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/* Copyright (C) 1991-2025 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 <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <scratch_buffer.h>
#include <stdbool.h>
#include <sys/param.h>
#include <sys/uio.h>
#include <errno.h>
static void
ifree (struct scratch_buffer *sbuf)
{
scratch_buffer_free (sbuf);
}
/* Read data from file descriptor FD, and put the result in the
buffers described by VECTOR, which is a vector of COUNT 'struct iovec's.
The buffers are filled in the order specified.
Operates just like 'read' (see <unistd.h>) except that data are
put in VECTOR instead of a contiguous buffer. */
ssize_t
__readv (int fd, const struct iovec *vector, int count)
{
/* Find the total number of bytes to be read. */
size_t bytes = 0;
for (int i = 0; i < count; ++i)
{
/* Check for ssize_t overflow. */
if (SSIZE_MAX - bytes < vector[i].iov_len)
{
__set_errno (EINVAL);
return -1;
}
bytes += vector[i].iov_len;
}
/* Allocate a temporary buffer to hold the data. Use a scratch_buffer
since it's faster for small buffer sizes but can handle larger
allocations as well. */
struct scratch_buffer __attribute__ ((__cleanup__ (ifree))) buf;
scratch_buffer_init (&buf);
if (!scratch_buffer_set_array_size (&buf, 1, bytes))
return -1;
char *buffer = buf.data;
/* Read the data. */
ssize_t bytes_read = __read (fd, buffer, bytes);
if (bytes_read < 0)
return -1;
/* Copy the data from BUFFER into the memory specified by VECTOR. */
bytes = bytes_read;
for (int i = 0; i < count; ++i)
{
size_t copy = MIN (vector[i].iov_len, bytes);
(void) memcpy ((void *) vector[i].iov_base, (void *) buffer, copy);
buffer += copy;
bytes -= copy;
if (bytes == 0)
break;
}
return bytes_read;
}
libc_hidden_def (__readv)
weak_alias (__readv, readv)
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