Updating HEAD branch #4; Merging CABAL -> HEAD.

[tinc] / lib / dropin.c

diff --git a/lib/dropin.c b/lib/dropin.c
new file mode 100644 (file)
index 0000000..15ee90c
--- /dev/null
+++ b/lib/dropin.c
@@ -0,0 +1,171 @@
+/*
+    dropin.c -- a set of drop-in replacements for libc functions
+    Copyright (C) 2000,2001 Ivo Timmermans <itimmermans@bigfoot.com>,
+                  2000,2001 Guus Sliepen <guus@sliepen.warande.net>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+    $Id: dropin.c,v 1.2 2002/04/09 15:26:00 zarq Exp $
+*/
+
+#include "config.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+
+#include <xalloc.h>
+
+#include <system.h>
+#include <errno.h>
+
+#ifndef HAVE_DAEMON
+/*
+  Replacement for the daemon() function.
+  
+  The daemon() function is for programs wishing to detach themselves
+  from the controlling terminal and run in the background as system
+  daemons.
+
+  Unless the argument nochdir is non-zero, daemon() changes the
+  current working directory to the root (``/'').
+
+  Unless the argument noclose is non-zero, daemon() will redirect
+  standard input, standard output and standard error to /dev/null.
+*/
+int daemon(int nochdir, int noclose)
+{
+  pid_t pid;
+  int fd;
+  
+  pid = fork();
+  
+  /* Check if forking failed */
+  if(pid < 0)
+    {
+      perror("fork");
+      exit(-1);
+    }
+
+  /* If we are the parent, terminate */
+  if(pid)
+    exit(0);
+
+  /* Detach by becoming the new process group leader */
+  if(setsid() < 0)
+    {
+      perror("setsid");
+      return -1;
+    }
+  
+  /* Change working directory to the root (to avoid keeping mount
+     points busy) */
+  if(!nochdir)
+    {
+      chdir("/");
+    }
+    
+  /* Redirect stdin/out/err to /dev/null */
+  if(!noclose)
+    {
+      fd = open("/dev/null", O_RDWR);
+
+      if(fd < 0)
+        {
+          perror("opening /dev/null");
+          return -1;
+        }
+      else
+        {
+          dup2(fd, 0);
+          dup2(fd, 1);
+          dup2(fd, 2);
+        }
+    }
+
+  return 0;
+}
+#endif
+
+
+
+
+#ifndef HAVE_GET_CURRENT_DIR_NAME
+/*
+  Replacement for the GNU get_current_dir_name function:
+
+  get_current_dir_name will malloc(3) an array big enough to hold the
+  current directory name.  If the environment variable PWD is set, and
+  its value is correct, then that value will be returned.
+*/
+char *get_current_dir_name(void)
+{
+  size_t size;
+  char *buf;
+  char *r;
+
+  /* Start with 100 bytes.  If this turns out to be insufficient to
+     contain the working directory, double the size.  */
+  size = 100;
+  buf = xmalloc(size);
+
+  errno = 0; /* Success */
+  r = getcwd(buf, size);
+  /* getcwd returns NULL and sets errno to ERANGE if the bufferspace
+     is insufficient to contain the entire working directory.  */
+  while(r == NULL && errno == ERANGE)
+    {
+      free(buf);
+      size <<= 1; /* double the size */
+      buf = xmalloc(size);
+      r = getcwd(buf, size);
+    }
+
+  return buf;
+}
+#endif
+
+#ifndef HAVE_ASPRINTF
+int asprintf(char **buf, const char *fmt, ...)
+{
+  int status;
+  va_list ap;
+  int len;
+  
+  len = 4096;
+  *buf = xmalloc(len);
+
+  va_start(ap, fmt);
+  status = vsnprintf (*buf, len, fmt, ap);
+  va_end (ap);
+
+  if(status >= 0)
+    *buf = xrealloc(*buf, status);
+
+  if(status > len-1)
+    {
+      len = status;
+      va_start(ap, fmt);
+      status = vsnprintf (*buf, len, fmt, ap);
+      va_end (ap);
+    }
+
+  return status;
+}
+#endif