r_mkdir: don't truncate the path on error (#322)

currently, in case of error, r_mkdir will leave the path at a truncated
state.

a7d39b0ab8 is the commit that introduced this change, and in it the
error printing is moved from r_mkdir to the caller, which makes me think
it was probably intentional.

make it so that the function itself prints the error/warning
message and returns the path back to the caller unharmed.

Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/322
Reviewed-by: Berke Kocaoğlu <berke.kocaoglu@metu.edu.tr>
Reviewed-by: TAAPArthur <taaparthur@noreply.codeberg.org>

thumbs.c

@@ -92,10 +92,8 @@ static void tns_cache_write(Imlib_Image im, const char *filepath, bool force)
 		{
 			if ((dirend = strrchr(cfile, '/')) != NULL) {
 				*dirend = '\0';
-				if (r_mkdir(cfile) == -1) {
-					error(0, errno, "%s", cfile);
+				if (r_mkdir(cfile) < 0)
 					goto end;
-				}
 				*dirend = '/';
 			}
 			imlib_context_set_image(im);

util.c

@@ -193,10 +193,11 @@ char* r_readdir(r_dir_t *rdir, bool skip_dotfiles)
 
 int r_mkdir(char *path)
 {
+	int rc = 0;
 	char c, *s = path;
 	struct stat st;
 
-	while (*s != '\0') {
+	while (*s != '\0' && rc == 0) {
 		if (*s == '/') {
 			s++;
 			continue;
@@ -204,12 +205,15 @@ int r_mkdir(char *path)
 		for (; *s != '\0' && *s != '/'; s++);
 		c = *s;
 		*s = '\0';
-		if (mkdir(path, 0755) == -1)
-			if (errno != EEXIST || stat(path, &st) == -1 || !S_ISDIR(st.st_mode))
-				return -1;
+		if (mkdir(path, 0755) == -1) {
+			if (errno != EEXIST || stat(path, &st) == -1 || !S_ISDIR(st.st_mode)) {
+				error(0, errno, "%s", path);
+				rc = -1;
+			}
+		}
 		*s = c;
 	}
-	return 0;
+	return rc;
 }
 
 void construct_argv(char **argv, unsigned int len, ...)