src/libopts/pgusage.c

   1
   2 /**
   3  * \file pgusage.c
   4  *
   5  * Time-stamp:      "2012-02-28 19:49:32 bkorb"
   6  *
   7  *   Automated Options Paged Usage module.
   8  *
   9  *  This routine will run run-on options through a pager so the
  10  *  user may examine, print or edit them at their leisure.
  11  *
  12  *  This file is part of AutoOpts, a companion to AutoGen.
  13  *  AutoOpts is free software.
  14  *  AutoOpts is Copyright (c) 1992-2012 by Bruce Korb - all rights reserved
  15  *
  16  *  AutoOpts is available under any one of two licenses.  The license
  17  *  in use must be one of these two and the choice is under the control
  18  *  of the user of the license.
  19  *
  20  *   The GNU Lesser General Public License, version 3 or later
  21  *      See the files "COPYING.lgplv3" and "COPYING.gplv3"
  22  *
  23  *   The Modified Berkeley Software Distribution License
  24  *      See the file "COPYING.mbsd"
  25  *
  26  *  These files have the following md5sums:
  27  *
  28  *  43b91e8ca915626ed3818ffb1b71248b pkg/libopts/COPYING.gplv3
  29  *  06a1a2e4760c90ea5e1dad8dfaac4d39 pkg/libopts/COPYING.lgplv3
  30  *  66a5cedaf62c4b2637025f049f9b826f pkg/libopts/COPYING.mbsd
  31  */
  32
  33 /*=export_func  optionPagedUsage
  34  * private:
  35  *
  36  * what:  Decipher a boolean value
  37  * arg:   + tOptions* + pOpts    + program options descriptor +
  38  * arg:   + tOptDesc* + pOptDesc + the descriptor for this arg +
  39  *
  40  * doc:
  41  *  Run the usage output through a pager.
  42  *  This is very handy if it is very long.
  43  *  This is disabled on platforms without a working fork() function.
  44 =*/
  45 void
  46 optionPagedUsage(tOptions * pOptions, tOptDesc * pOD)
  47 {
  48 #if ! defined(HAVE_WORKING_FORK)
  49     if ((pOD->fOptState & OPTST_RESET) != 0)
  50         return;
  51
  52     (*pOptions->pUsageProc)(pOptions, EXIT_SUCCESS);
  53 #else
  54     static pid_t     my_pid;
  55     char zPageUsage[ 1024 ];
  56
  57     /*
  58      *  IF we are being called after the usage proc is done
  59      *     (and thus has called "exit(2)")
  60      *  THEN invoke the pager to page through the usage file we created.
  61      */
  62     switch (pagerState) {
  63     case PAGER_STATE_INITIAL:
  64     {
  65         if ((pOD->fOptState & OPTST_RESET) != 0)
  66             return;
  67
  68         my_pid  = getpid();
  69         snprintf(zPageUsage, sizeof(zPageUsage), TMP_USAGE_FMT, (tAoUL)my_pid);
  70         unlink(zPageUsage);
  71
  72         /*
  73          *  Set usage output to this temporary file
  74          */
  75         option_usage_fp = fopen(zPageUsage, "w" FOPEN_BINARY_FLAG);
  76         if (option_usage_fp == NULL)
  77             _exit(EXIT_FAILURE);
  78
  79         pagerState = PAGER_STATE_READY;
  80
  81         /*
  82          *  Set up so this routine gets called during the exit logic
  83          */
  84         atexit((void(*)(void))optionPagedUsage);
  85
  86         /*
  87          *  The usage procedure will now put the usage information into
  88          *  the temporary file we created above.
  89          */
  90         (*pOptions->pUsageProc)(pOptions, EXIT_SUCCESS);
  91
  92         /* NOTREACHED */
  93         _exit(EXIT_FAILURE);
  94     }
  95
  96     case PAGER_STATE_READY:
  97     {
  98         tCC* pzPager  = (tCC*)getenv(PAGER_NAME);
  99
 100         /*
 101          *  Use the "more(1)" program if "PAGER" has not been defined
 102          */
 103         if (pzPager == NULL)
 104             pzPager = MORE_STR;
 105
 106         /*
 107          *  Page the file and remove it when done.
 108          */
 109         snprintf(zPageUsage, sizeof(zPageUsage), PAGE_USAGE_FMT, pzPager,
 110                  (tAoUL)my_pid);
 111         fclose(stderr);
 112         dup2(STDOUT_FILENO, STDERR_FILENO);
 113
 114         (void)system(zPageUsage);
 115     }
 116
 117     case PAGER_STATE_CHILD:
 118         /*
 119          *  This is a child process used in creating shell script usage.
 120          */
 121         break;
 122     }
 123 #endif
 124 }
 125
 126 /*
 127  * Local Variables:
 128  * mode: C
 129  * c-file-style: "stroustrup"
 130  * indent-tabs-mode: nil
 131  * End:
 132  * end of autoopts/pgusage.c */