Change the readelf and objdump programs so that they will automatically follow links to separate debug info files.

* configure.ac (follow-debug-links): Add option to enable or
	disable the following of debug links by default.  Set the
	default for the option to be 'follow'.
	* dwarf.c (do_follow_links): Initialise with DEFAULT_FOR_FOLLOW_LINKS.
	(dwarf_select_sections_by_names): Add no-follow-links option.
	(dwarf_select_sections_by_letter): Add 'N' option.
	* objdump.c (usage): Add conditional text describing the
	follow links option.
	(slurp_symtab): Ensure that there is a NULL entry at the end
	of the symbol table.
	(slurp_dynamic_symtab): Likewise.
	(dump_bfd): When extending the symbol table, ensure that there
	is still a NULL entry at the end.
	* readelf.c (usage): Add conditional text describing the
	follow links option.
	* doc/binutils.texi: Update documentation for objcopy and
	readelf.
	* doc/debug.options.texi: Update documentation of the
	follow-links option.
	* config.in: Regenerate.
	* configure: Regenerate.
	* testsuite/binutils-all/compress.exp: Add the -WN option to
	objdump command lines that are not expecting to follow links.
	* testsuite/binutils-all/readelf.exp: Add the
	--debug-dump=no-follow-links option to tests that are not
	expecting to follow debug links.

gas	* testsuite/gas/mach-o/sections-1.d: Stop automatic debug link
        following.
	* testsuite/gas/xgate/insns-dwarf2.d: Likewise.

ld	* testsuite/ld-elf/sec64k.exp: Stop readelf from automatically
	following debug links.

binutils/ChangeLog

@@ -1,3 +1,33 @@
+2021-02-12  Nick Clifton  <nickc@redhat.com>
+
+	* configure.ac (follow-debug-links): Add option to enable or
+	disable the following of debug links by default.  Set the
+	default for the option to be 'follow'.
+	* dwarf.c (do_follow_links): Initialise with DEFAULT_FOR_FOLLOW_LINKS.
+	(dwarf_select_sections_by_names): Add no-follow-links option.
+	(dwarf_select_sections_by_letter): Add 'N' option.
+	* objdump.c (usage): Add conditional text describing the
+	follow links option.
+	(slurp_symtab): Ensure that there is a NULL entry at the end
+	of the symbol table.
+	(slurp_dynamic_symtab): Likewise.
+	(dump_bfd): When extending the symbol table, ensure that there
+	is still a NULL entry at the end.
+	* readelf.c (usage): Add conditional text describing the
+	follow links option.
+	* doc/binutils.texi: Update documentation for objcopy and
+	readelf.
+	* doc/debug.options.texi: Update documentation of the
+	follow-links option.
+	* config.in: Regenerate.
+	* configure: Regenerate.
+	* testsuite/binutils-all/compress.exp: Add the -WN option to
+	objdump command lines that are not expecting to follow links.
+	* testsuite/binutils-all/readelf.exp: Add the
+	--debug-dump=no-follow-links option to tests that are not
+	expecting to follow debug links.
+	* NEWS: Mention the new behaviour.
+
 2021-02-12  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/binutils-all/objcopy.exp: Report "unsupported" when

binutils/NEWS

@@ -1,5 +1,12 @@
 -*- text -*-
 
+* Readelf and objdump will now follow links to separate debug info files by
+  default.  This behaviour can be stopped via the use of the new -wN or
+  --debug-dump=no-follow-links options for readelf and the -WN or
+  --dwarf=no-follow-links options for objdump.  Also the old behaviour can be
+  restored by the use of the --enable-follow-debug-links=no configure time
+  option.
+
 Changes in 2.36:
 
 * Update elfedit and readelf with LAM_U48 and LAM_U57 support.

binutils/config.in

@@ -18,6 +18,9 @@
 /* Should ar and ranlib use -D behavior by default? */
 #undef DEFAULT_AR_DETERMINISTIC
 
