Initial project import

tools/v/vlib/io/util/util.v

@@ -0,0 +1,85 @@
+module util
+
+import os
+import rand
+
+const retries = 10000
+
+@[params]
+pub struct TempFileOptions {
+pub:
+	path    string = os.temp_dir()
+	pattern string
+}
+
+// temp_file returns a uniquely named, open, writable, `os.File` and it's path.
+pub fn temp_file(tfo TempFileOptions) !(os.File, string) {
+	mut d := tfo.path
+	if d == '' {
+		d = os.temp_dir()
+	}
+	os.ensure_folder_is_writable(d) or {
+		return error(@FN +
+			' could not create temporary file in "${d}". Please ensure write permissions.')
+	}
+	d = d.trim_right(os.path_separator)
+	prefix, suffix := prefix_and_suffix(tfo.pattern) or { return error(@FN + ' ${err.msg()}') }
+	for retry := 0; retry < retries; retry++ {
+		path := os.join_path(d, prefix + random_number() + suffix)
+		mut mode := 'rw+'
+		$if windows {
+			mode = 'w+'
+		}
+		mut file := os.open_file(path, mode, 0o600) or { continue }
+		if os.exists(path) && os.is_file(path) {
+			return file, path
+		}
+	}
+	return error(@FN +
+		' could not create temporary file in "${d}". Retry limit (${retries}) exhausted. Please ensure write permissions.')
+}
+
+@[params]
+pub struct TempDirOptions {
+pub:
+	path    string = os.temp_dir()
+	pattern string
+}
+
+fn error_for_temporary_folder(fn_name string, d string) !string {
+	return error('${fn_name} could not create temporary directory "${d}". Please ensure you have write permissions for it.')
+}
+
+// temp_dir returns a uniquely named, writable, directory path.
+pub fn temp_dir(tdo TempDirOptions) !string {
+	mut d := tdo.path
+	if d == '' {
+		d = os.temp_dir()
+	}
+	os.ensure_folder_is_writable(d) or { return error_for_temporary_folder(@FN, d) }
+	d = d.trim_right(os.path_separator)
+	prefix, suffix := prefix_and_suffix(tdo.pattern) or { return error(@FN + ' ${err.msg()}') }
+	for retry := 0; retry < retries; retry++ {
+		path := os.join_path(d, prefix + random_number() + suffix)
+		os.mkdir_all(path) or { continue }
+		if os.is_dir(path) && os.exists(path) {
+			os.ensure_folder_is_writable(path) or { return error_for_temporary_folder(@FN, d) }
+			return path
+		}
+	}
+	return error('${@FN} could not create temporary directory "${d}". Retry limit (${retries}) exhausted.')
+}
+
+// * Utility functions
+fn random_number() string {
+	s := (1_000_000_000 + (u32(os.getpid()) + rand.u32n(1_000_000_000) or { 0 })).str()
+	return s.substr(1, s.len)
+}
+
+fn prefix_and_suffix(pattern string) !(string, string) {
+	if pattern.contains(os.path_separator) {
+		return error('pattern cannot contain path separators (${os.path_separator}).')
+	}
+	prefix, suffix := pattern.rsplit_once('*') or { pattern, '' }
+	return prefix, suffix
+}