expand_path.c

操作系统SunOS 4.1.3版本的源码

#ifndef lint
#ifdef sccs
static  char sccsid[] = "@(#)expand_path.c 1.1 92/07/30 SMI";
#endif
#endif

/*
 * Sun Microsystems, Inc.
 */

/*-

 Handles:
   ~/ => home dir
   ~user/ => user's home dir
   If the environment variable a = "foo" and b = "bar" then:
	$a	=>	foo
	$a$b	=>	foobar
	$a.c	=>	foo.c
	xxx$a	=>	xxxfoo
	${a}!	=>	foo!
	\$a	=>	\$a
  
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <pwd.h>
#include <ctype.h>
#include <strings.h>


/* input name in nm, pathname output to buf. */

void
expand_path(nm, buf)
	register char *nm, *buf;
{   
    register char *s, *d;
    char lnm[MAXPATHLEN];
    int q;
    register char *trimchars = "\n \t";
    char *getenv();

    /* Strip off leading & trailing whitespace and cr */
    while (index(trimchars,*nm) != NULL) nm++;
    s = nm + (q = strlen(nm)) - 1;
    while (q-- && index(trimchars, *s) != NULL) *s = '\0';

    s = nm;
    d = lnm;
    q = nm[0] == '\\' && nm[1] == '~';
    
    /* Expand inline environment variables */
    while (*d++ = *s) {
	if (*s == '\\') {
	    if (*(d-1) = *++s) {
		s++;
		continue;
	    } else break;
	} else if (*s++ == '$') {
	    register char *start = d;
	    register    braces = *s == '{';
	    register char *value;
	    while (*d++ = *s)
		if (braces ? *s == '}' : !isalnum(*s))
		    break;
		else
		    s++;
	    *--d = 0;
	    value = getenv(braces ? start + 1 : start);
	    if (value) {
		for (d = start - 1; *d++ = *value++;) ;
		d--;
		if (braces && *s) s++;
	    }
	}
    }
    
    /* Expand ~ and ~user */
    nm = lnm;
    s = "";
    if (nm[0] == '~' && !q) {			/* prefix ~ */
	if (nm[1] == '/' || nm[1] == 0) {	/* ~/filename */
	    if (s = getenv("HOME")) {
		if (*++nm) nm++;
	    }
	} else {				/* ~user/filename */
	    register char *nnm;
	    register struct passwd *pw;
	    for (s = nm; *s && *s != '/'; s++);
	    nnm = *s ? s + 1 : s;
	    *s = 0;
	    pw = (struct passwd *) getpwnam(nm + 1);
	    if (pw == 0) {
		*s = '/';
		s = "";
	    } else {
		nm = nnm;
		s = pw->pw_dir;
	    }
	}
    }

    d = buf;
    if (*s) {
	while (*d++ = *s++) ;
	*(d - 1) = '/';
    }

    s = nm;
    while (*d++ = *s++) ;
}