Inject matchpathcon_filespec_add64() if !defined(__INO_T_MATCHES_INO64_T) instead of using __BITS_PER_LONG < 64 as proxy

The __INO_T_MATCHES_INO64_T is defined
if ino_t would be the same size as ino64_t
if -D_FILE_OFFSET_BITS=64 were not defined.

This is /exactly/ what
  /* ABI backwards-compatible shim for non-LFS 32-bit systems */
  #if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64 && __BITS_PER_LONG < 64
is trying to get at, but currently fails because x32/RV32 are "LFS"
with 32-bit longs and 64-bit time_ts natively.

Thus, the
  static_assert(sizeof(unsigned long) == sizeof(__ino_t), "inode size mismatch");
assertion fails (__ino_t is the "kernel ino_t" type,
which generally corresponds to the kernel's ulong, which is u64 on x32).

glibc headers allow us to check the condition we care about directly.

Fixes: commit 9395cc0 ("Always build for LFS mode on 32-bit archs.")
Closes: #463
Closes: Debian#1098481
Signed-off-by: наб <nabijaczleweli@nabijaczleweli.xyz>
Cc: Alba Mendez <me@alba.sh>

Author: nabijaczleweli

libselinux/include/selinux/selinux.h

@@ -537,7 +537,7 @@ 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. */
-#if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64 && __BITS_PER_LONG < 64
+#if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64 && !defined(__INO_T_MATCHES_INO64_T)
 #define matchpathcon_filespec_add matchpathcon_filespec_add64
 #endif
 extern int matchpathcon_filespec_add(ino_t ino, int specind, const char *file);

libselinux/src/matchpathcon.c

@@ -261,7 +261,7 @@ int matchpathcon_filespec_add(ino_t ino, int specind, const char *file)
 	return -1;
 }
 
-#if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64 && __BITS_PER_LONG < 64
+#if (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64) && !defined(__INO_T_MATCHES_INO64_T)
 /* alias defined in the public header but we undefine it here */
 #undef matchpathcon_filespec_add
 
@@ -280,9 +280,13 @@ int matchpathcon_filespec_add(unsigned long ino, int specind,
 {
 	return matchpathcon_filespec_add64(ino, specind, file);
 }
+#elif (defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 64) || defined(__INO_T_MATCHES_INO64_T)
+
+static_assert(sizeof(uint64_t) == sizeof(ino_t), "inode size mismatch");
+
 #else
 
-static_assert(sizeof(unsigned long) == sizeof(ino_t), "inode size mismatch");
+static_assert(sizeof(uint32_t) == sizeof(ino_t), "inode size mismatch");
 
 #endif