1 files changed, 38 insertions, 0 deletions
diff --git a/src/libstddjb/lock_shnb.c b/src/libstddjb/lock_shnb.c
new file mode 100644
index 0000000..6a8fd42
--- /dev/null
+++ b/src/libstddjb/lock_shnb.c
@@ -0,0 +1,38 @@
+/* ISC license. */
+
+#include <skalibs/sysdeps.h>
+
+#ifdef SKALIBS_HASFLOCK
+
+#include <skalibs/nonposix.h>
+#include <errno.h>
+#include <sys/file.h>
+#include <skalibs/djbunix.h>
+
+int lock_shnb (int fd)
+{
+  register int r ;
+  do
+    r = flock(fd, LOCK_SH | LOCK_NB) ;
+  while ((r == -1) && (errno == EINTR)) ;
+  return r ;
+}
+
+#else
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/djbunix.h>
+
+int lock_shnb (int fd)
+{
+  register int r ;
+  do
+    r = lockf(fd, F_TLOCK, 0) ;
+  while ((r == -1) && (errno == EINTR)) ;
+  if ((r == -1) && (errno == EACCES)) errno = EAGAIN ;
+  return r ;
+}
+
+#endif