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d614a753 | 1 | /* Copyright (C) 1991-2020 Free Software Foundation, Inc. |
afd4eb37 | 2 | This file is part of the GNU C Library. |
28f540f4 | 3 | |
afd4eb37 | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
28f540f4 | 8 | |
afd4eb37 UD |
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 | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
28f540f4 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 15 | License along with the GNU C Library; if not, see |
5a82c748 | 16 | <https://www.gnu.org/licenses/>. */ |
28f540f4 | 17 | |
28f540f4 RM |
18 | #include <stdlib.h> |
19 | #include <unistd.h> | |
20 | #include <string.h> | |
9710f75d UD |
21 | #include <limits.h> |
22 | #include <stdbool.h> | |
23 | #include <sys/param.h> | |
28f540f4 | 24 | #include <sys/uio.h> |
bf2cc5fb | 25 | #include <errno.h> |
28f540f4 | 26 | |
2dbe6afe UD |
27 | |
28 | static void | |
29 | ifree (char **ptrp) | |
30 | { | |
31 | free (*ptrp); | |
32 | } | |
33 | ||
34 | ||
28f540f4 | 35 | /* Write data pointed by the buffers described by VECTOR, which |
2dbe6afe | 36 | is a vector of COUNT 'struct iovec's, to file descriptor FD. |
28f540f4 | 37 | The data is written in the order specified. |
2dbe6afe | 38 | Operates just like 'write' (see <unistd.h>) except that the data |
28f540f4 | 39 | are taken from VECTOR instead of a contiguous buffer. */ |
ebe3b3eb | 40 | ssize_t |
e19c95fd | 41 | __writev (int fd, const struct iovec *vector, int count) |
28f540f4 | 42 | { |
28f540f4 | 43 | /* Find the total number of bytes to be written. */ |
2dbe6afe UD |
44 | size_t bytes = 0; |
45 | for (int i = 0; i < count; ++i) | |
9710f75d UD |
46 | { |
47 | /* Check for ssize_t overflow. */ | |
48 | if (SSIZE_MAX - bytes < vector[i].iov_len) | |
49 | { | |
bf2cc5fb | 50 | __set_errno (EINVAL); |
9710f75d UD |
51 | return -1; |
52 | } | |
53 | bytes += vector[i].iov_len; | |
54 | } | |
28f540f4 | 55 | |
9710f75d UD |
56 | /* Allocate a temporary buffer to hold the data. We should normally |
57 | use alloca since it's faster and does not require synchronization | |
58 | with other threads. But we cannot if the amount of memory | |
6166815d | 59 | required is too large. */ |
2dbe6afe UD |
60 | char *buffer; |
61 | char *malloced_buffer __attribute__ ((__cleanup__ (ifree))) = NULL; | |
6166815d | 62 | if (__libc_use_alloca (bytes)) |
9710f75d UD |
63 | buffer = (char *) __alloca (bytes); |
64 | else | |
65 | { | |
2dbe6afe | 66 | malloced_buffer = buffer = (char *) malloc (bytes); |
9710f75d UD |
67 | if (buffer == NULL) |
68 | /* XXX I don't know whether it is acceptable to try writing | |
69 | the data in chunks. Probably not so we just fail here. */ | |
70 | return -1; | |
9710f75d | 71 | } |
28f540f4 RM |
72 | |
73 | /* Copy the data into BUFFER. */ | |
2dbe6afe UD |
74 | size_t to_copy = bytes; |
75 | char *bp = buffer; | |
76 | for (int i = 0; i < count; ++i) | |
28f540f4 | 77 | { |
9710f75d | 78 | size_t copy = MIN (vector[i].iov_len, to_copy); |
28f540f4 | 79 | |
86187531 | 80 | bp = __mempcpy ((void *) bp, (void *) vector[i].iov_base, copy); |
28f540f4 | 81 | |
28f540f4 | 82 | to_copy -= copy; |
86187531 | 83 | if (to_copy == 0) |
28f540f4 RM |
84 | break; |
85 | } | |
86 | ||
2dbe6afe | 87 | ssize_t bytes_written = __write (fd, buffer, bytes); |
9710f75d UD |
88 | |
89 | return bytes_written; | |
28f540f4 | 90 | } |
d6daff12 | 91 | libc_hidden_def (__writev) |
c1dcc541 | 92 | #ifndef __writev |
e19c95fd | 93 | weak_alias (__writev, writev) |
c1dcc541 | 94 | #endif |