[re-adding Python-Dev]
On Wed, 2005-09-14 at 02:00 +0200, Henrik Levkowetz wrote:
> Hi Peter,
>
> on 2005-09-10 21:29 Peter Jones said the following:
> > Hi,
> >
> > In Python 2.4.1, Python/sysmodule.c includes a function PySys_SetArgv().
> > One of the things it does is attempt to resolve symbolic links into
> > absolute paths. Currently, it uses readlink() if configure found that
> > your system supports it, and then it tries to do the same thing again
> > using realpath() if you system supports that.
> >
> > This seems wrong; there's really no reason to do both. So here's a
> > patch to move the realpath() usage into a #else following the
> > HAVE_READLINK test:
> >
>
> If a path component above the basename is a link, it will not be
> resolved by only doing readlink() on the basename, while realpath() will
> resolve it. So it seems to me that your proposed patch will accomplish
> less than the current code for systems which have realpath().
What the current code is doing is a buffer overrun. Nevertheless,
you're right that it would behave differently than the current code if
that code worked as intended.
Here's a different patch; it uses canonicalize_file_name instead, and if
you don't have that it just uses the same codepath that's already in the
tree. canonicalize_file_name is identical to realpath() when using the
glibc extension of allocating a buffer when you pass in a NULL target,
as in:
fullpath = realpath(path, NULL);
I chose to use canonicalize_file_name simply because the autoconf test
for it is easier than testing to see if the extension works.
Here's the new patch:
--- Python-2.4.1/pyconfig.h.in.canonicalize 2005-09-14 11:47:04.000000000
-0400
+++ Python-2.4.1/pyconfig.h.in 2005-09-14 11:47:02.000000000 -0400
@@ -58,6 +58,9 @@
/* Define if pthread_sigmask() does not work on your system. */
#undef HAVE_BROKEN_PTHREAD_SIGMASK
+/* Define to 1 if you have the `canonicalize_file_name' function. */
+#undef HAVE_CANONICALIZE_FILE_NAME
+
/* Define to 1 if you have the `chown' function. */
#undef HAVE_CHOWN
--- Python-2.4.1/Python/sysmodule.c.canonicalize 2005-09-14
11:53:30.000000000 -0400
+++ Python-2.4.1/Python/sysmodule.c 2005-09-14 11:52:04.000000000 -0400
@@ -1184,6 +1184,9 @@
char *p = NULL;
int n = 0;
PyObject *a;
+#ifdef HAVE_CANONICALIZE_FILE_NAME
+ argv0 = canonicalize_file_name(argv0);
+#else /* ! HAVE_CANONICALIZE_FILE_NAME */
#ifdef HAVE_READLINK
char link[MAXPATHLEN+1];
char argv0copy[2*MAXPATHLEN+1];
@@ -1256,6 +1259,7 @@
#endif /* Unix */
}
#endif /* All others */
+#endif /* ! HAVE_CANONICALIZE_FILE_NAME */
a = PyString_FromStringAndSize(argv0, n);
if (a == NULL)
Py_FatalError("no mem for sys.path insertion");
--- Python-2.4.1/configure.in.canonicalize 2005-09-14 11:46:00.000000000
-0400
+++ Python-2.4.1/configure.in 2005-09-14 11:47:22.000000000 -0400
@@ -2096,8 +2096,8 @@
AC_MSG_RESULT(MACHDEP_OBJS)
# checks for library functions
-AC_CHECK_FUNCS(alarm bind_textdomain_codeset chown clock confstr ctermid \
- execv fork fpathconf ftime ftruncate \
+AC_CHECK_FUNCS(alarm bind_textdomain_codeset canonicalize_file_name chown \
+ clock confstr ctermid execv fork fpathconf ftime ftruncate \
gai_strerror getgroups getlogin getloadavg getpeername getpgid getpid \
getpriority getpwent getsid getwd \
kill killpg lchown lstat mkfifo mknod mktime \
--
Peter
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