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3265 post 1 
/* Copyright (c) 2008, Tim Post <tinkertim@gmail.com>
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions are met:
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 *
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 * Redistributions of source code must retain the above copyright notice, this
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 * list of conditions and the following disclaimer.
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 *
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 * Redistributions in binary form must reproduce the above copyright notice,
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 * this list of conditions and the following disclaimer in the documentation
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 * and/or other materials provided with the distribution.
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 *
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 * Neither the name of the original program's authors nor the names of its
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 * contributors may be used to endorse or promote products derived from this
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 * software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 * POSSIBILITY OF SUCH DAMAGE.
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 */
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/* The VERY basics of execute in place support. These are buggy, leaky
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 * and not nearly done. Only here for beta testing!! You were warned!!
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 * TODO:
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 * Hash command lookups to save time
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 * Create a running pointer to **path and advance/rewind it as we go */
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <fcntl.h>
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#include "config.h"
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#include "util.h"
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#include "exec.h"
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#include "errors.h"
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/* FIXME: Just have find_command() return an allocated string */
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static char *found;
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static char *find_command(char *);
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static int try_access(const char *);
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/* work-around for access() */
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static int try_access(const char *f)
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{
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    int fd;
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    fd = open(f, O_RDONLY);
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    if (fd > -1) {
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        close(fd);
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        return 0;
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    } else
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        return -1;
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}
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/* Returns the full path of "cmd" if cmd is found, else just hand back
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 * cmd as it was presented */
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static char *find_command(char *cmd)
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{
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    char *path_tok;
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    char *path[PATH_MAX];
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    int n = 0, i = 0;
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    size_t x = str_size(cmd) + 2;
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    found = (char *)malloc(PATH_MAX);
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    /* The user has specified a full or relative path, just give it back. */
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    if (-1 != try_access(cmd)) {
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        return (char *) cmd;
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    }
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    path_tok = str_dup(PATH);
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    /* Extract the PATH env to a path[] array */
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    path[n] = strtok(path_tok, PATH_DELIM);
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    while (NULL != path[n]) {
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        if ((str_size(path[n]) + x ) > PATH_MAX) {
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            cli_error(CL_ENOTSUP,
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                "Segment %d of path is too large, search ends at segment %d",
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                n, n-1);
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            break;
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        }
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        path[++n] = strtok(NULL, PATH_DELIM);
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    }
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    /* We now have n places to look for the command */
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    for (i=0; path[i]; i++) {
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        memset(found, 0, sizeof(found));
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        snprintf(found, PATH_MAX, "%s/%s", path[i], cmd);
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        if (-1 != try_access(found)) {
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            free(path_tok);
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            return (char *) found;
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        }
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    }
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    /* We didn't find it, just give it back as-is. */
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    free(path_tok);
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    return (char *) cmd;
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}
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unsigned int try_exec(char *cmd, char **argv)
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{
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    task_id_t tid;
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    task_exit_t texit;
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    char *tmp;
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    int retval;
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    tmp = str_dup(find_command(cmd));
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    free(found);
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    tid = task_spawn((const char *)tmp, argv);
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    free(tmp);
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    if (tid == 0) {
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        cli_error(CL_EEXEC, "Cannot spawn `%s'.", cmd);
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        return 1;
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    }
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    task_wait(tid, &texit, &retval);
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    if (texit != TASK_EXIT_NORMAL) {
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        printf("Command failed (unexpectedly terminated).\n");
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    } else if (retval != 0) {
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        printf("Command failed (return value %d).\n", retval);
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    }
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    return 0;
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}