[PATCH v3 1/2] io/channel: fix crash when qio_channel_readv_all return 0

[Li Feng]

Root cause:
>From `man recvmsg`, the RETURN VALUE says:
These  calls return the number of bytes received, or -1 if an error occurred.
In the event of an error, errno is set to indicate the error.
The return value will be 0 when the peer has performed an orderly shutdown.

When an error happens, the socket will be closed, and recvmsg return 0,
then error_setg will trigger a crash.

This unit test could reproduce this issue:
tests/test-char -p /char/socket/client/reconnect-error/unix

The core file backtrace is :

(gdb) bt
    #0  0x00007ffff5ac3277 in raise () from /lib64/libc.so.6
    #1  0x00007ffff5ac4968 in abort () from /lib64/libc.so.6
    #2  0x00005555555aaa94 in error_handle_fatal (errp=<optimized out>, 
err=0x7fffec0012d0) at util/error.c:40
    #3  0x00005555555aab6d in error_setv (errp=0x555555802a08 <error_abort>, 
src=0x5555555c4280 "io/channel.c", line=148,
        func=0x5555555c4580 <__func__.17489> "qio_channel_readv_all", 
err_class=ERROR_CLASS_GENERIC_ERROR,
        fmt=<optimized out>, ap=0x7ffff423bae0, suffix=0x0) at util/error.c:73
    #4  0x00005555555aacf0 in error_setg_internal 
(errp=errp@entry=0x555555802a08 <error_abort>,
        src=src@entry=0x5555555c4280 "io/channel.c", line=line@entry=148,
        func=func@entry=0x5555555c4580 <__func__.17489> "qio_channel_readv_all",
        fmt=fmt@entry=0x5555555c43a0 "Unexpected end-of-file before all bytes 
were read") at util/error.c:97
    #5  0x000055555556c25c in qio_channel_readv_all (ioc=<optimized out>, 
iov=<optimized out>, niov=<optimized out>,
        errp=0x555555802a08 <error_abort>) at io/channel.c:147
    #6  0x000055555556c29a in qio_channel_read_all (ioc=<optimized out>, 
buf=<optimized out>, buflen=<optimized out>,
        errp=<optimized out>) at io/channel.c:247
    #7  0x000055555556ad22 in char_socket_ping_pong (ioc=0x7fffec0008c0) at 
tests/test-char.c:732
    #8  0x000055555556ae12 in char_socket_client_server_thread 
(data=data@entry=0x55555582e350) at tests/test-char.c:891
    #9  0x00005555555a95b6 in qemu_thread_start (args=<optimized out>) at 
util/qemu-thread-posix.c:519
    #10 0x00007ffff5e61e25 in start_thread () from /lib64/libpthread.so.0
    #11 0x00007ffff5b8bbad in clone () from /lib64/libc.so.6

Signed-off-by: Li Feng <address@hidden>
---
 io/channel.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/io/channel.c b/io/channel.c
index e4376eb0bc..1a4a505f01 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -144,8 +144,6 @@ int qio_channel_readv_all(QIOChannel *ioc,
 
     if (ret == 0) {
         ret = -1;
-        error_setg(errp,
-                   "Unexpected end-of-file before all bytes were read");
     } else if (ret == 1) {
         ret = 0;
     }
-- 
2.11.0