Support systems where fts.h can't be used with _FILE_OFFSET_BITS set

On some 32 systems (older glibc) the fts.h file cannot be included
"as-is" if the _FILE_OFFSET_BITS macro is set to 64.

This patch handles that case gently by including fts.h with
_FILE_OFFSET_BITS unset, but then by making sure fts.h can still
handle 64 bits file offset files.

	* configure.ac: Detect if we are on a system where fts.h cannot be
	included with _FILE_OFFSET_BITS defined.  If that is the case,
	then define the BAD_FTS macro.
	* src/abg-tools-utils.cc: If BAD_FTS is defined then include fts.h
	with _FILE_OFFSET_BITS not defined (that is, before config.h) but
	then make sure that open and fopen are 64 bits aware.
	* tools/abipkgdiff.cc: Likewise.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>

configure.ac

@@ -141,6 +141,20 @@ fi
 
 AC_SUBST(VISIBILITY_FLAGS)
 
+dnl Older glibc had a broken fts that didn't work with Large File Systems.
+dnl We want the version that can handler LFS, but include workaround if we
+dnl get a bad one. Add define to CFLAGS (not AC_DEFINE it) since we need to
+dnl check it before including config.h (which might define _FILE_OFFSET_BITS).
+AC_CACHE_CHECK([whether including fts.h with _FILE_OFFSET_BITS set breaks], ac_cv_bad_fts,
+  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+	#define _FILE_OFFSET_BITS 64
+	#include <fts.h>
+	]])],
+		     ac_cv_bad_fts=no, ac_cv_bad_fts=yes)])
+AS_IF([test "x$ac_cv_bad_fts" = "xyes"],
+      [CFLAGS="$CFLAGS -DBAD_FTS=1",
+       CXXFLAGS="$CXXFLAGS -DBAD_FTS=1"])
+
 dnl Check for dependency: libelf, libdw, libebl (elfutils)
 dnl Note that we need to use at least elfutils 0.159 but
 dnl at that time elfutils didnt have pkgconfig capabilities

src/abg-tools-utils.cc

@@ -20,22 +20,47 @@
 
 ///@file
 
+// In case we have a bad fts we include this before config.h because
+// it can't handle _FILE_OFFSET_BITS.  Everything we need here is fine
+// if its declarations just come first.  Also, include sys/types.h
+// before fts. On some systems fts.h is not self contained.
+#ifdef BAD_FTS
+  #include <sys/types.h>
+  #include <fts.h>
+#endif
+
+// For package configuration macros.
+#include "config.h"
+
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <time.h>
-#include <fts.h>
 #include <cstdlib>
 #include <cstring>
 #include <ctype.h>
 #include <errno.h>
 #include <libgen.h>
 #include <ext/stdio_filebuf.h> // For __gnu_cxx::stdio_filebuf
+// If fts.h is included before config.h, its indirect inclusions may
+// not give us the right LFS aliases of these functions, so map them
+// manually.
+#ifdef BAD_FTS
+  #ifdef _FILE_OFFSET_BITS
+    #define open open64
+    #define fopen fopen64
+  #endif
+#else
+  #include <sys/types.h>
+  #include <fts.h>
+#endif
+
 #include <fstream>
 #include <iostream>
 #include <sstream>
 
+
 #include "abg-dwarf-reader.h"
 #include "abg-internal.h"
 // <headers defining libabigail's API go under here>

tools/abipkgdiff.cc

@@ -56,22 +56,46 @@
 /// 4/ the reports are then emitted to standard output, always in the same
 /// order.
 
-#include <iostream>
-#include <string>
-#include <cstring>
-#include <cstdlib>
-#include <vector>
-#include <fts.h>
-#include <algorithm>
-#include <map>
+
+// In case we have a bad fts we include this before config.h because
+// it can't handle _FILE_OFFSET_BITS.  Everything we need here is fine
+// if its declarations just come first.  Also, include sys/types.h
+// before fts. On some systems fts.h is not self contained.
+#ifdef BAD_FTS
+  #include <sys/types.h>
+  #include <fts.h>
+#endif
+
+// For package configuration macros.
+#include "config.h"
+
 #include <assert.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <elf.h>
 #include <elfutils/libdw.h>
 
-// For package configuration macros.
-#include "config.h"
+// If fts.h is included before config.h, its indirect inclusions may
+// not give us the right LFS aliases of these functions, so map them
+// manually.
+#ifdef BAD_FTS
+  #ifdef _FILE_OFFSET_BITS
+    #define open open64
+    #define fopen fopen64
+  #endif
+#else
+  #include <sys/types.h>
+  #include <fts.h>
+#endif
+
+#include <iostream>
+#include <string>
+#include <cstring>
+#include <cstdlib>
+#include <vector>
+#include <algorithm>
+#include <map>
+
 #include "abg-workers.h"
 #include "abg-config.h"
 #include "abg-tools-utils.h"