View of xos/usr/lib/libc/getcwd.c

/* Copyright (C) 2008  Emmanuel Varoquaux
 
   This file is part of XOS.
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
#include "unistd.h"
 
#include "fcntl.h"
 
#include <limits.h>
#include <stdio.h>
#include <errno.h>
 
char __attribute__ ((weak, visibility ("default"))) *getcwd(char *buf, size_t size)
{
  char cwd_filename[PATH_MAX];
  int fd;
  ssize_t n;
  int errnum;
 
  if (!buf || !size) {
    errno = EINVAL;
    return NULL;
  }
  snprintf(cwd_filename, PATH_MAX, "/proc/%d/cwd", __getpid());
  if ((fd = __open(cwd_filename, O_RDONLY)) == -1)
    return NULL;
  if ((n = __read(fd, buf, size)) == -1) {
    errnum = errno;
    __close(fd);
    errno = errnum;
    return NULL;
  }
  __close(fd);
  if ((size_t)n >= size) {
    errno = ERANGE;
    return NULL;
  }
  buf[n] = '\0';
  return buf;
}