convert corelow to to_xclose

This converts corelow to be a to_xclose target.  It moves all the
corelow-related globals into a new subclass of target_ops and arranges
for core_open to push an instance of this.

This is preparatory work for multi-target.  After this patch, corelow
doesn't rely on global state and multiple instances can readily be
instantiated.

2014-07-29  Tom Tromey  <tromey@redhat.com>

	* corelow.c (struct core_target_ops_with_data): New struct.
	(core_vec, core_gdbarch, core_data): Remove.  Now fields of
	core_target_ops_with_data.
	(sniff_core_bfd): Add core_gdbarch parameter.
	(get_core_target_ops): New function.
	(core_xclose): Rename from core_close.  Update for
	core_target_ops_with_data.  Free the target.
	(core_close_cleanup): Rename parameter.  Update.
	(core_open): Use TARGET_NEW.  Update.
	(get_core_register_section, get_core_registers, core_files_info)
	(core_xfer_partial, core_read_description, core_pid_to_str): Use
	get_core_target_ops.  Update.
	(init_core_ops): Set to_xclose, not to_close.
	* target.c (allocate_target): New function.
	* target.h (allocate_target): Declare.
	(TARGET_NEW): New macro.

3 files changed, 146 insertions, 73 deletions

diff --git a/gdb/corelow.c b/gdb/corelow.c
index f7a8bb3..c0b636f 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -56,31 +56,36 @@
 
 static struct core_fns *core_file_fns = NULL;
 
-/* The core_fns for a core file handler that is prepared to read the
-   core file currently open on core_bfd.  */
+/* A subclass of target_ops that also holds data for a core
+   target.  */
 
-static struct core_fns *core_vec = NULL;
+struct core_target_ops_with_data
+{
+  /* The base class.  */
 
-/* FIXME: kettenis/20031023: Eventually this variable should
-   disappear.  */
+  struct target_ops base;
 
-static struct gdbarch *core_gdbarch = NULL;
+  /* The core_fns for a core file handler that is prepared to read the
+     core file currently open on core_bfd.  */
 
-/* Per-core data.  Currently, only the section table.  Note that these
-   target sections are *not* mapped in the current address spaces' set
-   of target sections --- those should come only from pure executable
-   or shared library bfds.  The core bfd sections are an
-   implementation detail of the core target, just like ptrace is for
-   unix child targets.  */
-static struct target_section_table *core_data;
+  struct core_fns *core_vec;
 
-static void core_files_info (struct target_ops *);
+  /* FIXME: kettenis/20031023: Eventually this variable should
+     disappear.  */
 
-static struct core_fns *sniff_core_bfd (bfd *);
+  struct gdbarch *core_gdbarch;
 
-static int gdb_check_format (bfd *);
+  /* The section table.  Note that these target sections are *not*
+     mapped in the current address spaces' set of target sections ---
+     those should come only from pure executable or shared library
+     bfds.  The core bfd sections are an implementation detail of the
+     core target, just like ptrace is for unix child targets.  */
+  struct target_section_table core_data;
+};
 
-static void core_close (struct target_ops *self);
+static void core_files_info (struct target_ops *);
+
+static int gdb_check_format (bfd *);
 
 static void core_close_cleanup (void *ignore);
 
@@ -125,7 +130,7 @@ default_core_sniffer (struct core_fns *our_fns, bfd *abfd)
    selected.  */
 
 static struct core_fns *
-sniff_core_bfd (bfd *abfd)
+sniff_core_bfd (bfd *abfd, struct gdbarch *core_gdbarch)
 {
   struct core_fns *cf;
   struct core_fns *yummy = NULL;
@@ -183,12 +188,35 @@ gdb_check_format (bfd *abfd)
   return (0);
 }
 
