Fix deadlocks.

1. Close pipe fds[1] as soon as possible. Otherwise it may block when
   reading from fds[0] even though the child process has exited early
   and closed its copy of fds[1].

2. Waitpid after pipe is closed. Otherwise the screencap child process
   may block while writing fds[1], because the fds[0] is not closed
   yet. If we close fds[0] first, then the screencap child process will
   die because of SIGPIPE, and waitpid will return correctly.

Change-Id: I433c95a5ba2eb3045727fc39a49fd9557fb1a1d1
Signed-off-by: Bao Haojun <baohaojun@gmail.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/adb/framebuffer_service.c b/adb/framebuffer_service.c
index fa7fd98..e42dcbf 100644
--- a/adb/framebuffer_service.c
+++ b/adb/framebuffer_service.c
@@ -76,6 +76,7 @@ void framebuffer_service(int fd, void *cookie)
         exit(1);
     }
 
+    close(fds[1]);
     fd_screencap = fds[0];
 
     /* read w, h & format */
@@ -173,10 +174,9 @@ void framebuffer_service(int fd, void *cookie)
     }
 
 done:
-    TEMP_FAILURE_RETRY(waitpid(pid, NULL, 0));
-
     close(fds[0]);
-    close(fds[1]);
+
+    TEMP_FAILURE_RETRY(waitpid(pid, NULL, 0));
 pipefail:
     close(fd);
 }