Date: Tue, 26 Feb 2002 04:20:09 -0800 (PST) From: "Jose M. Alcaide" <jose@we.lc.ehu.es> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/12244: realpath() fails when there is no permission to read the WD Message-ID: <200202261220.g1QCK9C67924@freefall.freebsd.org>
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The following reply was made to PR bin/12244; it has been noted by GNATS.
From: "Jose M. Alcaide" <jose@we.lc.ehu.es>
To: Sheldon Hearn <sheldonh@starjuice.net>
Cc: iedowse@FreeBSD.org, bug-followup@FreeBSD.org
Subject: Re: bin/12244: realpath() fails when there is no permission to read the WD
Date: Tue, 26 Feb 2002 13:19:09 +0100
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On Thu, Jan 31, 2002 at 05:13:11PM +0200, Sheldon Hearn wrote:
> On Mon, 21 Jan 2002 02:15:34 +0100, "Jose M. Alcaide" wrote:
> > Yes, it is. Realpath(3) continues using open()/fchdir() for
> > saving/restoring the current directory. I think that the getwd()/chdir()
> > method should be used as fallback.
>
> Could you submit a patch for that?
I have written a patch (attached). I did not tested it, but it is pretty
trivial. It is somewhat ugly, too ;-)
--
****** Jose M. Alcaide // jose@we.lc.ehu.es // jmas@FreeBSD.org ******
** "Beware of Programmers who carry screwdrivers" -- Leonard Brandwein **
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Content-Disposition: attachment; filename="realpath.c.patch"
--- lib/libc/stdlib/realpath.c.orig Fri Jan 28 00:06:50 2000
+++ lib/libc/stdlib/realpath.c Tue Feb 26 13:16:31 2002
@@ -63,14 +63,19 @@
{
struct stat sb;
int fd, n, rootd, serrno;
- char *p, *q, wbuf[MAXPATHLEN];
+ char *p, *q, wbuf[MAXPATHLEN], scwd[MAXPATHLEN];
int symlinks = 0;
- /* Save the starting point. */
- if ((fd = _open(".", O_RDONLY)) < 0) {
- (void)strcpy(resolved, ".");
- return (NULL);
- }
+ /*
+ * Save the starting point:
+ * First, try open()/fchdir() method and, if this fails,
+ * then try getcwd()/chdir().
+ */
+ if ((fd = _open(".", O_RDONLY)) < 0)
+ if (getcwd(scwd, MAXPATHLEN) == 0) {
+ (void)strcpy(resolved, ".");
+ return (NULL);
+ }
/*
* Find the dirname and basename from the path to be resolved.
@@ -96,7 +101,7 @@
q = resolved;
}
if (chdir(q) < 0)
- goto err1;
+ goto err;
} else
p = resolved;
@@ -105,17 +110,17 @@
if (S_ISLNK(sb.st_mode)) {
if (++symlinks > MAXSYMLINKS) {
errno = ELOOP;
- goto err1;
+ goto err;
}
n = readlink(p, resolved, MAXPATHLEN - 1);
if (n < 0)
- goto err1;
+ goto err;
resolved[n] = '\0';
goto loop;
}
if (S_ISDIR(sb.st_mode)) {
if (chdir(p) < 0)
- goto err1;
+ goto err;
p = "";
}
}
@@ -126,7 +131,7 @@
*/
(void)strcpy(wbuf, p);
if (getcwd(resolved, MAXPATHLEN) == 0)
- goto err1;
+ goto err;
/*
* Join the two strings together, ensuring that the right thing
@@ -140,26 +145,38 @@
if (*wbuf) {
if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
errno = ENAMETOOLONG;
- goto err1;
+ goto err;
}
if (rootd == 0)
(void)strcat(resolved, "/");
(void)strcat(resolved, wbuf);
}
- /* Go back to where we came from. */
- if (fchdir(fd) < 0) {
- serrno = errno;
- goto err2;
- }
+ /*
+ * Go back to where we came from. If fd < 0, we are using the
+ * getcwd()/chdir() method; else, we are using open()/fchdir().
+ */
+ if (fd < 0) {
+ if (chdir(scwd) < 0)
+ return (NULL);
+ } else if (fchdir(fd) < 0) {
+ serrno = errno;
+ (void)_close(fd);
+ errno = serrno;
+ return (NULL);
+ }
/* It's okay if the close fails, what's an fd more or less? */
(void)_close(fd);
return (resolved);
-err1: serrno = errno;
- (void)fchdir(fd);
-err2: (void)_close(fd);
+err: serrno = errno;
+ if (fd < 0)
+ (void)chdir(scwd);
+ else {
+ (void)fchdir(fd);
+ (void)_close(fd);
+ }
errno = serrno;
return (NULL);
}
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