Mercurial > hg > octave-jordi > gnulib-hg
annotate lib/flock.c @ 17587:344018b6e5d7
maint: update copyright
I ran 'make update-copyright'.
Signed-off-by: Eric Blake <eblake@redhat.com>
| author | Eric Blake <eblake@redhat.com> |
|---|---|
| date | Wed, 01 Jan 2014 00:04:40 -0700 |
| parents | e542fd46ad6f |
| children | ab58d4870664 |
| rev | line source |
|---|---|
| 10598 | 1 /* Emulate flock on platforms that lack it, primarily Windows and MinGW. |
| 2 | |
| 3 This is derived from sqlite3 sources. | |
| 4 http://www.sqlite.org/cvstrac/rlog?f=sqlite/src/os_win.c | |
| 5 http://www.sqlite.org/copyright.html | |
| 6 | |
| 7 Written by Richard W.M. Jones <rjones.at.redhat.com> | |
| 8 | |
| 17587 | 9 Copyright (C) 2008-2014 Free Software Foundation, Inc. |
| 10598 | 10 |
| 11 This library is free software; you can redistribute it and/or | |
| 12 modify it under the terms of the GNU Lesser General Public | |
| 13 License as published by the Free Software Foundation; either | |
| 14 version 2.1 of the License, or (at your option) any later version. | |
| 15 | |
| 16 This library is distributed in the hope that it will be useful, | |
| 17 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 19 Lesser General Public License for more details. | |
| 20 | |
| 14317 | 21 You should have received a copy of the GNU Lesser General Public License |
| 10598 | 22 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 23 | |
| 24 #include <config.h> | |
| 25 #include <sys/file.h> | |
| 26 | |
| 27 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ | |
| 28 | |
| 29 /* LockFileEx */ | |
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30 # define WIN32_LEAN_AND_MEAN |
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31 # include <windows.h> |
| 10598 | 32 |
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33 # include <errno.h> |
| 10598 | 34 |
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35 /* _get_osfhandle */ |
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36 # include "msvc-nothrow.h" |
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37 |
| 10598 | 38 /* Determine the current size of a file. Because the other braindead |
| 39 * APIs we'll call need lower/upper 32 bit pairs, keep the file size | |
| 40 * like that too. | |
| 41 */ | |
| 42 static BOOL | |
| 43 file_size (HANDLE h, DWORD * lower, DWORD * upper) | |
| 44 { | |
| 45 *lower = GetFileSize (h, upper); | |
| 46 return 1; | |
| 47 } | |
| 48 | |
| 49 /* LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems. */ | |
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50 # ifndef LOCKFILE_FAIL_IMMEDIATELY |
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51 # define LOCKFILE_FAIL_IMMEDIATELY 1 |
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52 # endif |
| 10598 | 53 |
| 54 /* Acquire a lock. */ | |
| 55 static BOOL | |
| 56 do_lock (HANDLE h, int non_blocking, int exclusive) | |
| 57 { | |
| 58 BOOL res; | |
| 59 DWORD size_lower, size_upper; | |
| 60 OVERLAPPED ovlp; | |
| 61 int flags = 0; | |
| 62 | |
| 63 /* We're going to lock the whole file, so get the file size. */ | |
| 64 res = file_size (h, &size_lower, &size_upper); | |
| 65 if (!res) | |
| 66 return 0; | |
| 67 | |
| 68 /* Start offset is 0, and also zero the remaining members of this struct. */ | |
| 69 memset (&ovlp, 0, sizeof ovlp); | |
| 70 | |
| 71 if (non_blocking) | |
| 72 flags |= LOCKFILE_FAIL_IMMEDIATELY; | |
| 73 if (exclusive) | |
| 74 flags |= LOCKFILE_EXCLUSIVE_LOCK; | |
| 75 | |
| 76 return LockFileEx (h, flags, 0, size_lower, size_upper, &ovlp); | |
| 77 } | |
| 78 | |
| 79 /* Unlock reader or exclusive lock. */ | |
| 80 static BOOL | |
| 81 do_unlock (HANDLE h) | |
| 82 { | |
| 83 int res; | |
| 84 DWORD size_lower, size_upper; | |
| 85 | |
| 86 res = file_size (h, &size_lower, &size_upper); | |
| 87 if (!res) | |
| 88 return 0; | |
| 89 | |
| 90 return UnlockFile (h, 0, 0, size_lower, size_upper); | |
| 91 } | |
| 92 | |
| 93 /* Now our BSD-like flock operation. */ | |
| 94 int | |
| 95 flock (int fd, int operation) | |
| 96 { | |
| 97 HANDLE h = (HANDLE) _get_osfhandle (fd); | |
| 98 DWORD res; | |
| 99 int non_blocking; | |
| 100 | |
| 101 if (h == INVALID_HANDLE_VALUE) | |
| 102 { | |
| 103 errno = EBADF; | |
| 104 return -1; | |
| 105 } | |
| 106 | |
| 107 non_blocking = operation & LOCK_NB; | |
| 108 operation &= ~LOCK_NB; | |
| 109 | |
| 110 switch (operation) | |
| 111 { | |
| 112 case LOCK_SH: | |
| 113 res = do_lock (h, non_blocking, 0); | |
| 114 break; | |
| 115 case LOCK_EX: | |
| 116 res = do_lock (h, non_blocking, 1); | |
| 117 break; | |
| 118 case LOCK_UN: | |
| 119 res = do_unlock (h); | |
| 120 break; | |
| 121 default: | |
| 122 errno = EINVAL; | |
| 123 return -1; | |
| 124 } | |
| 125 | |
| 126 /* Map Windows errors into Unix errnos. As usual MSDN fails to | |
| 127 * document the permissible error codes. | |
| 128 */ | |
| 129 if (!res) | |
| 130 { | |
| 131 DWORD err = GetLastError (); | |
| 132 switch (err) | |
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133 { |
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134 /* This means someone else is holding a lock. */ |
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135 case ERROR_LOCK_VIOLATION: |
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136 errno = EAGAIN; |
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137 break; |
| 10598 | 138 |
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139 /* Out of memory. */ |
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140 case ERROR_NOT_ENOUGH_MEMORY: |
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141 errno = ENOMEM; |
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142 break; |
| 10598 | 143 |
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144 case ERROR_BAD_COMMAND: |
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145 errno = EINVAL; |
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146 break; |
| 10598 | 147 |
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148 /* Unlikely to be other errors, but at least don't lose the |
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149 * error code. |
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150 */ |
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151 default: |
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152 errno = err; |
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153 } |
| 10598 | 154 |
| 155 return -1; | |
| 156 } | |
| 157 | |
| 158 return 0; | |
| 159 } | |
| 160 | |
| 161 #else /* !Windows */ | |
| 162 | |
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163 # ifdef HAVE_STRUCT_FLOCK_L_TYPE |
| 10598 | 164 /* We know how to implement flock in terms of fcntl. */ |
| 165 | |
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166 # include <fcntl.h> |
| 10598 | 167 |
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168 # ifdef HAVE_UNISTD_H |
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169 # include <unistd.h> |
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170 # endif |
| 10598 | 171 |
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172 # include <errno.h> |
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173 # include <string.h> |
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174 |
| 10598 | 175 int |
| 176 flock (int fd, int operation) | |
| 177 { | |
| 178 int cmd, r; | |
| 179 struct flock fl; | |
| 180 | |
| 181 if (operation & LOCK_NB) | |
| 182 cmd = F_SETLK; | |
| 183 else | |
| 184 cmd = F_SETLKW; | |
| 185 operation &= ~LOCK_NB; | |
| 186 | |
| 187 memset (&fl, 0, sizeof fl); | |
| 188 fl.l_whence = SEEK_SET; | |
| 189 /* l_start & l_len are 0, which as a special case means "whole file". */ | |
| 190 | |
| 191 switch (operation) | |
| 192 { | |
| 193 case LOCK_SH: | |
| 194 fl.l_type = F_RDLCK; | |
| 195 break; | |
| 196 case LOCK_EX: | |
| 197 fl.l_type = F_WRLCK; | |
| 198 break; | |
| 199 case LOCK_UN: | |
| 200 fl.l_type = F_UNLCK; | |
| 201 break; | |
| 202 default: | |
| 203 errno = EINVAL; | |
| 204 return -1; | |
| 205 } | |
| 206 | |
| 207 r = fcntl (fd, cmd, &fl); | |
| 208 if (r == -1 && errno == EACCES) | |
| 209 errno = EAGAIN; | |
| 210 | |
| 211 return r; | |
| 212 } | |
| 213 | |
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214 # else /* !HAVE_STRUCT_FLOCK_L_TYPE */ |
| 10598 | 215 |
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216 # error "This platform lacks flock function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib." |
| 10598 | 217 |
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218 # endif /* !HAVE_STRUCT_FLOCK_L_TYPE */ |
| 10598 | 219 |
| 220 #endif /* !Windows */ |