util: when using basename() for creating temporary files, verify the resulting name is actually valid

Also, rename filename_is_safe() to filename_is_valid(), since it
actually does a full validation for what the kernel will accept as file
name, it's not just a heuristic.

NOTE: eudev doesn't have filename_is_safe() -- AGB

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

2 files changed, 8 insertions, 7 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index 1b9edad70c..b53042182d 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -385,7 +385,7 @@ const char* split(const char **state, size_t *l, const char *separator, bool quo
                 *l = strcspn_escaped(current + 1, quotechars);
                 if (current[*l + 1] == '\0' ||
                     (current[*l + 2] && !strchr(separator, current[*l + 2]))) {
-                        /* right quote missing or garbage at the end*/
+                        /* right quote missing or garbage at the end */
                         *state = current;
                         return NULL;
                 }
@@ -1044,15 +1044,15 @@ int fd_wait_for_event(int fd, int event, usec_t t) {
 int fopen_temporary(const char *path, FILE **_f, char **_temp_path) {
         FILE *f;
         char *t;
-        int fd;
+        int r, fd;
 
         assert(path);
         assert(_f);
         assert(_temp_path);
 
-        t = tempfn_xxxxxx(path);
-        if (!t)
-                return -ENOMEM;
+        r = tempfn_xxxxxx(path, &t);
+        if (r < 0)
+                return r;
 
 #if HAVE_DECL_MKOSTEMP
         fd = mkostemp_safe(t, O_WRONLY|O_CLOEXEC);
@@ -1577,7 +1577,8 @@ char *tempfn_xxxxxx(const char *p) {
 
         strcpy(stpcpy(stpcpy(mempcpy(t, p, k), "."), fn), "XXXXXX");
 
-        return t;
+        *ret = t;
+        return 0;
 }
 
 int is_dir(const char* path, bool follow) {
diff --git a/src/shared/util.h b/src/shared/util.h
index 21e977dc51..5cc8452407 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -453,7 +453,7 @@ union file_handle_union {
         char padding[sizeof(struct file_handle) + MAX_HANDLE_SZ];
 };
 
-char *tempfn_xxxxxx(const char *p);
+int tempfn_xxxxxx(const char *p, char **ret);
 
 int is_dir(const char *path, bool follow);