Subversion Repositories HelenOS

/* Copyright (c) 2008, Tim Post <tinkertim@gmail.com>

 * 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.

 *

 * Neither the name of the original program's authors nor the names of its

 * contributors may be used to endorse or promote products derived from this

 * software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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 <string.h>

#include <fcntl.h>

#ifndef HELENOS

#include <linux/limits.h>

#include <sys/errno.h>

#include <sys/wait.h>

#endif

#include "config.h"

#include "util.h"

#include "exec.h"

#include "errors.h"

/* TODO: create exec, exev, execve wrappers for task_spawn() */

/* Easiest way to handle a shared + allocated string */

char *found;

/* work-around for access() */

unsigned int try_access(const char *f)

{

    int fd;

    fd = open(f, O_RDONLY);

    if (fd > -1) {

        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 */

char *find_command(char *cmd)

{

    char *path_orig, *path_tok;

    char *path[PATH_MAX];

    int n = 0, i = 0;

    size_t x = strlen(cmd) + 2;

    found = (char *)malloc(PATH_MAX);

    /* The user has specified a full or relative path, just give it back. */

#ifdef HELENOS

    if (-1 != try_access(cmd))

#else

    if (-1 != access(cmd, F_OK))

#endif

    {

        return (char *) cmd;

    }

#ifdef HELENOS

    path_orig = PATH;

#else

    path_orig = getenv("PATH");

    if (NULL == path_orig)

        path_orig = PATH;

#endif

    path_tok = cli_strdup(path_orig);

    /* Extract the PATH env to a path[] array */

    path[n] = cli_strtok(path_tok, PATH_DELIM);

    while (NULL != path[n]) {

        if ((strlen(path[n]) + x ) > PATH_MAX) {

            cli_error(CL_ENOTSUP,

                "Segment %d of path is too large, search ends at segment %d",

                n, n-1);

            break;

        }

        path[++n] = cli_strtok(NULL, PATH_DELIM);

    }

    /* We now have n places to look for the command */

    for (i=0; path[i]; i++) {

        memset(found, 0, sizeof(found));

        snprintf(found, PATH_MAX, "%s/%s", path[i], cmd);

#ifdef HELENOS

        if (-1 != try_access(found))

#else

        if (-1 != access(found, F_OK))

#endif

        {

            free(path_tok);

            return (char *) found;

        }

    }

    /* We didn't find it, just give it back as-is. Could be an alias

     * set in the parent shell */

    free(path_tok);

    return (char *) cmd;

}

#ifdef HELENOS

task_id_t try_exec(char *cmd, char **argv)

{

    task_id_t tid;

    char *tmp;

    tmp = cli_strdup(find_command(cmd));

    free(found);

    /* TODO: put the cwd in front of tmp if tmp[0] != root

     * which fixes relative paths fed to task_spawn */

    tid = task_spawn((const char *)tmp, (const char **)argv);

    free(tmp);

    if (tid == 0)

        /* HelenOS does not set errno, so all we can do is report

         * a task ID of 0 as a generic failure. */

        cli_error(CL_EEXEC, "Can not spawn %s", cmd);

    return tid;

}

#else

int try_exec(char *cmd, char **argv)

{

    char *tmp;

    pid_t pid;

    int status;

    /* Copy the result of allocated 'found' */

    tmp = cli_strdup(find_command(cmd));

    /* free the pointer, no longer needed */

    free(found);

    if (-1 == (access(tmp, F_OK))) {

        cli_error(CL_EFAIL,

            "%s : No such external, modular or builtin command", tmp);

        free(tmp);

        return CL_EFAIL;

    }

    /* Create a child to run the program */

    pid = fork();

    if (pid == 0) {

        execv(tmp, argv);

        exit(errno);

    } else if (pid > 0) {

        /* Block until we get a PID (and result) */

        wait(&status);

        status = status / 256;

    } else {

        /* Could not fork, ulimit or out of memory */

        cli_error(CL_ENOMEM, "Could not fork");

        free(tmp);

        return CL_ENOMEM;

    }

    free(tmp);

    /* Decode any errors from execv() (these explain themselves) */

    switch (status) {

    case ENOTDIR:

        cli_error(CL_EFAIL, "%s : No such file or directory", tmp);

        status = CL_EFAIL;

        break;

    case EISDIR:

        cli_error(CL_EFAIL, "%s : Command is a directory", tmp);

        status = CL_EFAIL;

        break;

    case EACCES:

        cli_error(CL_EPERM, "%s :", tmp);

        status = CL_EFAIL;

        break;

    case ENOMEM:

        cli_error(CL_ENOMEM, "%s :", tmp);

        status = CL_EFAIL;

        break;

    case ENAMETOOLONG:

        cli_error(CL_EFAIL, "Argument list too long");

        status = CL_EFAIL;

        break;

    case EFAULT:

        cli_error(CL_EFAIL, "Invalid argument pointer\n(please report "

            "this to %s)", PACKAGE_BUGREPORT);

        status = CL_EFAIL;

        break;

    }

    return status;

}

#endif /* HELENOS */