args.c

/*
Copyright (c) 2014. The YARA Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#include <assert.h>
#include <string.h>
#include <stdlib.h>

#include "args.h"

#define args_is_long_arg(arg)  \
    (arg[0] == '-' && arg[1] == '-' && arg[2] != '\0')


#define args_is_short_arg(arg)  \
    (arg[0] == '-' && arg[1] != '-' && arg[1] != '\0')


args_option_t* args_get_short_option(
    args_option_t *options,
    const char opt)
{
  while (options->type != ARGS_OPT_END)
  {
    if (opt == options->short_name)
      return options;

    options++;
  }

  return NULL;
}


args_option_t* args_get_long_option(
    args_option_t *options,
    const char* arg)
{
  arg += 2; // skip starting --

  while (options->type != ARGS_OPT_END)
  {
    if (options->long_name != NULL)
    {
      size_t l = strlen(options->long_name);

      if ((arg[l] == '\0' || arg[l] == '=') &&
          strstr(arg, options->long_name) == arg)
      {
        return options;
      }
    }

    options++;
  }

  return NULL;
}


args_error_type_t args_parse_option(
    args_option_t* opt,
    const char* opt_arg,
    int* opt_arg_was_used)
{
  char *endptr = NULL;

  if (opt_arg_was_used != NULL)
      *opt_arg_was_used = 0;

  if (opt->count == opt->max_count)
    return ARGS_ERROR_TOO_MANY;

  switch (opt->type)
  {
    case ARGS_OPT_BOOLEAN:
      *(int*) opt->value = 1;
      break;

    case ARGS_OPT_INTEGER:

      if (opt_arg == NULL)
        return ARGS_ERROR_REQUIRED_INTEGER_ARG;

      *(int*) opt->value = strtol(opt_arg, &endptr, 0);

      if (*endptr != '\0')
        return ARGS_ERROR_REQUIRED_INTEGER_ARG;

      if (opt_arg_was_used != NULL)
        *opt_arg_was_used = 1;

      break;

    case ARGS_OPT_STRING:

      if (opt_arg == NULL)
        return ARGS_ERROR_REQUIRED_STRING_ARG;

      if (opt->max_count > 1)
        ((const char**)opt->value)[opt->count] = opt_arg;
      else
        *(const char**) opt->value = opt_arg;

      if (opt_arg_was_used != NULL)
        *opt_arg_was_used = 1;

      break;

    default:
      assert(0);
  }

  opt->count++;

  return ARGS_ERROR_OK;
}


void args_print_error(
    args_error_type_t error,
    const char* option)
{
  switch(error)
  {
    case ARGS_ERROR_UKNOWN_OPT:
      fprintf(stderr, "unknown option `%s`\n", option);
      break;
    case ARGS_ERROR_TOO_MANY:
      fprintf(stderr, "too many `%s` options\n", option);
      break;
    case ARGS_ERROR_REQUIRED_INTEGER_ARG:
      fprintf(stderr, "option `%s` requieres an integer argument\n", option);
      break;
    case ARGS_ERROR_REQUIRED_STRING_ARG:
      fprintf(stderr, "option `%s` requieres a string argument\n", option);
      break;
    case ARGS_ERROR_UNEXPECTED_ARG:
      fprintf(stderr, "option `%s` doesn't expect an argument\n", option);
      break;
    default:
      return;
  }
}


int args_parse(
    args_option_t *options,
    int argc,
    const char **argv)
{
  args_error_type_t error = ARGS_ERROR_OK;

  int i = 1;  // start with i = 1, argv[0] is the program name
  int o = 0;

  while (i < argc)
  {
    const char* arg = argv[i];

    if (args_is_long_arg(arg))
    {
      args_option_t* opt = args_get_long_option(options, arg);

      if (opt != NULL)
      {
        const char* equal = strchr(arg, '=');

        if (equal)
          error = args_parse_option(opt, equal + 1, NULL);
        else
          error = args_parse_option(opt, NULL, NULL);
      }
      else
      {
        error = ARGS_ERROR_UKNOWN_OPT;
      }
    }
    else if (args_is_short_arg(arg))
    {
      for (int j = 1; arg[j] != '\0'; j++)
      {
        args_option_t* opt = args_get_short_option(options, arg[j]);

        if (opt != NULL)
        {
          if (arg[j + 1] == '\0')
          {
            int arg_used;

            // short option followed by a space, argv[i + 1] could be
            // an argument for the option (i.e: -a <arg>)
            error = args_parse_option(opt, argv[i + 1], &arg_used);

            // argv[i + 1] was actually an argument to the option, skip it.
            if (arg_used)
              i++;
          }
          else
          {
            // short option followed by another option (i.e: -ab), no
            // argument for this option
            error = args_parse_option(opt, NULL, NULL);
          }
        }
        else
        {
          error = ARGS_ERROR_UKNOWN_OPT;
        }

        if (error != ARGS_ERROR_OK)
          break;
      }
    }
    else
    {
      argv[o++] = arg;
    }

    if (error != ARGS_ERROR_OK)
    {
      args_print_error(error, arg);
      exit(1);
    }

    i++;
  }

  return o;
}


void args_print_usage(
    args_option_t *options,
    int help_alignment)
{
  char buffer[128];

  for (; options->type != ARGS_OPT_END; options++)
  {
    int len = sprintf(buffer, "  ");

    if (options->short_name != '\0')
      len += sprintf(buffer + len, "-%c", options->short_name);
    else
      len += sprintf(buffer + len, "     ");

    if (options->short_name != '\0' && options->long_name != NULL)
      len += sprintf(buffer + len, ",  ");

    if (options->long_name != NULL)
      len += sprintf(buffer + len, "--%s", options->long_name);

    if (options->type == ARGS_OPT_STRING ||
       options->type == ARGS_OPT_INTEGER)
    {
      len += sprintf(
          buffer + len,
          "%s%s",
          (options->long_name != NULL) ? "=" : " ",
          options->type_help);
    }

    printf("%-*s%s\n", help_alignment, buffer, options->help);
  }
}