1 /* POSIX compatible write() function.
2 Copyright (C) 2008-2023 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2008.
4
5 This file is free software: you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 This file is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include <unistd.h>
22
23 /* On native Windows platforms, SIGPIPE does not exist. When write() is
24 called on a pipe with no readers, WriteFile() fails with error
25 GetLastError() = ERROR_NO_DATA, and write() in consequence fails with
26 error EINVAL. */
27
28 #if defined _WIN32 && ! defined __CYGWIN__
29
30 # include <errno.h>
31 # include <signal.h>
32 # include <io.h>
33
34 # define WIN32_LEAN_AND_MEAN /* avoid including junk */
35 # include <windows.h>
36
37 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
38 # include "msvc-inval.h"
39 # endif
40 # if GNULIB_MSVC_NOTHROW
41 # include "msvc-nothrow.h"
42 # else
43 # include <io.h>
44 # endif
45
46 /* Don't assume that UNICODE is not defined. */
47 # undef GetNamedPipeHandleState
48 # define GetNamedPipeHandleState GetNamedPipeHandleStateA
49
50 # undef write
51
52 # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
53 static ssize_t
54 write_nothrow (int fd, const void *buf, size_t count)
55 {
56 ssize_t result;
57
58 TRY_MSVC_INVAL
59 {
60 result = _write (fd, buf, count);
61 }
62 CATCH_MSVC_INVAL
63 {
64 result = -1;
65 errno = EBADF;
66 }
67 DONE_MSVC_INVAL;
68
69 return result;
70 }
71 # else
72 # define write_nothrow _write
73 # endif
74
75 ssize_t
76 rpl_write (int fd, const void *buf, size_t count)
77 {
78 for (;;)
79 {
80 ssize_t ret = write_nothrow (fd, buf, count);
81
82 if (ret < 0)
83 {
84 # if GNULIB_NONBLOCKING
85 if (errno == ENOSPC)
86 {
87 HANDLE h = (HANDLE) _get_osfhandle (fd);
88 if (GetFileType (h) == FILE_TYPE_PIPE)
89 {
90 /* h is a pipe or socket. */
91 DWORD state;
92 if (GetNamedPipeHandleState (h, &state, NULL, NULL, NULL,
93 NULL, 0)
94 && (state & PIPE_NOWAIT) != 0)
95 {
96 /* h is a pipe in non-blocking mode.
97 We can get here in four situations:
98 1. When the pipe buffer is full.
99 2. When count <= pipe_buf_size and the number of
100 free bytes in the pipe buffer is < count.
101 3. When count > pipe_buf_size and the number of free
102 bytes in the pipe buffer is > 0, < pipe_buf_size.
103 4. When count > pipe_buf_size and the pipe buffer is
104 entirely empty.
105 The cases 1 and 2 are POSIX compliant. In cases 3 and
106 4 POSIX specifies that write() must split the request
107 and succeed with a partial write. We fix case 4.
108 We don't fix case 3 because it is not essential for
109 programs. */
110 DWORD out_size; /* size of the buffer for outgoing data */
111 DWORD in_size; /* size of the buffer for incoming data */
112 if (GetNamedPipeInfo (h, NULL, &out_size, &in_size, NULL))
113 {
114 size_t reduced_count = count;
115 /* In theory we need only one of out_size, in_size.
116 But I don't know which of the two. The description
117 is ambiguous. */
118 if (out_size != 0 && out_size < reduced_count)
119 reduced_count = out_size;
120 if (in_size != 0 && in_size < reduced_count)
121 reduced_count = in_size;
122 if (reduced_count < count)
123 {
124 /* Attempt to write only the first part. */
125 count = reduced_count;
126 continue;
127 }
128 }
129 /* Change errno from ENOSPC to EAGAIN. */
130 errno = EAGAIN;
131 }
132 }
133 }
134 else
135 # endif
136 {
137 # if GNULIB_SIGPIPE
138 if (GetLastError () == ERROR_NO_DATA
139 && GetFileType ((HANDLE) _get_osfhandle (fd))
140 == FILE_TYPE_PIPE)
141 {
142 /* Try to raise signal SIGPIPE. */
143 raise (SIGPIPE);
144 /* If it is currently blocked or ignored, change errno from
145 EINVAL to EPIPE. */
146 errno = EPIPE;
147 }
148 # endif
149 }
150 }
151 return ret;
152 }
153 }
154
155 #endif