+/* Have readelf and objdump follow debug links by default */
+#undef DEFAULT_FOR_FOLLOW_LINKS
+
 /* Have nm use F and f for global and local ifunc symbols */
 #undef DEFAULT_F_FOR_IFUNC_SYMBOLS
 

binutils/configure

@@ -822,6 +822,7 @@ enable_targets
 enable_deterministic_archives
 enable_default_strings_all
 enable_f_for_ifunc_symbols
+enable_follow_debug_links
 with_debuginfod
 enable_libctf
 enable_werror
@@ -1489,6 +1490,9 @@ Optional Features:
   --enable-f-for-ifunc-symbols
                           Have nm use F and f for global and local ifunc
                           symbols
+  --enable-follow-debug-links
+                          Have readelf and objdump follow debug links by
+                          default
   --enable-libctf         Handle .ctf type-info sections [default=yes]
   --enable-werror         treat compile warnings as errors
   --enable-build-warnings enable build-time compiler warnings
@@ -11577,7 +11581,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11580 "configure"
+#line 11584 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11683,7 +11687,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11686 "configure"
+#line 11690 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12359,6 +12363,27 @@ _ACEOF
 
 
 
+# Check whether --enable-follow-debug-links was given.
+if test "${enable_follow_debug_links+set}" = set; then :
+  enableval=$enable_follow_debug_links;
+if test "${enableval}" = no; then
+  default_for_follow_links=0
+else
+  default_for_follow_links=1
+fi
+else
+  default_for_follow_links=1
+fi
+
+
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_FOR_FOLLOW_LINKS $default_for_follow_links
+_ACEOF
+
+
+
+
 
 
 

binutils/configure.ac

@@ -82,6 +82,20 @@ fi], [default_f_for_ifunc=0])
 AC_DEFINE_UNQUOTED(DEFAULT_F_FOR_IFUNC_SYMBOLS, $default_f_for_ifunc,
 		   [Have nm use F and f for global and local ifunc symbols])
 
+
+AC_ARG_ENABLE(follow-debug-links,
+[AS_HELP_STRING([--enable-follow-debug-links],
+	[Have readelf and objdump follow debug links by default])], [
+if test "${enableval}" = no; then
+  default_for_follow_links=0
+else
+  default_for_follow_links=1
+fi], [default_for_follow_links=1])
+
+AC_DEFINE_UNQUOTED(DEFAULT_FOR_FOLLOW_LINKS, $default_for_follow_links,
+		   [Have readelf and objdump follow debug links by default])
+
+
 AC_DEBUGINFOD
 
 GCC_ENABLE([libctf], [yes], [], [Handle .ctf type-info sections])

binutils/doc/binutils.texi

@@ -2187,8 +2187,10 @@ objdump [@option{-a}|@option{--archive-headers}]
         [@option{-r}|@option{--reloc}]
         [@option{-R}|@option{--dynamic-reloc}]
         [@option{-s}|@option{--full-contents}]
-        [@option{-W[lLiaprmfFsoORtUuTgAckK]}|
+        [@option{-W[lLiaprmfFsoORtUuTgAck]}|
-         @option{--dwarf}[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links,=follow-links]]
+         @option{--dwarf}[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links]]
+        [@option{-WK}|@option{--dwarf=follow-links}]
+        [@option{-WN}|@option{--dwarf=no-follow-links}]
         [@option{--ctf=}@var{section}]
         [@option{-G}|@option{--stabs}]
         [@option{-t}|@option{--syms}]
@@ -2325,7 +2327,7 @@ will stop at the end of the function, otherwise it will stop when the
 next symbol is encountered.  If there are no matches for @var{symbol}
 then nothing will be displayed.
 
-Note if the @option{--dwarf=follow-links} option has also been enabled
+Note if the @option{--dwarf=follow-links} option is enabled
 then any symbol tables in linked debug info files will be read in and
 used when disassembling.
 
