1 files changed, 89 insertions, 0 deletions
diff --git a/otherlibs/unix/lockf.c b/otherlibs/unix/lockf.c
new file mode 100644
index 000000000..bfc22c77d
--- /dev/null
+++ b/otherlibs/unix/lockf.c
@@ -0,0 +1,89 @@
+#include <mlvalues.h>
+#include "unix.h"
+
+#ifdef HAS_LOCKF
+#ifdef HAS_UNISTD
+#include <unistd.h>
+#else
+#define F_ULOCK 0
+#define F_LOCK 1
+#define F_TLOCK 2
+#define F_TEST 3
+#endif
+
+static int lock_command_table[] = {
+  F_ULOCK, F_LOCK, F_TLOCK, F_TEST
+};
+
+value unix_lockf(fd, cmd, span)  /* ML */
+     value fd, cmd, span;
+{
+  if (lockf(Int_val(fd), lock_command_table[Tag_val(cmd)], Long_val(span))
+      == -1) uerror("lockf", Nothing);
+  return Atom(0);
+}
+
+#else
+
+#include <errno.h>
+#include <fcntl.h>
+
+#ifdef F_SETLK
+
+value unix_lockf(fd, cmd, span)  /* ML */
+     value fd, cmd, span;
+{
+  struct flock l;
+  int ret;
+  int fildes;
+  long size;
+
+  fildes = Int_val(fd);
+  size = Long_val(span);
+  l.l_whence = 1;
+  if (size < 0) {
+    l.l_start = size;
+    l.l_len = -size;
+  } else {
+    l.l_start = 0L;
+    l.l_len = size;
+  }
+  switch (Tag_val(cmd)) {
+  case 0: /* F_ULOCK */
+    l.l_type = F_UNLCK;
+    ret = fcntl(fildes, F_SETLK, &l);
+    break;
+  case 1: /* F_LOCK */
+    l.l_type = F_WRLCK;
+    ret = fcntl(fildes, F_SETLKW, &l);
+    break;
+  case 2: /* F_TLOCK */
+    l.l_type = F_WRLCK;
+    ret = fcntl(fildes, F_SETLK, &l);
+    break;
+  case 3: /* F_TEST */
+    l.l_type = F_WRLCK;
+    ret = fcntl(fildes, F_GETLK, &l);
+    if (ret != -1) {
+      if (l.l_type == F_UNLCK)
+        ret = 0;
+      else {
+        errno = EACCES;
+        ret = -1;
+      }
+    }
+    break;
+  default:
+    errno = EINVAL;
+    ret = -1;
+  }
+  if (ret == -1) uerror("lockf", Nothing);
+  return Val_unit;
+}
+
+#else
+
+value unix_lockf() { invalid_argument("lockf not implemented"); }
+
+#endif
+#endif