From: Felix Fietkau <nbd@nbd.name>
Date: Thu, 9 Oct 2025 14:11:55 +0200
Subject: [PATCH] fs: add mkdtemp() method for creating temporary directories

Returns the directory path as a string, following the same template
handling pattern as mkstemp().

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/lib/fs.c
+++ b/lib/fs.c
@@ -2636,6 +2636,86 @@ uc_fs_mkstemp(uc_vm_t *vm, size_t nargs)
 }
 
 /**
+ * Creates a unique temporary directory based on the given template.
+ *
+ * If the template argument is given and contains a relative path, the created
+ * directory will be placed relative to the current working directory.
+ *
+ * If the template argument is given and contains an absolute path, the created
+ * directory will be placed relative to the given directory.
+ *
+ * If the template argument is given but does not contain a directory separator,
+ * the directory will be placed in `/tmp/`.
+ *
+ * If no template argument is given, the default `/tmp/XXXXXX` is used.
+ *
+ * The template argument must end with six consecutive X characters (`XXXXXX`),
+ * which will be replaced with a random string to create the unique directory name.
+ * If the template does not end with `XXXXXX`, it will be automatically appended.
+ *
+ * Returns a string containing the path of the created directory on success.
+ *
+ * Returns `null` if an error occurred, e.g. on insufficient permissions or
+ * inaccessible directory.
+ *
+ * @function module:fs#mkdtemp
+ *
+ * @param {string} [template="/tmp/XXXXXX"]
+ * The path template to use when forming the temporary directory name.
+ *
+ * @returns {?string}
+ *
+ * @example
+ * // Create a unique temporary directory in the current working directory
+ * const tempDir = mkdtemp('./data-XXXXXX');
+ */
+static uc_value_t *
+uc_fs_mkdtemp(uc_vm_t *vm, size_t nargs)
+{
+	uc_value_t *template = uc_fn_arg(0);
+	bool ends_with_template = false;
+	char *path, *t, *result;
+	uc_value_t *rv;
+	size_t l;
+
+	if (template && ucv_type(template) != UC_STRING)
+		err_return(EINVAL);
+
+	t = ucv_string_get(template);
+	l = ucv_string_length(template);
+
+	ends_with_template = (l >= 6 && strcmp(&t[l - 6], "XXXXXX") == 0);
+
+	if (t && strchr(t, '/')) {
+		if (ends_with_template)
+			xasprintf(&path, "%s", t);
+		else
+			xasprintf(&path, "%s.XXXXXX", t);
+	}
+	else if (t) {
+		if (ends_with_template)
+			xasprintf(&path, "/tmp/%s", t);
+		else
+			xasprintf(&path, "/tmp/%s.XXXXXX", t);
+	}
+	else {
+		xasprintf(&path, "/tmp/XXXXXX");
+	}
+
+	result = mkdtemp(path);
+
+	if (!result) {
+		free(path);
+		err_return(errno);
+	}
+
+	rv = ucv_string_new(result);
+	free(path);
+
+	return rv;
+}
+
+/**
  * Checks the accessibility of a file or directory.
  *
  * The optional modes argument specifies the access modes which should be
@@ -3069,6 +3149,7 @@ static const uc_function_list_t global_f
 	{ "basename",	uc_fs_basename },
 	{ "lsdir",		uc_fs_lsdir },
 	{ "mkstemp",	uc_fs_mkstemp },
+	{ "mkdtemp",	uc_fs_mkdtemp },
 	{ "access",		uc_fs_access },
 	{ "readfile",	uc_fs_readfile },
 	{ "writefile",	uc_fs_writefile },