/*
 * Copyright (c) 2008 Tim Post
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* The VERY basics of execute in place support. These are buggy, leaky
 * and not nearly done. Only here for beta testing!! You were warned!!
 * TODO:
 * Hash command lookups to save time
 * Create a running pointer to **path and advance/rewind it as we go */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <str.h>
#include <fcntl.h>
#include <str_error.h>
#include <errno.h>
#include <vfs/vfs.h>

#include "config.h"
#include "util.h"
#include "exec.h"
#include "errors.h"

/* FIXME: Just have find_command() return an allocated string */
static char *found;

static char *find_command(char *);
static int try_access(const char *);

const char *search_dir[] = { "/app", "/srv", NULL };

/* work-around for access() */
static int try_access(const char *f)
{
	int fd;

	fd = open(f, O_RDONLY);
	if (fd >= 0) {
		close(fd);
		return 0;
	} else
		return -1;
}

/* Returns the full path of "cmd" if cmd is found, else just hand back
 * cmd as it was presented */
static char *find_command(char *cmd)
{
	size_t i;

	found = (char *)malloc(PATH_MAX);

	/* The user has specified a full or relative path, just give it back. */
	if (-1 != try_access(cmd)) {
		return (char *) cmd;
	}

	/* We now have n places to look for the command */
	for (i = 0; search_dir[i] != NULL; i++) {
		memset(found, 0, PATH_MAX);
		snprintf(found, PATH_MAX, "%s/%s", search_dir[i], cmd);
		if (-1 != try_access(found)) {
			return (char *) found;
		}
	}

	/* We didn't find it, just give it back as-is. */
	return (char *) cmd;
}

unsigned int try_exec(char *cmd, char **argv, iostate_t *io)
{
	task_id_t tid;
	task_wait_t twait;
	task_exit_t texit;
	char *tmp;
	int rc, retval, i;
	int file_handles[3];
	int *file_handles_p[4];
	FILE *files[3];

	tmp = str_dup(find_command(cmd));
	free(found);
	
	files[0] = io->stdin;
	files[1] = io->stdout;
	files[2] = io->stderr;
	
	for (i = 0; i < 3 && files[i] != NULL; i++) {
		if (vfs_fhandle(files[i], &file_handles[i]) == EOK) {
			file_handles_p[i] = &file_handles[i];
		}
		else {
			file_handles_p[i] = NULL;
		}
	}
	file_handles_p[i] = NULL;

	rc = task_spawnvf(&tid, &twait, tmp, (const char **) argv, file_handles_p);
	free(tmp);

	if (rc != 0) {
		cli_error(CL_EEXEC, "%s: Cannot spawn `%s' (%s)", progname, cmd,
		    str_error(rc));
		return 1;
	}
	
	rc = task_wait(&twait, &texit, &retval);
	if (rc != EOK) {
		printf("%s: Failed waiting for command (%s)\n", progname,
		    str_error(rc));
		return 1;
	} else if (texit != TASK_EXIT_NORMAL) {
		printf("%s: Command failed (unexpectedly terminated)\n", progname);
		return 1;
	} else if (retval != 0) {
		printf("%s: Command failed (exit code %d)\n",
		    progname, retval);
		return 1;
	}

	return 0;
}