diff mbox series

[PULL,6/9] linux-user: don't short-circuit read with zero length

Message ID 20190307100656.14044-7-laurent@vivier.eu
State New
Headers show
Series [PULL,1/9] linux-user: fix recvmsg emulation | expand

Commit Message

Laurent Vivier March 7, 2019, 10:06 a.m. UTC 
From: Andreas Schwab <schwab@suse.de>

A zero-length read still needs to do the usual checks, thus it may return
errors like EBADF.  This makes the read syscall emulation consistent with
the pread64 syscall emulation.

Signed-off-by: Andreas Schwab <schwab@suse.de>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <mvm5zsxz2we.fsf@suse.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/syscall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5f72209debc9..9f7eb7d7a896 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7009,8 +7009,8 @@  static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
         _exit(arg1);
         return 0; /* avoid warning */
     case TARGET_NR_read:
-        if (arg3 == 0) {
-            return 0;
+        if (arg2 == 0 && arg3 == 0) {
+            return get_errno(safe_read(arg1, 0, 0));
         } else {
             if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0)))
                 return -TARGET_EFAULT;