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glibc/sysdeps/posix/getcwd.c

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initial import
1995-02-18 01:27:10 +00:00
/* Copyright (C) 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
/* Wants:
AC_STDC_HEADERS
AC_DIR_HEADER
AC_UNISTD_H
AC_MEMORY_H
AC_CONST
AC_ALLOCA
*/
/* AIX requires this to be the first thing in the file. */
#if defined (_AIX) && !defined (__GNUC__)
#pragma alloca
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef STDC_HEADERS
#include <stddef.h>
#endif
#if !defined(__GNU_LIBRARY__) && !defined(STDC_HEADERS)
extern int errno;
#endif
#ifndef NULL
#define NULL 0
#endif
#if defined (USGr3) && !defined (DIRENT)
#define DIRENT
#endif /* USGr3 */
#if defined (Xenix) && !defined (SYSNDIR)
#define SYSNDIR
#endif /* Xenix */
#if defined (POSIX) || defined (DIRENT) || defined (__GNU_LIBRARY__)
#include <dirent.h>
#ifndef __GNU_LIBRARY__
#define D_NAMLEN(d) strlen((d)->d_name)
#else
#define HAVE_D_NAMLEN
#define D_NAMLEN(d) ((d)->d_namlen)
#endif
#else /* not POSIX or DIRENT */
#define dirent direct
#define D_NAMLEN(d) ((d)->d_namlen)
#define HAVE_D_NAMLEN
#if defined (USG) && !defined (sgi)
#if defined (SYSNDIR)
#include <sys/ndir.h>
#else /* Not SYSNDIR */
#include "ndir.h"
#endif /* SYSNDIR */
#else /* not USG */
#include <sys/dir.h>
#endif /* USG */
#endif /* POSIX or DIRENT or __GNU_LIBRARY__ */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#if (defined (STDC_HEADERS) || defined (__GNU_LIBRARY__) \
|| defined (POSIX))
#include <stdlib.h>
#include <string.h>
#define ANSI_STRING
#else /* No standard headers. */
#ifdef USG
#include <string.h>
#ifdef NEED_MEMORY_H
#include <memory.h>
#endif
#define ANSI_STRING
#else /* Not USG. */
#ifdef NeXT
#include <string.h>
#else /* Not NeXT. */
#include <strings.h>
#ifndef bcmp
extern int bcmp ();
#endif
#ifndef bzero
extern void bzero ();
#endif
#ifndef bcopy
extern void bcopy ();
#endif
#endif /* NeXT. */
#endif /* USG. */
extern char *malloc (), *realloc ();
extern void free ();
#endif /* Standard headers. */
#ifndef ANSI_STRING
#define memcpy(d, s, n) bcopy((s), (d), (n))
#define memmove memcpy
#endif /* Not ANSI_STRING. */
#if !defined(__alloca) && !defined(__GNU_LIBRARY__)
#ifdef __GNUC__
#undef alloca
#define alloca(n) __builtin_alloca (n)
#else /* Not GCC. */
#if defined (sparc) || defined (HAVE_ALLOCA_H)
#include <alloca.h>
#else /* Not sparc or HAVE_ALLOCA_H. */
#ifndef _AIX
extern char *alloca ();
#endif /* Not _AIX. */
#endif /* sparc or HAVE_ALLOCA_H. */
#endif /* GCC. */
#define __alloca alloca
#endif
#if (defined (HAVE_LIMITS_H) || defined (STDC_HEADERS) || \
defined (__GNU_LIBRARY__))
#include <limits.h>
#else
#include <sys/param.h>
#endif
#ifndef PATH_MAX
#ifdef MAXPATHLEN
#define PATH_MAX MAXPATHLEN
#else
#define PATH_MAX 1024
#endif
#endif
#ifndef STDC_HEADERS
#undef size_t
#define size_t unsigned int
#endif
#if !__STDC__ && !defined (const)
#define const
#endif
#ifndef __GNU_LIBRARY__
#define __lstat stat
#endif
/* Get the pathname of the current working directory, and put it in SIZE
bytes of BUF. Returns NULL if the directory couldn't be determined or
SIZE was too small. If successful, returns BUF. In GNU, if BUF is
NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
