From b8e8f5b0c490063a351a1cb5740419b8ba45a2e6 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Sun, 22 Aug 2021 02:05:58 +0000
Subject:  Add ipc_bind_reuse_perms

Signed-off-by: Laurent Bercot <ska@appnovation.com>
---
 src/libstddjb/ipc_bind_reuse_lock_perms.c | 43 +++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 src/libstddjb/ipc_bind_reuse_lock_perms.c

(limited to 'src/libstddjb/ipc_bind_reuse_lock_perms.c')

diff --git a/src/libstddjb/ipc_bind_reuse_lock_perms.c b/src/libstddjb/ipc_bind_reuse_lock_perms.c
new file mode 100644
index 0000000..6e4d9ff
--- /dev/null
+++ b/src/libstddjb/ipc_bind_reuse_lock_perms.c
@@ -0,0 +1,43 @@
+/* ISC license. */
+
+#include <skalibs/nonposix.h>
+
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+
+#include <skalibs/djbunix.h>
+#include <skalibs/socket.h>
+
+int ipc_bind_reuse_lock_perms (int s, char const *p, int *fdlock, unsigned int perms)
+{
+  unsigned int opt = 1 ;
+  size_t len = strlen(p) ;
+  int fd ;
+  int r ;
+  mode_t m ;
+  char lockname[len + 6] ;
+  memcpy(lockname, p, len) ;
+  memcpy(lockname + len, ".lock", 6) ;
+  fd = open3(lockname, O_WRONLY | O_NONBLOCK | O_CREAT | O_CLOEXEC, 0600) ;
+  if (fd < 0) return -1 ;
+  r = fd_lock(fd, 1, 1) ;
+  if (r < 0) return -1 ;
+  if (!r) return (errno = EBUSY, -1) ;
+  r = errno ;
+  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof opt) ;
+  errno = r ;
+  unlink_void(p) ;
+  if (perms) m = umask(~perms & 0777) ;
+  if (ipc_bind(s, p) < 0)
+  {
+    if (perms) umask(m) ;
+    return -1 ;
+  }
+  if (perms) umask(m) ;
+  *fdlock = fd ;
+  return 0 ;
+}
-- 
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