src/process.h

   1 /* process.h -- header for child process routines for vlock,
   2  *              the VT locking program for linux
   3  *
   4  * This program is copyright (C) 2007 Frank Benkstein, and is free
   5  * software which is freely distributable under the terms of the
   6  * GNU General Public License version 2, included as the file COPYING in this
   7  * distribution.  It is NOT public domain software, and any
   8  * redistribution not permitted by the GNU General Public License is
   9  * expressly forbidden without prior written permission from
  10  * the author.
  11  *
  12  */
  13
  14 #include <stdbool.h>
  15 #include <sys/types.h>
  16
  17 /* Wait for the given amount of time for the death of the given child process.
  18  * If the child process dies in the given amount of time or already was dead
  19  * true is returned and false otherwise. */
  20 bool wait_for_death(pid_t pid, long sec, long usec);
  21
  22 /* Try hard to kill the given child process. */
  23 void ensure_death(pid_t pid);
  24
  25 #define NO_REDIRECT (-2)
  26 #define REDIRECT_DEV_NULL (-3)
  27 #define REDIRECT_PIPE (-4)
  28
  29 struct child_process {
  30   /* Function that will be run in the child. */
  31   int (*function)(void *argument);
  32   /* Argument for the function. */
  33   void *argument;
  34   /* First argument to execv. */
  35   const char *path;
  36   /* Second argument to execv. */
  37   const char *const *argv;
  38   /* The child's stdin. */
  39   int stdin_fd;
  40   /* The child's stdout. */
  41   int stdout_fd;
  42   /* The child's stderr. */
  43   int stderr_fd;
  44   /* The child's PID. */
  45   pid_t pid;
  46 };
  47
  48 /* Create a new child process.  All file descriptors except stdin, stdout and
  49  * stderr are closed and privileges are dropped.  All fields of the child
  50  * struct except pid must be set.  If a stdio file descriptor field has the
  51  * special value of REDIRECT_DEV_NULL it is redirected from or to /dev/null.
  52  * If it has the value REDIRECT_PIPE a pipe will be created and one end will be
  53  * connected to the respective descriptor of the child.  The file descriptor of
  54  * the other end is stored in the field after the call.  It is up to the caller
  55  * to close the pipe descriptor(s). */
  56 bool create_child(struct child_process *child);