Commit: Changing readelf's lint mode

Commit: Changing readelf's lint mode

[Nick Clifton]

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Hi Guys,

  I have had a change of heart about readelf's lint mode.  I now think
  that it would be better to leave the existing warning messages alone
  and only make new warnings test for lint-mode being enabled, and then
  only if they are of file-quality type rather than a file-problem type.

  So I am checking the attached patch to revert my changes to the warn()
  function, restoring it to its old behaviour.  In the course of doing
  this I also came across a bug in line number table decoder which was
  not coping with an empty DWARF-5 format line number table.  So I have
  fixed this as well.

Cheers
  Nick

binutils/ChangeLog
2020-05-05  Nick Clifton  <nickc@redhat.com>

	* dwarf.c (do_checks): New global variable.
	(display_formatted_table): Warn about an unexpected number of
	columns in the table, if checks are enabled.  Do not complain
	about the lack of data following the number of entries in the
	table if the table is empty.
	(display_debug_lines_decoded): Only warn about an unexpected
	number of columns in a table if checks are enabled.
	* dwarf.h (do_checks): Add a prototype.
	* elfcomm.c (error): Remove weak attribute.
	(warn): Likewise.
	* readelf.c (do_checks): Delete.
	(warn): Delete.
	(process_section_headers): Only warn about empty sections if
	checks are enabled.

gas/ChangeLog
2020-05-05  Nick Clifton  <nickc@redhat.com>

	* dwarf2dbg.c (out_dir_and_file_list): Add comments describing the
	construction of a DWARF-5 directory name table.
	* testsuite/gas/elf/pr25917.d: Update expected output.


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[-- Attachment #2: readelf-lint.patch --]
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diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index 61373bf44a..7b5f7af8a1 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -98,6 +98,7 @@ int do_debug_cu_index;
 int do_wide;
 int do_debug_links;
 int do_follow_links;
+bfd_boolean do_checks;
 
 int dwarf_cutoff_level = -1;
 unsigned long dwarf_start_die;
@@ -3739,6 +3740,10 @@ display_formatted_table (unsigned char *                   data,
   const char * table_name = is_dir ? N_("Directory Table") : N_("File Name Table");
   
   SAFE_BYTE_GET_AND_INC (format_count, data, 1, end);
+  if (do_checks && format_count > 5)
+    warn (_("Unexpectedly large number of columns in the %s (%u)\n"),
+	  table_name, format_count);
+
   format_start = data;
   for (formati = 0; formati < format_count; formati++)
     {
@@ -3752,17 +3757,18 @@ display_formatted_table (unsigned char *                   data,
     }
 
   READ_ULEB (data_count, data, end);
-  if (data == end)
+  if (data_count == 0)
     {
-      warn (_("%s: Corrupt entry count\n"), table_name);
+      printf (_("\n The %s is empty.\n"), table_name);
       return data;
     }
-
-  if (data_count == 0)
+  else if (data == end)
     {
-      printf (_("\n The %s is empty.\n"), table_name);
+      warn (_("%s: Corrupt entry count - expected %s but none found\n"),
+	    table_name, dwarf_vmatoa ("x", data_count));
       return data;
     }
+
   else if (format_count == 0)
     {
       warn (_("%s: format count is zero, but the table is not empty\n"),
@@ -4343,8 +4349,9 @@ display_debug_lines_decoded (struct dwarf_section *  section,
 
 	      /* Skip directories format.  */
 	      SAFE_BYTE_GET_AND_INC (format_count, data, 1, end);
-	      if (format_count > 1)
-		warn ("Unexpectedly large number of columns in the directory name table (%u)\n", format_count);
+	      if (do_checks && format_count > 1)
+		warn (_("Unexpectedly large number of columns in the directory name table (%u)\n"),
+		      format_count);
 	      format_start = data;
 	      for (formati = 0; formati < format_count; formati++)
 		{
@@ -4416,9 +4423,9 @@ display_debug_lines_decoded (struct dwarf_section *  section,
 
 	      /* Skip files format.  */
 	      SAFE_BYTE_GET_AND_INC (format_count, data, 1, end);
-	      if (format_count > 5)
-		warn ("Unexpectedly large number of columns in the file name table (%u)\n", format_count);
-	      format_count = 2;
+	      if (do_checks && format_count > 5)
+		warn (_("Unexpectedly large number of columns in the file name table (%u)\n"),
+		      format_count);
 	      format_start = data;
 	      for (formati = 0; formati < format_count; formati++)
 		{
diff --git a/binutils/dwarf.h b/binutils/dwarf.h
index 27f8a51521..0c9f366107 100644
--- a/binutils/dwarf.h
+++ b/binutils/dwarf.h
@@ -221,6 +221,7 @@ extern int do_debug_cu_index;
 extern int do_wide;
 extern int do_debug_links;
 extern int do_follow_links;
+extern bfd_boolean do_checks;
 
 extern int dwarf_cutoff_level;
 extern unsigned long dwarf_start_die;
diff --git a/binutils/elfcomm.c b/binutils/elfcomm.c
index fc47b40757..5ec4690e13 100644
--- a/binutils/elfcomm.c
+++ b/binutils/elfcomm.c
@@ -34,15 +34,6 @@
 
 extern char *program_name;
 
