From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Sat, 28 Jun 2025 19:34:10 +0000 (+0200)
Subject: basic/errno-list: add helper to print errno names
X-Git-Tag: v258-rc1~206^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6020ca2c23b8ab8fd7a8101bad4859c7ace19768;p=thirdparty%2Fsystemd.git

basic/errno-list: add helper to print errno names
---

diff --git a/src/basic/errno-list.c b/src/basic/errno-list.c
index 5bfd8aa076a..8de98880839 100644
--- a/src/basic/errno-list.c
+++ b/src/basic/errno-list.c
@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "errno-list.h"
@@ -33,7 +35,6 @@ const char* errno_to_name(int id) {
 #  include "errno-to-name.inc"
 
 const char* errno_to_name(int id) {
-
         if (id < 0)
                 id = -id;
 
@@ -43,3 +44,11 @@ const char* errno_to_name(int id) {
         return errno_names[id];
 }
 #endif
+
+const char* errno_name_full(int id, char buf[static ERRNO_NAME_BUF_LEN]) {
+        const char *a = errno_to_name(id);
+        if (a)
+                return a;
+        snprintf(buf, ERRNO_NAME_BUF_LEN, "%d", abs(id));
+        return buf;
+}
diff --git a/src/basic/errno-list.h b/src/basic/errno-list.h
index 5b29642ce49..6ce2d75c09a 100644
--- a/src/basic/errno-list.h
+++ b/src/basic/errno-list.h
@@ -9,3 +9,10 @@ int errno_from_name(const char *name) _pure_;
 static inline bool errno_is_valid(int n) {
         return n > 0 && n <= ERRNO_MAX;
 }
+
+#define ERRNO_NAME_BUF_LEN DECIMAL_STR_MAX(int)
+/* Like errno_name, but always returns a string. */
+const char* errno_name_full(int id, char buf[static ERRNO_NAME_BUF_LEN]);
+
+/* A helper to print the errno "name" or number if name is not defined. */
+#define ERRNO_NAME_FULL(errnum) errno_name_full(errnum, (char[ERRNO_NAME_BUF_LEN]){})
diff --git a/src/test/test-errno-list.c b/src/test/test-errno-list.c
index 3bd9ee232ca..c72f657123f 100644
--- a/src/test/test-errno-list.c
+++ b/src/test/test-errno-list.c
@@ -29,4 +29,26 @@ TEST(errno_list) {
         ASSERT_STREQ(errno_to_name(ECONNREFUSED), "ECONNREFUSED");
 }
 
+TEST(errno_name_full) {
+        char buf[ERRNO_NAME_BUF_LEN];
+
+        ASSERT_STREQ(errno_name_full(0, buf), "0");
+        ASSERT_STREQ(errno_name_full(EPERM, buf), "EPERM");
+        ASSERT_STREQ(errno_name_full(ENOENT, buf), "ENOENT");
+        ASSERT_STREQ(errno_name_full(200, buf), "200");
+        ASSERT_STREQ(errno_name_full(-200, buf), "200");
+}
+
+TEST(ERRNO_NAME_FULL) {
+        ASSERT_STREQ(ERRNO_NAME_FULL(0), "0");
+        ASSERT_STREQ(ERRNO_NAME_FULL(EPERM), "EPERM");
+        ASSERT_STREQ(ERRNO_NAME_FULL(ENOENT), "ENOENT");
+        ASSERT_STREQ(ERRNO_NAME_FULL(200), "200");
+        ASSERT_STREQ(ERRNO_NAME_FULL(-200), "200");
+
+        int x = 0;
+        ASSERT_STREQ(ERRNO_NAME_FULL(++x), "EPERM");  /* Confirm that eval happens just once. */
+        ASSERT_EQ(x, 1);
+}
+
 DEFINE_TEST_MAIN(LOG_INFO);