Final separate debug info patch

[Alexander Larsson <alexl@redhat.com>]

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After a few iterations I stopped getting comments, so I guess this patch 
is mature now. I forward ported the patch to cvs HEAD, so this should be 
fine to go in.

The docs changes are approved by Eli, and Daniel Jacobowitz promised to 
handle the test suite changes if this goes in.

The patch doesn't have any autoconf-generated changes in it, because I 
don't have the exact same version of autoconf that gdb seems to use.

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 Alexander Larsson                                            Red Hat, Inc 
                   alexl@redhat.com    alla@lysator.liu.se 
He's an unconventional zombie gangster on a mission from God. She's a 
provocative tempestuous former first lady who dreams of becoming Elvis. They 
fight crime! 

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Index: gdb/acconfig.h
===================================================================
RCS file: /cvs/src/src/gdb/acconfig.h,v
retrieving revision 1.18
diff -u -p -r1.18 acconfig.h
--- gdb/acconfig.h	11 Apr 2002 18:32:51 -0000	1.18
+++ gdb/acconfig.h	9 Oct 2002 08:21:16 -0000
@@ -176,3 +176,7 @@
 
 /* nativefile */
 #undef GDB_NM_FILE
+
+/* debugdir */
+#undef DEBUGDIR
+
Index: gdb/acinclude.m4
===================================================================
RCS file: /cvs/src/src/gdb/acinclude.m4,v
retrieving revision 1.4
diff -u -p -r1.4 acinclude.m4
--- gdb/acinclude.m4	20 Sep 2002 00:24:01 -0000	1.4
+++ gdb/acinclude.m4	9 Oct 2002 08:21:16 -0000
@@ -1044,3 +1044,18 @@ size_t iconv();
   fi
   AC_SUBST(LIBICONV)
 ])
+
+dnl written by Guido Draheim <guidod@gmx.de>, original by Alexandre Oliva 
+dnl Version 1.3 (2001/03/02)
+dnl source http://www.gnu.org/software/ac-archive/Miscellaneous/ac_define_dir.html
+
+AC_DEFUN([AC_DEFINE_DIR], [
+  test "x$prefix" = xNONE && prefix="$ac_default_prefix"
+  test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
+  ac_define_dir=`eval echo [$]$2`
+  ac_define_dir=`eval echo [$]ac_define_dir`
+  ifelse($3, ,
+    AC_DEFINE_UNQUOTED($1, "$ac_define_dir"),
+    AC_DEFINE_UNQUOTED($1, "$ac_define_dir", $3))
+])
+
Index: gdb/configure.in
===================================================================
RCS file: /cvs/src/src/gdb/configure.in,v
retrieving revision 1.91
diff -u -p -r1.91 configure.in
--- gdb/configure.in	20 Sep 2002 00:24:01 -0000	1.91
+++ gdb/configure.in	9 Oct 2002 08:21:18 -0000
@@ -237,6 +237,14 @@ fi
 AC_CHECK_LIB(socket, socketpair)
 AC_CHECK_FUNCS(socketpair)
 
+debugdir=${libdir}/debug
+	 
+AC_ARG_WITH(separate-debug-dir,
+[  --with-separate-debug-dir=path   Look for global separate debug info in this path [LIBDIR/debug]],
+[debugdir="${withval}"])
+	
+AC_DEFINE_DIR(DEBUGDIR, debugdir)
+#AC_DEFINE_UNQUOTED(DEBUGDIR, "$debugdir"),
 
 BFD_NEED_DECLARATION(malloc)
 BFD_NEED_DECLARATION(realloc)
Index: gdb/defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.99
diff -u -p -r1.99 defs.h
--- gdb/defs.h	27 Sep 2002 22:08:51 -0000	1.99
+++ gdb/defs.h	9 Oct 2002 08:21:18 -0000
@@ -385,6 +385,8 @@ extern void *address_to_host_pointer (CO
 extern char *gdb_realpath (const char *);
 extern char *xfullpath (const char *);
 
+extern unsigned long calc_crc32 (unsigned long crc, unsigned char *buf, size_t len);
+
 /* From demangle.c */
 
 extern void set_demangling_style (char *);
Index: gdb/objfiles.c
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.c,v
retrieving revision 1.22
diff -u -p -r1.22 objfiles.c
--- gdb/objfiles.c	29 Jul 2002 22:55:26 -0000	1.22
+++ gdb/objfiles.c	9 Oct 2002 08:21:18 -0000
@@ -333,6 +333,30 @@ allocate_objfile (bfd *abfd, int flags)
   return (objfile);
 }
 
