--- /dev/null
+/*
+ * $XFree86: $
+ *
+ * Copyright © 2002 Keith Packard, member of The XFree86 Project, Inc.
+ *
+ * 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.
+ *
+ * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL KEITH PACKARD 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
+ *
+ * Four files:
+ * 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
+ */
+
+#include "fcint.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <time.h>
+
+#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;
+
+ 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;
+
+ 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, "%d\n", 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);
+ 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 (stat ((char *) atomic->lck, &lck_stat) >= 0)
+ {
+ time_t now = time (0);
+ if ((long int) (now - lck_stat.st_mtime) > 10 * 60)
+ {
+ if (unlink ((char *) atomic->lck) == 0)
+ return FcAtomicLock (atomic);
+ }
+ }
+ 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)
+{
+ 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)
+{
+ unlink ((char *) atomic->lck);
+}
+
+void
+FcAtomicDestroy (FcAtomic *atomic)
+{
+ free (atomic);
+}
projects / fontconfig.git / commitdiff