/**

 * \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) 1992-2015 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 */