Tempel <soeren@soeren-tempel.net>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libmount/src/optstr.c b/libmount/src/optstr.c
index a8b56e212f71ee3f98965e13c81b740fe623e788..4fbbb085950c41df729203a53aee41d2ac0ce638 100644 (file)
--- a/libmount/src/optstr.c
+++ b/libmount/src/optstr.c
@@ -58,6 +58,8 @@ static int mnt_optstr_locate_option(char *optstr, const char *name,
        assert(name);
 
        namesz = strlen(name);
+       if (!namesz)
+               return 1;
 
        do {
                rc = ul_optstr_next(&optstr, &n, &nsz,
@@ -808,6 +810,8 @@ err:
  * The "no" prefix interpretation could be disabled by the "+" prefix, for example
  * "+noauto" matches if @optstr literally contains the "noauto" string.
  *
+ * The alone "no" is error and all matching ends with False.
+ *
  * "xxx,yyy,zzz" : "nozzz"     -> False
  *
  * "xxx,yyy,zzz" : "xxx,noeee" -> True
@@ -820,6 +824,17 @@ err:
  *
  * "bar,zzz"     : "+nofoo"     -> False       (does not contain "nofoo")
  *
+ * "bar,zzz"     : "" or  "+"   -> True                (empty pattern is matching)
+ *
+ * ""            : ""           -> True
+ *
+ * ""            : "foo"        -> False
+ *
+ * ""            : "nofoo"      -> True
+ *
+ * ""            : "no,foo"     -> False       (alone "no" is error)
+ *
+ * "no"          : "+no"        -> True                ("no" is an option due to "+")
  *
  * Returns: 1 if pattern is matching, else 0. This function also returns 0
  *          if @pattern is NULL and @optstr is non-NULL.
@@ -827,35 +842,50 @@ err:
 int mnt_match_options(const char *optstr, const char *pattern)
 {
        char *name, *pat = (char *) pattern;
-       char *buf, *patval;
+       char *buf = NULL, *patval;
        size_t namesz = 0, patvalsz = 0;
        int match = 1;
 
        if (!pattern && !optstr)
                return 1;
+       if (pattern && optstr && !*pattern && !*optstr)
+               return 1;
        if (!pattern)
                return 0;
 
-       buf = malloc(strlen(pattern) + 1);
-       if (!buf)
-               return 0;
-
        /* walk on pattern string
         */
        while (match && !mnt_optstr_next_option(&pat, &name, &namesz,
                                                &patval, &patvalsz)) {
                char *val;
-               size_t sz;
+               size_t sz = 0;
                int no = 0, rc;
 
                if (*name == '+')
                        name++, namesz--;
-               else if ((no = (startswith(name, "no") != NULL)))
+               else if ((no = (startswith(name, "no") != NULL))) {
                        name += 2, namesz -= 2;
+                       if (!*name) {
+                               match = 0;
+                               break;  /* alone "no" keyword is error */
+                       }
+               }
 
-               xstrncpy(buf, name, namesz + 1);
+               if (optstr && *optstr && *name) {
+                       if (!buf) {
+                               buf = malloc(strlen(pattern) + 1);
+                               if (!buf)
+                                       return 0;
+                       }
 
-               rc = mnt_optstr_get_option(optstr, buf, &val, &sz);
+                       xstrncpy(buf, name, namesz + 1);
+                       rc = mnt_optstr_get_option(optstr, buf, &val, &sz);
+
+               } else if (!*name) {
+                       rc = 0;         /* empty pattern matches */
+               } else {
+                       rc = 1;         /* not found in empty string */
+               }
 
                /* check also value (if the pattern is "foo=value") */
                if (rc == 0 && patvalsz > 0 &&
@@ -873,7 +903,6 @@ int mnt_match_options(const char *optstr, const char *pattern)
                        match = 0;
                        break;
                }
-
        }
 
        free(buf);
@@ -1091,6 +1120,21 @@ static int test_dedup(struct libmnt_test *ts, int argc, char *argv[])
        return rc;
 }
 
