Ultrix-3.1/src/libc/sysV/getcwd.c

/**********************************************************************
 *   Copyright (c) Digital Equipment Corporation 1984, 1985, 1986.    *
 *   All Rights Reserved. 					      *
 *   Reference "/usr/src/COPYRIGHT" for applicable restrictions.      *
 **********************************************************************/

/*	SCCSID: @(#)getcwd.c	3.0	4/22/86	*/
/*	(System 5)	1.2	*/
/*LINTLIBRARY*/
/*
 * Library routine to GET the Current Working Directory.
 * arg1 is a pointer to a character buffer into which the
 * path name of the current directory is placed by the
 * subroutine.  arg1 may be zero, in which case the 
 * subroutine will call malloc to get the required space.
 * arg2 is the length of the buffer space for the path-name.
 * If the actual path-name is longer than (arg2-2), or if
 * the value of arg2 is not at least 3, the subroutine will
 * return a value of zero, with errno set as appropriate.
 */

#include <stdio.h>
#include <sys/errno.h>

extern FILE *popen();
extern char *malloc(), *fgets(), *strchr();
extern int errno, pclose();

char *
getcwd(arg1, arg2)
char	*arg1;
int	arg2;
{
	FILE	*pipe;
	char	*trm;

	if(arg2 == 0) {
		errno = EINVAL;
		return(0);
	}
	if(arg1 == 0)
		if((arg1 = malloc((unsigned)arg2)) == 0) {
			errno = ENOMEM;
			return(0);
		}
	errno = 0;
	if((pipe = popen("/bin/pwd", "r")) == 0)
		return(0);
	(void) fgets(arg1, arg2, pipe);
	(void) pclose(pipe);
	trm = strchr(arg1, '\0');
	if(*(trm-1) != '\n') {
		errno = ERANGE;
		return(0);
	}
	*(trm-1) = '\0';
	return(arg1);
}