/*      $NetBSD: pgusage.c,v 1.8 2024/08/18 20:47:25 christos Exp $     */


/**
* \file pgusage.c
*
*   Automated Options Paged Usage module.
*
* @addtogroup autoopts
* @{
*/
/*
*  This routine will run run-on options through a pager so the
*  user may examine, print or edit them at their leisure.
*
*  This file is part of AutoOpts, a companion to AutoGen.
*  AutoOpts is free software.
*  AutoOpts is Copyright (C) 1992-2018 by Bruce Korb - all rights reserved
*
*  AutoOpts is available under any one of two licenses.  The license
*  in use must be one of these two and the choice is under the control
*  of the user of the license.
*
*   The GNU Lesser General Public License, version 3 or later
*      See the files "COPYING.lgplv3" and "COPYING.gplv3"
*
*   The Modified Berkeley Software Distribution License
*      See the file "COPYING.mbsd"
*
*  These files have the following sha256 sums:
*
*  8584710e9b04216a394078dc156b781d0b47e1729104d666658aecef8ee32e95  COPYING.gplv3
*  4379e7444a0e2ce2b12dd6f5a52a27a4d02d39d247901d3285c88cf0d37f477b  COPYING.lgplv3
*  13aa749a5b0a454917a944ed8fffc530b784f5ead522b1aacaf4ec8aa55a6239  COPYING.mbsd
*/

#if defined(HAVE_WORKING_FORK)
static inline FILE *
open_tmp_usage(char ** buf)
{
   char * bf;
   size_t bfsz;

   {
       unsigned int my_pid = (unsigned int)getpid();
       char const * tmpdir = getenv(TMPDIR);
       if (tmpdir == NULL)
           tmpdir = tmp_dir;
       bfsz = TMP_FILE_FMT_LEN + strlen(tmpdir) + 10;
       bf   = AGALOC(bfsz, "tmp fil");
       snprintf(bf, bfsz, TMP_FILE_FMT, tmpdir, my_pid);
   }

   {
       static mode_t const cmask = S_IRWXO | S_IRWXG;
       mode_t svmsk = umask(cmask);
       int fd = mkstemp(bf);
       (void)umask(svmsk);

       if (fd < 0) {
           AGFREE(bf);
           return NULL;
       }
       *buf = bf;
       return fdopen(fd, "w");
   }
}

static inline char *
mk_pager_cmd(char const * fname)
{
   /*
    * Page the file and remove it when done.  For shell script processing,
    * we must redirect the output to the current stderr, otherwise stdout.
    */
   fclose(option_usage_fp);
   option_usage_fp = NULL;

   {
       char const * pager  = (char const *)getenv(PAGER_NAME);
       size_t bfsz;
       char * res;

       /*
        *  Use the "more(1)" program if "PAGER" has not been defined
        */
       if (pager == NULL)
           pager = MORE_STR;

       bfsz = 2 * strlen(fname) + strlen(pager) + PAGE_USAGE_FMT_LEN;
       res  = AGALOC(bfsz, "more cmd");
       snprintf(res, bfsz, PAGE_USAGE_FMT, pager, fname);
       AGFREE(fname);
       return res;
   }
}
#endif

/*=export_func  optionPagedUsage
* private:
*
* what:  emit help text and pass through a pager program.
* arg:   + tOptions * + opts + program options descriptor +
* arg:   + tOptDesc * + od   + the descriptor for this arg +
*
* doc:
*  Run the usage output through a pager.
*  This is very handy if it is very long.
*  This is disabled on platforms without a working fork() function.
=*/
void
optionPagedUsage(tOptions * opts, tOptDesc * od)
{
#if ! defined(HAVE_WORKING_FORK)
   if ((od->fOptState & OPTST_RESET) != 0)
       return;

   (*opts->pUsageProc)(opts, EXIT_SUCCESS);
#else
   static bool sv_print_exit = false;
   static char * fil_name = NULL;

   /*
    *  IF we are being called after the usage proc is done
    *     (and thus has called "exit(2)")
    *  THEN invoke the pager to page through the usage file we created.
    */
   switch (pagerState) {
   case PAGER_STATE_INITIAL:
   {
       if ((od->fOptState & OPTST_RESET) != 0)
           return;
       option_usage_fp = open_tmp_usage(&fil_name);
       if (option_usage_fp == NULL)
           (*opts->pUsageProc)(opts, EXIT_SUCCESS);

       pagerState    = PAGER_STATE_READY;
       sv_print_exit = print_exit;

       /*
        *  Set up so this routine gets called during the exit logic
        */
       atexit((void(*)(void))optionPagedUsage);

       /*
        *  The usage procedure will now put the usage information into
        *  the temporary file we created above.  Keep any shell commands
        *  out of the result.
        */
       print_exit = false;
       (*opts->pUsageProc)(opts, EXIT_SUCCESS);

       /* NOTREACHED */
       _exit(EXIT_FAILURE);
   }

   case PAGER_STATE_READY:
       fil_name = mk_pager_cmd(fil_name);

       if (sv_print_exit) {
           fputs("\nexit 0\n", stdout);
           fclose(stdout);
           dup2(STDERR_FILENO, STDOUT_FILENO);

       } else {
           fclose(stderr);
           dup2(STDOUT_FILENO, STDERR_FILENO);
       }

       ignore_val( system( fil_name));
       AGFREE(fil_name);

   case PAGER_STATE_CHILD:
       /*
        *  This is a child process used in creating shell script usage.
        */
       break;
   }
#endif
}

/** @}
*
* Local Variables:
* mode: C
* c-file-style: "stroustrup"
* indent-tabs-mode: nil
* End:
* end of autoopts/pgusage.c */