Re: [PATCH] Always build for LFS mode on 32-bit archs.

[Steve Langasek <steve.langasek@canonical.com>]

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Sorry, I clearly don't know how to operate git send-email.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek@ubuntu.com                                     vorlon@debian.org

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From 76049abc81d6209e0692fa96e8cfb4053b717201 Mon Sep 17 00:00:00 2001
From: Steve Langasek <steve.langasek@canonical.com>
Date: Thu, 15 Feb 2024 15:22:45 -0800
Subject: [PATCH] Always build for LFS mode on 32-bit archs.

Maintains the type signature of the existing matchpathcon_filespec_add()
entry point on 32-bit archs but maps the API to a new
matchpathcon_filespec_add64() entry point that takes a 64-bit ino_t argument
instead.

Software on 32-bit Linux ports which historically use a 32-bit time_t (thus
affected by the y2038 problem) have, as a precondition of migrating to
64-bit time_t, that they also migrate to large filesystem support because
glibc does not provide entry points for the cross-product of
(LFS: yes, LFS: no) x (time_t: 32, time_t: 64).

In order to support smooth migration of such operating systems from 32-bit
time_t to 64-bit time_t, it is useful for libselinux to:

- provide entry points on 32-bit systems for both LFS and non-LFS variants
  of the API (as glibc itself does)
- use LFS internally for all filesystem calls (just in case)
- map the API call to the correct implementation based on the build
  environment of the caller.

Signed-off-by: Steve Langasek <steve.langasek@canonical.com>
---
 libselinux/include/selinux/selinux.h |  7 ++++++-
 libselinux/src/Makefile              |  1 +
 libselinux/src/libselinux.map        |  1 +
 libselinux/src/matchpathcon.c        | 15 ++++++++++++++-
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/libselinux/include/selinux/selinux.h b/libselinux/include/selinux/selinux.h
index a0948853..78953870 100644
--- a/libselinux/include/selinux/selinux.h
+++ b/libselinux/include/selinux/selinux.h
@@ -1,6 +1,7 @@
 #ifndef _SELINUX_H_
 #define _SELINUX_H_
 
+#include <stdint.h>
 #include <sys/types.h>
 #include <stdarg.h>
 
@@ -521,7 +522,11 @@ extern int matchpathcon_index(const char *path,
    with the same inode (e.g. due to multiple hard links).  If so, then
    use the latter of the two specifications based on their order in the 
    file contexts configuration.  Return the used specification index. */
-extern int matchpathcon_filespec_add(ino_t ino, int specind, const char *file);
+typedef uint64_t libselinux_ino_t;
+#if _FILE_OFFSET_BITS == 64 && __BITS_PER_LONG < 64
+#define matchpathcon_filespec_add matchpathcon_filespec_add64
+#endif
+extern int matchpathcon_filespec_add(libselinux_ino_t ino, int specind, const char *file);
 
 /* Destroy any inode associations that have been added, e.g. to restart
    for a new filesystem. */
diff --git a/libselinux/src/Makefile b/libselinux/src/Makefile
index d3b981fc..267291aa 100644
--- a/libselinux/src/Makefile
+++ b/libselinux/src/Makefile
@@ -87,6 +87,7 @@ CFLAGS ?= -O -Wall -W -Wundef -Wformat-y2k -Wformat-security -Winit-self -Wmissi
           -fstack-protector-all --param=ssp-buffer-size=4 -fexceptions \
           -fasynchronous-unwind-tables -fdiagnostics-show-option \
           -Werror -Wno-aggregate-return \
+          -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 \
           $(EXTRA_CFLAGS)
 
 LD_SONAME_FLAGS=-soname,$(LIBSO),--version-script=libselinux.map,-z,defs,-z,relro
diff --git a/libselinux/src/libselinux.map b/libselinux/src/libselinux.map
index 5e00f45b..88c9b3e5 100644
--- a/libselinux/src/libselinux.map
+++ b/libselinux/src/libselinux.map
@@ -251,4 +251,5 @@ LIBSELINUX_3.5 {
   global:
     getpidprevcon;
     getpidprevcon_raw;
+    matchpathcon_filespec_add64;
 } LIBSELINUX_3.4;
diff --git a/libselinux/src/matchpathcon.c b/libselinux/src/matchpathcon.c
index e44734c3..189e00fb 100644
--- a/libselinux/src/matchpathcon.c
+++ b/libselinux/src/matchpathcon.c
@@ -195,7 +195,8 @@ static file_spec_t *fl_head;
  * then use the specification that occurs later in the
  * specification array.
  */
-int matchpathcon_filespec_add(ino_t ino, int specind, const char *file)
+int matchpathcon_filespec_add(libselinux_ino_t ino, int specind,
+                              const char *file)
 {
 	file_spec_t *prevfl, *fl;
 	int h, ret;
@@ -261,6 +262,18 @@ int matchpathcon_filespec_add(ino_t ino, int specind, const char *file)
 	return -1;
 }
 
+#if _FILE_OFFSET_BITS == 64 && __BITS_PER_LONG < 64
+/* alias defined in the public header but we undefine it here */
+#undef matchpathcon_filespec_add
+
+/* ABI backwards-compatible shim for non-LFS 32-bit systems */
+int matchpathcon_filespec_add(unsigned long ino, int specind,
+                              const char *file)
+{
+	return matchpathcon_filespec_add64(ino, specind, file);
+}
+#endif
+
 /*
  * Evaluate the association hash table distribution.
  */
-- 
2.40.1


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