This is a maintenance fork
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.h"
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/iovec.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/sysv/consts/iov.h"
#include "libc/sysv/errfuns.h"
#define __NR_pwritev_linux 0x0128
/**
* Writes data from multiple buffers to offset.
*
* Please note that it's not an error for a short write to happen. This
* can happen in the kernel if EINTR happens after some of the write has
* been committed. It can also happen if we need to polyfill this system
* call using pwrite().
*
* @param count is recommended to be 16 or fewer; if it exceeds IOV_MAX
* then the extra buffers are simply ignored
* @return number of bytes actually sent, or -1 w/ errno
*/
ssize_t pwritev(int fd, const struct iovec *iovec, int count, int64_t off) {
static bool once, demodernize;
int olderr;
ssize_t rc;
if (!count) return 0;
if ((count = min(count, IOV_MAX)) < 0) return einval();
/*
* NT, XNU, and 2007-era Linux don't support this system call.
*/
if (!once) {
once = true;
if (IsModeDbg() || (IsLinux() && iovec->iov_len >= __NR_pwritev_linux)) {
/*
* Write size is too large to detect older kernels safely without
* introducing nontrivial mechanics. We'll try again later.
*/
once = false;
demodernize = true;
} else {
olderr = errno;
rc = pwritev$sysv(fd, iovec, count, off);
if (rc == -1 && errno == ENOSYS) {
errno = olderr;
demodernize = true;
} else if (IsLinux() &&
rc == __NR_pwritev_linux /*RHEL5:CVE-2010-3301*/) {
demodernize = true;
} else {
return rc;
}
}
}
if (!demodernize) {
return pwritev$sysv(fd, iovec, count, off);
} else {
return pwrite(fd, iovec[0].iov_base, iovec[0].iov_len, off);
}
}