From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 12 Dec 2017 22:21:09 +0000 (+0100)
Subject: io-util: make flush_fd() return how many bytes where flushed
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=cccf9018aecbbb5f7c31fa9b552622d053f79a45;p=elogind.git

io-util: make flush_fd() return how many bytes where flushed

This is useful so that callers know whether anything at all and how much
was flushed.

This patches through users of this functions to ensure that the return
values > 0 which may be returned now are not propagated in public APIs.

Also, users that ignore the return value are changed to do so explicitly
now.
---

diff --git a/src/basic/io-util.c b/src/basic/io-util.c
index 77c9bdc73..08ad42ed9 100644
--- a/src/basic/io-util.c
+++ b/src/basic/io-util.c
@@ -33,6 +33,7 @@ int flush_fd(int fd) {
                 .fd = fd,
                 .events = POLLIN,
         };
+        int count = 0;
 
         /* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
          * read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
@@ -52,7 +53,7 @@ int flush_fd(int fd) {
                         return -errno;
 
                 } else if (r == 0)
-                        return 0;
+                        return count;
 
                 l = read(fd, buf, sizeof(buf));
                 if (l < 0) {
@@ -61,11 +62,13 @@ int flush_fd(int fd) {
                                 continue;
 
                         if (errno == EAGAIN)
-                                return 0;
+                                return count;
 
                         return -errno;
                 } else if (l == 0)
-                        return 0;
+                        return count;
+
+                count += (int) l;
         }
 }
 
diff --git a/src/libelogind/sd-login/sd-login.c b/src/libelogind/sd-login/sd-login.c
index a7de8f1c1..bc5f83eb3 100644
--- a/src/libelogind/sd-login/sd-login.c
+++ b/src/libelogind/sd-login/sd-login.c
@@ -1091,10 +1091,15 @@ _public_ sd_login_monitor* sd_login_monitor_unref(sd_login_monitor *m) {
 }
 
 _public_ int sd_login_monitor_flush(sd_login_monitor *m) {
+        int r;
 
         assert_return(m, -EINVAL);
 
-        return flush_fd(MONITOR_TO_FD(m));
+        r = flush_fd(MONITOR_TO_FD(m));
+        if (r < 0)
+                return r;
+
+        return 0;
 }
 
 _public_ int sd_login_monitor_get_fd(sd_login_monitor *m) {