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  1. /* Copyright (c) 2008, Tim Post <tinkertim@gmail.com>
  2.  * All rights reserved.
  3.  *
  4.  * Redistribution and use in source and binary forms, with or without
  5.  * modification, are permitted provided that the following conditions are met:
  6.  *
  7.  * Redistributions of source code must retain the above copyright notice, this
  8.  * list of conditions and the following disclaimer.
  9.  *
  10.  * Redistributions in binary form must reproduce the above copyright notice,
  11.  * this list of conditions and the following disclaimer in the documentation
  12.  * and/or other materials provided with the distribution.
  13.  *
  14.  * Neither the name of the original program's authors nor the names of its
  15.  * contributors may be used to endorse or promote products derived from this
  16.  * software without specific prior written permission.
  17.  *
  18.  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  19.  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20.  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21.  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  22.  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  23.  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  24.  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  25.  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  26.  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  27.  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28.  * POSSIBILITY OF SUCH DAMAGE.
  29.  */
  30.  
  31. /* The VERY basics of execute in place support. These are buggy, leaky
  32.  * and not nearly done. Only here for beta testing!! You were warned!!
  33.  * TODO:
  34.  * Hash command lookups to save time
  35.  * Create a running pointer to **path and advance/rewind it as we go */
  36.  
  37. #include <stdio.h>
  38. #include <stdlib.h>
  39. #include <unistd.h>
  40. #include <string.h>
  41. #include <fcntl.h>
  42.  
  43. #ifndef HELENOS
  44. #include <linux/limits.h>
  45. #include <sys/errno.h>
  46. #include <sys/wait.h>
  47. #endif
  48.  
  49. #include "config.h"
  50. #include "util.h"
  51. #include "exec.h"
  52. #include "errors.h"
  53.  
  54. /* TODO: create exec, exev, execve wrappers for task_spawn() */
  55.  
  56. /* Easiest way to handle a shared + allocated string */
  57. char *found;
  58.  
  59. /* work-around for access() */
  60. unsigned int try_access(const char *f)
  61. {
  62.     int fd;
  63.  
  64.     fd = open(f, O_RDONLY);
  65.     if (fd > -1) {
  66.         close(fd);
  67.         return 0;
  68.     } else
  69.         return -1;
  70. }
  71.  
  72. /* Returns the full path of "cmd" if cmd is found, else just hand back
  73.  * cmd as it was presented */
  74. char *find_command(char *cmd)
  75. {
  76.     char *path_orig, *path_tok;
  77.     char *path[PATH_MAX];
  78.     int n = 0, i = 0;
  79.     size_t x = strlen(cmd) + 2;
  80.  
  81.     found = (char *)malloc(PATH_MAX);
  82.  
  83.     /* The user has specified a full or relative path, just give it back. */
  84. #ifdef HELENOS
  85.     if (-1 != try_access(cmd))
  86. #else
  87.     if (-1 != access(cmd, F_OK))
  88. #endif
  89.     {
  90.         return (char *) cmd;
  91.     }
  92.  
  93. #ifdef HELENOS
  94.     path_orig = PATH;
  95. #else
  96.     path_orig = getenv("PATH");
  97.     if (NULL == path_orig)
  98.         path_orig = PATH;
  99. #endif
  100.  
  101.     path_tok = cli_strdup(path_orig);
  102.  
  103.     /* Extract the PATH env to a path[] array */
  104.     path[n] = cli_strtok(path_tok, PATH_DELIM);
  105.     while (NULL != path[n]) {
  106.         if ((strlen(path[n]) + x ) > PATH_MAX) {
  107.             cli_error(CL_ENOTSUP,
  108.                 "Segment %d of path is too large, search ends at segment %d",
  109.                 n, n-1);
  110.             break;
  111.         }
  112.         path[++n] = cli_strtok(NULL, PATH_DELIM);
  113.     }
  114.  
