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-rw-r--r--gl/open.c140
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1/* Open a descriptor to a file.
2 Copyright (C) 2007-2008 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
8
9 This program 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
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
16
17/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
18
19#include <config.h>
20
21/* Get the original definition of open. It might be defined as a macro. */
22#define __need_system_fcntl_h
23#include <fcntl.h>
24#undef __need_system_fcntl_h
25#include <sys/types.h>
26
27static inline int
28orig_open (const char *filename, int flags, mode_t mode)
29{
30 return open (filename, flags, mode);
31}
32
33/* Specification. */
34#include <fcntl.h>
35
36#include <errno.h>
37#include <stdarg.h>
38#include <string.h>
39#include <sys/types.h>
40#include <sys/stat.h>
41
42int
43open (const char *filename, int flags, ...)
44{
45 mode_t mode;
46 int fd;
47
48 mode = 0;
49 if (flags & O_CREAT)
50 {
51 va_list arg;
52 va_start (arg, flags);
53
54 /* If mode_t is narrower than int, use the promoted type (int),
55 not mode_t. Use sizeof to guess whether mode_t is narrower;
56 we don't know of any practical counterexamples. */
57 mode = (sizeof (mode_t) < sizeof (int)
58 ? va_arg (arg, int)
59 : va_arg (arg, mode_t));
60
61 va_end (arg);
62 }
63
64#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
65 if (strcmp (filename, "/dev/null") == 0)
66 filename = "NUL";
67#endif
68
69#if OPEN_TRAILING_SLASH_BUG
70 /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
71 is specified, then fail.
72 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
73 says that
74 "A pathname that contains at least one non-slash character and that
75 ends with one or more trailing slashes shall be resolved as if a
76 single dot character ( '.' ) were appended to the pathname."
77 and
78 "The special filename dot shall refer to the directory specified by
79 its predecessor."
80 If the named file already exists as a directory, then
81 - if O_CREAT is specified, open() must fail because of the semantics
82 of O_CREAT,
83 - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
84 <http://www.opengroup.org/susv3/functions/open.html> says that it
85 fails with errno = EISDIR in this case.
86 If the named file does not exist or does not name a directory, then
87 - if O_CREAT is specified, open() must fail since open() cannot create
88 directories,
89 - if O_WRONLY or O_RDWR is specified, open() must fail because the
90 file does not contain a '.' directory. */
91 if (flags & (O_CREAT | O_WRONLY | O_RDWR))
92 {
93 size_t len = strlen (filename);
94 if (len > 0 && filename[len - 1] == '/')
95 {
96 errno = EISDIR;
97 return -1;
98 }
99 }
100#endif
101
102 fd = orig_open (filename, flags, mode);
103
104#if OPEN_TRAILING_SLASH_BUG
105 /* If the filename ends in a slash and fd does not refer to a directory,
106 then fail.
107 Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
108 says that
109 "A pathname that contains at least one non-slash character and that
110 ends with one or more trailing slashes shall be resolved as if a
111 single dot character ( '.' ) were appended to the pathname."
112 and
113 "The special filename dot shall refer to the directory specified by
114 its predecessor."
115 If the named file without the slash is not a directory, open() must fail
116 with ENOTDIR. */
117 if (fd >= 0)
118 {
119 size_t len = strlen (filename);
120 if (len > 0 && filename[len - 1] == '/')
121 {
122 struct stat statbuf;
123
124 if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
125 {
126 close (fd);
127 errno = ENOTDIR;
128 return -1;
129 }
130 }
131 }
132#endif
133
134#ifdef FCHDIR_REPLACEMENT
135 if (fd >= 0)
136 _gl_register_fd (fd, filename);
137#endif
138
139 return fd;
140}