[commit] Handle files without DW_AT_comp_dir

[Daniel Jacobowitz <drow at false dot org>]

Joseph Myers discovered a case where GCC emits an absolute path in
DW_AT_name, no DW_AT_comp_dir, and relative pathnames in the directory
table.  GDB could not handle this, and failed to locate header files
in the correct paths.

The GCC behavior is a bug, and I think Joseph's working on a fix for
it.  But it's been around for a long time, so I think it's worthwhile
to handle it in GDB.  I tested the patch below on x86_64-linux and
checked it in.

-- 
Daniel Jacobowitz
CodeSourcery

2007-06-04  Daniel Jacobowitz  <dan@codesourcery.com>

	* defs.h (ldirname): New prototype.
	* dwarf2read.c (read_file_scope): Use DW_AT_name if DW_AT_comp_dir is
	missing.
	* utils.c (ldirname): New function.
	* xml-tdesc.c (file_read_description_xml): Use ldirname.

Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.206
diff -u -p -r1.206 defs.h
--- defs.h	31 May 2007 17:00:06 -0000	1.206
+++ defs.h	4 Jun 2007 12:32:21 -0000
@@ -417,6 +417,8 @@ extern unsigned long gnu_debuglink_crc32
 
 ULONGEST strtoulst (const char *num, const char **trailer, int base);
 
+char *ldirname (const char *filename);
+
 /* From demangle.c */
 
 extern void set_demangling_style (char *);
Index: dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.220
diff -u -p -r1.220 dwarf2read.c
--- dwarf2read.c	18 May 2007 19:42:42 -0000	1.220
+++ dwarf2read.c	4 Jun 2007 12:32:23 -0000
@@ -2783,7 +2783,7 @@ read_file_scope (struct die_info *die, s
   CORE_ADDR lowpc = ((CORE_ADDR) -1);
   CORE_ADDR highpc = ((CORE_ADDR) 0);
   struct attribute *attr;
-  char *name = "<unknown>";
+  char *name = NULL;
   char *comp_dir = NULL;
   struct die_info *child_die;
   bfd *abfd = objfile->obfd;
@@ -2806,21 +2806,29 @@ read_file_scope (struct die_info *die, s
     {
       name = DW_STRING (attr);
     }
+
   attr = dwarf2_attr (die, DW_AT_comp_dir, cu);
   if (attr)
+    comp_dir = DW_STRING (attr);
+  else if (name != NULL && IS_ABSOLUTE_PATH (name))
     {
-      comp_dir = DW_STRING (attr);
-      if (comp_dir)
-	{
-	  /* Irix 6.2 native cc prepends <machine>.: to the compilation
-	     directory, get rid of it.  */
-	  char *cp = strchr (comp_dir, ':');
+      comp_dir = ldirname (name);
+      if (comp_dir != NULL)
+	make_cleanup (xfree, comp_dir);
+    }
+  if (comp_dir != NULL)
+    {
+      /* Irix 6.2 native cc prepends <machine>.: to the compilation
+	 directory, get rid of it.  */
+      char *cp = strchr (comp_dir, ':');
 
-	  if (cp && cp != comp_dir && cp[-1] == '.' && cp[1] == '/')
-	    comp_dir = cp + 1;
-	}
+      if (cp && cp != comp_dir && cp[-1] == '.' && cp[1] == '/')
+	comp_dir = cp + 1;
     }
 
+  if (name == NULL)
+    name = "<unknown>";
+
   attr = dwarf2_attr (die, DW_AT_language, cu);
   if (attr)
     {
Index: utils.c
===================================================================
RCS file: /cvs/src/src/gdb/utils.c,v
retrieving revision 1.176
diff -u -p -r1.176 utils.c
--- utils.c	30 Mar 2007 09:31:31 -0000	1.176
+++ utils.c	4 Jun 2007 12:32:23 -0000
@@ -3195,3 +3195,31 @@ strtoulst (const char *num, const char *
   else
     return result;
 }
+
+/* Simple, portable version of dirname that does not modify its
+   argument.  */
+
+char *
+ldirname (const char *filename)
+{
+  const char *base = lbasename (filename);
+  char *dirname;
+
+  while (base > filename && IS_DIR_SEPARATOR (base[-1]))
+    --base;
+
+  if (base == filename)
+    return NULL;
+
+  dirname = xmalloc (base - filename + 2);
+  memcpy (dirname, filename, base - filename);
+
+  /* On DOS based file systems, convert "d:foo" to "d:.", so that we
+     create "d:./bar" later instead of the (different) "d:/bar".  */
+  if (base - filename == 2 && IS_ABSOLUTE_PATH (base)
+      && !IS_DIR_SEPARATOR (filename[0]))
+    dirname[base++ - filename] = '.';
+
+  dirname[base - filename] = '\0';
+  return dirname;
+}
Index: xml-tdesc.c
===================================================================
RCS file: /cvs/src/src/gdb/xml-tdesc.c,v
retrieving revision 1.5
diff -u -p -r1.5 xml-tdesc.c
--- xml-tdesc.c	13 Feb 2007 15:48:05 -0000	1.5
+++ xml-tdesc.c	4 Jun 2007 12:32:23 -0000
@@ -487,7 +487,6 @@ file_read_description_xml (const char *f
   struct target_desc *tdesc;
   char *tdesc_str;
   struct cleanup *back_to;
-  const char *base;
   char *dirname;
 
   tdesc_str = fetch_xml_from_file (filename, NULL);
@@ -499,28 +498,9 @@ file_read_description_xml (const char *f
 
   back_to = make_cleanup (xfree, tdesc_str);
 
-  /* Simple, portable version of dirname that does not modify its
-     argument.  */
-  base = lbasename (filename);
-  while (base > filename && IS_DIR_SEPARATOR (base[-1]))
-    --base;
-  if (base > filename)
-    {
-      dirname = xmalloc (base - filename + 2);
-      memcpy (dirname, filename, base - filename);
-
-      /* On DOS based file systems, convert "d:foo" to "d:.", so that
-	 we create "d:./bar" later instead of the (different)
-	 "d:/bar".  */
-      if (base - filename == 2 && IS_ABSOLUTE_PATH (base)
-	  && !IS_DIR_SEPARATOR (filename[0]))
-	dirname[base++ - filename] = '.';
-
-      dirname[base - filename] = '\0';
-      make_cleanup (xfree, dirname);
-    }
-  else
-    dirname = NULL;
+  dirname = ldirname (filename);
+  if (dirname != NULL)
+    make_cleanup (xfree, dirname);
 
   tdesc = tdesc_parse_xml (tdesc_str, fetch_xml_from_file, dirname);
   do_cleanups (back_to);