1 files changed, 130 insertions, 0 deletions
diff --git a/lock.c b/lock.c
index e69de29b..5780c056 100644
--- a/lock.c
+++ b/lock.c
@@ -0,0 +1,130 @@
+/*
+ * lock.c -- cross-platform concurrency locking for fetchmail
+ *
+ * For license terms, see the file COPYING in this directory.
+ */
+#include "config.h"
+
+#include <stdio.h>
+#if defined(STDC_HEADERS)
+#include <stdlib.h>
+#endif
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#include <fcntl.h>
+
+#include "fetchmail.h"
+#include "i18n.h"
+
+static char *lockfile;		/* name of lockfile */
+static int lock_acquired;	/* have we acquired a lock */
+
+void lock_setup(void)
+/* set up the global lockfile name */
+{
+    /* set up to do lock protocol */
+#define	FETCHMAIL_PIDFILE	"fetchmail.pid"
+    if (!getuid()) {
+	xalloca(lockfile, char *,
+		sizeof(PID_DIR) + sizeof(FETCHMAIL_PIDFILE));
+	sprintf(lockfile, "%s/%s", PID_DIR, FETCHMAIL_PIDFILE);
+    } else {
+	xalloca(lockfile, char *, strlen(fmhome) + sizeof(FETCHMAIL_PIDFILE) + 2);
+	strcpy(lockfile, fmhome);
+	strcat(lockfile, "/");
+        if (fmhome == home)
+ 	   strcat(lockfile, ".");
+	strcat(lockfile, FETCHMAIL_PIDFILE);
+    }
+#undef FETCHMAIL_PIDFILE
+}
+
+#ifdef HAVE_ON_EXIT
+static void unlockit(int n, void *p)
+#else
+static void unlockit(void)
+#endif
+/* must-do actions for exit (but we can't count on being able to do malloc) */
+{
+    if (lockfile && lock_acquired)
+	unlink(lockfile);
+}
+
+void lock_dispose(void)
+/* arrange for a lock to be removed on process exit */
+{
+#ifdef HAVE_ATEXIT
+    atexit(unlockit);
+#endif
+#ifdef HAVE_ON_EXIT
+    on_exit(unlockit, (char *)NULL);
+#endif
+}
+
+int lock_state(void)
+{
+    int 	pid, st;
+    FILE	*lockfp;
+    int		bkgd = FALSE;
+
+    pid = 0;
+    if ((lockfp = fopen(lockfile, "r")) != NULL )
+    {
+	bkgd = (fscanf(lockfp, "%d %d", &pid, &st) == 2);
+
+	if (kill(pid, 0) == -1) {
+	    fprintf(stderr,_("fetchmail: removing stale lockfile\n"));
+	    pid = 0;
+	    unlink(lockfile);
+	}
+	fclose(lockfp);	/* not checking should be safe, file mode was "r" */
+    }
+
+    return(bkgd ? -pid : pid);
+}
+
+void lock_assert(void)
+/* assert that we already posess a lock */
+{
+    lock_acquired = TRUE;
+}
+
+void lock_or_die(void)
+/* get a lock on a given host or exit */
+{
+    int fd;
+    char	tmpbuf[20];
+
+#ifndef O_SYNC
+#define O_SYNC	0	/* use it if we have it */
+#endif
+    if (!lock_acquired)
+    {
+      if ((fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL|O_SYNC, 0666)) != -1)
+      {
+	  sprintf(tmpbuf,"%d", getpid());
+	  write(fd, tmpbuf, strlen(tmpbuf));
+	  if (run.poll_interval)
+	  {
+	      sprintf(tmpbuf," %d", run.poll_interval);
+	      write(fd, tmpbuf, strlen(tmpbuf));
+	  }
+	  close(fd);	/* should be safe, fd was opened with O_SYNC */
+	  lock_acquired = TRUE;
+      }
+      else
+      {
+	  fprintf(stderr,	_("fetchmail: lock creation failed.\n"));
+	  exit(PS_EXCLUDE);
+      }
+    }
+}
+
+void lock_release(void)
+/* release a lock on a given host */
+{
+    unlink(lockfile);
+}
+
+/* lock.c ends here */