src/process/execvp.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <unistd.h>
   4 #include <errno.h>
   5 #include <limits.h>
   6
   7 extern char **__environ;
   8
   9 int __execvpe(const char *file, char *const argv[], char *const envp[])
  10 {
  11         const char *p, *z, *path = getenv("PATH");
  12         size_t l, k;
  13         int seen_eacces = 0;
  14
  15         errno = ENOENT;
  16         if (!*file) return -1;
  17
  18         if (strchr(file, '/'))
  19                 return execve(file, argv, envp);
  20
  21         if (!path) path = "/usr/local/bin:/bin:/usr/bin";
  22         k = strnlen(file, NAME_MAX+1);
  23         if (k > NAME_MAX) {
  24                 errno = ENAMETOOLONG;
  25                 return -1;
  26         }
  27         l = strnlen(path, PATH_MAX-1)+1;
  28
  29         for(p=path; ; p=z) {
  30                 char b[l+k+1];
  31                 z = __strchrnul(p, ':');
  32                 if (z-p >= l) {
  33                         if (!*z++) break;
  34                         continue;
  35                 }
  36                 memcpy(b, p, z-p);
  37                 b[z-p] = '/';
  38                 memcpy(b+(z-p)+(z>p), file, k+1);
  39                 execve(b, argv, envp);
  40                 switch (errno) {
  41                 case EACCES:
  42                         seen_eacces = 1;
  43                 case ENOENT:
  44                 case ENOTDIR:
  45                         break;
  46                 default:
  47                         return -1;
  48                 }
  49                 if (!*z++) break;
  50         }
  51         if (seen_eacces) errno = EACCES;
  52         return -1;
  53 }
  54
  55 int execvp(const char *file, char *const argv[])
  56 {
  57         return __execvpe(file, argv, __environ);
  58 }
  59
  60 weak_alias(__execvpe, execvpe);