Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!ssc-vax!uvicctr!tholm
From: tholm@uvicctr.UUCP (Terrence W. Holm)
Newsgroups: comp.os.minix
Subject: getcwd(3)
Message-ID: <482@uvicctr.UUCP>
Date: 26 Aug 88 00:15:16 GMT
Reply-To: tholm@uvicctr.UUCP (Terrence W. Holm)
Organization: University of Victoria, Victoria B.C. Canada
Lines: 244

EFTH MINIX report #38  - August 1988 -  getcwd(3)


There follows an implementation of getcwd(3), derived from
Adri Koppes' pwd(1).

Also included is a pwd(1) which uses getcwd(3). This
should be used, as the MINIX V1.1-V1.3 pwd(1) does not
handle 14 character file names. [Yes, V1.3 had a patch,
but it was wrong.]


----------------------------------------------------------
echo x - getcwd.3
gres '^X' '' > getcwd.3 << '/'
XSUBROUTINES
X    getcwd(3)		- current working directory
X
XINVOCATION
X    char *getcwd( buffer, size )
X      char *buffer;
X      int   size;
X
XEXPLANATION
X    The name of the current working directory is placed into
X    the <buffer>. <size> is the size of the buffer, it should
X    be at least 128 (PATH_MAX+1).
X
XRESULTS
X    NULL : Error.
X    o/w  : Pointer to name at <buffer>.
/
echo x - pwd.1
gres '^X' '' > pwd.1 << '/'
XCOMMANDS
X    pwd(1)		- print working directory
X
XINVOCATION
X    pwd
X
XEXPLANATION
X    The path name, from the root, of the current directory
X    is written to standard output.
/
echo x - getcwd.c
gres '^X' '' > getcwd.c << '/'
X/*  getcwd(3)
X *
X *  Author: Terrence W. Holm          Aug. 1988
X *
X *  Directly derived from Adri Koppes' pwd(1).
X */
X
X#include <sys/types.h>
X#include <sys/stat.h>
X#include <sys/dir.h>
X#include <errno.h>
X
X#define  NULL         (char *) 0
X#define  O_RDONLY     0
X#define  DIRECT_SIZE  (sizeof (struct direct))
X#define  PATH_MAX     127
X
Xextern char *rindex();
X
Xextern int errno;
X
X
Xchar *getcwd( buffer, size )
X  char *buffer;
X  int   size;
X
X  {
X  static char path[ PATH_MAX + 1 ];
X  struct stat current;
X
X  if ( buffer == NULL  ||  size == 0 )
X    {
X    errno = EINVAL;
X    return( NULL );
X    }
X
X  path[0] = '\0';
X
X  /*  Get the inode for the current directory  */
X   
X  if ( stat( ".", &current ) == -1 )
X    return( NULL );
X
X  if ( (current.st_mode & S_IFMT) != S_IFDIR )
X    return( NULL );
X
X
X  /*  Run backwards up the directory tree, grabbing 	*/
X  /*  directory names on the way.			*/
X
X  while (1)
X    {
X    struct stat parent;
X    struct direct d;
X    int same_device = 0;
X    int found = 0;
X    int fd;
X
X    /*  Get the inode for the parent directory  */
X
X    if ( chdir( ".." ) == -1 )
X	return( NULL );
X
X    if ( stat( ".", &parent ) == -1 )
X	return( NULL );
X
X    if ( (parent.st_mode & S_IFMT) != S_IFDIR )
X	return( NULL );
X
X    if ( current.st_dev == parent.st_dev )
X	same_device = 1;
X
X
X    /*  At the root, "." is the same as ".."  */
X
X    if ( same_device  &&  current.st_ino == parent.st_ino )
X	break;
X
X
X    /*  Search the parent directory for the current entry  */
X
X    if ( (fd = open( ".", O_RDONLY )) == -1 )
X	return( NULL );
X
X    while ( ! found  &&  read(fd, &d, DIRECT_SIZE) == DIRECT_SIZE )
X	{
X	if ( same_device )
X	    {
X	    if ( current.st_ino == d.d_ino )
X		found = 1;
X	    }
X	else
X	    {
X	    static char temp_name[ DIRSIZ + 1 ];
X	    static struct stat dir_entry;
X
X	    temp_name[0] = '\0';
X	    strncat( temp_name, d.d_name, DIRSIZ );
X
X	    if ( stat( temp_name, &dir_entry ) == -1 )
X		{
X		close( fd );
X		return( NULL );
X		}
X
X	    if ( current.st_dev == dir_entry.st_dev  &&
X	         current.st_ino == dir_entry.st_ino )
X		found = 1;
X	    }
X	}
X
X    close( fd );
X
X    if ( ! found )
X    	return( NULL );
X
X    if ( strlen(path) + DIRSIZ + 1 > PATH_MAX )
X	{
X	errno = ERANGE;
X	return( NULL );
X	}
X
X    strcat( path, "/" );
X    strncat( path, d.d_name, DIRSIZ );
X 
X    current.st_dev = parent.st_dev;
X    current.st_ino = parent.st_ino;
X    }
X
X
X  /*  Copy the reversed path name into <buffer>  */
X
X  if ( strlen(path) + 1 > size )
X    {
X    errno = ERANGE;
X    return( NULL );
X    }
X
X  if ( strlen(path) == 0 )
X    {
X    strcpy( buffer, "/" );
X    return( buffer );
X    }
X
X  *buffer = '\0';
X
X  {
X  char *r;
X
X  while ( (r = rindex( path, '/' )) != NULL )
X    {
X    strcat( buffer, r );
X    *r = '\0';
X    }
X  }
X
X  return( buffer );
X  }
/
echo x - pwd.c
gres '^X' '' > pwd.c << '/'
X/*  pwd(1)
X *
X *  Author: Terrence W. Holm          Aug. 1988
X */
X
X#define  NULL  		(char *) 0
X#define  PATH_MAX	127
X
Xextern char *getcwd();
X
X
Xmain()
X  {
X  char buffer[ PATH_MAX + 1 ];
X  char *path;
X
X  path = getcwd( buffer, PATH_MAX + 1 );
X
X  if ( path == NULL )
X    {
X    perror( ".." );
X    exit( 1 );
X    }
X
X  write( 1, path, strlen(path) );
X  write( 1, "\n", 1 );
X
X  exit( 0 );
X  }
/
----------------------------------------------------------

		Edwin L. Froese
		  uw-beaver!ubc-cs!mprg!handel!froese

		Terrence W. Holm
		  uw-beaver!uvicctr!tholm