Fix mkpath() ignoring mode when umask is more restrictive

mkpath(dir, 0755) with umask 0027 silently creates a 0750 directory,
since mkdir(2) applies the umask to the requested mode.  Callers pass
an explicit mode and expect exactly that.

Apply the mode with chmod() after each successful mkdir().

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

ChangeLog.md

@@ -4,6 +4,14 @@ Change Log
 All notable changes to the project are documented in this file.
 
 
+[UNRELEASED][]
+--------------
+
+### Fixes
+- Fix `mkpath()`, and `fmkpath()`, not applying the given mode when the
+  process umask is more restrictive, e.g., requesting 0755 with umask
+  0027 silently created a 0750 directory
+
 [v2.6.2][] - 2025-11-22
 -----------------------
 

src/makepath.c

@@ -35,6 +35,9 @@
  * @param dir   Directory to created, relative or absolute
  * @param mode  A &mode_t mode to create @a dir with
  *
+ * Directories are created with exactly @a mode, the process umask is
+ * not applied like it is for mkdir(2).
+ *
  * @returns POSIX OK(0) on success, otherwise -1 with @a errno set.
  */
 int mkpath(const char *dir, mode_t mode)
@@ -51,7 +54,10 @@ int mkpath(const char *dir, mode_t mode)
 
 	mkpath(dirname(strdupa(dir)), mode);
 
-	return mkdir(dir, mode);
+	if (mkdir(dir, mode))
+		return -1;
+
+	return chmod(dir, mode);
 }
 
 /**

test/makepath.c

@@ -50,6 +50,34 @@ int test_fmkpath(const char *subdir)
 	return ret;
 }
 
+/* mkpath() must apply mode as given, not mode & ~umask */
+int test_umask(void)
+{
+	const char *dirs[] = { BASEDIR "/um", BASEDIR "/um/sub", NULL };
+	mode_t old = umask(0077);
+	struct stat sb;
+	int i, ret;
+
+	ret = mkpath(dirs[1], 0755);
+	umask(old);
+	if (ret) {
+		perror("Failed");
+		return ret;
+	}
+
+	for (i = 0; dirs[i]; i++) {
+		if (checkpath(dirs[i]) || stat(dirs[i], &sb))
+			return 1;
+		if ((sb.st_mode & 07777) != 0755) {
+			fprintf(stderr, "Failed: %s mode %04o, expected 0755\n",
+				dirs[i], sb.st_mode & 07777);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 int main(void)
 {
 	int i, ret = 0;
@@ -66,14 +94,18 @@ int main(void)
 
 	mkdir(BASEDIR, 0755);
 
-	printf("Pass 1/2: makepath() =========================\n");
+	printf("Pass 1/3: makepath() =========================\n");
 	for (i = 0; list[i] && !ret; i++)
 		ret |= test_makepath(list[i]);
 
-	printf("Pass 2/2: fmkpath() ==========================\n");
+	printf("Pass 2/3: fmkpath() ==========================\n");
 	for (i = 0; list[i] && !ret; i++)
 		ret |= test_fmkpath(list[i] + strlen(BASEDIR) + 1);
 
+	printf("Pass 3/3: mkpath() with umask ================\n");
+	if (!ret)
+		ret |= test_umask();
+
 	printf("Done: Cleaning up ============================\n");
 	system("rm -rf " BASEDIR);