bin/182098: [patch] Change kldxref fts_open ordering so it produces a consistent linker.hints between machines of the same architecture.

[Derek Schrock]

>Number:         182098
>Category:       bin
>Synopsis:       [patch] Change kldxref fts_open ordering so it produces a consistent linker.hints between machines of the same architecture.
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 14 19:40:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Derek Schrock
>Release:        9.1-RELEASE-p7
>Organization:
>Environment:
FreeBSD ircbsd 9.1-RELEASE-p7 FreeBSD 9.1-RELEASE-p7 #0: Mon Sep  9 21:34:37 UTC 2013     root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64
>Description:
Currently there an issue with linker.hints being different between machines that create binary update for freebsd-update.

http://www.freebsd.org/cgi/query-pr.cgi?pr=amd64/178247

Use freebsd-update to update:

$ freebsd-update fetch
Looking up update.FreeBSD.org mirrors... 5 mirrors found.
Fetching metadata signature for 9.1-RELEASE from update2.freebsd.org... done.
Fetching metadata index... done.
Inspecting system... done.
Preparing to download files... done.

The following files will be updated as part of updating to 9.1-RELEASE-p7:
/boot/kernel/linker.hints

$ freebsd-update install
Installing updates... done.

$ freebsd-update fetch
Looking up update.FreeBSD.org mirrors... 5 mirrors found.
Fetching metadata signature for 9.1-RELEASE from update5.freebsd.org... done.
Fetching metadata index... done.
Inspecting system... done.
Preparing to download files... done.

The following files will be updated as part of updating to 9.1-RELEASE-p7:
/boot/kernel/linker.hints


Looking at /boot/kernel on two different systems:

Host A /boot/kernel/:
$ sha256 /boot/kernel/* | sha256
6193fe0ea115ae745f8b99273906892d5a8714d7fd55f506f24064ef0396f1eb

Host B /boot/kernel:
$ sha256 /boot/kernel/* | sha256
6193fe0ea115ae745f8b99273906892d5a8714d7fd55f506f24064ef0396f1eb

'kldxref /boot/kernel/' will produce different linker.hints due to the way the fts_open() traverses the file system:

Host A:
$ kldxref /boot/kernel/
$ sha256 /boot/kernel/linker.hints 
SHA256 (/boot/kernel/linker.hints) = 3deeb3eb746b40b009f67238b924c32d1a6d0d586f127aded45bef0010345290

Host B:
$ kldxref /boot/kernel/
$ sha256 /boot/kernel/linker.hints
SHA256 (/boot/kernel/linker.hints) = ec6c0c80e745371f83faa100f1fe1a36062903c527d20dce7e0161ce26c82e54

If you change fts_open() to order the files in /boot/kernel/ the same linker.hints should be created between systems:

Host A:
$ ./patched.kldxref /boot/kernel/
$ sha256 /boot/kernel/linker.hints
SHA256 (/boot/kernel/linker.hints) = 2bda1a7568108dfb511d5156efce2d4df173dc8e91124e0c9300a5fef90218c8

$ sha256 /boot/kernel/linker.hints
SHA256 (/boot/kernel/linker.hints) = 2bda1a7568108dfb511d5156efce2d4df173dc8e91124e0c9300a5fef90218c8


>How-To-Repeat:
Find a system the produces a different linker.hints than another system's.

Host A:
$ kldxref /boot/kernel/
$ sha256 /boot/kernel/linker.hints 
SHA256 (/boot/kernel/linker.hints) = 3deeb3eb746b40b009f67238b924c32d1a6d0d586f127aded45bef0010345290

Host B:
$ kldxref /boot/kernel/
$ sha256 /boot/kernel/linker.hints
SHA256 (/boot/kernel/linker.hints) = ec6c0c80e745371f83faa100f1fe1a36062903c527d20dce7e0161ce26c82e54
>Fix:
patch kldxref.c to use fts_open() with a compare function to order the filenames.

(another possible fix would be to not include linker.hints in freebsd-update binary updates)

Patch attached with submission follows:

--- kldxref.c.old	2013-09-14 00:31:05.000000000 -0400
+++ kldxref.c	2013-09-14 14:53:53.000000000 -0400
@@ -275,6 +275,16 @@
 	exit(1);
 }
 
+int 
+compare(const FTSENT* const* a, const FTSENT* const* b)
+{
+    const char *pa = (const char *)((*a)->fts_name);
+    const char *pb = (const char *)((*b)->fts_name);
+    size_t as = (*a)->fts_namelen;
+    size_t bs = (*b)->fts_namelen;
+    return strncmp(pa, pb, as > bs ? bs : as);
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -316,7 +326,7 @@
 		err(1, "%s", argv[0]);
 	}
 
-	ftsp = fts_open(argv, fts_options, 0);
+	ftsp = fts_open(argv, fts_options, compare);
 	if (ftsp == NULL)
 		exit(1);
 


>Release-Note:
>Audit-Trail:
>Unformatted: