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git.wh0rd.org - fontconfig.git/blob - src/fcatomic.c
2 * $XFree86: xc/lib/fontconfig/src/fcatomic.c,v 1.2 2002/03/04 21:15:28 tsi Exp $
4 * Copyright © 2002 Keith Packard, member of The XFree86 Project, Inc.
6 * Permission to use, copy, modify, distribute, and sell this software and its
7 * documentation for any purpose is hereby granted without fee, provided that
8 * the above copyright notice appear in all copies and that both that
9 * copyright notice and this permission notice appear in supporting
10 * documentation, and that the name of Keith Packard not be used in
11 * advertising or publicity pertaining to distribution of the software without
12 * specific, written prior permission. Keith Packard makes no
13 * representations about the suitability of this software for any purpose. It
14 * is provided "as is" without express or implied warranty.
16 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
17 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
18 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
19 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
20 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
21 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
22 * PERFORMANCE OF THIS SOFTWARE.
28 * Lock cache and configuration files for atomic update
30 * Uses only regular filesystem calls so it should
31 * work even in the absense of functioning file locking
34 * file - the data file accessed by other apps.
35 * new - a new version of the data file while it's being written
37 * tmp - a temporary file made unique with mkstemp
39 * Here's how it works:
40 * Create 'tmp' and store our PID in it
41 * Attempt to link it to 'lck'
43 * If the link succeeded, the lock is held
47 #include <sys/types.h>
54 #define NEW_NAME ".NEW"
55 #define LCK_NAME ".LCK"
56 #define TMP_NAME ".TMP-XXXXXX"
59 FcAtomicCreate (const FcChar8
*file
)
61 int file_len
= strlen ((char *) file
);
62 int new_len
= file_len
+ sizeof (NEW_NAME
);
63 int lck_len
= file_len
+ sizeof (LCK_NAME
);
64 int tmp_len
= file_len
+ sizeof (TMP_NAME
);
65 int total_len
= (sizeof (FcAtomic
) +
70 FcAtomic
*atomic
= malloc (total_len
);
73 FcMemAlloc (FC_MEM_ATOMIC
, total_len
);
75 atomic
->file
= (FcChar8
*) (atomic
+ 1);
76 strcpy ((char *) atomic
->file
, (char *) file
);
78 atomic
->new = atomic
->file
+ file_len
+ 1;
79 strcpy ((char *) atomic
->new, (char *) file
);
80 strcat ((char *) atomic
->new, NEW_NAME
);
82 atomic
->lck
= atomic
->new + new_len
+ 1;
83 strcpy ((char *) atomic
->lck
, (char *) file
);
84 strcat ((char *) atomic
->lck
, LCK_NAME
);
86 atomic
->tmp
= atomic
->lck
+ lck_len
+ 1;
92 FcAtomicLock (FcAtomic
*atomic
)
99 strcpy ((char *) atomic
->tmp
, (char *) atomic
->file
);
100 strcat ((char *) atomic
->tmp
, TMP_NAME
);
101 fd
= mkstemp ((char *) atomic
->tmp
);
104 f
= fdopen (fd
, "w");
108 unlink ((char *) atomic
->tmp
);
111 ret
= fprintf (f
, "%ld\n", (long)getpid());
115 unlink ((char *) atomic
->tmp
);
118 if (fclose (f
) == EOF
)
120 unlink ((char *) atomic
->tmp
);
123 ret
= link ((char *) atomic
->tmp
, (char *) atomic
->lck
);
124 (void) unlink ((char *) atomic
->tmp
);
128 * If the file is around and old (> 10 minutes),
129 * assume the lock is stale. This assumes that any
130 * machines sharing the same filesystem will have clocks
131 * reasonably close to each other.
133 if (stat ((char *) atomic
->lck
, &lck_stat
) >= 0)
135 time_t now
= time (0);
136 if ((long int) (now
- lck_stat
.st_mtime
) > 10 * 60)
138 if (unlink ((char *) atomic
->lck
) == 0)
139 return FcAtomicLock (atomic
);
144 (void) unlink ((char *) atomic
->new);
149 FcAtomicNewFile (FcAtomic
*atomic
)
155 FcAtomicOrigFile (FcAtomic
*atomic
)
161 FcAtomicReplaceOrig (FcAtomic
*atomic
)
163 if (rename ((char *) atomic
->new, (char *) atomic
->file
) < 0)
169 FcAtomicDeleteNew (FcAtomic
*atomic
)
171 unlink ((char *) atomic
->new);
175 FcAtomicUnlock (FcAtomic
*atomic
)
177 unlink ((char *) atomic
->lck
);
181 FcAtomicDestroy (FcAtomic
*atomic
)
183 FcMemFree (FC_MEM_ATOMIC
, sizeof (FcAtomic
) +
184 strlen ((char *) atomic
->file
) * 4 + 1 +
185 sizeof (NEW_NAME
) + sizeof (LCK_NAME
) +