1 files changed, 27 insertions, 0 deletions
diff --git a/src/libs6/s6lockd-helper.c b/src/libs6/s6lockd-helper.c
new file mode 100644
index 0000000..8979c67
--- /dev/null
+++ b/src/libs6/s6lockd-helper.c
@@ -0,0 +1,27 @@
+/* ISC license. */
+
+#include <skalibs/allreadwrite.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+
+#define USAGE "s6lockd-helper lockfile"
+#define dieusage() strerr_dieusage(100, USAGE)
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  int fd ;
+  char const *x = env_get2(envp, "S6LOCK_EX") ;
+  char c ;
+  PROG = "s6lockd-helper" ;
+  if (argc < 2) dieusage() ;
+  fd = open_create(argv[1]) ;
+  if (fd < 0) strerr_diefu2sys(111, "open ", argv[1]) ;
+  if (((x && *x) ? lock_ex(fd) : lock_sh(fd)) < 0)
+    strerr_diefu2sys(111, "lock ", argv[1]) ;
+  if (fd_write(1, "!", 1) <= 0)
+    strerr_diefu1sys(111, "write to stdout") ;
+  if (fd_read(0, &c, 1) < 0)
+    strerr_diefu1sys(111, "read from stdin") ;
+  return 0 ;
+}