HelenOS sources

root/uspace/app/bdsh/exec.c

DEFINITIONS

1. try_access
2. find_command
3. try_exec

/*
 * 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 <str.h>
#include <str_error.h>
#include <errno.h>
#include <vfs/vfs.h>

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

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

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

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

        errno_t rc = vfs_lookup_open(f, WALK_REGULAR, MODE_READ, &fd);
        if (rc == EOK) {
                vfs_put(fd);
                return 0;
        } else
                return -1;
}

/** Returns EOK if no internal failure or else ENOMEM
 *
 * When the parameter `cmd` can be found then the absolute path will be set in `found`.
 * Or else `found` will be NULL.
 * `found` will be newly allocated and must be freed by the caller
 */
static errno_t find_command(char *cmd, char **found)
{
        /* The user has specified a full or relative path, just give it back. */
        if (is_path(cmd)) {
                if (-1 != try_access(cmd)) {
                        *found = str_dup(cmd);
                        return EOK;
                }

                *found = NULL;
                return EOK;
        }

        *found = (char *)malloc(PATH_MAX);
        if (*found == NULL) {
                return ENOMEM;
        }

        /* We now have n places to look for the command */
        size_t i;
        size_t cmd_length = str_length(cmd);
        for (i = 0; search_dir[i] != NULL; i++) {
                if (str_length(search_dir[i]) + cmd_length + 2 > PATH_MAX) {
                        free(*found);
                        return ENOMEM;
                }

                memset(*found, 0, PATH_MAX);
                snprintf(*found, PATH_MAX, "%s/%s", search_dir[i], cmd);
                if (-1 != try_access(*found)) {
                        return EOK;
                }
        }
        free(*found);
        *found = NULL;

        /* We didn't find it, return NULL */
        return EOK;
}

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;
        errno_t rc;
        int retval, i;
        int file_handles[3] = { -1, -1, -1 };
        FILE *files[3];

        rc = find_command(cmd, &tmp);
        if (rc != EOK) {
                cli_error(CL_ENOMEM, "%s: failure executing find_command()", progname);
                return 1;
        }

        if (tmp == NULL) {
                cli_error(CL_EEXEC, "%s: Command not found '%s'", progname, cmd);
                return 1;
        }

        files[0] = io->stdin;
        files[1] = io->stdout;
        files[2] = io->stderr;

        for (i = 0; i < 3 && files[i] != NULL; i++) {
                vfs_fhandle(files[i], &file_handles[i]);
        }

        rc = task_spawnvf(&tid, &twait, tmp, (const char **) argv,
            file_handles[0], file_handles[1], file_handles[2]);
        free(tmp);

        if (rc != EOK) {
                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;
}