i386: Move futex functions from lowlevellock.h to lowlevellock-futex.h.
[glibc.git] / libio / iofdopen.c
blobb36d21d0413420f9d48aa57687a97106ac199244
1 /* Copyright (C) 1993-2014 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 <http://www.gnu.org/licenses/>.
18 As a special exception, if you link the code in this file with
19 files compiled with a GNU compiler to produce an executable,
20 that does not cause the resulting executable to be covered by
21 the GNU Lesser General Public License. This exception does not
22 however invalidate any other reasons why the executable file
23 might be covered by the GNU Lesser General Public License.
24 This exception applies to code released by its copyright holders
25 in files containing the exception. */
27 #include <stdlib.h>
28 #include "libioP.h"
29 #include <fcntl.h>
31 #ifdef _LIBC
32 # include <shlib-compat.h>
33 #endif
35 #ifndef _IO_fcntl
36 #ifdef _LIBC
37 #define _IO_fcntl __fcntl
38 #else
39 #define _IO_fcntl fcntl
40 #endif
41 #endif
43 _IO_FILE *
44 _IO_new_fdopen (fd, mode)
45 int fd;
46 const char *mode;
48 int read_write;
49 int posix_mode = 0;
50 struct locked_FILE
52 struct _IO_FILE_plus fp;
53 #ifdef _IO_MTSAFE_IO
54 _IO_lock_t lock;
55 #endif
56 struct _IO_wide_data wd;
57 } *new_f;
58 int fd_flags;
59 int i;
60 int use_mmap = 0;
62 /* Decide whether we modify the offset of the file we attach to and seek to
63 the end of file. We only do this if the mode is 'a' and if the file
64 descriptor did not have O_APPEND in its flags already. */
65 bool do_seek = false;
67 switch (*mode)
69 case 'r':
70 read_write = _IO_NO_WRITES;
71 break;
72 case 'w':
73 read_write = _IO_NO_READS;
74 break;
75 case 'a':
76 posix_mode = O_APPEND;
77 read_write = _IO_NO_READS|_IO_IS_APPENDING;
78 break;
79 default:
80 MAYBE_SET_EINVAL;
81 return NULL;
83 for (i = 1; i < 5; ++i)
85 switch (*++mode)
87 case '\0':
88 break;
89 case '+':
90 read_write &= _IO_IS_APPENDING;
91 break;
92 case 'm':
93 use_mmap = 1;
94 continue;
95 case 'x':
96 case 'b':
97 default:
98 /* Ignore */
99 continue;
101 break;
103 #ifdef F_GETFL
104 fd_flags = _IO_fcntl (fd, F_GETFL);
105 #ifndef O_ACCMODE
106 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
107 #endif
108 if (fd_flags == -1)
109 return NULL;
111 if (((fd_flags & O_ACCMODE) == O_RDONLY && !(read_write & _IO_NO_WRITES))
112 || ((fd_flags & O_ACCMODE) == O_WRONLY && !(read_write & _IO_NO_READS)))
114 MAYBE_SET_EINVAL;
115 return NULL;
118 /* The May 93 draft of P1003.4/D14.1 (redesignated as 1003.1b)
119 [System Application Program Interface (API) Amendment 1:
120 Realtime Extensions], Rationale B.8.3.3
121 Open a Stream on a File Descriptor says:
123 Although not explicitly required by POSIX.1, a good
124 implementation of append ("a") mode would cause the
125 O_APPEND flag to be set.
127 (Historical implementations [such as Solaris2] do a one-time
128 seek in fdopen.)
130 However, we do not turn O_APPEND off if the mode is "w" (even
131 though that would seem consistent) because that would be more
132 likely to break historical programs.
134 if ((posix_mode & O_APPEND) && !(fd_flags & O_APPEND))
136 do_seek = true;
137 #ifdef F_SETFL
138 if (_IO_fcntl (fd, F_SETFL, fd_flags | O_APPEND) == -1)
139 #endif
140 return NULL;
142 #endif
144 new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
145 if (new_f == NULL)
146 return NULL;
147 #ifdef _IO_MTSAFE_IO
148 new_f->fp.file._lock = &new_f->lock;
149 #endif
150 _IO_no_init (&new_f->fp.file, 0, 0, &new_f->wd,
151 #ifdef _G_HAVE_MMAP
152 (use_mmap && (read_write & _IO_NO_WRITES))
153 ? &_IO_wfile_jumps_maybe_mmap :
154 #endif
155 &_IO_wfile_jumps);
156 _IO_JUMPS (&new_f->fp) =
157 #ifdef _G_HAVE_MMAP
158 (use_mmap && (read_write & _IO_NO_WRITES)) ? &_IO_file_jumps_maybe_mmap :
159 #endif
160 &_IO_file_jumps;
161 _IO_file_init (&new_f->fp);
162 #if !_IO_UNIFIED_JUMPTABLES
163 new_f->fp.vtable = NULL;
164 #endif
165 /* We only need to record the fd because _IO_file_init will have unset the
166 offset. It is important to unset the cached offset because the real
167 offset in the file could change between now and when the handle is
168 activated and we would then mislead ftell into believing that we have a
169 valid offset. */
170 new_f->fp.file._fileno = fd;
171 new_f->fp.file._flags &= ~_IO_DELETE_DONT_CLOSE;
173 _IO_mask_flags (&new_f->fp.file, read_write,
174 _IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);
176 /* For append mode, set the file offset to the end of the file if we added
177 O_APPEND to the file descriptor flags. Don't update the offset cache
178 though, since the file handle is not active. */
179 if (do_seek && ((read_write & (_IO_IS_APPENDING | _IO_NO_READS))
180 == (_IO_IS_APPENDING | _IO_NO_READS)))
182 _IO_off64_t new_pos = _IO_SYSSEEK (&new_f->fp.file, 0, _IO_seek_end);
183 if (new_pos == _IO_pos_BAD && errno != ESPIPE)
184 return NULL;
186 return &new_f->fp.file;
188 libc_hidden_ver (_IO_new_fdopen, _IO_fdopen)
190 strong_alias (_IO_new_fdopen, __new_fdopen)
191 versioned_symbol (libc, _IO_new_fdopen, _IO_fdopen, GLIBC_2_1);
192 versioned_symbol (libc, __new_fdopen, fdopen, GLIBC_2_1);