  115.     /* We now have n places to look for the command */
  116.     for (i=0; path[i]; i++) {
  117.         memset(found, 0, sizeof(found));
  118.         snprintf(found, PATH_MAX, "%s/%s", path[i], cmd);
  119. #ifdef HELENOS
  120.         if (-1 != try_access(found))
  121. #else
  122.         if (-1 != access(found, F_OK))
  123. #endif
  124.         {
  125.             free(path_tok);
  126.             return (char *) found;
  127.         }
  128.     }
  129.  
  130.     /* We didn't find it, just give it back as-is. Could be an alias
  131.      * set in the parent shell */
  132.     free(path_tok);
  133.     return (char *) cmd;
  134. }
  135.  
  136. #ifdef HELENOS
  137. task_id_t try_exec(char *cmd, char **argv)
  138. {
  139.     task_id_t tid;
  140.     char *tmp;
  141.  
  142.     tmp = cli_strdup(find_command(cmd));
  143.     free(found);
  144.  
  145.     /* TODO: put the cwd in front of tmp if tmp[0] != root
  146.      * which fixes relative paths fed to task_spawn */
  147.  
  148.     tid = task_spawn((const char *)tmp, (const char **)argv);
  149.     free(tmp);
  150.  
  151.     if (tid == 0)
  152.         /* HelenOS does not set errno, so all we can do is report
  153.          * a task ID of 0 as a generic failure. */
  154.         cli_error(CL_EEXEC, "Can not spawn %s", cmd);
  155.  
  156.     return tid;
  157. }
  158.  
  159. #else
  160. int try_exec(char *cmd, char **argv)
  161. {
  162.     char *tmp;
  163.     pid_t pid;
  164.     int status;
  165.  
  166.     /* Copy the result of allocated 'found' */
  167.     tmp = cli_strdup(find_command(cmd));
  168.     /* free the pointer, no longer needed */
  169.     free(found);
  170.  
  171.     if (-1 == (access(tmp, F_OK))) {
  172.         cli_error(CL_EFAIL,
  173.             "%s : No such external, modular or builtin command", tmp);
  174.         free(tmp);
  175.         return CL_EFAIL;
  176.     }
  177.  
  178.     /* Create a child to run the program */
  179.     pid = fork();
  180.     if (pid == 0) {
  181.         execv(tmp, argv);
  182.         exit(errno);
  183.     } else if (pid > 0) {
  184.         /* Block until we get a PID (and result) */
  185.         wait(&status);
  186.         status = status / 256;
  187.     } else {
  188.         /* Could not fork, ulimit or out of memory */
  189.         cli_error(CL_ENOMEM, "Could not fork");
  190.         free(tmp);
  191.         return CL_ENOMEM;
  192.     }
  193.  
  194.     free(tmp);
  195.  
  196.     /* Decode any errors from execv() (these explain themselves) */
  197.     switch (status) {
  198.     case ENOTDIR:
  199.         cli_error(CL_EFAIL, "%s : No such file or directory", tmp);
  200.         status = CL_EFAIL;
  201.         break;
  202.     case EISDIR:
  203.         cli_error(CL_EFAIL, "%s : Command is a directory", tmp);
  204.         status = CL_EFAIL;
  205.         break;
  206.     case EACCES:
  207.         cli_error(CL_EPERM, "%s :", tmp);
  208.         status = CL_EFAIL;
  209.         break;
  210.     case ENOMEM:
  211.         cli_error(CL_ENOMEM, "%s :", tmp);
  212.         status = CL_EFAIL;
  213.         break;
  214.     case ENAMETOOLONG:
  215.         cli_error(CL_EFAIL, "Argument list too long");
  216.         status = CL_EFAIL;
  217.         break;
  218.     case EFAULT:
  219.         cli_error(CL_EFAIL, "Invalid argument pointer\n(please report "
  220.             "this to %s)", PACKAGE_BUGREPORT);
  221.         status = CL_EFAIL;
  222.         break;
  223.     }
  224.  
  225.     return status;
  226. }
  227.  
  228. #endif /* HELENOS */
  229.