fusl/src/process/execvp.c

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include "libc.h"

extern char** __environ;

int __execvpe(const char* file, char* const argv[], char* const envp[]) {
  const char *p, *z, *path = getenv("PATH");
  size_t l, k;
  int seen_eacces = 0;

  errno = ENOENT;
  if (!*file)
    return -1;

  if (strchr(file, '/'))
    return execve(file, argv, envp);

  if (!path)
    path = "/usr/local/bin:/bin:/usr/bin";
  k = strnlen(file, NAME_MAX + 1);
  if (k > NAME_MAX) {
    errno = ENAMETOOLONG;
    return -1;
  }
  l = strnlen(path, PATH_MAX - 1) + 1;

  for (p = path;; p = z) {
    char b[l + k + 1];
    z = strchr(p, ':');
    if (!z)
      z = p + strlen(p);
    if (z - p >= l) {
      if (!*z++)
        break;
      continue;
    }
    memcpy(b, p, z - p);
    b[z - p] = '/';
    memcpy(b + (z - p) + (z > p), file, k + 1);
    execve(b, argv, envp);
    if (errno == EACCES)
      seen_eacces = 1;
    else if (errno != ENOENT)
      return -1;
    if (!*z++)
      break;
  }
  if (seen_eacces)
    errno = EACCES;
  return -1;
}

int execvp(const char* file, char* const argv[]) {
  return __execvpe(file, argv, __environ);
}

weak_alias(__execvpe, execvpe);