+/* Put one object file before a specified on in the global list.
+   This can be used to make sure an object file is destroyed before
+   another when using ALL_OBJFILES_SAFE to free all objfiles. */
+void
+put_objfile_before (struct objfile *objfile, struct objfile *before_this)
+{
+  struct objfile **objp;
+
+  unlink_objfile (objfile);
+  
+  for (objp = &object_files; *objp != NULL; objp = &((*objp)->next))
+    {
+      if (*objp == before_this)
+	{
+	  objfile->next = *objp;
+	  *objp = objfile;
+	  return;
+	}
+    }
+  
+  internal_error (__FILE__, __LINE__,
+		  "put_objfile_before: before objfile not in list");
+}
+
 /* Put OBJFILE at the front of the list.  */
 
 void
@@ -405,6 +429,18 @@ unlink_objfile (struct objfile *objfile)
 void
 free_objfile (struct objfile *objfile)
 {
+  if (objfile->separate_debug_objfile)
+    {
+      free_objfile (objfile->separate_debug_objfile);
+    }
+  
+  if (objfile->separate_debug_objfile_backlink)
+    {
+      /* We freed the separate debug file, make sure the base objfile
+	 doesn't reference it.  */
+      objfile->separate_debug_objfile_backlink->separate_debug_objfile = NULL;
+    }
+  
   /* First do any symbol file specific actions required when we are
      finished with a particular symbol file.  Note that if the objfile
      is using reusable symbol information (via mmalloc) then each of
Index: gdb/objfiles.h
===================================================================
RCS file: /cvs/src/src/gdb/objfiles.h,v
retrieving revision 1.15
diff -u -p -r1.15 objfiles.h
--- gdb/objfiles.h	5 Aug 2002 16:17:41 -0000	1.15
+++ gdb/objfiles.h	9 Oct 2002 08:21:18 -0000
@@ -414,6 +414,15 @@ struct objfile
     ExportEntry *export_list;
     int export_list_size;
 
+    /* Link to objfile that contains the debug symbols for this one.
+       One is loaded if this file has an debug link to an existing
+       debug file with the right checksum */
+    struct objfile *separate_debug_objfile;
+
+    /* If this is a separate debug object, this is used as a link to the
+       actual executable objfile. */
+    struct objfile *separate_debug_objfile_backlink;
+    
     /* Place to stash various statistics about this objfile */
       OBJSTATS;
   };
@@ -504,6 +513,8 @@ extern struct objfile *object_files;
 extern struct objfile *allocate_objfile (bfd *, int);
 
 extern int build_objfile_section_table (struct objfile *);
+
+extern void put_objfile_before (struct objfile *, struct objfile *);
 
 extern void objfile_to_front (struct objfile *);
 
Index: gdb/symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.69
diff -u -p -r1.69 symfile.c
--- gdb/symfile.c	20 Sep 2002 14:58:58 -0000	1.69
+++ gdb/symfile.c	9 Oct 2002 08:21:19 -0000
@@ -38,6 +38,7 @@
 #include "complaints.h"
 #include "demangle.h"
 #include "inferior.h"		/* for write_pc */
+#include "filenames.h"		/* for DOSish file names */
 #include "gdb-stabs.h"
 #include "gdb_obstack.h"
 #include "completer.h"
@@ -147,6 +148,8 @@ static void set_ext_lang_command (char *
 
 static void info_ext_lang_command (char *args, int from_tty);
 
+static char *find_separate_debug_file (struct objfile *objfile, const char *name);
+
 static void init_filename_language_table (void);
 
 void _initialize_symfile (void);
@@ -826,7 +829,12 @@ symbol_file_add (char *name, int from_tt
 {
   struct objfile *objfile;
   struct partial_symtab *psymtab;
+  char *debugfile;
   bfd *abfd;
+  struct section_addr_info orig_addrs;
+  
+  if (addrs)
+    orig_addrs = *addrs;
 
   /* Open a bfd for the file, and give user a chance to burp if we'd be
      interactively wiping out any existing symbols.  */
@@ -919,6 +927,28 @@ symbol_file_add (char *name, int from_tt
   if (target_new_objfile_hook)
     target_new_objfile_hook (objfile);
 
+  debugfile = find_separate_debug_file (objfile, name);
+  if (debugfile)
+    {
+      printf_filtered ("loading separate debug info from '%s'\n", debugfile);
+
+      if (addrs != NULL)
+	{
+	  objfile->separate_debug_objfile = symbol_file_add (debugfile, from_tty, &orig_addrs, 0, flags);
+	}
+      else
+	{
+	  objfile->separate_debug_objfile = symbol_file_add (debugfile, from_tty, NULL, 0, flags);
+	}
+      objfile->separate_debug_objfile->separate_debug_objfile_backlink = objfile;
+      
+      /* Put the separate debug object before the normal one, this is so that
+         usage of the ALL_OBJFILES_SAFE macro will stay safe. */
+      put_objfile_before (objfile->separate_debug_objfile, objfile);
+      
+      xfree (debugfile);
+    }
+  
   return (objfile);
 }
 
