[PATCH 1/9] add a key to target sections

[Tom Tromey <tromey at redhat dot com>]

In my earlier BFD-sharing patch series (the minsym-sharing one), I
noticed that BFD-sharing actually caused bugs, because the
target-section code relied on BFD uniqueness.

This patch adds a key to target sections so we can share BFDs without
accidentally unpushing the target when a BFD is unrefed.  The key is
just any handy 'void*'.

	* exec.c (exec_close, exec_file_attach): Update.
	(add_to_section_table): Initialize 'key' field.
	(add_target_sections, remove_target_sections): Add 'key' argument.
	* exec.h (add_target_sections, remove_target_sections): Add
	'key' argument.
	* solib.c (solib_map_sections, update_solib_list, clear_solib)
	(reload_shared_libraries_1): Update.
	* target.h (struct target_section) <key>: New field.
---
 gdb/exec.c   |   20 +++++++++++++-------
 gdb/exec.h   |    5 +++--
 gdb/solib.c  |    8 ++++----
 gdb/target.h |    6 ++++++
 4 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/gdb/exec.c b/gdb/exec.c
index e076609..de1b0b6 100644
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -107,7 +107,7 @@ exec_close (void)
       exec_bfd = NULL;
       exec_bfd_mtime = 0;
 
-      remove_target_sections (abfd);
+      remove_target_sections (&exec_bfd, abfd);
     }
 }
 
@@ -284,7 +284,7 @@ exec_file_attach (char *filename, int from_tty)
       /* Add the executable's sections to the current address spaces'
 	 list of sections.  This possibly pushes the exec_ops
 	 target.  */
-      add_target_sections (sections, sections_end);
+      add_target_sections (&exec_bfd, sections, sections_end);
       xfree (sections);
 
       /* Tell display code (if any) about the changed file name.  */
@@ -378,6 +378,7 @@ add_to_section_table (bfd *abfd, struct bfd_section *asect,
   if (!(aflag & SEC_ALLOC))
     return;
 
+  (*table_pp)->key = NULL;
   (*table_pp)->bfd = abfd;
   (*table_pp)->the_bfd_section = asect;
   (*table_pp)->addr = bfd_section_vma (abfd, asect);
@@ -438,7 +439,8 @@ build_section_table (struct bfd *some_bfd, struct target_section **start,
    current set of target sections.  */
 
 void
-add_target_sections (struct target_section *sections,
+add_target_sections (void *key,
+		     struct target_section *sections,
 		     struct target_section *sections_end)
 {
   int count;
@@ -449,9 +451,13 @@ add_target_sections (struct target_section *sections,
   if (count > 0)
     {
       int space = resize_section_table (table, count);
+      int i;
 
-      memcpy (table->sections + space,
-	      sections, count * sizeof (sections[0]));
+      for (i = 0; i < count; ++i)
+	{
+	  table->sections[space + i] = sections[i];
+	  table->sections[space + i].key = key;
+	}
 
       /* If these are the first file sections we can provide memory
 	 from, push the file_stratum target.  */
@@ -466,14 +472,14 @@ add_target_sections (struct target_section *sections,
 /* Remove all target sections taken from ABFD.  */
 
 void
-remove_target_sections (bfd *abfd)
+remove_target_sections (void *key, bfd *abfd)
 {
   struct target_section *src, *dest;
   struct target_section_table *table = current_target_sections;
 
   dest = table->sections;
   for (src = table->sections; src < table->sections_end; src++)
-    if (src->bfd != abfd)
+    if (src->key != key || src->bfd != abfd)
       {
 	/* Keep this section.  */
 	if (dest < src)
diff --git a/gdb/exec.h b/gdb/exec.h
index a0f9eab..c5bb2a8 100644
--- a/gdb/exec.h
+++ b/gdb/exec.h
@@ -83,12 +83,13 @@ extern void exec_set_section_address (const char *, int, CORE_ADDR);
 
 /* Remove all target sections taken from ABFD.  */
 
-extern void remove_target_sections (bfd *abfd);
+extern void remove_target_sections (void *key, bfd *abfd);
 
 /* Add the sections array defined by [SECTIONS..SECTIONS_END[ to the
    current set of target sections.  */
 
-extern void add_target_sections (struct target_section *sections,
+extern void add_target_sections (void *key,
+				 struct target_section *sections,
 				 struct target_section *sections_end);
 
 /* Prints info about all sections defined in the TABLE.  ABFD is
diff --git a/gdb/solib.c b/gdb/solib.c
index 73773f1..3081f35 100644
--- a/gdb/solib.c
+++ b/gdb/solib.c
@@ -504,7 +504,7 @@ solib_map_sections (struct so_list *so)
      section tables.  Do this immediately after mapping the object so
      that later nodes in the list can query this object, as is needed
      in solib-osf.c.  */
-  add_target_sections (so->sections, so->sections_end);
+  add_target_sections (so, so->sections, so->sections_end);
 
   return 1;
 }
@@ -772,7 +772,7 @@ update_solib_list (int from_tty, struct target_ops *target)
 
 	  /* Some targets' section tables might be referring to
 	     sections from so->abfd; remove them.  */
-	  remove_target_sections (gdb->abfd);
+	  remove_target_sections (gdb, gdb->abfd);
 
 	  free_so (gdb);
 	  gdb = *gdb_link;
@@ -1154,7 +1154,7 @@ clear_solib (void)
       so_list_head = so->next;
       observer_notify_solib_unloaded (so);
       if (so->abfd)
-	remove_target_sections (so->abfd);
+	remove_target_sections (so, so->abfd);
       free_so (so);
     }
 
@@ -1247,7 +1247,7 @@ reload_shared_libraries_1 (int from_tty)
 	  if (so->objfile && ! (so->objfile->flags & OBJF_USERLOADED)
 	      && !solib_used (so))
 	    free_objfile (so->objfile);
-	  remove_target_sections (so->abfd);
+	  remove_target_sections (so, so->abfd);
 	  free_so_symbols (so);
 	}
 
diff --git a/gdb/target.h b/gdb/target.h
index 95cfbe2..382dacb 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1804,6 +1804,12 @@ struct target_section
 
     struct bfd_section *the_bfd_section;
 
+    /* A given BFD may appear multiple times in the target section
+       list, so each BFD is associated with a given key.  The key is
+       just some convenient pointer that can be used to differentiate
+       the BFDs.  These are managed only by convention.  */
+    void *key;
+
     bfd *bfd;			/* BFD file pointer */
   };
 
-- 
1.7.7.6