From b992db748b9ffe8d88d609950f5da28b5a1db135 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Sun, 8 Nov 2020 09:32:32 +0000
Subject:  Add ipc_bind_reuse_lock, rewrite ipc_bind_reuse to use it

---
 src/include/skalibs/webipc.h        |  1 +
 src/libstddjb/ipc_bind_reuse.c      |  9 ++-------
 src/libstddjb/ipc_bind_reuse_lock.c | 28 ++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 7 deletions(-)
 create mode 100644 src/libstddjb/ipc_bind_reuse_lock.c

(limited to 'src')

diff --git a/src/include/skalibs/webipc.h b/src/include/skalibs/webipc.h
index eba6f6b..2a7e95e 100644
--- a/src/include/skalibs/webipc.h
+++ b/src/include/skalibs/webipc.h
@@ -40,6 +40,7 @@ extern int ipc_pair_internal (int *, unsigned int) ;
 
 extern int ipc_bind (int, char const *) ;
 extern int ipc_bind_reuse (int, char const *) ;
+extern int ipc_bind_reuse_lock (int, char const *, int *) ;
 extern int ipc_listen (int, int) ;
 
 #define ipc_accept(s, path, len, trunc) ipc_accept_internal(s, path, len, (trunc), 0)
diff --git a/src/libstddjb/ipc_bind_reuse.c b/src/libstddjb/ipc_bind_reuse.c
index 31db745..ce5c7a4 100644
--- a/src/libstddjb/ipc_bind_reuse.c
+++ b/src/libstddjb/ipc_bind_reuse.c
@@ -1,14 +1,9 @@
 /* ISC license. */
 
-#include <skalibs/nonposix.h>
-#include <sys/socket.h>
-#include <unistd.h>
 #include <skalibs/webipc.h>
 
 int ipc_bind_reuse (int s, char const *p)
 {
-  unsigned int opt = 1 ;
-  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof opt) ;
-  unlink(p) ;
-  return ipc_bind(s, p) ;
+  int fdlock ;
+  return ipc_bind_reuse_lock(s, p, &fdlock) ;
 }
diff --git a/src/libstddjb/ipc_bind_reuse_lock.c b/src/libstddjb/ipc_bind_reuse_lock.c
new file mode 100644
index 0000000..aede744
--- /dev/null
+++ b/src/libstddjb/ipc_bind_reuse_lock.c
@@ -0,0 +1,28 @@
+/* ISC license. */
+
+#include <skalibs/nonposix.h>
+
+#include <string.h>
+#include <unistd.h>
+#include <sys/socket.h>
+
+#include <skalibs/djbunix.h>
+#include <skalibs/webipc.h>
+
+int ipc_bind_reuse_lock (int s, char const *p, int *fdlock)
+{
+  unsigned int opt = 1 ;
+  size_t len = strlen(p) ;
+  int fd ;
+  char lockname[len + 6] ;
+  memcpy(lockname, p, len) ;
+  memcpy(lockname + len, ".lock", 6) ;
+  fd = openc_create(lockname) ;
+  if (fd < 0) return -1 ;
+  if (lock_exnb(fd) < 0) return -1 ;
+  setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof opt) ;
+  unlink(p) ;
+  if (ipc_bind(s, p) < 0) return -1 ;
+  *fdlock = fd ;
+  return 0 ;
+}
-- 
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