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-rw-r--r--missing/flock.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/missing/flock.c b/missing/flock.c
new file mode 100644
index 0000000000..a4a9544b56
--- /dev/null
+++ b/missing/flock.c
@@ -0,0 +1,90 @@
+#include "config.h"
+
+#if defined(HAVE_LOCKF)
+
+#include <unistd.h>
+#include <errno.h>
+
+/* Emulate flock() with lockf() or fcntl(). This is just to increase
+ portability of scripts. The calls might not be completely
+ interchangeable. What's really needed is a good file
+ locking module.
+*/
+
+# ifndef F_ULOCK
+# define F_ULOCK 0 /* Unlock a previously locked region */
+# endif
+# ifndef F_LOCK
+# define F_LOCK 1 /* Lock a region for exclusive use */
+# endif
+# ifndef F_TLOCK
+# define F_TLOCK 2 /* Test and lock a region for exclusive use */
+# endif
+# ifndef F_TEST
+# define F_TEST 3 /* Test a region for other processes locks */
+# endif
+
+/* These are the flock() constants. Since this sytems doesn't have
+ flock(), the values of the constants are probably not available.
+*/
+# ifndef LOCK_SH
+# define LOCK_SH 1
+# endif
+# ifndef LOCK_EX
+# define LOCK_EX 2
+# endif
+# ifndef LOCK_NB
+# define LOCK_NB 4
+# endif
+# ifndef LOCK_UN
+# define LOCK_UN 8
+# endif
+
+int
+flock(fd, operation)
+ int fd;
+ int operation;
+{
+ int i;
+ switch (operation) {
+
+ /* LOCK_SH - get a shared lock */
+ case LOCK_SH:
+ /* LOCK_EX - get an exclusive lock */
+ case LOCK_EX:
+ i = lockf (fd, F_LOCK, 0);
+ break;
+
+ /* LOCK_SH|LOCK_NB - get a non-blocking shared lock */
+ case LOCK_SH|LOCK_NB:
+ /* LOCK_EX|LOCK_NB - get a non-blocking exclusive lock */
+ case LOCK_EX|LOCK_NB:
+ i = lockf (fd, F_TLOCK, 0);
+ if (i == -1)
+ if ((errno == EAGAIN) || (errno == EACCES))
+ errno = EWOULDBLOCK;
+ break;
+
+ /* LOCK_UN - unlock */
+ case LOCK_UN:
+ i = lockf (fd, F_ULOCK, 0);
+ break;
+
+ /* Default - can't decipher operation */
+ default:
+ i = -1;
+ errno = EINVAL;
+ break;
+ }
+ return i;
+}
+#else
+int
+flock(fd, operation)
+ int fd;
+ int operation;
+{
+ rb_notimplement();
+ return -1;
+}
+#endif