1 files changed, 60 insertions, 0 deletions
diff --git a/src/serverlib/s6rc_lock.c b/src/serverlib/s6rc_lock.c
new file mode 100644
index 0000000..d3ae2b5
--- /dev/null
+++ b/src/serverlib/s6rc_lock.c
@@ -0,0 +1,60 @@
+/* ISC license. */
+
+#include <string.h>
+#include <errno.h>
+#include <skalibs/djbunix.h>
+#include <s6-rc/s6rc-utils.h>
+
+static inline int lockex (int fd, int blocking)
+{
+  return blocking ? lock_ex(fd) : lock_exnb(fd) ;
+}
+
+static inline int locksh (int fd, int blocking)
+{
+  return blocking ? lock_sh(fd) : lock_shnb(fd) ;
+}
+
+int s6rc_lock (char const *live, int lwhat, int *llfd, char const *compiled, int cwhat, int *ccfd, int blocking)
+{
+  int lfd = -1, cfd = -1 ;
+
+  if (lwhat)
+  {
+    size_t llen = strlen(live) ;
+    char lfn[llen + 6] ;
+    memcpy(lfn, live, llen) ;
+    memcpy(lfn + llen, "/lock", 6) ;
+    lfd = open_create(lfn) ;
+    if (lfd < 0) return 0 ;
+    if (coe(lfd) < 0) goto lerr ;
+    if ((lwhat > 1 ? lockex(lfd, blocking) : locksh(lfd, blocking)) < 0) goto lerr ;
+  }
+
+  if (cwhat)
+  {
+    size_t clen = strlen(compiled) ;
+    char cfn[clen + 6] ;
+    memcpy(cfn, compiled, clen) ;
+    memcpy(cfn + clen, "/lock", 6) ;
+    cfd = open_create(cfn) ;
+    if (cfd < 0)
+      if (cwhat > 1 || errno != EROFS) goto lerr ;
+      else cfd = -errno ;
+    else
+    {
+      if (coe(cfd) < 0) goto cerr ;
+      if ((cwhat > 1 ? lockex(cfd, blocking) : locksh(cfd, blocking)) < 0) goto cerr ;
+    }
+  }
+
+  if (lwhat) *llfd = lfd ;
+  if (cwhat) *ccfd = cfd ;
+  return 1 ;
+
+ cerr:
+  fd_close(cfd) ;
+ lerr:
+  if (lwhat) fd_close(lfd) ;
+  return 0 ;
+}