@@ -978,6 +1008,145 @@ symbol_file_clear (int from_tty)
 #endif
 }
 
+static char *
+get_debug_link_info (struct objfile *objfile, unsigned long *crc32_out)
+{
+  asection *sect;
+  bfd_size_type debuglink_size;
+  unsigned long crc32;
+  char *contents;
+  int crc_offset;
+  unsigned char *crc_data;
+  unsigned char *p;
+  
+  sect = bfd_get_section_by_name (objfile->obfd, ".gnu_debuglink");
+
+  if (sect == NULL)
+    return NULL;
+
+  debuglink_size = bfd_section_size (objfile->obfd, sect);
+  
+  contents = xmalloc (debuglink_size);
+  bfd_get_section_contents (objfile->obfd, sect, contents,
+			    (file_ptr)0, (bfd_size_type)debuglink_size);
+
+  /* Crc value is stored after the filename, aligned up to 4 bytes. */
+  crc_offset = strlen (contents) + 1;
+  if (crc_offset & 3)
+    crc_offset += 4 - (crc_offset & 3);
+  crc_data = contents + crc_offset;
+
+  crc32 = 0;
+  if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
+    {
+      for (p = crc_data; p < crc_data + 4; ++p)
+	crc32 = (crc32 << 8) | *p;
+    }
+  else
+    {
+      for (p = crc_data + 4 - 1; p >= crc_data; --p)
+	crc32 = (crc32 << 8) | *p;
+    }
+  
+  *crc32_out = crc32;
+  return contents;
+}
+
+static int
+separate_debug_file_exists (const char *name, unsigned long crc)
+{
+  unsigned long file_crc = 0;
+  int fd;
+  char buffer[8*1024];
+  int count;
+
+  fd = open (name, O_RDONLY | O_BINARY);
+  if (fd < 0)
+    return 0;
+
+  while ((count = read (fd, buffer, sizeof (buffer))) > 0)
+    file_crc = calc_crc32 (file_crc, buffer, count);
+
+  close (fd);
+
+  return crc == file_crc;
+}
+
+static char *debug_file_directory = NULL;
+
+static char *
+find_separate_debug_file (struct objfile *objfile, const char *name)
+{
+  asection *sect;
+  char *basename;
+  char *dir;
+  char *debugfile;
+  char *name_copy;
+  bfd_size_type debuglink_size;
+  unsigned long crc32;
+  int i;
+
+  basename = get_debug_link_info (objfile, &crc32);
+
+  if (basename == NULL)
+    return NULL;
+  
+  dir = xstrdup (name);
+
+  /* Strip off filename part */
+  for (i = strlen(dir) - 1; i >= 0; i--)
+    {
+      if (IS_DIR_SEPARATOR (dir[i]))
+	break;
+    }
+  dir[i+1] = '\0';
+  
+  debugfile = alloca (strlen (debug_file_directory) + 1 +
+		      strlen (dir) + strlen (".debug/") + strlen (basename) + 1);
+
+  /* First try in the same directory as the original file: */
+  strcpy (debugfile, dir);
+  strcat (debugfile, basename);
+
+  if (separate_debug_file_exists (debugfile, crc32))
+    {
+      xfree (basename);
+      xfree (dir);
+      return xstrdup (debugfile);
+    }
+  
+  /* Then try in a subdirectory called .debug */
+  strcpy (debugfile, dir);
+  strcat (debugfile, ".debug/");
+  strcat (debugfile, basename);
+
+  if (separate_debug_file_exists (debugfile, crc32))
+    {
+      xfree (basename);
+      xfree (dir);
+      return xstrdup (debugfile);
+    }
+  
+  /* Then try in the global debugfile directory */
+  strcpy (debugfile, debug_file_directory);
+  strcat (debugfile, "/");
+  strcat (debugfile, dir);
+  strcat (debugfile, "/");
+  strcat (debugfile, basename);
+
+  if (separate_debug_file_exists (debugfile, crc32))
+    {
+      xfree (basename);
+      xfree (dir);
+      return xstrdup (debugfile);
+    }
+  
+  xfree (basename);
+  xfree (dir);
+  return NULL;
+}
+
+
 /* This is the symbol-file command.  Read the file, analyze its
    symbols, and add a struct symtab to a symtab list.  The syntax of
    the command is rather bizarre--(1) buildargv implements various
@@ -1637,6 +1806,8 @@ reread_symbols (void)
   long new_modtime;
   int reread_one = 0;
   struct stat new_statbuf;
+  char *debug_file;
+  unsigned long crc32;
   int res;
 
