retitle 473682 fakechroot does not properly wrap *at syscalls (openat, unlinkat, fstatat, etc) tags 473682 +patch thanks
I think i've narrowed down what's happening here.
/bin/rm from coreutils 6.10 appears to use the new fstatat64() and
unlinkat() system calls (they were added to the kernel in 2.6.16,
according to the section 2 manpages). The NOTES section of openat(2)
has the justification for these new syscalls, and path_resolution(7)
offers more in-depth information.
I needed to use the version of strace from unstable (4.5.15-1.2) to
see a record of the *at syscalls -- the version in lenny at the moment
(4.5.14-2) can't even identify them properly.
It looks like /bin/rm is now unlinking files with an invocation like
this:
unlinkat(AT_FDCWD, "/tmp/cdtemp.E32444/x", 0) = 0
It appears that fakechroot just doesn't know about these system calls,
and so doesn't wrap them properly.
The patch below seems to fix /bin/rm for the test case i outlined
above, but needs to be expanded to cover the other *at calls. I'm
sure it also needs to be made more portable -- i just grepped "objdump
-T /bin/rm" to figure out which flavor of fstatat64 i needed to
support and kludged it up to create the patch.
Please let me know if there's anything else i can do to get this
change through. Without something like this, fakechroot won't let me
debootstrap a lenny instance!
Regards,
--dkg
--- ../libfakechroot.c.orig 2008-03-31 23:10:37.000000000 -0400
+++ src/libfakechroot.c 2008-04-01 00:11:29.000000000 -0400
@@ -463,6 +463,8 @@
static int (*next_truncate64) (const char *path, off64_t length) = NULL;
#endif
static int (*next_unlink) (const char *pathname) = NULL;
+static int (*next_unlinkat) (int dirfd, const char *pathname, int flags) =
NULL;
+static int (*next___fxstatat64) (int ver, int dirfd, const char *pathname,
struct stat64 *buf, int flags) = NULL;
#ifdef HAVE_ULCKPWDF
/* static int (*next_ulckpwdf) (void) = NULL; */
#endif
@@ -678,6 +680,8 @@
nextsym(truncate64, "truncate64");
#endif
nextsym(unlink, "unlink");
+ nextsym(unlinkat, "unlinkat");
+ nextsym(__fxstatat64, "__fxstatat64");
#ifdef HAVE_ULCKPWDF
/* nextsym(ulckpwdf, "ulckpwdf"); */
#endif
@@ -2222,6 +2226,24 @@
return next_unlink(pathname);
}
+/* #include <fcntl.h> */
+int unlinkat (int dirfd, const char *pathname, int flags)
+{
+ char *fakechroot_path, *fakechroot_ptr, fakechroot_buf[FAKECHROOT_MAXPATH];
+ expand_chroot_path(pathname, fakechroot_path, fakechroot_ptr,
fakechroot_buf);
+ if (next_unlinkat == NULL) fakechroot_init();
+ return next_unlinkat(dirfd, pathname, flags);
+}
+
+/* #include <fcntl.h> */
+/* #include <sys/stat.h> */
+int __fxstatat64 (int ver, int dirfd, const char *pathname, struct stat64
*buf, int flags)
+{
+ char *fakechroot_path, *fakechroot_ptr, fakechroot_buf[FAKECHROOT_MAXPATH];
+ expand_chroot_path(pathname, fakechroot_path, fakechroot_ptr,
fakechroot_buf);
+ if (next___fxstatat64 == NULL) fakechroot_init();
+ return next___fxstatat64(ver, dirfd, pathname, buf, flags);
+}
/* #include <sys/types.h> */
/* #include <utime.h> */
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