1 /* Copyright (C) 1991-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
22 #include <scratch_buffer.h>
24 #include <sys/param.h>
30 ifree (struct scratch_buffer *sbuf)
32 scratch_buffer_free (sbuf);
35 /* Write data pointed by the buffers described by VECTOR, which
36 is a vector of COUNT 'struct iovec's, to file descriptor FD.
37 The data is written in the order specified.
38 Operates just like 'write' (see <unistd.h>) except that the data
39 are taken from VECTOR instead of a contiguous buffer. */
41 __writev (int fd, const struct iovec *vector, int count)
43 /* Find the total number of bytes to be written. */
45 for (int i = 0; i < count; ++i)
47 /* Check for ssize_t overflow. */
48 if (SSIZE_MAX - bytes < vector[i].iov_len)
53 bytes += vector[i].iov_len;
56 /* Allocate a temporary buffer to hold the data. Use a scratch_buffer
57 since it's faster for small buffer sizes but can handle larger
58 allocations as well. */
60 struct scratch_buffer __attribute__ ((__cleanup__ (ifree))) buf;
61 scratch_buffer_init (&buf);
62 if (!scratch_buffer_set_array_size (&buf, 1, bytes))
63 /* XXX I don't know whether it is acceptable to try writing
64 the data in chunks. Probably not so we just fail here. */
66 char *buffer = buf.data;
68 /* Copy the data into BUFFER. */
69 size_t to_copy = bytes;
71 for (int i = 0; i < count; ++i)
73 size_t copy = MIN (vector[i].iov_len, to_copy);
75 bp = __mempcpy ((void *) bp, (void *) vector[i].iov_base, copy);
82 ssize_t bytes_written = __write (fd, buffer, bytes);
86 libc_hidden_def (__writev)
88 weak_alias (__writev, writev)