From: "Mark E." <snowball3 AT bigfoot DOT com>
To: djgpp-workers AT delorie DOT com
Date: Mon, 11 Jun 2001 23:39:39 -0400
MIME-Version: 1.0
Content-type: text/plain; charset=US-ASCII
Content-transfer-encoding: 7BIT
Subject: getconf
Message-ID: <3B2556BB.3255.1FD3D5@localhost>
X-mailer: Pegasus Mail for Win32 (v3.12c)
Reply-To: djgpp-workers AT delorie DOT com

Hello,

getconf is a tool I could make use of, so I implemented it. Below is my first 
version.

/* Copyright (C) 2001 DJ Delorie, see COPYING.DJ for details */

#include <unistd.h>
#include <limits.h>
#include <stdio.h>

#define constant_var 0
#define confstr_var  1
#define pathconf_var 2
#define sysconf_var  3

struct variable
{
  const char *name;
  long value;
  unsigned int type;
};

const struct variable var_list[] =
{
  { "ARG_MAX", _SC_ARG_MAX, sysconf_var },
  { "CHILD_MAX", _SC_CHILD_MAX, sysconf_var },
  { "CLK_TCK", _SC_CLK_TCK, sysconf_var },
  { "LINK_MAX", _PC_LINK_MAX, pathconf_var },
  { "MAX_CANON", _PC_MAX_CANON, pathconf_var },
  { "MAX_INPUT", _PC_MAX_INPUT, pathconf_var },
  { "NAME_MAX", _PC_NAME_MAX, pathconf_var },
  { "NGROUPS_MAX", _SC_NGROUPS_MAX, sysconf_var },
  { "OPEN_MAX", _SC_OPEN_MAX, sysconf_var },
#ifdef _CS_PATH
  { "PATH", _CS_PATH, confstr_var },
#endif
  { "PATH_MAX", _PC_PATH_MAX, pathconf_var },
  { "PIPE_BUF", _PC_PIPE_BUF, pathconf_var },
  { "STREAM_MAX", _SC_STREAM_MAX, sysconf_var },
#ifdef _PC_SYMLINK_MAX
  { "SYMLINK_MAX", _PC_SYMLINK_MAX, pathconf_var },
#endif
  { "TZNAME_MAX", _SC_TZNAME_MAX, sysconf_var },
  { "_POSIX_ARG_MAX", _POSIX_ARG_MAX, constant_var },
  { "_POSIX_CHILD_MAX", _POSIX_CHILD_MAX, constant_var },
  { "_POSIX_CHOWN_RESTRICTED", _PC_CHOWN_RESTRICTED, pathconf_var },
  { "_POSIX_LINK_MAX", _POSIX_LINK_MAX, constant_var },
  { "_POSIX_MAX_CANON",  _POSIX_MAX_CANON, constant_var },
  { "_POSIX_MAX_INPUT", _POSIX_MAX_INPUT, constant_var },
  { "_POSIX_NAME_MAX", _POSIX_NAME_MAX, constant_var },
  { "_POSIX_NGROUPS_MAX", _POSIX_NGROUPS_MAX, constant_var },
  { "_POSIX_NO_TRUNC", _PC_NO_TRUNC, pathconf_var },
  { "_POSIX_JOB_CONTROL", _SC_JOB_CONTROL, sysconf_var },
  { "_POSIX_OPEN_MAX", _POSIX_OPEN_MAX, constant_var },
  { "_POSIX_PATH_MAX", _POSIX_PATH_MAX, constant_var },
  { "_POSIX_PIPE_BUF", _POSIX_PIPE_BUF, constant_var },
  { "_POSIX_SAVED_IDS", _SC_SAVED_IDS, sysconf_var },
  { "_POSIX_SSIZE_MAX", _POSIX_SSIZE_MAX, constant_var },
  { "_POSIX_STREAM_MAX", _POSIX_STREAM_MAX, constant_var },
  { "_POSIX_TZNAME_MAX", _POSIX_TZNAME_MAX, constant_var },
  { "_POSIX_VERSION", _SC_VERSION, sysconf_var },
  { "_POSIX_VDISABLE", _PC_VDISABLE, pathconf_var },
};

static void usage(void);
static void help(void);

int main(int argc, char *argv[])
{
  char c;
  const char *spec;
  const char *var_name;
  const struct variable *var;
  int print_usage;
  int i, cmp;
  int beg, end;

  if (argc == 1)
    usage();

  beg = 0;
  end = sizeof(var_list) / sizeof(var_list[0]);

  /* For now, any option will trigger the usage text.  */
  while ((c = getopt(argc, argv, "h")) != -1)
  {
    switch (c)
    {
      case 'h':
      {
        help();
        break;
      }
      default:
      {
        usage();
        break;
      }
    }
  }

  var_name = argv[optind];

  while (beg <= end)
  {
    i = (end + beg) / 2;
    cmp = strcmp (var_name, var_list[i].name);
    if (cmp == 0)
    {
      beg = end = i;
      break;
    }
    if (cmp > 0)
    {
      beg = i + 1;
    }
    else
    {
      end = i - 1;
    }
  }

  if (beg != end)
  {
    fprintf(stderr, "undefined\n");
    return 1;
  }

  var = var_list + beg;

  if ((argc - optind) != ((var->type == pathconf_var) ? 2 : 1))
    usage();

  switch (var->type)
  {
    case constant_var:
    {
      printf("%l\n", var->value);
      break;
    }

    case confstr_var:
    {
      size_t buf_len, ret;
      char *buf;

      buf_len = confstr(var->value, 0, 0);
      buf = alloca(buf_len);
      ret = confstr(var->value, buf, buf_len);
      printf("%s\n", buf);
      break;
    }

    case sysconf_var:
    {
      long val;
      
      val = sysconf(var->value);
      if (val != -1)
        printf("%d\n", val);
      else
        printf("undefined\n");
      break;
    }

   case pathconf_var:
   {
     long val;
     
     val = pathconf(argv[optind + 1], var->value);
     if (val != -1)
       printf("%d\n", val);
     else
       printf("undefined\n");
     break;
   }

  }
  
  return 0;
}

static void
usage(void)
{
  fprintf(stderr, "Usage: getopt [-h] [var] [pathvar path]\n");
  exit(1);
}

static void
help(void)
{
  int i;

  fprintf(stderr, "Usage: getopt var\n");
  for (i = 0; i < sizeof(var_list) / sizeof(var_list[0]); ++i)
  {
    if (var_list[0].type != pathconf_var)
      fprintf(stderr, "%s\n", var_list[i].name);
  } 

  fprintf(stderr, "\nUsage: getopt pathvar path\n");
  
  for (i = 0; i < sizeof(var_list) / sizeof(var_list[0]); ++i)
  {
    if (var_list[i].type == pathconf_var)
      fprintf(stderr, "%s\n", var_list[i].name);
  } 
}