+
+
+/* Return the core_target_ops_with_data for the current target stack,
+   if any.  */
+
+static struct core_target_ops_with_data *
+get_core_target_ops (void)
+{
+  struct target_ops *targ = find_target_at (process_stratum);
+
+  if (targ == NULL || targ->to_identity != &core_ops)
+    return NULL;
+
+  /* Downcast.  */
+  return (struct core_target_ops_with_data *) targ;
+}
+
 /* Discard all vestiges of any previous core file and mark data and
    stack spaces as empty.  */
 
 static void
-core_close (struct target_ops *self)
+core_xclose (struct target_ops *self)
 {
+  /* Downcast.  */
+  struct core_target_ops_with_data *cops
+    = (struct core_target_ops_with_data *) self;
+
+  gdb_assert (self->to_identity == &core_ops);
+
   if (core_bfd)
     {
       int pid = ptid_get_pid (inferior_ptid);
@@ -201,24 +229,18 @@ core_close (struct target_ops *self)
          comments in clear_solib in solib.c.  */
       clear_solib ();
 
-      if (core_data)
-	{
-	  xfree (core_data->sections);
-	  xfree (core_data);
-	  core_data = NULL;
-	}
-
       gdb_bfd_unref (core_bfd);
       core_bfd = NULL;
     }
-  core_vec = NULL;
-  core_gdbarch = NULL;
+
+  xfree (cops->core_data.sections);
+  xfree (cops);
 }
 
 static void
-core_close_cleanup (void *ignore)
+core_close_cleanup (void *arg)
 {
-  core_close (NULL);
+  core_xclose (arg);
 }
 
 /* Look for sections whose names start with `.reg/' so that we can
@@ -278,7 +300,9 @@ core_open (const char *arg, int from_tty)
   bfd *temp_bfd;
   int scratch_chan;
   int flags;
+  volatile struct gdb_exception except;
   char *filename;
+  struct core_target_ops_with_data *cops;
 
   target_preopen (from_tty);
   if (!arg)
@@ -334,21 +358,21 @@ core_open (const char *arg, int from_tty)
   do_cleanups (old_chain);
   unpush_target (&core_ops);
   core_bfd = temp_bfd;
-  old_chain = make_cleanup (core_close_cleanup, 0 /*ignore*/);
 
-  core_gdbarch = gdbarch_from_bfd (core_bfd);
+  cops = TARGET_NEW (struct core_target_ops_with_data, &core_ops);
+  old_chain = make_cleanup (core_close_cleanup, cops);
+
+  cops->core_gdbarch = gdbarch_from_bfd (core_bfd);
 
   /* Find a suitable core file handler to munch on core_bfd */
-  core_vec = sniff_core_bfd (core_bfd);
+  cops->core_vec = sniff_core_bfd (core_bfd, cops->core_gdbarch);
 
   validate_files ();
 
-  core_data = XCNEW (struct target_section_table);
-
   /* Find the data section */
   if (build_section_table (core_bfd,
-			   &core_data->sections,
-			   &core_data->sections_end))
+			   &cops->core_data.sections,
+			   &cops->core_data.sections_end))
     error (_("\"%s\": Can't find sections: %s"),
 	   bfd_get_filename (core_bfd), bfd_errmsg (bfd_get_error ()));
 
@@ -359,7 +383,7 @@ core_open (const char *arg, int from_tty)
   if (!exec_bfd)
     set_gdbarch_from_file (core_bfd);
 
-  push_target (&core_ops);
+  push_target (&cops->base);
   discard_cleanups (old_chain);
 
   /* Do this before acknowledging the inferior, so if
@@ -404,7 +428,7 @@ core_open (const char *arg, int from_tty)
 	switch_to_thread (thread->ptid);
     }
 
-  post_create_inferior (&core_ops, from_tty);
+  post_create_inferior (&cops->base, from_tty);
 
