/* Copyright (C) 2000 Bruce Guenter <bruceg@em.ca>
  *
  * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
 #include <stdio.h>
 #include <sys/fcntl.h>
 #include <unistd.h>
 
 #define QQ_WRITE_ERROR 53
 #define QQ_INTERNAL 81
 
 #ifndef BUFSIZE
 #define BUFSIZE 4096
 #endif
 
 #ifndef TMPDIR
 #define TMPDIR "/tmp"
 #endif
 
 typedef int bool;
 const bool false = 0;
 const bool true = 0 == 0;
 
 /* Create a temporary invisible file opened for read/write */
 int mktmpfile(void)
 {
   const char* filename = tempnam(TMPDIR, "fixheaders.");
   int fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
   if(fd == -1)
     return -1;
 
   /* The following makes the temporary file disappear immediately on
      program exit by removing the only filename that links to it. */
   if(unlink(filename) == -1)
     return -1;
   
   return fd;
 }
 
 /* Copy the message from FD0 to the first temporary file */
 int copy_message(void)
 {
   int tmp = mktmpfile();
   if(tmp == -1)
     return -QQ_WRITE_ERROR;
   
   /* Copy the message into the temporary file */
   for(;;) {
     char buf[BUFSIZE];
     ssize_t rd = read(0, buf, BUFSIZE);
     if(rd == -1)
       return -QQ_WRITE_ERROR;
     if(rd == 0)
       break;
     if(write(tmp, buf, rd) != rd)
       return -QQ_WRITE_ERROR;
   }
 
   if(lseek(tmp, 0, SEEK_SET) != 0)
     return -QQ_WRITE_ERROR;
 
   return tmp;
 }
 
 void usage(void)
 {
   write(2, "usage: filepipe program [args...]\n", 34);
   exit(1);
 }
 
 int main(int argc, char* argv[])
 {
   int tmpfd;
   if(argc < 2)
     usage();
   
   tmpfd = copy_message();
   if(tmpfd < 0)
     return -tmpfd;
 
   if(close(0) || dup2(tmpfd, 0) || close(tmpfd))
     return QQ_INTERNAL;
 
   execvp(argv[1], argv+1);
   return QQ_INTERNAL;
 }