On 04/23/2014 08:06 AM, qq qq wrote: > writev() does not accept count 0 but it should
POSIX says: http://pubs.opengroup.org/onlinepubs/9699919799/functions/writev.html If fildes refers to a regular file and all of the iov_len members in the array pointed to by iov are 0, writev() shall return 0 and have no other effect. For other file types, the behavior is unspecified. > > $ cat test.c > #include <stdio.h> > #include <errno.h> > #include <stdlib.h> > #include <string.h> > #include <sys/uio.h> > > int main() > { > struct iovec vec; > > memset(&vec, 0, sizeof(vec)); > if (writev(1, &vec, 0) < 0) But in your case, fd 1 is a terminal... > Cygwin: > $ gcc -Wall test.c > $ ./a.exe > writev: Invalid argument so your argument is flawed - you have triggered undefined behavior. That said, if you can reproduce it with ./a.exe > file, you have proven a bug; furthermore, cygwin should emulate Linux behavior, even if POSIX doesn't define the behavior. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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