+static int test_match(struct libmnt_test *ts, int argc, char *argv[])
+{
+       char *optstr, *pattern;
+
+       if (argc < 3)
+               return -EINVAL;
+
+       optstr = argv[1];
+       pattern = argv[2];
+       printf("%-6s: \"%s\"\t:\t\"%s\"\n",
+                       mnt_match_options(optstr, pattern) == 1 ? "true" : "false",
+                       optstr, pattern);
+       return 0;
+}
+
 int main(int argc, char *argv[])
 {
        struct libmnt_test tss[] = {
@@ -1100,6 +1144,7 @@ int main(int argc, char *argv[])
                { "--get",    test_get,    "<optstr> <name>            search name in optstr" },
                { "--remove", test_remove, "<optstr> <name>            remove name in optstr" },
                { "--dedup",  test_dedup,  "<optstr> <name>            deduplicate name in optstr" },
+               { "--match",  test_match,  "<optstr> <pattern>         compare optstr with pattern" },
                { "--split",  test_split,  "<optstr>                   split into FS, VFS and userspace" },
                { "--flags",  test_flags,  "<optstr>                   convert options to MS_* flags" },
                { "--apply",  test_apply,  "--{linux,user} <optstr> <mask>    apply mask to optstr" },

diff --git a/tests/expected/libmount/optstr-match b/tests/expected/libmount/optstr-match
new file mode 100644 (file)
index 0000000..1fc862f
--- /dev/null
+++ b/tests/expected/libmount/optstr-match
@@ -0,0 +1,13 @@
+false : "xxx,yyy,zzz"  :       "nozzz"
+true  : "xxx,yyy,zzz"  :       "xxx,noeee"
+true  : "bar,zzz"      :       "nofoo"
+true  : "nofoo,bar"    :       "nofoo"
+true  : "nofoo,bar"    :       "+nofoo"
+false : "bar,zzz"      :       "+nofoo"
+true  : "bar,zzz"      :       ""
+true  : "bar,zzz"      :       "+"
+true  : ""     :       ""
+false : ""     :       "foo"
+true  : ""     :       "nofoo"
+false : ""     :       "no,foo"
+true  : "no"   :       "+no"

diff --git a/tests/ts/libmount/optstr b/tests/ts/libmount/optstr
index 65fa8a31ac48b0526ff43b2aed46c2130613ec51..26d9b73f4ab30eaab1df25816b10cfa0806ba6d8 100755 (executable)
--- a/tests/ts/libmount/optstr
+++ b/tests/ts/libmount/optstr
@@ -141,4 +141,20 @@ ts_init_subtest "deduplicate-empty"
 ts_run $TESTPROG --dedup bbb,ccc,AAA,xxx,AAA=a,AAA=bbb,ddd,AAA=,fff=eee AAA &> $TS_OUTPUT
 ts_finalize_subtest
 
+ts_init_subtest "match"
+ts_run $TESTPROG --match "xxx,yyy,zzz" "nozzz"         &>> $TS_OUTPUT
+ts_run $TESTPROG --match "xxx,yyy,zzz" "xxx,noeee"     &>> $TS_OUTPUT
+ts_run $TESTPROG --match "bar,zzz"     "nofoo"         &>> $TS_OUTPUT
+ts_run $TESTPROG --match "nofoo,bar"   "nofoo"         &>> $TS_OUTPUT
+ts_run $TESTPROG --match "nofoo,bar"   "+nofoo"                &>> $TS_OUTPUT
+ts_run $TESTPROG --match "bar,zzz"     "+nofoo"                &>> $TS_OUTPUT
+ts_run $TESTPROG --match "bar,zzz"     ""              &>> $TS_OUTPUT
+ts_run $TESTPROG --match "bar,zzz"     "+"             &>> $TS_OUTPUT
+ts_run $TESTPROG --match ""            ""              &>> $TS_OUTPUT
+ts_run $TESTPROG --match ""            "foo"           &>> $TS_OUTPUT
+ts_run $TESTPROG --match ""            "nofoo"         &>> $TS_OUTPUT
+ts_run $TESTPROG --match ""            "no,foo"                &>> $TS_OUTPUT
+ts_run $TESTPROG --match "no"          "+no"           &>> $TS_OUTPUT
+ts_finalize_subtest
+
 ts_finalize