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linux-user: don't short-circuit read with zero length

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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>
This commit is contained in:
Andreas Schwab 2019-03-05 17:45:05 +01:00 committed by Laurent Vivier
parent 14c8a3a157
commit ba584f1de3
1 changed files with 2 additions and 2 deletions
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linux-user/syscall.c
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@ -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;