   /* Now go through the target stack looking for threads since there
      may be a thread_stratum target loaded on top of target core by
@@ -437,11 +461,11 @@ core_open (const char *arg, int from_tty)
 	 implementation for that gdbarch, as a fallback measure,
 	 assume the host signal mapping.  It'll be correct for native
 	 cores, but most likely incorrect for cross-cores.  */
-      enum gdb_signal sig = (core_gdbarch != NULL
-			     && gdbarch_gdb_signal_from_target_p (core_gdbarch)
-			     ? gdbarch_gdb_signal_from_target (core_gdbarch,
-							       siggy)
-			     : gdb_signal_from_host (siggy));
+      enum gdb_signal sig
+	= (cops->core_gdbarch != NULL
+	   && gdbarch_gdb_signal_from_target_p (cops->core_gdbarch)
+	   ? gdbarch_gdb_signal_from_target (cops->core_gdbarch, siggy)
+	   : gdb_signal_from_host (siggy));
 
       printf_filtered (_("Program terminated with signal %s, %s.\n"),
 		       gdb_signal_to_name (sig), gdb_signal_to_string (sig));
@@ -517,6 +541,7 @@ get_core_register_section (struct regcache *regcache,
   struct bfd_section *section;
   bfd_size_type size;
   char *contents;
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
 
   xfree (section_name);
 
@@ -544,10 +569,12 @@ get_core_register_section (struct regcache *regcache,
   if (size != min_size && !(regset->flags & REGSET_VARIABLE_SIZE))
     {
       warning (_("Unexpected size of section `%s' in core file."),
-	       section_name);
+ 	       section_name);
     }
 
   contents = (char *) alloca (size);
+
+  contents = alloca (size);
   if (! bfd_get_section_contents (core_bfd, section, contents,
 				  (file_ptr) 0, size))
     {
@@ -562,10 +589,10 @@ get_core_register_section (struct regcache *regcache,
       return;
     }
 
-  gdb_assert (core_vec);
-  core_vec->core_read_registers (regcache, contents, size, which,
-				 ((CORE_ADDR)
-				  bfd_section_vma (core_bfd, section)));
+  gdb_assert (cops->core_vec);
+  cops->core_vec->core_read_registers (regcache, contents, size, which,
+				       ((CORE_ADDR)
+					bfd_section_vma (core_bfd, section)));
 }
 
 /* Callback for get_core_registers that handles a single core file
@@ -608,20 +635,22 @@ static void
 get_core_registers (struct target_ops *ops,
 		    struct regcache *regcache, int regno)
 {
+  struct core_regset_section *sect_list;
   int i;
-  struct gdbarch *gdbarch;
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
 
-  if (!(core_gdbarch && gdbarch_iterate_over_regset_sections_p (core_gdbarch))
-      && (core_vec == NULL || core_vec->core_read_registers == NULL))
+  if (!(cops->core_gdbarch
+	&& gdbarch_iterate_over_regset_sections_p (cops->core_gdbarch))
+      && (cops->core_vec == NULL
+	  || cops->core_vec->core_read_registers == NULL))
     {
       fprintf_filtered (gdb_stderr,
 		     "Can't fetch registers from this type of core file\n");
       return;
     }
 
-  gdbarch = get_regcache_arch (regcache);
-  if (gdbarch_iterate_over_regset_sections_p (gdbarch))
-    gdbarch_iterate_over_regset_sections (gdbarch,
+  if (gdbarch_iterate_over_regset_sections_p (cops->core_gdbarch))
+    gdbarch_iterate_over_regset_sections (cops->core_gdbarch,
 					  get_core_registers_cb,
 					  (void *) regcache, NULL);
   else
@@ -641,7 +670,9 @@ get_core_registers (struct target_ops *ops,
 static void
 core_files_info (struct target_ops *t)
 {
-  print_section_info (core_data, core_bfd);
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
+
+  print_section_info (&cops->core_data, core_bfd);
 }
 
