text: /* These functions find the absolute path to the current working directory.  */
  
  #include <stdlib.h>
  #include <errno.h>
  #include <sys/stat.h>
  #include <dirent.h>
  #include <string.h>
  #include <sys/syscall.h>
  
  #ifdef __NR_getcwd
  
  #ifndef INLINE_SYSCALL
  #define INLINE_SYSCALL(name, nr, args...) __syscall_getcwd (args)
  #define __NR___syscall_getcwd __NR_getcwd
  static inline _syscall2(int, __syscall_getcwd, char *, buf, unsigned long, size);
  #endif
  
  char *getcwd(char *buf, int size)
  {
      int olderrno, ret;
      char *allocbuf;
  
      if (size == 0) {
  	if (buf != NULL) {
  	    __set_errno(EINVAL);
  	    return NULL;
  	}
  	size = PATH_MAX;
      }
      if (size < 3) {
  	__set_errno(ERANGE);
  	return NULL;
      }
      allocbuf=NULL;
      olderrno = errno;
      if (buf == NULL) {
  	buf = allocbuf = malloc (size);
  	if (buf == NULL)
  	    return NULL;
      }
      ret = INLINE_SYSCALL(getcwd, 2, buf, size);
      if (ret < 0) {
  	if (allocbuf) {
  	    free(allocbuf);
  	}
  	return NULL;
      } 
      __set_errno(olderrno);
      return buf;
  }
  #else
  
  /* If the syscall is not present, we have to walk up the
   * directory tree till we hit the root.  Now we _could_
   * use /proc/self/cwd if /proc is mounted... That approach
   * is left an an exercise for the reader... */
  
  
  /* Seems a few broken filesystems (like coda) don't like this */
  /* #undef FAST_DIR_SEARCH_POSSIBLE on Linux */
  
  
  /* Routine to find the step back down */
  static char *search_dir(dev_t this_dev, ino_t this_ino, char *path_buf, int path_size)
  {
  	DIR *dp;
  	struct dirent *d;
  	char *ptr;
  	int slen;
  	struct stat st;
  
  #ifdef FAST_DIR_SEARCH_POSSIBLE
  	/* The test is for ELKS lib 0.0.9, this should be fixed in the real kernel */
  	int slow_search = (sizeof(ino_t) != sizeof(d->d_ino));
  #endif
  
  	if (stat(path_buf, &st) < 0)
  		return 0;
  #ifdef FAST_DIR_SEARCH_POSSIBLE
  	if (this_dev != st.st_dev)
  		slow_search = 1;
  #endif
  
  	slen = strlen(path_buf);
  	ptr = path_buf + slen - 1;
  	if (*ptr != '/') {
  		if (slen + 2 > path_size) {
  			__set_errno(ERANGE);
  			return 0;
  		}
  		strcpy(++ptr, "/");
  		slen++;
  	}
  	slen++;
  
  	dp = opendir(path_buf);
  	if (dp == 0)
  		return 0;
  
  	while ((d = readdir(dp)) != 0) {
  #ifdef FAST_DIR_SEARCH_POSSIBLE
  		if (slow_search || this_ino == d->d_ino) {
  #endif
  			if (slen + strlen(d->d_name) > path_size) {
  				__set_errno(ERANGE);
  				return 0;
  			}
  			strcpy(ptr + 1, d->d_name);
  			if (stat(path_buf, &st) < 0)
  				continue;
  			if (st.st_ino == this_ino && st.st_dev == this_dev) {
  				closedir(dp);
  				return path_buf;
  			}
  #ifdef FAST_DIR_SEARCH_POSSIBLE
  		}
  #endif
  	}
  
  	closedir(dp);
  	__set_errno(ENOENT);
  	return 0;
  }
  
  /* Routine to go up tree */
  static char *recurser(char *path_buf, int path_size, dev_t root_dev, ino_t root_ino)
  {
  	struct stat st;
  	dev_t this_dev;
  	ino_t this_ino;
  
  	if (stat(path_buf, &st) < 0)
  		return 0;
  	this_dev = st.st_dev;
  	this_ino = st.st_ino;
  	if (this_dev == root_dev && this_ino == root_ino) {
  		strcpy(path_buf, "/");
  		return path_buf;
  	}
  	if (strlen(path_buf) + 4 > path_size) {
  		__set_errno(ERANGE);
  		return 0;
  	}
  	strcat(path_buf, "/..");
  	if (recurser(path_buf, path_size, root_dev, root_ino) == 0)
  		return 0;
  
  	return search_dir(this_dev, this_ino, path_buf, path_size);
  }
  
  
  char *getcwd(char *buf, int size)
  {
      struct stat st;
  
      if (size == 0) {
  	if (buf != NULL) {
  	    __set_errno(EINVAL);
  	    return NULL;
  	}
  	size = PATH_MAX;
      }
      if (size < 3) {
  	__set_errno(ERANGE);
  	return NULL;
      }
  
      if (buf == NULL) {
  	buf = malloc (size);
  	if (buf == NULL)
  	    return NULL;
      }
  
      strcpy(buf, ".");
      if (stat("/", &st) < 0) {
  	return NULL;
      }
  
      return recurser(buf, size, st.st_dev, st.st_ino);
  }
  
  #endif
  