From 0be452a82a50bb6bb371b1439b4b8633bf5d9d27 Mon Sep 17 00:00:00 2001
From: Evgeny Vereshchagin <evvers@ya.ru>
Date: Thu, 6 Aug 2020 13:59:35 +0000
Subject: [PATCH] build-system: stop looking for %ms and %as

Looks like those specifiers haven't been used since 6c9ab254aefb6ce7e0e
(where sscanf was removed) was merged. This should help to get
util-linux to compile with MSan. Currently it's failing with
```
...
configure: error: libmount selected, but required scanf string alloc modifier not available
...
configure:20240: ./conftest
==116617==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x496fd6 in main /home/vagrant/util-linux/conftest.c:171:6
    #1 0x7f5eb85ea1a2 in __libc_start_main (/lib64/libc.so.6+0x271a2)
    #2 0x41c2cd in _start (/home/vagrant/util-linux/conftest+0x41c2cd)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /home/vagrant/util-linux/conftest.c:171:6 in main
Exiting
configure:20240: $? = 77
...
configure:20265: $? = 0
configure:20265: ./conftest
MemorySanitizer: bad pointer 0x000000496e60
==116627==MemorySanitizer CHECK failed: /builddir/build/BUILD/compiler-rt-9.0.1.src/lib/msan/../sanitizer_common/sanitizer_allocator_secondary.h:177 "((IsAligned(reinterpret_cast<uptr>(p), page_size_))) != (0)" (0x0, 0x0)
    #0 0x41d1d8 in MsanCheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) (/home/vagrant/util-linux/conftest+0x41d1d8)
    #1 0x484e1e in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) (/home/vagrant/util-linux/conftest+0x484e1e)
    #2 0x42066c in __msan::MsanDeallocate(__sanitizer::StackTrace*, void*) (/home/vagrant/util-linux/conftest+0x42066c)
    #3 0x424bc9 in free (/home/vagrant/util-linux/conftest+0x424bc9)
    #4 0x496fae in main /home/vagrant/util-linux/conftest.c:173:2
    #5 0x7f2245f311a2 in __libc_start_main (/lib64/libc.so.6+0x271a2)
    #6 0x41c2cd in _start (/home/vagrant/util-linux/conftest+0x41c2cd)

configure:20265: $? = 77
configure: program exited with status 77
...
| }
configure:22568: result: no
configure:22926: error: libmount selected, but required scanf string alloc modifier not available
```

Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>
---
 configure.ac | 64 ----------------------------------------------------
 include/c.h  |  9 --------
 2 files changed, 73 deletions(-)

diff --git a/configure.ac b/configure.ac
index 97f404f92..4d357d9d5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -694,69 +694,6 @@ AS_CASE([$enable_all_programs],
 
 AX_CHECK_TLS
 
-AC_DEFUN([UL_SCANF_TYPE_MODIFIER], [dnl
-# include <stdio.h>
-# include <stdlib.h>
-int main()
-{
-	int i;
-	int rc = 1;
-	char *s;
-	i = sscanf("x", $1, &s);
-	if (i == 1  && *s == 'x')
-		rc = 0;
-	free(s);
-	return rc;
-}])
-
-AC_CACHE_VAL([scanf_cv_alloc_modifier],
-  AC_RUN_IFELSE([AC_LANG_SOURCE([UL_SCANF_TYPE_MODIFIER(["%ms"])])],
-    [scanf_cv_alloc_modifier=ms],
-    AC_RUN_IFELSE([AC_LANG_SOURCE([UL_SCANF_TYPE_MODIFIER(["%as"])])],
-      [scanf_cv_alloc_modifier=as],
-      [scanf_cv_alloc_modifier=no]
-    )
-    ,
-
-    [AC_COMPILE_IFELSE([AC_LANG_SOURCE([
-     #include <stdio.h>
-     #include <unistd.h>
-
-     #if defined(__GLIBC__) && !defined(__UCLIBC__)
-
-     #if !(__GLIBC_PREREQ(2, 7))
-     #error %m is not available
-     #endif
-
-     #elif defined(_POSIX_VERSION)
-
-     #if _POSIX_VERSION < 200809L
-     #error %m is not available
-     #endif
-
-     #else
-     #error Your C-library is not supported.
-     #endif
-     ])],
-    [scanf_cv_alloc_modifier=ms],
-    [scanf_cv_alloc_modifier=no])]
-  )
-)
-
-AC_MSG_CHECKING([scanf string alloc modifiers])
-AS_CASE([$scanf_cv_alloc_modifier],
-  [ms],
-    [AC_MSG_RESULT([(%ms) yes])
-     AC_DEFINE([HAVE_SCANF_MS_MODIFIER], [1], [scanf %ms modifier])
-     have_scanf_alloc_modifier=yes],
-  [as],
-    [AC_MSG_RESULT([(%as) yes])
-     have_scanf_alloc_modifier=yes
-     AC_DEFINE([HAVE_SCANF_AS_MODIFIER], [1], [scanf %as modifier])],
-  [AC_MSG_RESULT([no])
-   have_scanf_alloc_modifier=no]
-)
-
 have_pty=no
 AC_ARG_WITH([util], AS_HELP_STRING([--without-util], [compile without libutil]),
   [], [with_util=auto]
@@ -1131,7 +1068,6 @@ AC_ARG_ENABLE([libmount],
 )
 UL_BUILD_INIT([libmount])
 UL_REQUIRES_BUILD([libmount], [libblkid])
-UL_REQUIRES_HAVE([libmount], [scanf_alloc_modifier], [scanf string alloc modifier])
 UL_REQUIRES_HAVE([libmount], [dirfd,ddfd], [dirfd or ddfd function])
 AM_CONDITIONAL([BUILD_LIBMOUNT], [test "x$build_libmount" = xyes])
 AM_CONDITIONAL([BUILD_LIBMOUNT_TESTS], [test "x$build_libmount" = xyes -a "x$enable_static" = xyes])
diff --git a/include/c.h b/include/c.h
index 64cf5c3fb..ae0813109 100644
--- a/include/c.h
+++ b/include/c.h
@@ -377,15 +377,6 @@ static inline int xusleep(useconds_t usec)
 		exit(eval); \
 })
 
-/*
- * scanf modifiers for "strings allocation"
- */
-#ifdef HAVE_SCANF_MS_MODIFIER
-#define UL_SCNsA	"%ms"
-#elif defined(HAVE_SCANF_AS_MODIFIER)
-#define UL_SCNsA	"%as"
-#endif
-
 /*
  * seek stuff
  */