argp subcommand example

argp-subcommand.c

/*
 * Sample command line parser.
 *
 * Implements sub-commands with their own option handlers.
 * 
 */

#include <assert.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <argp.h>

/** Argp Wrapper Functions **/

const char* argp_key(int key, char* keystr)
{
  keystr[0] = key;
  keystr[1] = 0;

  switch(key)
  {
    case ARGP_KEY_ARG:     return "ARGP_KEY_ARG";
    case ARGP_KEY_ARGS:    return "ARGP_KEY_ARGS";
    case ARGP_KEY_END:     return "ARGP_KEY_END";
    case ARGP_KEY_NO_ARGS: return "ARGP_KEY_NO_ARGS";
    case ARGP_KEY_INIT:    return "ARGP_KEY_INIT";
    case ARGP_KEY_SUCCESS: return "ARGP_KEY_SUCCESS";
    case ARGP_KEY_ERROR:   return "ARGP_KEY_ERROR";
    case ARGP_KEY_FINI:    return "ARGP_KEY_FINI";
  }

  return keystr;
};

/** Local Prototypes **/

struct arg_global;

void log_printf(struct arg_global* g, int level, const char* fmt, ...);

void cmd_global(int argc, char**argv);
void cmd_aa(struct argp_state* state);

/** Global Options **/

struct arg_global
{
  int verbosity;
};

const char *argp_program_version = "x, version 0.0";
const char *argp_program_bug_address = "[email protected]";
error_t argp_err_exit_status = 1;

static struct argp_option opt_global[] =
{
/* { name, key, arg-name, flags,
 *      doc, group } */

  { "verbose", 'v', "level", OPTION_ARG_OPTIONAL,
        "Increase or set the verbosity level.", -1},

  { "quiet", 'q', 0, 0,
        "Set verbosity to 0.", -1},

  // make -h an alias for --help
  { 0 }
};

static char doc_global[] =
  "\n"
  "Example of parsing a nested command line."
  "\v"
  "Supported commands are:\n"
  "  aa    Do aa with great panache."
  ;

static error_t
parse_global(int key, char* arg, struct argp_state* state)
{
  struct arg_global* global = state->input;
  char keystr[2];

  log_printf(global, 3, "x: parsing %s = '%s'\n",
      argp_key(key, keystr), arg ? arg : "(null)");

  switch(key)
  {
    case 'v':
      if(arg)
        global->verbosity = atoi(arg);
      else
        global->verbosity++;
      log_printf(global, 2, "x: set verbosity to %d\n", global->verbosity);
      break;

    case 'q':
      log_printf(global, 2, "x: setting verbosity to 0\n");
      global->verbosity = 0;
      break;
   
    case ARGP_KEY_ARG:
      assert( arg );
      if(strcmp(arg, "aa") == 0) {
        cmd_aa(state);
      } else {
        argp_error(state, "%s is not a valid command", arg);
      }
      break;

    default:
      return ARGP_ERR_UNKNOWN;
  }

  return 0;
}

static struct argp argp =
{
  opt_global,
  parse_global,
  "[<cmd> [CMD-OPTIONS]]...",
  doc_global,
};

void cmd_global(int argc, char**argv)
{
  struct arg_global global =
  {
      1, /* default verbosity */
  };

  log_printf(&global, 3, "x: begin (argc = %d, argv[0] = %s)\n",
      argc, argv[0]);

  argp_parse(&argp, argc, argv, ARGP_IN_ORDER, NULL, &global);
}

/** AA Command **/

struct arg_aa
{
  struct arg_global* global;

  char* name;
};

static struct argp_option opt_aa[] =
{
  { "out", 'o', "file", 0,
        "The output file." },

  { "external", 'x', 0, 0,
        "External." },

  { 0 }
};

static char doc_aa[] =
  "\n"
  "The aa doc prefix."
  "\v"
  "The aa doc suffix."
  ;

static error_t
parse_aa(int key, char* arg, struct argp_state* state)
{
  struct arg_aa* aa = state->input;
  char keystr[2];
  
  assert( aa );
  assert( aa->global );

  log_printf(aa->global, 3, "x aa: parsing %s = '%s'\n",
      argp_key(key, keystr), arg ? arg : "(null)");

  switch(key)
  {
    case 'o':
      log_printf(aa->global, 2, "x aa: -o, output = %s \n", arg);
      break;

    case 'x':
      log_printf(aa->global, 2, "x aa: -x, external\n");
      break;

    default:
      return ARGP_ERR_UNKNOWN;
  }

  return 0;
}

static struct argp argp_aa =
{
  opt_aa,
  parse_aa,
  0,
  doc_aa
};

void cmd_aa(struct argp_state* state)
{
  struct arg_aa aa = { 0, };
  int    argc = state->argc - state->next + 1;
  char** argv = &state->argv[state->next - 1];
  char*  argv0 =  argv[0];

  aa.global = state->input;

  log_printf(aa.global, 3, "x aa: begin (argc = %d, argv[0] = %s)\n",
      argc, argv[0]);

  argv[0] = malloc(strlen(state->name) + strlen(" aa") + 1);

  if(!argv[0])
    argp_failure(state, 1, ENOMEM, 0);

  sprintf(argv[0], "%s aa", state->name);

  argp_parse(&argp_aa, argc, argv, ARGP_IN_ORDER, &argc, &aa);

  free(argv[0]);

  argv[0] = argv0;

  state->next += argc - 1;

  log_printf(aa.global, 3, "x aa: end (next = %d, argv[next] = %s)\n",
      state->next, state->argv[state->next]);

  return;
}

/** Main **/

int main(int argc, char** argv)
{
  setvbuf(stdout, (char *)NULL, _IOLBF, 0);
  setvbuf(stderr, (char *)NULL, _IOLBF, 0);

  cmd_global(argc, argv);

  return 0;
}

/** Logging **/

void log_printf(struct arg_global* g, int level, const char* fmt, ...)
{
  va_list ap;
  FILE* f = stdout;

  if(g->verbosity < level)
    return;

  if(level == 0)
    f = stderr;

  va_start(ap, fmt);

  vfprintf(f, fmt, ap);

  va_end(ap);
}