@@ -2347,7 +2349,7 @@ If the target is an ARM architecture this switch also has the effect
 of forcing the disassembler to decode pieces of data found in code
 sections as if they were instructions.
 
-Note if the @option{--dwarf=follow-links} option has also been enabled
+Note if the @option{--dwarf=follow-links} option is enabled
 then any symbol tables in linked debug info files will be read in and
 used when disassembling.
 
@@ -4753,8 +4755,10 @@ readelf [@option{-a}|@option{--all}]
         [@option{-R} <number or name>|@option{--relocated-dump=}<number or name>]
         [@option{-z}|@option{--decompress}]
         [@option{-c}|@option{--archive-index}]
-        [@option{-w[lLiaprmfFsoORtUuTgAckK]}|
+        [@option{-w[lLiaprmfFsoORtUuTgAck]}|
-         @option{--debug-dump}[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links,=follow-links]]
+         @option{--debug-dump}[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,=trace_info,=trace_abbrev,=trace_aranges,=gdb_index,=addr,=cu_index,=links]]
+        [@option{-wK}|@option{--debug-dump=follow-links}]
+        [@option{-wN}|@option{--debug-dump=no-follow-links}]
         [@option{--dwarf-depth=@var{n}}]
         [@option{--dwarf-start=@var{n}}]
         [@option{--ctf=}@var{section}]

binutils/doc/debug.options.texi

@@ -61,6 +61,17 @@ In addition, when displaying DWARF attributes, if a form is found that
 references the separate debug info file, then the referenced contents
 will also be displayed.
 
+Note - in some distributions this option is enabled by default.  It
+can be disabled via the @option{N} debug option.  The default can be
+chosen when configuring the binutils via the
+@option{--enable-follow-debug-links=yes} or
+@option{--enable-follow-debug-links=no} options.  If these are not
+used then the default is to enable the following of debug links.
+
+@item N
+@itemx =no-follow-links
+Disables the following of links to separate debug info files.
+
 @item l
 @itemx =rawline
 Displays the contents of the @samp{.debug_line} section in a raw

binutils/dwarf.c

@@ -99,7 +99,7 @@ int do_debug_addr;
 int do_debug_cu_index;
 int do_wide;
 int do_debug_links;
-int do_follow_links;
+int do_follow_links = DEFAULT_FOR_FOLLOW_LINKS;
 bfd_boolean do_checks;
 
 int dwarf_cutoff_level = -1;
@@ -11373,6 +11373,7 @@ dwarf_select_sections_by_names (const char *names)
       { "links", & do_debug_links, 1 },
       { "loc",  & do_debug_loc, 1 },
       { "macro", & do_debug_macinfo, 1 },
+      { "no-follow-links", & do_follow_links, 0 },
       { "pubnames", & do_debug_pubnames, 1 },
       { "pubtypes", & do_debug_pubtypes, 1 },
       /* This entry is for compatibility
@@ -11402,7 +11403,7 @@ dwarf_select_sections_by_names (const char *names)
 	  if (strncmp (p, entry->option, len) == 0
 	      && (p[len] == ',' || p[len] == '\0'))
 	    {
-	      * entry->variable |= entry->val;
+	      * entry->variable = entry->val;
 
 	      /* The --debug-dump=frames-interp option also
 		 enables the --debug-dump=frames option.  */
@@ -11443,6 +11444,7 @@ dwarf_select_sections_by_letters (const char *letters)
       case 'g':	do_gdb_index = 1; break;
       case 'i':	do_debug_info = 1; break;
       case 'K': do_follow_links = 1; break;
+      case 'N': do_follow_links = 0; break;
       case 'k':	do_debug_links = 1; break;
       case 'l':	do_debug_lines |= FLAG_DEBUG_LINES_RAW;	break;
       case 'L':	do_debug_lines |= FLAG_DEBUG_LINES_DECODED; break;

