From fee78fd6d2f8dfdfd447a33c34323dd5bd3193a2 Mon Sep 17 00:00:00 2001
From: Michael Tokarev <mjt@tls.msk.ru>
Date: Thu, 30 Oct 2014 17:40:48 +0300
Subject: [PATCH] pidfile: stop making pidfile error a special case

In case of -daemonize, we write non-zero to the daemon
pipe only if pidfile creation failed, so the parent will
report error about pidfile problem.  There's no need to
make special case for this, since all other errors are
reported by the child just fine.  Let the parent report
error and simplify logic in os_daemonize().

This way, we don't need os_pidfile_error() function, since
it only prints error now, so put the error reporting printf
into the only place where qemu_create_pidfile() is called,
in vl.c.

While at it, fix wrong indentation in os_daemonize().

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 include/qemu-common.h |  1 -
 os-posix.c            | 31 ++++++++-----------------------
 os-win32.c            |  5 -----
 vl.c                  |  2 +-
 4 files changed, 9 insertions(+), 30 deletions(-)

diff --git a/include/qemu-common.h b/include/qemu-common.h
index b87e9c2d8bf..f8622141a80 100644
--- a/include/qemu-common.h
+++ b/include/qemu-common.h
@@ -357,7 +357,6 @@ char *qemu_find_file(int type, const char *name);
 void os_setup_early_signal_handling(void);
 char *os_find_datadir(void);
 void os_parse_cmd_args(int index, const char *optarg);
-void os_pidfile_error(void);
 
 /* Convert a byte between binary and BCD.  */
 static inline uint8_t to_bcd(uint8_t val)
diff --git a/os-posix.c b/os-posix.c
index eada8d46856..52e989797da 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -221,18 +221,14 @@ void os_daemonize(void)
             do {
                 len = read(fds[0], &status, 1);
             } while (len < 0 && errno == EINTR);
-            if (len != 1) {
-                exit(1);
-            }
-            else if (status == 1) {
-                fprintf(stderr, "Could not acquire pidfile\n");
-                exit(1);
-            } else {
-                exit(0);
-            }
-            } else if (pid < 0) {
-                exit(1);
-            }
+
+            /* only exit successfully if our child actually wrote
+             * a one-byte zero to our pipe, upon successful init */
+            exit(len == 1 && status == 0 ? 0 : 1);
+
+        } else if (pid < 0) {
+            exit(1);
+        }
 
         close(fds[0]);
         daemon_pipe = fds[1];
@@ -290,17 +286,6 @@ void os_setup_post(void)
     }
 }
 
-void os_pidfile_error(void)
-{
-    if (daemonize) {
-        uint8_t status = 1;
-        if (write(daemon_pipe, &status, 1) != 1) {
-            perror("daemonize. Writing to pipe\n");
-        }
-    } else
-        fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
-}
-
 void os_set_line_buffering(void)
 {
     setvbuf(stdout, NULL, _IOLBF, 0);
diff --git a/os-win32.c b/os-win32.c
index 5f95caac159..c0daf8e189e 100644
--- a/os-win32.c
+++ b/os-win32.c
@@ -104,11 +104,6 @@ void os_parse_cmd_args(int index, const char *optarg)
     return;
 }
 
-void os_pidfile_error(void)
-{
-    fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
-}
-
 int qemu_create_pidfile(const char *filename)
 {
     char buffer[128];
diff --git a/vl.c b/vl.c
index f6b35469428..150524c718f 100644
--- a/vl.c
+++ b/vl.c
@@ -3999,7 +3999,7 @@ int main(int argc, char **argv, char **envp)
 #endif
 
     if (pid_file && qemu_create_pidfile(pid_file) != 0) {
-        os_pidfile_error();
+        fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
         exit(1);
     }
 
-- 
2.39.5