Le 08/09/2018 à 20:22, Tony Garnock-Jones a écrit : > Bring linux-user write(2) handling into line with linux for the case > of a 0-byte write with a NULL buffer. Based on a patch originally > written by Zhuowei Zhang. > > Addresses https://bugs.launchpad.net/qemu/+bug/1716292. > > From Zhuowei Zhang's patch > (https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg08073.html): > > Linux returns success for the special case of calling write with a > zero-length NULL buffer: compiling and running > > int main() { > ssize_t ret = write(STDOUT_FILENO, NULL, 0); > fprintf(stderr, "write returned %ld\n", ret); > return 0; > } > > gives "write returned 0" when run directly, but "write returned > -1" in QEMU. > > This commit checks for this situation and returns success if > found. > > Subsequent discussion raised the following questions (and my answers): > > - Q. Should TARGET_NR_read pass through to safe_read in this > situation too? > A. I'm wary of changing unrelated code to the specific problem I'm > addressing. TARGET_NR_read is already consistent with Linux for > this case. > > - Q. Do pread64/pwrite64 need to be changed similarly? > A. Experiment suggests not: both linux and linux-user yield -1 for > NULL 0-length reads/writes. > > Signed-off-by: Tony Garnock-Jones <tonygarnockjo...@gmail.com> > --- > linux-user/syscall.c | 3 +++ > 1 file changed, 3 insertions(+)
Reviewed-by: Laurent Vivier <laur...@vivier.eu>
