From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Wed, 31 Mar 2021 10:43:00 +0000 (+0200)
Subject: varlink: use two local flag variables to silence gcc warning
X-Git-Tag: v249-rc1~490^2~10
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4990d4b8ffc4fc866d558b7dba727e7fa4e36844;p=thirdparty%2Fsystemd.git

varlink: use two local flag variables to silence gcc warning

[59/655] Compiling C object src/shared/libsystemd-shared-248.a.p/varlink.c.o
../src/shared/varlink.c: In function ‘varlink_write’:
../src/shared/varlink.c:459:12: warning: ‘n’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  459 |         if (n < 0) {
      |            ^
../src/shared/varlink.c: In function ‘varlink_process’:
../src/shared/varlink.c:541:12: warning: ‘n’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  541 |         if (n < 0) {
      |            ^
../src/shared/varlink.c:486:17: note: ‘n’ was declared here
  486 |         ssize_t n;
      |                 ^
---

diff --git a/src/shared/varlink.c b/src/shared/varlink.c
index 6ed72075ba5..a271082ac33 100644
--- a/src/shared/varlink.c
+++ b/src/shared/varlink.c
@@ -448,13 +448,16 @@ static int varlink_write(Varlink *v) {
         assert(v->fd >= 0);
 
         /* We generally prefer recv()/send() (mostly because of MSG_NOSIGNAL) but also want to be compatible
-         * with non-socket IO, hence fall back automatically */
-        if (!v->prefer_read_write) {
+         * with non-socket IO, hence fall back automatically.
+         *
+         * Use a local variable to help gcc figure out that we set 'n' in all cases. */
+        bool prefer_write = v->prefer_read_write;
+        if (!prefer_write) {
                 n = send(v->fd, v->output_buffer + v->output_buffer_index, v->output_buffer_size, MSG_DONTWAIT|MSG_NOSIGNAL);
                 if (n < 0 && errno == ENOTSOCK)
-                        v->prefer_read_write = true;
+                        prefer_write = v->prefer_read_write = true;
         }
-        if (v->prefer_read_write)
+        if (prefer_write)
                 n = write(v->fd, v->output_buffer + v->output_buffer_index, v->output_buffer_size);
         if (n < 0) {
                 if (errno == EAGAIN)
@@ -531,12 +534,13 @@ static int varlink_read(Varlink *v) {
 
         rs = v->input_buffer_allocated - (v->input_buffer_index + v->input_buffer_size);
 
-        if (!v->prefer_read_write) {
+        bool prefer_read = v->prefer_read_write;
+        if (!prefer_read) {
                 n = recv(v->fd, v->input_buffer + v->input_buffer_index + v->input_buffer_size, rs, MSG_DONTWAIT);
                 if (n < 0 && errno == ENOTSOCK)
-                        v->prefer_read_write = true;
+                        prefer_read = v->prefer_read_write = true;
         }
-        if (v->prefer_read_write)
+        if (prefer_read)
                 n = read(v->fd, v->input_buffer + v->input_buffer_index + v->input_buffer_size, rs);
         if (n < 0) {
                 if (errno == EAGAIN)