/*
 *  SPL - The SPL Programming Language
 *  Copyright (C) 2004, 2005  Clifford Wolf <clifford@clifford.at>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  mod_system.c: Module for calling shell commands
 */

/**
 * This module provides a simple API for calling shell commands
 */

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "spl.h"
#include "compat.h"

extern void SPL_ABI(spl_mod_system_init)(struct spl_vm *vm, struct spl_module *mod, int restore);
extern void SPL_ABI(spl_mod_system_done)(struct spl_vm *vm, struct spl_module *mod);

/**
 * This function calls the specified shell command and returns the text written
 * to stdout.
 *
 * If the output is not UTF-8 encoded, the encoding must be specified with a
 * 2nd parameter. Valid encodings are the same as for the '#encoding' compiler
 * pragma (see 'SPL Language Reference' for a list).
 *
 * If UTF-8 encoding is expected but the output fails to pass the UTF-8 test,
 * the output is assumed to be latin1 encoded.
 *
 * A newline at the end of the output is automatically removed.
 */
// builtin system(command, encoding)
static struct spl_node *handler_system(struct spl_task *task, void UNUSED(*data))
{
	char *command = spl_clib_get_string(task);
	char *encoding = spl_clib_get_string(task);
	char *output = malloc(512);

	int len = 0;
	int buffer = 512;

	int p[2];
	pipe(p);

	int pid = fork();

	if ( !pid ) {
		close(1);
		close(p[0]);
		dup2(p[1], 1);
		if (task->vm->current_dir_name)
			chdir(task->vm->current_dir_name);
		execlp("sh", "sh", "-c", command, NULL);
		_exit(1);
	}

	close(p[1]);
	while (1) {
		int rc = read(p[0], output+len, 512);
		if (rc <= 0) break;

		len += rc;
		if (len + 512 > buffer) {
			buffer = len*2 + 512;
			output = realloc(output, buffer);
		}
	}
	close(p[0]);
	waitpid(pid, 0, 0);

	output = realloc(output, len+1);
	output[len] = 0;

	if (len > 0 && output[len-1] == '\n')
		output[len-1] = 0;

	if (*encoding) {
		char *old_output = output;
		output = spl_utf8_import(old_output, encoding);

		if (!output)
			output = old_output;
		else
			free(old_output);
	}

	if (spl_utf8_check(output)) {
		char *old_output = output;
		output = spl_utf8_import(old_output, "latin_1");
		free(old_output);

		/* this should never happen */
		if (!output) output = strdup("");
	}

	return SPL_NEW_STRING(output);
}

void SPL_ABI(spl_mod_system_init)(struct spl_vm *vm, struct spl_module UNUSED(*mod), int UNUSED(restore))
{
	spl_clib_reg(vm, "system", handler_system, 0);
}

void SPL_ABI(spl_mod_system_done)(struct spl_vm UNUSED(*vm), struct spl_module UNUSED(*mod))
{
	return;
}