| 1 | /* Copyright (C) 1991-2024 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library; if not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | #include <stdlib.h> |
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| 19 | #include <unistd.h> |
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| 20 | #include <string.h> |
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| 21 | #include <limits.h> |
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| 22 | #include <scratch_buffer.h> |
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| 23 | #include <stdbool.h> |
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| 24 | #include <sys/param.h> |
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| 25 | #include <sys/uio.h> |
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| 26 | #include <errno.h> |
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| 27 | |
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| 28 | |
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| 29 | static void |
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| 30 | ifree (struct scratch_buffer *sbuf) |
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| 31 | { |
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| 32 | scratch_buffer_free (buffer: sbuf); |
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| 33 | } |
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| 34 | |
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| 35 | /* Write data pointed by the buffers described by VECTOR, which |
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| 36 | is a vector of COUNT 'struct iovec's, to file descriptor FD. |
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| 37 | The data is written in the order specified. |
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| 38 | Operates just like 'write' (see <unistd.h>) except that the data |
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| 39 | are taken from VECTOR instead of a contiguous buffer. */ |
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| 40 | ssize_t |
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| 41 | __writev (int fd, const struct iovec *vector, int count) |
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| 42 | { |
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| 43 | /* Find the total number of bytes to be written. */ |
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| 44 | size_t bytes = 0; |
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| 45 | for (int i = 0; i < count; ++i) |
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| 46 | { |
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| 47 | /* Check for ssize_t overflow. */ |
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| 48 | if (SSIZE_MAX - bytes < vector[i].iov_len) |
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| 49 | { |
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| 50 | __set_errno (EINVAL); |
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| 51 | return -1; |
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| 52 | } |
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| 53 | bytes += vector[i].iov_len; |
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| 54 | } |
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| 55 | |
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| 56 | /* Allocate a temporary buffer to hold the data. Use a scratch_buffer |
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| 57 | since it's faster for small buffer sizes but can handle larger |
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| 58 | allocations as well. */ |
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| 59 | |
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| 60 | struct scratch_buffer __attribute__ ((__cleanup__ (ifree))) buf; |
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| 61 | scratch_buffer_init (buffer: &buf); |
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| 62 | if (!scratch_buffer_set_array_size (buffer: &buf, nelem: 1, size: bytes)) |
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| 63 | /* XXX I don't know whether it is acceptable to try writing |
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| 64 | the data in chunks. Probably not so we just fail here. */ |
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| 65 | return -1; |
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| 66 | char *buffer = buf.data; |
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| 67 | |
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| 68 | /* Copy the data into BUFFER. */ |
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| 69 | size_t to_copy = bytes; |
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| 70 | char *bp = buffer; |
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| 71 | for (int i = 0; i < count; ++i) |
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| 72 | { |
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| 73 | size_t copy = MIN (vector[i].iov_len, to_copy); |
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| 74 | |
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| 75 | bp = __mempcpy ((void *) bp, (void *) vector[i].iov_base, copy); |
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| 76 | |
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| 77 | to_copy -= copy; |
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| 78 | if (to_copy == 0) |
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| 79 | break; |
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| 80 | } |
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| 81 | |
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| 82 | ssize_t bytes_written = __write (fd, buffer, bytes); |
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| 83 | |
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| 84 | return bytes_written; |
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| 85 | } |
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| 86 | libc_hidden_def (__writev) |
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| 87 | #ifndef __writev |
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| 88 | weak_alias (__writev, writev) |
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| 89 | #endif |
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| 90 | |
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