binutils/objdump.c

@@ -229,13 +229,24 @@ usage (FILE *stream, int status)
   -g, --debugging          Display debug information in object file\n\
   -e, --debugging-tags     Display debug information using ctags style\n\
   -G, --stabs              Display (in raw form) any STABS info in the file\n\
-  -W[lLiaprmfFsoORtUuTgAckK] or\n\
+  -W[lLiaprmfFsoORtUuTgAck] or\n\
   --dwarf[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,\n\
           =frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,\n\
           =gdb_index,=trace_info,=trace_abbrev,=trace_aranges,\n\
-          =addr,=cu_index,=links,=follow-links]\n\
+          =addr,=cu_index,=links]\n\
                            Display DWARF info in the file\n\
 "));
+#if DEFAULT_FOR_FOLLOW_LINKS
+  fprintf (stream, _("\
+  -WK,--dwarf=follow-links     Follow links to separate debug info files (default)\n\
+  -WN,--dwarf=no-follow-links  Do not follow links to separate debug info files\n\
+"));
+#else
+  fprintf (stream, _("\
+  -WK,--dwarf=follow-links     Follow links to separate debug info files\n\
+  -WN,--dwarf=no-follow-links  Do not follow links to separate debug info files (default)\n\
+"));
+#endif
 #ifdef ENABLE_LIBCTF
   fprintf (stream, _("\
   --ctf=SECTION            Display CTF info from SECTION\n\
@@ -737,8 +748,9 @@ slurp_symtab (bfd *abfd)
       non_fatal (_("failed to read symbol table from: %s"), bfd_get_filename (abfd));
       bfd_fatal (_("error message was"));
     }
-  if (storage)
+  /* Add an extra entry (at the end) with a NULL pointer.  */
-    {
+  storage += sizeof (asymbol *);
+
   off_t filesize = bfd_get_file_size (abfd);
 
   /* qv PR 24707.  */
@@ -757,11 +769,11 @@ slurp_symtab (bfd *abfd)
     }
 
   sy = (asymbol **) xmalloc (storage);
-    }
-
   symcount = bfd_canonicalize_symtab (abfd, sy);
   if (symcount < 0)
     bfd_fatal (bfd_get_filename (abfd));
+  /* assert (symcount < (storage / sizeof (asymbol *))) */
+  sy[symcount] = NULL;
   return sy;
 }
 
@@ -774,6 +786,7 @@ slurp_dynamic_symtab (bfd *abfd)
   long storage;
 
   storage = bfd_get_dynamic_symtab_upper_bound (abfd);
+  /* Add an extra entry (at the end) with a NULL pointer.  */
   if (storage < 0)
     {
       if (!(bfd_get_file_flags (abfd) & DYNAMIC))
@@ -786,12 +799,15 @@ slurp_dynamic_symtab (bfd *abfd)
 
       bfd_fatal (bfd_get_filename (abfd));
     }
-  if (storage)
+
+  storage += sizeof (asymbol *);
   sy = (asymbol **) xmalloc (storage);
 
   dynsymcount = bfd_canonicalize_dynamic_symtab (abfd, sy);
   if (dynsymcount < 0)
     bfd_fatal (bfd_get_filename (abfd));
+  /* assert (symcount < (storage / sizeof (asymbol *))) */
+  sy[dynsymcount] = NULL;
   return sy;
 }
 
