src/libudev/conf-files.c: fix bug of using basename

BASENAME(3) Linux Programmer's Manual say:
> These functions may return pointers to statically allocated memory
> which may be overwritten by subsequent calls.

Using basename return value as key of hashmap is not safe, it may
cause that hashmap_put always return -EEXIST if hash collision happen.

Using basename return value as strcmp first and second parameters may
always return 0.

Signed-off-by: xiaofan <xiaofan@iscas.ac.cn>

src/shared/conf-files.c

@@ -71,7 +71,7 @@ static int files_add(Hashmap *h, const char *root, const char *path, const char
                 if (!p)
                         return -ENOMEM;
 
-                r = hashmap_put(h, basename(p), p);
+                r = hashmap_put(h, eudev_basename(p), p);
                 if (r == -EEXIST) {
                         log_debug("Skipping overridden file: %s.", p);
                         free(p);
@@ -92,7 +92,7 @@ static int base_cmp(const void *a, const void *b) {
 
         s1 = *(char * const *)a;
         s2 = *(char * const *)b;
-        return strcmp(basename(s1), basename(s2));
+        return strcmp(eudev_basename(s1), eudev_basename(s2));
 }
 
 static int conf_files_list_strv_internal(char ***strv, const char *suffix, const char *root, char **dirs) {

src/shared/util.c

@@ -1725,7 +1725,7 @@ int tempfn_xxxxxx(const char *p, char **ret) {
          *         /foo/bar/.#waldoXXXXXX
          */
 
-        fn = basename((char*)p);
+        fn = eudev_basename(p);
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
@@ -1967,3 +1967,11 @@ void cmsg_close_all(struct msghdr *mh) {
                 if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS)
                         close_many((int*) CMSG_DATA(cmsg), (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int));
 }
+
+const char *eudev_basename(const char *filename) {
+        const char *p = strrchr(filename, '/');
+
+        if (p)
+                return p + 1;
+        return filename;
+}

src/shared/util.h

@@ -433,3 +433,4 @@ union inotify_event_buffer {
 };
 
 void cmsg_close_all(struct msghdr *mh);
+const char *eudev_basename(const char *filename);