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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. /* Easiest way to handle a shared + allocated string, a structure with
  55.  * one member is sort of silly :) */
  56. char *found;
  57.  
  58. /* work-around for access() */
  59. unsigned int try_access(const char *f)
  60. {
  61.     int fd;
  62.  
  63.     fd = open(f, O_RDONLY);
  64.     if (fd > 0) {
  65.         close(fd);
  66.         return 1;
  67.     } else
  68.         return 0;
  69. }
  70.  
  71. /* Returns the full path of "cmd" if cmd is found, else just hand back
  72.  * cmd as it was presented */
  73. char *find_command(char *cmd)
  74. {
  75.     char *path_orig, *path_tok;
  76.     char *path[PATH_MAX];
  77.     int rc, n = 0, i = 0;
  78.     size_t x = strlen(cmd) + 2;
  79.  
  80.     found = (char *)malloc(PATH_MAX);
  81.  
  82.     /* The user has specified the full path, just give it back. Don't test it,
  83.      * they seem to know what they're doing. */
  84.     if (cmd[0] == '/' || cmd [0] == '.')
  85.         return (char *)cmd;
  86.  
  87. #ifdef HELENOS
  88.     path_orig = PATH;
  89. #else
  90.     path_orig = getenv("PATH");
  91.     if (NULL == path_orig)
  92.         path_orig = PATH;
  93. #endif
  94.  
  95.     path_tok = cli_strdup(path_orig);
  96.  
  97.     /* Extract the PATH env to a path[] array */
  98.     path[n] = cli_strtok(path_tok, PATH_DELIM);
  99.     while (NULL != path[n]) {
  100.         if ((strlen(path[n]) + x ) > PATH_MAX) {
  101.             cli_error(CL_ENOTSUP,
  102.                 "Segment %d of path is too large, search ends at segment %d",
  103.                 n, n-1);
  104.             break;
  105.         }
  106.         path[++n] = cli_strtok(NULL, PATH_DELIM);
  107.     }
  108.  
  109.     /* We now have n places to look for the command */
  110.     for (i=0; path[i]; i++) {
  111.         memset(found, 0, sizeof(found));
  112.         snprintf(found, PATH_MAX, "%s/%s", path[i], cmd);
  113. #ifdef HELENOS
  114.         rc = try_access(found);
  115. #else
  116.         rc = access(found, F_OK);
  117. #endif
  118.         if (rc >= 0) {
  119.             /* We found it */
  120.             free(path_tok);
  121.             return (char *) found;
  122.         }
  123.     }
  124.  
  125.     /* We didn't find it, just give it back as-is. Could be an alias
  126.      * set in the parent shell */
  127.     free(path_tok);
  128.     return (char *) cmd;
  129. }
  130.  
  131. #ifdef HELENOS
  132. task_id_t try_exec(char *cmd, char **argv)
  133. {
  134.     task_id_t tid;
  135.     char *tmp;
  136.  
  137.     tmp = cli_strdup(find_command(cmd));
  138.     free(found);
  139.  
  140.     tid = task_spawn((const char *)tmp, (const char **)argv);
  141.     free(tmp);
  142.  
  143.     if (tid == 0)
  144.         /* HelenOS does not set errno, so all we can do is report
  145.          * a task ID of 0 as a generic failure. */
  146.         cli_error(CL_EEXEC, "Can not spawn %s", cmd);
  147.  
  148.     return tid;
  149. }
  150.  
  151. #else
  152. int try_exec(char *cmd, char **argv)
  153. {
  154.     char *tmp;
  155.     pid_t pid;
  156.     int status;
  157.  
  158.     /* Copy the result of allocated 'found' */
  159.     tmp = cli_strdup(find_command(cmd));
  160.     /* free the pointer, no longer needed */
  161.     free(found);
  162.  
  163.     if (-1 == (access(tmp, F_OK))) {
  164.         cli_error(CL_EFAIL,
  165.             "%s : No such external, modular or builtin command", tmp);
  166.         free(tmp);
  167.         return CL_EFAIL;
  168.     }
  169.  
  170.     /* Create a child to run the program */
  171.     pid = fork();
  172.     if (pid == 0) {
  173.         execv(tmp, argv);
  174.         exit(errno);
  175.     } else if (pid > 0) {
  176.         /* Block until we get a PID (and result) */
  177.         wait(&status);
  178.         status = status / 256;
  179.     } else {
  180.         /* Could not fork, ulimit or out of memory */
  181.         cli_error(CL_ENOMEM, "Could not fork");
  182.         free(tmp);
  183.         return CL_ENOMEM;
  184.     }
  185.  
  186.     free(tmp);
  187.  
  188.     /* No need to go any further if status == 0 */
  189.     /*
  190.     if (status == 0)
  191.         return status;
  192.     */
  193.     /* Decode any errors from execv() (these explain themselves) */
  194.     switch (status) {
  195.     case ENOTDIR:
  196.         cli_error(CL_EFAIL, "%s : No such file or directory", tmp);
  197.         status = CL_EFAIL;
  198.         break;
  199.     case EISDIR:
  200.         cli_error(CL_EFAIL, "%s : Command is a directory", tmp);
  201.         status = CL_EFAIL;
  202.         break;
  203.     case EACCES:
  204.         cli_error(CL_EPERM, "%s :", tmp);
  205.         status = CL_EFAIL;
  206.         break;
  207.     case ENOMEM:
  208.         cli_error(CL_ENOMEM, "%s :", tmp);
  209.         status = CL_EFAIL;
  210.         break;
  211.     case ENAMETOOLONG:
  212.         cli_error(CL_EFAIL, "Argument list too long");
  213.         status = CL_EFAIL;
  214.         break;
  215.     case EFAULT:
  216.         cli_error(CL_EFAIL, "Invalid argument pointer\n(please report "
  217.             "this to %s)", PACKAGE_BUGREPORT);
  218.         status = CL_EFAIL;
  219.         break;
  220.     }
  221.  
  222.     return status;
  223. }
  224.  
  225. #endif /* HELENOS */
  226.