unless SIZE <= 0, in which case it is as big as necessary. */
char *
getcwd (buf, size)
char *buf;
size_t size;
{
static const char dots[]
= "../../../../../../../../../../../../../../../../../../../../../../../\
../../../../../../../../../../../../../../../../../../../../../../../../../../\
../../../../../../../../../../../../../../../../../../../../../../../../../..";
const char *dotp, *dotlist;
size_t dotsize;
dev_t rootdev, thisdev;
ino_t rootino, thisino;
char *path;
register char *pathp;
struct stat st;
if (size == 0)
{
if (buf != NULL)
{
errno = EINVAL;
return NULL;
}
size = PATH_MAX + 1;
}
if (buf != NULL)
path = buf;
else
{
path = malloc (size);
if (path == NULL)
return NULL;
}
pathp = path + size;
*--pathp = '\0';
if (__lstat (".", &st) < 0)
return NULL;
thisdev = st.st_dev;
thisino = st.st_ino;
if (__lstat ("/", &st) < 0)
return NULL;
rootdev = st.st_dev;
rootino = st.st_ino;
dotsize = sizeof (dots) - 1;
dotp = &dots[sizeof (dots)];
dotlist = dots;
while (!(thisdev == rootdev && thisino == rootino))
{
register DIR *dirstream;
register struct dirent *d;
dev_t dotdev;
ino_t dotino;
char mount_point;
/* Look at the parent directory. */
if (dotp == dotlist)
{
/* My, what a deep directory tree you have, Grandma. */
char *new;
if (dotlist == dots)
{
new = malloc (dotsize * 2 + 1);
if (new == NULL)
return NULL;
memcpy (new, dots, dotsize);
}
else
{
new = realloc ((__ptr_t) dotlist, dotsize * 2 + 1);
if (new == NULL)
goto lose;
}
memcpy (&new[dotsize], new, dotsize);
dotp = &new[dotsize];
dotsize *= 2;
new[dotsize] = '\0';
dotlist = new;
}
dotp -= 3;
/* Figure out if this directory is a mount point. */
if (__lstat (dotp, &st) < 0)
goto lose;
dotdev = st.st_dev;
dotino = st.st_ino;
mount_point = dotdev != thisdev;
/* Search for the last directory. */
dirstream = opendir (dotp);
if (dirstream == NULL)
goto lose;
while ((d = readdir (dirstream)) != NULL)
{
if (d->d_name[0] == '.' &&
(d->d_namlen == 1 || (d->d_namlen == 2 && d->d_name[1] == '.')))
continue;
if (mount_point || d->d_ino == thisino)
{
char *name = __alloca (dotlist + dotsize - dotp +
1 + d->d_namlen + 1);
memcpy (name, dotp, dotlist + dotsize - dotp);
name[dotlist + dotsize - dotp] = '/';
memcpy (&name[dotlist + dotsize - dotp + 1],
d->d_name, d->d_namlen + 1);
if (__lstat (name, &st) < 0)
{
int save = errno;
(void) closedir (dirstream);
errno = save;
goto lose;
}
if (st.st_dev == thisdev && st.st_ino == thisino)
break;
}
}
if (d == NULL)
{
int save = errno;
(void) closedir (dirstream);
errno = save;
goto lose;
}
else
{
if (pathp - path < d->d_namlen + 1)
{
if (buf != NULL)
{
errno = ERANGE;
return NULL;
}
else
{
size *= 2;
buf = realloc (path, size);
if (buf == NULL)
{
(void) closedir (dirstream);
free (path);
errno = ENOMEM; /* closedir might have changed it. */
return NULL;
}
pathp = &buf[pathp - path];
path = buf;
}
}
pathp -= d->d_namlen;
(void) memcpy (pathp, d->d_name, d->d_namlen);
*--pathp = '/';
(void) closedir (dirstream);
}
thisdev = dotdev;
thisino = dotino;
}
if (pathp == &path[size - 1])
*--pathp = '/';
if (dotlist != dots)
free ((__ptr_t) dotlist);
memmove (path, pathp, path + size - pathp);
return path;
lose:
if (dotlist != dots)
free ((__ptr_t) dotlist);
return NULL;
}
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