add undaemonise

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

2 files changed, 68 insertions, 4 deletions

diff --git a/include/unistd.h b/include/unistd.h
index 4629e8e..963bb96 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -1138,6 +1138,8 @@ int daemon(int, int)
  * should be used instead of /run for the runtime data-files
  * directory, in which the PID file is stored.
  * 
+ * This is a slibc extension.
+ * 
  * @etymology  (Daemonise) the process!
  * 
  * @param   name   The name of the daemon. Use a hardcoded value,
@@ -1174,6 +1176,23 @@ int daemon(int, int)
  */
 int daemonise(const char*, int)
   __GCC_ONLY(__attribute__((__nonnull__, __warn_unused_result__)));
+
+/**
+ * Remove the PID file created by `daemonise`. This shall
+ * always be called before exiting after calling `daemonise`,
+ * even if it failed.
+ * 
+ * This is a slibc extension.
+ * 
+ * @etymology  (Un)link PID file created by `(daemonise)`!
+ * 
+ * @return  Zero on success, -1 on error.
+ * 
+ * @throws  Any error specified for unlink(3).
+ * 
+ * @since  Always.
+ */
+int undaemonise(void);
 #endif
 
 
diff --git a/src/unistd/daemonise.c b/src/unistd/daemonise.c
index a8fe3ab..f3ebe3a 100644
--- a/src/unistd/daemonise.c
+++ b/src/unistd/daemonise.c
@@ -21,6 +21,7 @@
 #include <fcntl.h>
 #include <signal.h>
 #include <string.h>
+#include <stdlib.h>
 #include <errno.h>
 #include <sys/resource.h>
 
@@ -31,6 +32,11 @@
  */
 extern char** environ;
 
+/**
+ * The pidfile created by `daemonise`.
+ */
+static char* __pidfile = NULL;
+
 
 
 /**
@@ -96,6 +102,8 @@ extern char** environ;
  * should be used instead of /run for the runtime data-files
  * directory, in which the PID file is stored.
  * 
+ * This is a slibc extension.
+ * 
  * @etymology  (Daemonise) the process!
  * 
  * @param   name   The name of the daemon. Use a hardcoded value,
@@ -221,16 +229,24 @@ int daemonise(const char* name, int flags)
   run = getenv("XDG_RUNTIME_DIR");
   if (run && *run)
     {
-      pidpath = alloca(sizeof("/.pid") + (strlen(run) + strlen(name)) * sizeof(char));
+      pidpath = malloc(sizeof("/.pid") + (strlen(run) + strlen(name)) * sizeof(char));
+      t (pidfile == NULL);
       stpcpy(stpcpy(stpcpy(stpcpy(pidpath, run), "/"), name), ".pid");
     }
   else
     {
-      pidpath = alloca(sizeof("/run/.pid") + strlen(name) * sizeof(char));
+      pidpath = malloc(sizeof("/run/.pid") + strlen(name) * sizeof(char));
+      t (pidfile == NULL);
       stpcpy(stpcpy(stpcpy(pidpath, "/run/"), name), ".pid");
     }
   fd = open(pidpath, O_WRONLY | O_CREAT | O_EXCL, 0644);
-  t (fd == -1);
+  if (fd == -1)
+    {
+      saved_errno = errno;
+      free(pidpath), pidpath = NULL;
+      errno = saved_errno;
+      goto fail;
+    }
   pid = getpid();
   t (dprintf(fd, "%lli\n", (long long int)pid)) < 0;
   t (close(fd) && (errno != EINTR));
@@ -260,12 +276,13 @@ int daemonise(const char* name, int flags)
     {
       if (flags & DAEMONISE_KEEP_STDERR)
 	return -1;
+      undaemonise();
       abort(); /* Do not overcomplicate things, just abort in this unlikely event. */
     }
   
   return 0;
  fail:
-  saved_errno = err;
+  saved_errno = errno;
   if (pipe_rw[0] >= 0)  close(pipe_rw[0]);
   if (pipe_rw[1] >= 0)  close(pipe_rw[1]);
   if (fd         >= 0)  close(fd);
@@ -273,3 +290,31 @@ int daemonise(const char* name, int flags)
   return -1;
 }
 
+
+/**
+ * Remove the PID file created by `daemonise`. This shall
+ * always be called before exiting after calling `daemonise`,
+ * even if it failed.
+ * 
+ * This is a slibc extension.
+ * 
+ * @etymology  (Un)link PID file created by `(daemonise)`!
+ * 
+ * @return  Zero on success, -1 on error.
+ * 
+ * @throws  Any error specified for unlink(3).
+ * 
+ * @since  Always.
+ */
+int undaemonise(void)
+{
+  int r, saved_errno;
+  if (pidfile == NULL)
+    return 0;
+  r = unlink(pidfile);
+  saved_errno = errno;
+  free(pidfile), pidfile = NULL;
+  errno = saved_errno;
+  return r;
+}
+