@@ -4899,10 +4915,12 @@ dump_bfd (bfd *abfd, bfd_boolean is_mainfile)
 		    }
 		  else
 		    {
-		      syms = xrealloc (syms, (symcount + old_symcount) * sizeof (asymbol *));
+		      syms = xrealloc (syms, (symcount + old_symcount + 1) * sizeof (asymbol *));
 		      memcpy (syms + old_symcount,
 			      extra_syms,
 			      symcount * sizeof (asymbol *));
+		      /* Preserve the NULL entry at the end of the symbol table.  */
+		      syms[symcount + old_symcount] = NULL;
 		    }
 		}
 

binutils/readelf.c

@@ -4624,12 +4624,23 @@ usage (FILE * stream)
   -R --relocated-dump=<number|name>\n\
                          Dump the contents of section <number|name> as relocated bytes\n\
   -z --decompress        Decompress section before dumping it\n\
-  -w[lLiaprmfFsoORtUuTgAckK] or\n\
+  -w[lLiaprmfFsoORtUuTgAck] or\n\
   --debug-dump[=rawline,=decodedline,=info,=abbrev,=pubnames,=aranges,=macro,=frames,\n\
                =frames-interp,=str,=str-offsets,=loc,=Ranges,=pubtypes,\n\
                =gdb_index,=trace_info,=trace_abbrev,=trace_aranges,\n\
-               =addr,=cu_index,=links,=follow-links]\n\
+               =addr,=cu_index,=links]\n\
                          Display the contents of DWARF debug sections\n"));
+#if DEFAULT_FOR_FOLLOW_LINKS
+  fprintf (stream, _("\
+  -wK,--debug-dump=follow-links     Follow links to separate debug info files (default)\n\
+  -wN,--debug-dump=no-follow-links  Do not follow links to separate debug info files\n\
+"));
+#else
+  fprintf (stream, _("\
+  -wK,--debug-dump=follow-links     Follow links to separate debug info files\n\
+  -wN,--debug-dump=no-follow-links  Do not follow links to separate debug info files (default)\n\
+"));
+#endif
   fprintf (stream, _("\
   --dwarf-depth=N        Do not display DIEs at depth N or greater\n\
   --dwarf-start=N        Display DIEs starting with N, at the same depth\n\

binutils/testsuite/binutils-all/compress.exp

@@ -717,7 +717,7 @@ proc test_gnu_debuglink {} {
 	fail "$test (objcopy link decompress)"
 	return
     }
-    set got [remote_exec host "$OBJDUMP -S tmpdir/testprog" "" "/dev/null" "tmpdir/testprog.decompress.dump"]
+    set got [remote_exec host "$OBJDUMP -S -WN tmpdir/testprog" "" "/dev/null" "tmpdir/testprog.decompress.dump"]
     if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
 	fail "$test (objcopy dump decompress)"
 	return
@@ -726,7 +726,7 @@ proc test_gnu_debuglink {} {
 	fail "$test (objcopy link compress)"
 	return
     }
-    set got [remote_exec host "$OBJDUMP -S tmpdir/testprog" "" "/dev/null" "tmpdir/testprog.compress.dump"]
+    set got [remote_exec host "$OBJDUMP -S -WN tmpdir/testprog" "" "/dev/null" "tmpdir/testprog.compress.dump"]
     if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
 	fail "$test (objcopy dump compress)"
 	return

binutils/testsuite/binutils-all/objdump.exp

@@ -606,7 +606,7 @@ if { [is_elf_format] } then {
 	set testfile tmpdir/debuglink.${obj}
     }
 
-    set got [remote_exec host "$OBJDUMP $OBJDUMPFLAGS -Wk $testfile" "" "/dev/null" "objdump.out"]
+    set got [remote_exec host "$OBJDUMP $OBJDUMPFLAGS -Wk -WN $testfile" "" "/dev/null" "objdump.out"]
 
     if { [lindex $got 0] != 0 || ![string match "" [lindex $got 1]] } then {
 	fail "objdump -Wk (reason: unexpected output)"
@@ -615,7 +615,7 @@ if { [is_elf_format] } then {
     }
 
     if { [regexp_diff objdump.out $srcdir/$subdir/objdump.Wk] } then {
-	fail "objdump -Wk"
+	fail "objdump -Wk (reason: output does not match expectations)"
     } else {
 	pass "objdump -Wk"
     }

binutils/testsuite/binutils-all/readelf.exp

@@ -507,7 +507,7 @@ if {![binutils_assemble $srcdir/$subdir/debuglink.s tmpdir/debuglink.o]} then {
 	set tempfile [remote_download host tmpdir/debuglink.o]
     }
 