-/* FIXME:  This definition really ought to be in ansidecl.h.  */
-#ifndef ATTRIBUTE_WEAK
-#define ATTRIBUTE_WEAK __attribute__((weak))
-#endif
-
-/* Allow the following two functions to be overridden if desired.  */
-void error (const char *, ...) ATTRIBUTE_WEAK;
-void warn (const char *, ...) ATTRIBUTE_WEAK;
-
 void
 error (const char *message, ...)
 {
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 25c2cce21a..6bf6d5294c 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -231,7 +231,6 @@ static bfd_boolean do_ctf = FALSE;
 static bfd_boolean do_arch = FALSE;
 static bfd_boolean do_notes = FALSE;
 static bfd_boolean do_archive_index = FALSE;
-static bfd_boolean do_checks = FALSE;
 static bfd_boolean check_all = FALSE;
 static bfd_boolean is_32bit_elf = FALSE;
 static bfd_boolean decompress_dumps = FALSE;
@@ -387,25 +386,6 @@ bfd_vmatoa (char *fmtch, bfd_vma value)
   return ret;
 }
 
-/* A version of the warn() function that is disabled if do_checks is not active.  */
-
-void
-warn (const char *message, ...)
-{
-  va_list args;
-
-  if (!do_checks)
-    return;
-
-  /* Try to keep warning messages in sync with the program's normal output.  */
-  fflush (stdout);
-
-  va_start (args, message);
-  fprintf (stderr, _("%s: Warning: "), program_name);
-  vfprintf (stderr, message, args);
-  va_end (args);
-}
-
 /* Retrieve NMEMB structures, each SIZE bytes long from FILEDATA starting at
    OFFSET + the offset of the current archive member, if we are examining an
    archive.  Put the retrieved data into VAR, if it is not NULL.  Otherwise
@@ -6378,21 +6358,22 @@ process_section_headers (Filedata * filedata)
 
 	case SHT_REL:
 	  CHECK_ENTSIZE (section, i, Rel);
-	  if (section->sh_size == 0)
+	  if (do_checks && section->sh_size == 0)
 	    warn (_("Section '%s': zero-sized relocation section\n"), name);
 	  break;
 
 	case SHT_RELA:
 	  CHECK_ENTSIZE (section, i, Rela);
-	  if (section->sh_size == 0)
+	  if (do_checks && section->sh_size == 0)
 	    warn (_("Section '%s': zero-sized relocation section\n"), name);
 	  break;
 
 	case SHT_NOTE:
 	case SHT_PROGBITS:
-	  if (section->sh_size == 0)
-	    /* This is not illegal according to the ELF standard, but
-	       it might be an indication that something is wrong.  */
+	  /* Having a zero sized section is not illegal according to the
+	     ELF standard, but it might be an indication that something
+	     is wrong.  So issue a warning if we are running in lint mode.  */
+	  if (do_checks && section->sh_size == 0)
 	    warn (_("Section '%s': has a size of zero - is this intended ?\n"), name);
 	  break;
 
diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index 071450e19a..69955fea5b 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -1983,11 +1983,16 @@ out_dir_and_file_list (void)
   /* Output the Directory Table.  */
   if (DWARF2_LINE_VERSION >= 5)
     {
+      /* We only have one column in the directory table.  */
       out_byte (1);
+
+      /* Describe the purpose and format of the column.  */
       out_uleb128 (DW_LNCT_path);
       /* FIXME: it would be better to store these strings in
 	 the .debug_line_str section and reference them here.  */
       out_uleb128 (DW_FORM_string);
+
+      /* Now state how many rows there are in the table.  */
       out_uleb128 (dirs_in_use);
     }
       
diff --git a/gas/testsuite/gas/elf/pr25917.d b/gas/testsuite/gas/elf/pr25917.d
index 6f83bbb5c5..ce031e7186 100644
--- a/gas/testsuite/gas/elf/pr25917.d
+++ b/gas/testsuite/gas/elf/pr25917.d
@@ -1,9 +1,9 @@
 #as: --gdwarf-5
-#name: DWARF5: no files or directories
+#name: DWARF5: no files or directories (PR 25917)
 #readelf: -wl
 
 #...
  The Directory Table is empty.
 
- No Line Number Statements.
+ The File Name Table is empty.
 #pass