   /* With the addition of shared libraries, this should be modified,
@@ -1823,6 +1994,27 @@ reread_symbols (void)
 	         needs to keep track of (such as _sigtramp, or whatever).  */
 
 	      TARGET_SYMFILE_POSTREAD (objfile);
+
+	      /* Verify the checksum of a previously loaded separate debug file. */
+	      if (objfile->separate_debug_objfile)
+		{
+		  debug_file = get_debug_link_info (objfile, &crc32);
+		  if (debug_file)
+		    {
+		      if (!separate_debug_file_exists (objfile->separate_debug_objfile->name, crc32))
+			{
+			  /* The old separate debug symbols file is invalid */
+			  free_objfile (objfile->separate_debug_objfile);
+			}
+		      xfree (debug_file);
+		    }
+		  else
+		    {
+		      /* No more debug link, kill old separate debug symbols */
+		      free_objfile (objfile->separate_debug_objfile);
+		    }
+		}
+	      
 	    }
 	}
     }
@@ -3337,4 +3529,17 @@ Usage: set extension-language .foo bar",
 		  "cache.\n",
 		  &setlist),
      &showlist);
+
+  debug_file_directory = xstrdup (DEBUGDIR);
+  c = add_set_cmd ("debug-file-directory", class_support, var_string,
+		   (char *) &debug_file_directory,
+		   "Set the directory where separate debug symbols are searched for.\n"
+		   "Separate debug symbols are first searched for in the same\n"
+		   "directory as the binary, then in the .debug subdirectory,\n"
+		   "and lastly at the path of the directory of the binary with\n"
+		   "the global debug-file directory prepended\n",
+		   &setlist);
+  add_show_from_set (c, &showlist);
+  set_cmd_completer (c, filename_completer);
+
 }
Index: gdb/utils.c
===================================================================
RCS file: /cvs/src/src/gdb/utils.c,v
retrieving revision 1.80
diff -u -p -r1.80 utils.c
--- gdb/utils.c	20 Sep 2002 00:24:01 -0000	1.80
+++ gdb/utils.c	9 Oct 2002 08:21:19 -0000
@@ -2728,3 +2728,69 @@ xfullpath (const char *filename)
   xfree (real_path);
   return result;
 }
+
+unsigned long
+calc_crc32 (unsigned long crc, unsigned char *buf, size_t len)
+{
+  static const unsigned long crc32_table[256] =
+    {
+      0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
+      0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+      0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
+      0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+      0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
+      0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+      0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
+      0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+      0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
+      0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+      0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
+      0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+      0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
+      0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+      0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
+      0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+      0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
+      0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+      0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
+      0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+      0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
+      0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+      0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
+      0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+      0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
+      0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+      0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
+      0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+      0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
+      0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+      0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
+      0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+      0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
+      0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+      0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
+      0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+      0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
+      0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+      0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
+      0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+      0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
+      0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+      0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
+      0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+      0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
+      0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+      0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
+      0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+      0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
+      0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+      0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
+      0x2d02ef8d
+    };
+  unsigned char *end;
+
+  crc = ~crc & 0xffffffff;
+  for (end = buf + len; buf < end; ++buf)
+    crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
+  return ~crc & 0xffffffff;;
+}
Index: gdb/doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.130
diff -u -p -r1.130 gdb.texinfo
--- gdb/doc/gdb.texinfo	3 Oct 2002 05:56:40 -0000	1.130
+++ gdb/doc/gdb.texinfo	9 Oct 2002 08:21:24 -0000
@@ -10206,6 +10206,29 @@ Mb).
 Display the current autoloading size threshold, in megabytes.
 @end table
 
+On @sc{elf} based systems, @value{GDBN} supports automatically loading
+symbol tables and debug information from a file separate from the
+executable.  This works by putting information in the executable about
+the name and checksum of the file with debug information.  When
+@value{GDBN} reads such an executable it automatically tries to locate
+the debug file and load it. 
+
+@value{GDBN} searchs for the file first in the same directory as the
+executable, and then in a subdirectory called @file{.debug}. 
+If both these fail @value{GDBN} looks in the global debug directory, with the
+full pathname of the executable.  So if you are loading
+@file{/usr/bin/ls} and it references the debug file @file{ls.debug}
+@value{GDBN} will look for @file{usr/bin/ls.debug} in the global debug
+directory.
+
+@table @code
+@kindex set debug-file-directory
+@item set debug-file-directory @var{directory}
+Set the global directory where @value{GDBN} searches for separate
+debug files to @var{directory}.
+@end table
+
+
 @node Symbol Errors
 @section Errors reading symbol files