1/* POSIX compatible write() function. 2 Copyright (C) 2008-2014 Free Software Foundation, Inc. 3 Written by Bruno Haible <bruno@clisp.org>, 2008. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program 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 General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://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 __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# include "msvc-inval.h" 38# include "msvc-nothrow.h" 39 40# undef write 41 42# if HAVE_MSVC_INVALID_PARAMETER_HANDLER 43static ssize_t 44write_nothrow (int fd, const void *buf, size_t count) 45{ 46 ssize_t result; 47 48 TRY_MSVC_INVAL 49 { 50 result = write (fd, buf, count); 51 } 52 CATCH_MSVC_INVAL 53 { 54 result = -1; 55 errno = EBADF; 56 } 57 DONE_MSVC_INVAL; 58 59 return result; 60} 61# else 62# define write_nothrow write 63# endif 64 65ssize_t 66rpl_write (int fd, const void *buf, size_t count) 67{ 68 for (;;) 69 { 70 ssize_t ret = write_nothrow (fd, buf, count); 71 72 if (ret < 0) 73 { 74# if GNULIB_NONBLOCKING 75 if (errno == ENOSPC) 76 { 77 HANDLE h = (HANDLE) _get_osfhandle (fd); 78 if (GetFileType (h) == FILE_TYPE_PIPE) 79 { 80 /* h is a pipe or socket. */ 81 DWORD state; 82 if (GetNamedPipeHandleState (h, &state, NULL, NULL, NULL, 83 NULL, 0) 84 && (state & PIPE_NOWAIT) != 0) 85 { 86 /* h is a pipe in non-blocking mode. 87 We can get here in four situations: 88 1. When the pipe buffer is full. 89 2. When count <= pipe_buf_size and the number of 90 free bytes in the pipe buffer is < count. 91 3. When count > pipe_buf_size and the number of free 92 bytes in the pipe buffer is > 0, < pipe_buf_size. 93 4. When count > pipe_buf_size and the pipe buffer is 94 entirely empty. 95 The cases 1 and 2 are POSIX compliant. In cases 3 and 96 4 POSIX specifies that write() must split the request 97 and succeed with a partial write. We fix case 4. 98 We don't fix case 3 because it is not essential for 99 programs. */ 100 DWORD out_size; /* size of the buffer for outgoing data */ 101 DWORD in_size; /* size of the buffer for incoming data */ 102 if (GetNamedPipeInfo (h, NULL, &out_size, &in_size, NULL)) 103 { 104 size_t reduced_count = count; 105 /* In theory we need only one of out_size, in_size. 106 But I don't know which of the two. The description 107 is ambiguous. */ 108 if (out_size != 0 && out_size < reduced_count) 109 reduced_count = out_size; 110 if (in_size != 0 && in_size < reduced_count) 111 reduced_count = in_size; 112 if (reduced_count < count) 113 { 114 /* Attempt to write only the first part. */ 115 count = reduced_count; 116 continue; 117 } 118 } 119 /* Change errno from ENOSPC to EAGAIN. */ 120 errno = EAGAIN; 121 } 122 } 123 } 124 else 125# endif 126 { 127# if GNULIB_SIGPIPE 128 if (GetLastError () == ERROR_NO_DATA 129 && GetFileType ((HANDLE) _get_osfhandle (fd)) 130 == FILE_TYPE_PIPE) 131 { 132 /* Try to raise signal SIGPIPE. */ 133 raise (SIGPIPE); 134 /* If it is currently blocked or ignored, change errno from 135 EINVAL to EPIPE. */ 136 errno = EPIPE; 137 } 138# endif 139 } 140 } 141 return ret; 142 } 143} 144 145#endif 146