| Message ID | mvm5zsxz2we.fsf@suse.de |
|---|---|
| State | New |
| Headers | show |
| Series | linux-user: don't short-circuit read with zero length | expand |
Le 05/03/2019 à 17:45, Andreas Schwab a écrit : > 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> > --- > linux-user/syscall.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index ff912e89e1..7fac8e318f 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -7047,8 +7047,8 @@ 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; > Reviewed-by: Laurent Vivier <laurent@vivier.eu>
On 05/03/2019 17:45, Andreas Schwab wrote: > 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> > --- > linux-user/syscall.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index ff912e89e1..7fac8e318f 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -7047,8 +7047,8 @@ 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; > Applied to my linux-user branch. Thanks, Laurent
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index ff912e89e1..7fac8e318f 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7047,8 +7047,8 @@ 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;
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> --- linux-user/syscall.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)