At the time of this writing, glibc-2.26 has a bug where #85
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sysconf(_SC_IOV_MAX); always returns -1. Versions known to have this bug are glibc-2.26-8 in Fedora 27 beta and glibc-2.26.90-16 in Fedora 28 rawhide. Upstream glibc BZ at https://sourceware.org/bugzilla/show_bug.cgi?id=22321 Linux does have a limit on the size of the iovec that is passed in readv/writev syscalls; defined as UIO_MAXIOV (i.e. 1024) in .../include/uapi/linux/uio.h. See kernel source readv/writev syscalls. It's also possible to get _XOPEN_IOV_MAX (i.e. 16) and IOV_MAX (1024) by wrapping <limits.h> with #define __USE_XOPEN ... #undef but that's XOpen and theoretically Linux could change.
dang
approved these changes
Oct 19, 2017
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sysconf(_SC_IOV_MAX);
always returns -1.
Versions known to have this bug are glibc-2.26-8 in Fedora 27 beta
and glibc-2.26.90-16 in Fedora 28 rawhide.
Upstream glibc BZ at
https://sourceware.org/bugzilla/show_bug.cgi?id=22321
Linux does have a limit on the size of the iovec that is passed in
readv/writev syscalls; defined as UIO_MAXIOV (i.e. 1024) in
.../include/uapi/linux/uio.h. See kernel source readv/writev syscalls.
It's also possible to get _XOPEN_IOV_MAX (i.e. 16) and IOV_MAX (1024)
by wrapping <limits.h> with #define __USE_XOPEN ... #undef but that's
XOpen and theoretically Linux could change.