-    readelf_test {--debug-dump=links} $tempfile readelf.k  {}
+    readelf_test {--debug-dump=links -wN} $tempfile readelf.k  {}
 
     # Check that debug link sections can be followed.
     if {![binutils_assemble $srcdir/$subdir/linkdebug.s tmpdir/linkdebug.debug]} then {
@@ -530,7 +530,7 @@ if {![binutils_assemble $srcdir/$subdir/dwo.s tmpdir/dwo.o]} then {
 	set tempfile [remote_download host tmpdir/dwo.o]
     }
 
-    readelf_test {--debug-dump=links} $tempfile readelf.k2  {}
+    readelf_test {--debug-dump=links --debug-dump=no-follow-links} $tempfile readelf.k2  {}
 }
 
 if {![binutils_assemble $srcdir/$subdir/zero-sec.s tmpdir/zero-sec.o]} then {
@@ -555,6 +555,6 @@ if ![is_remote host] {
     if {[catch "system \"bzip2 -dc $test > $tempfile\""] != 0} {
 	untested "bzip2 -dc ($testname)"
     } else {
-	readelf_test {--debug-dump=macro} $tempfile pr26112.r {}
+	readelf_test {--debug-dump=macro -wN} $tempfile pr26112.r {}
     }
 }

gas/ChangeLog

@@ -1,3 +1,9 @@
+2021-02-12  Nick Clifton  <nickc@redhat.com>
+
+	* testsuite/gas/mach-o/sections-1.d: Stop automatic debug link
+        following.
+	* testsuite/gas/xgate/insns-dwarf2.d: Likewise.
+
 2021-02-12  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/gas/all/pr27381.err: Don't match source file name.

gas/testsuite/gas/mach-o/sections-1.d

@@ -1,4 +1,4 @@
-#objdump: -P section
+#objdump: -P section -WN
 .*: +file format mach-o.*
 #...
  Section: __text           __TEXT           \(bfdname: .text\)

gas/testsuite/gas/xgate/insns-dwarf2.d

@@ -1,4 +1,4 @@
-#objdump: -S
+#objdump: -S -WN
 #as: -gdwarf2
 #name: Dwarf2 test on insns.s
 #source: insns.s

ld/ChangeLog

@@ -1,3 +1,8 @@
+2021-02-12  Nick Clifton  <nickc@redhat.com>
+
+	* testsuite/ld-elf/sec64k.exp: Stop readelf from automatically
+	following debug links.
+
 2021-02-11  Alan Modra  <amodra@gmail.com>
 
 	* NEWS: Mention arm-symbianelf removal.

ld/testsuite/ld-elf/sec64k.exp

@@ -135,7 +135,7 @@ if { ![istarget "m32r-*-*"] } then {
 	puts $ofd "#as: -ez80-adl"
     }
     puts $ofd "#ld: -r"
-    puts $ofd "#readelf: -W -Ss"
+    puts $ofd "#readelf: -W -wN -Ss"
     puts $ofd "There are 680.. section headers.*:"
     puts $ofd "#..."
     puts $ofd "  \\\[ 0\\\] .* 680\[0-9\]\[0-9\]\[ \]+0\[ \]+0"
@@ -190,7 +190,7 @@ if { ![istarget "d10v-*-*"]
     if { [istarget "z80-*-*"] } then {
 	puts $ofd "#as: -ez80-adl"
     }
-    puts $ofd "#readelf: -W -Ss"
+    puts $ofd "#readelf: -W -wN -Ss"
     puts $ofd "There are 660.. section headers.*:"
     puts $ofd "#..."
     puts $ofd "  \\\[ 0\\\] .* 660..\[ \]+0\[ \]+0"