From 1fc7e3473c2fec27bdc0b19753e4ea84cd39644f Mon Sep 17 00:00:00 2001
From: Mike Yuan <me@yhndnzj.com>
Date: Wed, 24 Jul 2024 16:28:48 +0200
Subject: [PATCH] basic/log: do not treat all negative errnos as synthetic

Currently, IS_SYNTHETIC_ERRNO() evaluates to true for all negative errnos,
because of the two's-complement negative value representation.
Subsequently, ERRNO= is not logged for most of our own code.
Let's fix this, by formatting all synthetic errnos as positive.
Then, treat all negative values as non-synthetic.

While at it, mark the evaluation order explicitly, and remove
unneeded comment.

Fixes #33800

(cherry picked from commit 268f58076f7e0258dce75f521d08199092279853)
(cherry picked from commit 4ad6b2631d73a574859a62d33715a7bdef810bcf)

Conflict:NA
Reference:https://github.com/systemd/systemd/commit/1fc7e3473c2fec27bdc0b19753e4ea84cd39644f
---
 src/basic/log.h     |  5 ++---
 src/test/test-log.c | 14 +++++++++-----
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/basic/log.h b/src/basic/log.h
index 9008d47390..12b310575e 100644
--- a/src/basic/log.h
+++ b/src/basic/log.h
@@ -34,9 +34,8 @@ typedef enum LogTarget{
  * used a regular log level. */
 #define LOG_NULL (LOG_EMERG - 1)
 
-/* Note to readers: << and >> have lower precedence (are evaluated earlier) than & and | */
-#define SYNTHETIC_ERRNO(num)                (1 << 30 | (num))
-#define IS_SYNTHETIC_ERRNO(val)             ((val) >> 30 & 1)
+#define SYNTHETIC_ERRNO(num)                (abs(num) | (1 << 30))
+#define IS_SYNTHETIC_ERRNO(val)             (((val) >> 30) == 1)
 #define ERRNO_VALUE(val)                    (abs(val) & ~(1 << 30))
 
 /* The callback function to be invoked when syntax warnings are seen
diff --git a/src/test/test-log.c b/src/test/test-log.c
index b5ba67b74b..cc8c400cc1 100644
--- a/src/test/test-log.c
+++ b/src/test/test-log.c
@@ -13,11 +13,6 @@
 #include "strv.h"
 #include "tests.h"
 
-assert_cc(IS_SYNTHETIC_ERRNO(SYNTHETIC_ERRNO(EINVAL)));
-assert_cc(!IS_SYNTHETIC_ERRNO(EINVAL));
-assert_cc(IS_SYNTHETIC_ERRNO(SYNTHETIC_ERRNO(0)));
-assert_cc(!IS_SYNTHETIC_ERRNO(0));
-
 #define X10(x) x x x x x x x x x x
 #define X100(x) X10(X10(x))
 #define X1000(x) X100(X10(x))
@@ -207,6 +202,15 @@ static void test_log_prefix(void) {
 int main(int argc, char* argv[]) {
         test_setup_logging(LOG_DEBUG);
 
+        assert_se(IS_SYNTHETIC_ERRNO(SYNTHETIC_ERRNO(EINVAL)));
+        assert_se(IS_SYNTHETIC_ERRNO(SYNTHETIC_ERRNO(-EINVAL)));
+        assert_cc(!IS_SYNTHETIC_ERRNO(EINVAL));
+        assert_cc(!IS_SYNTHETIC_ERRNO(-EINVAL));
+        assert_se(IS_SYNTHETIC_ERRNO(SYNTHETIC_ERRNO(0)));
+        assert_cc(!IS_SYNTHETIC_ERRNO(0));
+        assert_se(ERRNO_VALUE(EINVAL) == EINVAL);
+        assert_se(ERRNO_VALUE(SYNTHETIC_ERRNO(-EINVAL)) == EINVAL);
+
         test_file();
 
         assert_se(log_info_errno(SYNTHETIC_ERRNO(EUCLEAN), "foo") == -EUCLEAN);
-- 
2.33.0

