OpenSolaris_b135/lib/libbc/libc/gen/common/realpath.c
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* Copyright (c) 1987 by Sun Microsystems, Inc.
*/
#include <strings.h>
#include <sys/param.h>
#include <errno.h>
extern char *getwd();
/* LINTLIBRARY */
/*
* Input name in raw, canonicalized pathname output to canon. If dosymlinks
* is nonzero, resolves all symbolic links encountered during canonicalization
* into an equivalent symlink-free form. Returns 0 on success, -1 on failure.
* The routine fails if the current working directory can't be obtained or if
* either of the arguments is NULL.
*
* Sets errno on failure.
*/
int
pathcanon(raw, canon, dosymlinks)
char *raw,
*canon;
int dosymlinks;
{
register char *s,
*d;
register char *limit = canon + MAXPATHLEN;
char *modcanon;
int nlink = 0;
/*
* Do a bit of sanity checking.
*/
if (raw == NULL || canon == NULL) {
errno = EINVAL;
return (-1);
}
/*
* If the path in raw is not already absolute, convert it to that form.
* In any case, initialize canon with the absolute form of raw. Make
* sure that none of the operations overflow the corresponding buffers.
* The code below does the copy operations by hand so that it can easily
* keep track of whether overflow is about to occur.
*/
s = raw;
d = canon;
if (*s != '/') {
/* Relative; prepend the working directory. */
if (getwd(d) == NULL) {
/* Use whatever errno value getwd may have left around. */
return (-1);
}
d += strlen(d);
/* Add slash to separate working directory from relative part. */
if (d < limit)
*d++ = '/';
modcanon = d;
} else
modcanon = canon;
while (d < limit && *s)
*d++ = *s++;
/* Add a trailing slash to simplify the code below. */
s = "/";
while (d < limit && (*d++ = *s++))
continue;
/*
* Canonicalize the path. The strategy is to update in place, with
* d pointing to the end of the canonicalized portion and s to the
* current spot from which we're copying. This works because
* canonicalization doesn't increase path length, except as discussed
* below. Note also that the path has had a slash added at its end.
* This greatly simplifies the treatment of boundary conditions.
*/
d = s = modcanon;
while (d < limit && *s) {
if ((*d++ = *s++) == '/' && d > canon + 1) {
register char *t = d - 2;
switch (*t) {
case '/':
/* Found // in the name. */
d--;
continue;
case '.':
switch (*--t) {
case '/':
/* Found /./ in the name. */
d -= 2;
continue;
case '.':
if (*--t == '/') {
/* Found /../ in the name. */
while (t > canon && *--t != '/')
continue;
d = t + 1;
}
continue;
default:
break;
}
break;
default:
break;
}
/*
* We're at the end of a component. If dosymlinks is set
* see whether the component is a symbolic link. If so,
* replace it by its contents.
*/
if (dosymlinks) {
char link[MAXPATHLEN + 1];
register int llen;
/*
* See whether it's a symlink by trying to read it.
*
* Start by isolating it.
*/
*(d - 1) = '\0';
if ((llen = readlink(canon, link, sizeof link)) >= 0) {
/* Make sure that there are no circular links. */
nlink++;
if (nlink > MAXSYMLINKS) {
errno = ELOOP;
return (-1);
}
/*
* The component is a symlink. Since its value can be
* of arbitrary size, we can't continue copying in place.
* Instead, form the new path suffix in the link buffer
* and then copy it back to its proper spot in canon.
*/
t = link + llen;
*t++ = '/';
/*
* Copy the remaining unresolved portion to the end
* of the symlink. If the sum of the unresolved part and
* the readlink exceeds MAXPATHLEN, the extra bytes
* will be dropped off. Too bad!
*/
(void) strncpy(t, s, sizeof link - llen - 1);
link[sizeof link - 1] = '\0';
/*
* If the link's contents are absolute, copy it back
* to the start of canon, otherwise to the beginning of
* the link's position in the path.
*/
if (link[0] == '/') {
/* Absolute. */
(void) strcpy(canon, link);
d = s = canon;
}
else {
/*
* Relative: find beginning of component and copy.
*/
--d;
while (d > canon && *--d != '/')
continue;
s = ++d;
/*
* If the sum of the resolved part, the readlink
* and the remaining unresolved part exceeds
* MAXPATHLEN, the extra bytes will be dropped off.
*/
if (strlen(link) >= (limit - s)) {
(void) strncpy(s, link, limit - s);
*(limit - 1) = '\0';
} else {
(void) strcpy(s, link);
}
}
continue;
} else {
/*
* readlink call failed. It can be because it was
* not a link (i.e. a file, dir etc.) or because the
* the call actually failed.
*/
if (errno != EINVAL)
return (-1);
*(d - 1) = '/'; /* Restore it */
}
} /* if (dosymlinks) */
}
} /* while */
/* Remove the trailing slash that was added above. */
if (*(d - 1) == '/' && d > canon + 1)
d--;
*d = '\0';
return (0);
}
/*
* Canonicalize the path given in raw, resolving away all symbolic link
* components. Store the result into the buffer named by canon, which
* must be long enough (MAXPATHLEN bytes will suffice). Returns NULL
* on failure and canon on success.
*
* The routine indirectly invokes the readlink() system call and getwd()
* so it inherits the possibility of hanging due to inaccessible file
* system resources.
*/
char *
realpath(raw, canon)
char *raw;
char *canon;
{
return (pathcanon(raw, canon, 1) < 0 ? NULL : canon);
}