systemd/1232-Introduce-RET_GATHER-and-use-it-in-src-shared.patch

From 5bec9826a14483e7e612879fe2630f1b517e37be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Sun, 9 Jul 2023 13:25:42 -0600
Subject: [PATCH] Introduce RET_GATHER and use it in src/shared/

The idea is to make it easier to implement the common pattern of
accumulating errors (negative values) in an accumulator to return
the first error.

(cherry picked from commit 809c3a84e1a572ccaaa7eca5394c0b842118c22f)

Resolves: RHEL-108598
---
 src/basic/errno-util.h     | 10 ++++++++++
 src/shared/bus-util.c      | 10 ++--------
 src/shared/devnode-acl.c   |  4 ++--
 src/shared/nscd-flush.c    | 16 +++++-----------
 src/test/test-errno-util.c | 11 +++++++++++
 5 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/src/basic/errno-util.h b/src/basic/errno-util.h
index b10dd755c9..27804e6382 100644
--- a/src/basic/errno-util.h
+++ b/src/basic/errno-util.h
@@ -74,6 +74,16 @@ static inline int RET_NERRNO(int ret) {
         return ret;
 }
 
+/* Collect possible errors in <acc>, so that the first error can be returned.
+ * Returns (possibly updated) <acc>. */
+#define RET_GATHER(acc, err)                    \
+        ({                                      \
+                int *__a = &(acc), __e = (err); \
+                if (*__a >= 0 && __e < 0)       \
+                        *__a = __e;             \
+                *__a;                           \
+        })
+
 static inline int errno_or_else(int fallback) {
         /* To be used when invoking library calls where errno handling is not defined clearly: we return
          * errno if it is set, and the specified error otherwise. The idea is that the caller initializes
diff --git a/src/shared/bus-util.c b/src/shared/bus-util.c
index 5e6d17d201..7c8d2aa6f5 100644
--- a/src/shared/bus-util.c
+++ b/src/shared/bus-util.c
@@ -484,14 +484,8 @@ int bus_track_add_name_many(sd_bus_track *t, char **l) {
 
         /* Continues adding after failure, and returns the first failure. */
 
-        STRV_FOREACH(i, l) {
-                int k;
-
-                k = sd_bus_track_add_name(t, *i);
-                if (k < 0 && r >= 0)
-                        r = k;
-        }
-
+        STRV_FOREACH(i, l)
+                RET_GATHER(r, sd_bus_track_add_name(t, *i));
         return r;
 }
 
diff --git a/src/shared/devnode-acl.c b/src/shared/devnode-acl.c
index 66e3a40f2f..8c961061cf 100644
--- a/src/shared/devnode-acl.c
+++ b/src/shared/devnode-acl.c
@@ -220,8 +220,8 @@ int devnode_acl_all(const char *seat,
                 k = devnode_acl(n, flush, del, old_uid, add, new_uid);
                 if (k == -ENOENT)
                         log_debug("Device %s disappeared while setting ACLs", n);
-                else if (k < 0 && r == 0)
-                        r = k;
+                else
+                        RET_GATHER(r, k);
         }
 
         return r;
diff --git a/src/shared/nscd-flush.c b/src/shared/nscd-flush.c
index 9b0ba2d67a..d2b41f2b4d 100644
--- a/src/shared/nscd-flush.c
+++ b/src/shared/nscd-flush.c
@@ -128,21 +128,15 @@ static int nscd_flush_cache_one(const char *database, usec_t end) {
 }
 
 int nscd_flush_cache(char **databases) {
-        usec_t end;
         int r = 0;
 
-        /* Tries to invalidate the specified database in nscd. We do this carefully, with a 5s timeout, so that we
-         * don't block indefinitely on another service. */
+        /* Tries to invalidate the specified database in nscd. We do this carefully, with a 5s timeout,
+         * so that we don't block indefinitely on another service. */
 
-        end = usec_add(now(CLOCK_MONOTONIC), NSCD_FLUSH_CACHE_TIMEOUT_USEC);
+        usec_t end = usec_add(now(CLOCK_MONOTONIC), NSCD_FLUSH_CACHE_TIMEOUT_USEC);
 
-        STRV_FOREACH(i, databases) {
-                int k;
-
-                k = nscd_flush_cache_one(*i, end);
-                if (k < 0 && r >= 0)
-                        r = k;
-        }
+        STRV_FOREACH(i, databases)
+                RET_GATHER(r, nscd_flush_cache_one(*i, end));
 
         return r;
 }
diff --git a/src/test/test-errno-util.c b/src/test/test-errno-util.c
index cac0d5402b..77fb7d0011 100644
--- a/src/test/test-errno-util.c
+++ b/src/test/test-errno-util.c
@@ -67,4 +67,15 @@ TEST(ERRNO_IS_TRANSIENT) {
         assert_se(!ERRNO_IS_NEG_TRANSIENT(INTMAX_MIN));
 }
 
+TEST(RET_GATHER) {
+        int x = 0, y = 2;
+
+        assert_se(RET_GATHER(x, 5) == 0);
+        assert_se(RET_GATHER(x, -5) == -5);
+        assert_se(RET_GATHER(x, -1) == -5);
+
+        assert_se(RET_GATHER(x, y++) == -5);
+        assert_se(y == 3);
+}
+
 DEFINE_TEST_MAIN(LOG_INFO);