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/* Copyright (C) 2011-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <fcntl.h>
#include <limits.h>
#include <paths.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/uio.h>
/* The purpose of this test is to verify that the INTERNAL_[V]SYSCALL_NCS
macros on 64-bit platforms don't cast the return type to (int) which would
erroneously sign extend the return value should the high bit of the bottom
half of the word be '1'. */
#if 0
/* Used to test the non power-of-2 code path. */
#undef IOV_MAX
#define IOV_MAX 1000
#endif
/* writev() should report that it has written EXPECTED number of bytes. */
#define EXPECTED ((size_t) INT32_MAX + 1)
static int
do_test (void)
{
struct iovec iv[IOV_MAX];
/* POSIX doesn't guarantee that IOV_MAX is pow of 2 but we're optimistic. */
size_t bufsz = EXPECTED / IOV_MAX;
size_t bufrem = EXPECTED % IOV_MAX;
/* If there's a remainder then IOV_MAX probably isn't a power of 2 and we
need to make bufsz bigger so that the last iovec, iv[IOV_MAX-1], is free
for the remainder. */
if (bufrem)
{
bufsz = bufsz + 1;
bufrem = EXPECTED - (bufsz * (IOV_MAX - 1));
}
/* We writev to /dev/null since we're just testing writev's return value. */
int fd = open (_PATH_DEVNULL, O_WRONLY);
if (fd == -1)
{
printf ("Unable to open /dev/null for writing.\n");
return -1;
}
iv[0].iov_base = malloc (bufsz);
if (iv[0].iov_base == NULL)
{
printf ("malloc (%zu) failed.\n", bufsz);
close (fd);
return -1;
}
iv[0].iov_len = bufsz;
/* We optimistically presume that there isn't a remainder and set all iovec
instances to the same base and len as the first instance. */
for (int i = 1; i < IOV_MAX; i++)
{
/* We don't care what the data is so reuse the allocation from iv[0]; */
iv[i].iov_base = iv[0].iov_base;
iv[i].iov_len = iv[0].iov_len;
}
/* If there is a remainder then we correct the last iov_len. */
if (bufrem)
iv[IOV_MAX - 1].iov_len = bufrem;
/* Write junk to /dev/null with the writev syscall in order to get a return
of INT32_MAX+1 bytes to verify that the INTERNAL_SYSCALL wrappers aren't
mangling the result if the signbit of a 32-bit number is set. */
ssize_t ret = writev (fd, iv, IOV_MAX);
free (iv[0].iov_base);
close (fd);
if (ret != (ssize_t) EXPECTED)
{
#ifdef ARTIFICIAL_LIMIT
if (ret != (ssize_t) ARTIFICIAL_LIMIT)
#endif
{
printf ("writev() return value: %zd != EXPECTED: %zd\n",
ret, EXPECTED);
return 1;
}
}
return 0;
}
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
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