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Diffstat (limited to 'fontconfig/src/fcatomic.c')
| -rw-r--r-- | fontconfig/src/fcatomic.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/fontconfig/src/fcatomic.c b/fontconfig/src/fcatomic.c new file mode 100644 index 000000000..89cae6183 --- /dev/null +++ b/fontconfig/src/fcatomic.c @@ -0,0 +1,216 @@ +/* + * fontconfig/src/fcatomic.c + * + * Copyright © 2002 Keith Packard + * + * Permission to use, copy, modify, distribute, and sell this software and its + * documentation for any purpose is hereby granted without fee, provided that + * the above copyright notice appear in all copies and that both that + * copyright notice and this permission notice appear in supporting + * documentation, and that the name of Keith Packard not be used in + * advertising or publicity pertaining to distribution of the software without + * specific, written prior permission. Keith Packard makes no + * representations about the suitability of this software for any purpose. It + * is provided "as is" without express or implied warranty. + * + * THE AUTHOR(S) DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO + * EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY SPECIAL, INDIRECT OR + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, + * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER + * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR + * PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * fcatomic.c + * + * Lock cache and configuration files for atomic update + * + * Uses only regular filesystem calls so it should + * work even in the absense of functioning file locking + * + * On Unix, four files are used: + * file - the data file accessed by other apps. + * new - a new version of the data file while it's being written + * lck - the lock file + * tmp - a temporary file made unique with mkstemp + * + * Here's how it works: + * Create 'tmp' and store our PID in it + * Attempt to link it to 'lck' + * Unlink 'tmp' + * If the link succeeded, the lock is held + * + * On Windows, where there are no links, no tmp file is used, and lck + * is a directory that's mkdir'ed. If the mkdir succeeds, the lock is + * held. + */ + +#include "fcint.h" +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <unistd.h> +#include <stdlib.h> +#include <time.h> + +#ifdef _WIN32 +#define mkdir(path,mode) _mkdir(path) +#endif + +#define NEW_NAME ".NEW" +#define LCK_NAME ".LCK" +#define TMP_NAME ".TMP-XXXXXX" + +FcAtomic * +FcAtomicCreate (const FcChar8 *file) +{ + int file_len = strlen ((char *) file); + int new_len = file_len + sizeof (NEW_NAME); + int lck_len = file_len + sizeof (LCK_NAME); + int tmp_len = file_len + sizeof (TMP_NAME); + int total_len = (sizeof (FcAtomic) + + file_len + 1 + + new_len + 1 + + lck_len + 1 + + tmp_len + 1); + FcAtomic *atomic = malloc (total_len); + if (!atomic) + return 0; + FcMemAlloc (FC_MEM_ATOMIC, total_len); + + atomic->file = (FcChar8 *) (atomic + 1); + strcpy ((char *) atomic->file, (char *) file); + + atomic->new = atomic->file + file_len + 1; + strcpy ((char *) atomic->new, (char *) file); + strcat ((char *) atomic->new, NEW_NAME); + + atomic->lck = atomic->new + new_len + 1; + strcpy ((char *) atomic->lck, (char *) file); + strcat ((char *) atomic->lck, LCK_NAME); + + atomic->tmp = atomic->lck + lck_len + 1; + + return atomic; +} + +FcBool +FcAtomicLock (FcAtomic *atomic) +{ + int fd = -1; + FILE *f = 0; + int ret; + struct stat lck_stat; + +#ifdef HAVE_LINK + strcpy ((char *) atomic->tmp, (char *) atomic->file); + strcat ((char *) atomic->tmp, TMP_NAME); + fd = mkstemp ((char *) atomic->tmp); + if (fd < 0) + return FcFalse; + f = fdopen (fd, "w"); + if (!f) + { + close (fd); + unlink ((char *) atomic->tmp); + return FcFalse; + } + ret = fprintf (f, "%ld\n", (long)getpid()); + if (ret <= 0) + { + fclose (f); + unlink ((char *) atomic->tmp); + return FcFalse; + } + if (fclose (f) == EOF) + { + unlink ((char *) atomic->tmp); + return FcFalse; + } + ret = link ((char *) atomic->tmp, (char *) atomic->lck); + (void) unlink ((char *) atomic->tmp); +#else + ret = mkdir ((char *) atomic->lck, 0600); +#endif + if (ret < 0) + { + /* + * If the file is around and old (> 10 minutes), + * assume the lock is stale. This assumes that any + * machines sharing the same filesystem will have clocks + * reasonably close to each other. + */ + if (FcStat ((char *) atomic->lck, &lck_stat) >= 0) + { + time_t now = time (0); + if ((long int) (now - lck_stat.st_mtime) > 10 * 60) + { +#ifdef HAVE_LINK + if (unlink ((char *) atomic->lck) == 0) + return FcAtomicLock (atomic); +#else + if (rmdir ((char *) atomic->lck) == 0) + return FcAtomicLock (atomic); +#endif + } + } + return FcFalse; + } + (void) unlink ((char *) atomic->new); + return FcTrue; +} + +FcChar8 * +FcAtomicNewFile (FcAtomic *atomic) +{ + return atomic->new; +} + +FcChar8 * +FcAtomicOrigFile (FcAtomic *atomic) +{ + return atomic->file; +} + +FcBool +FcAtomicReplaceOrig (FcAtomic *atomic) +{ +#ifdef _WIN32 + unlink (atomic->file); +#endif + if (rename ((char *) atomic->new, (char *) atomic->file) < 0) + return FcFalse; + return FcTrue; +} + +void +FcAtomicDeleteNew (FcAtomic *atomic) +{ + unlink ((char *) atomic->new); +} + +void +FcAtomicUnlock (FcAtomic *atomic) +{ +#ifdef HAVE_LINK + unlink ((char *) atomic->lck); +#else + rmdir ((char *) atomic->lck); +#endif +} + +void +FcAtomicDestroy (FcAtomic *atomic) +{ + FcMemFree (FC_MEM_ATOMIC, sizeof (FcAtomic) + + strlen ((char *) atomic->file) * 4 + 4 + + sizeof (NEW_NAME) + sizeof (LCK_NAME) + + sizeof (TMP_NAME)); + + free (atomic); +} +#define __fcatomic__ +#include "fcaliastail.h" +#undef __fcatomic__ |