 struct spuid_list
@@ -709,13 +740,15 @@ core_xfer_partial (struct target_ops *ops, enum target_object object,
 		   const gdb_byte *writebuf, ULONGEST offset,
 		   ULONGEST len, ULONGEST *xfered_len)
 {
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
+
   switch (object)
     {
     case TARGET_OBJECT_MEMORY:
       return section_table_xfer_memory_partial (readbuf, writebuf,
 						offset, len, xfered_len,
-						core_data->sections,
-						core_data->sections_end,
+						cops->core_data.sections,
+						cops->core_data.sections_end,
 						NULL);
 
     case TARGET_OBJECT_AUXV:
@@ -789,16 +822,17 @@ core_xfer_partial (struct target_ops *ops, enum target_object object,
       return TARGET_XFER_E_IO;
 
     case TARGET_OBJECT_LIBRARIES:
-      if (core_gdbarch
-	  && gdbarch_core_xfer_shared_libraries_p (core_gdbarch))
+      if (cops->core_gdbarch
+	  && gdbarch_core_xfer_shared_libraries_p (cops->core_gdbarch))
 	{
 	  if (writebuf)
 	    return TARGET_XFER_E_IO;
 	  else
 	    {
-	      *xfered_len = gdbarch_core_xfer_shared_libraries (core_gdbarch,
-								readbuf,
-								offset, len);
+	      *xfered_len
+		= gdbarch_core_xfer_shared_libraries (cops->core_gdbarch,
+						      readbuf,
+						      offset, len);
 
 	      if (*xfered_len == 0)
 		return TARGET_XFER_EOF;
@@ -809,15 +843,15 @@ core_xfer_partial (struct target_ops *ops, enum target_object object,
       /* FALL THROUGH */
 
     case TARGET_OBJECT_LIBRARIES_AIX:
-      if (core_gdbarch
-	  && gdbarch_core_xfer_shared_libraries_aix_p (core_gdbarch))
+      if (cops->core_gdbarch
+	  && gdbarch_core_xfer_shared_libraries_aix_p (cops->core_gdbarch))
 	{
 	  if (writebuf)
 	    return TARGET_XFER_E_IO;
 	  else
 	    {
 	      *xfered_len
-		= gdbarch_core_xfer_shared_libraries_aix (core_gdbarch,
+		= gdbarch_core_xfer_shared_libraries_aix (cops->core_gdbarch,
 							  readbuf, offset,
 							  len);
 
@@ -941,11 +975,14 @@ core_thread_alive (struct target_ops *ops, ptid_t ptid)
 static const struct target_desc *
 core_read_description (struct target_ops *target)
 {
-  if (core_gdbarch && gdbarch_core_read_description_p (core_gdbarch))
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
+
+  if (cops->core_gdbarch
+      && gdbarch_core_read_description_p (cops->core_gdbarch))
     {
       const struct target_desc *result;
 
-      result = gdbarch_core_read_description (core_gdbarch, 
+      result = gdbarch_core_read_description (cops->core_gdbarch, 
 					      target, core_bfd);
       if (result != NULL)
 	return result;
@@ -960,12 +997,13 @@ core_pid_to_str (struct target_ops *ops, ptid_t ptid)
   static char buf[64];
   struct inferior *inf;
   int pid;
+  struct core_target_ops_with_data *cops = get_core_target_ops ();
 
   /* The preferred way is to have a gdbarch/OS specific
      implementation.  */
-  if (core_gdbarch
-      && gdbarch_core_pid_to_str_p (core_gdbarch))
-    return gdbarch_core_pid_to_str (core_gdbarch, ptid);
+  if (cops->core_gdbarch
+      && gdbarch_core_pid_to_str_p (cops->core_gdbarch))
+    return gdbarch_core_pid_to_str (cops->core_gdbarch, ptid);
 
   /* Otherwise, if we don't have one, we'll just fallback to
      "process", with normal_pid_to_str.  */
@@ -977,7 +1015,7 @@ core_pid_to_str (struct target_ops *ops, ptid_t ptid)
 
   /* Otherwise, this isn't a "threaded" core -- use the PID field, but
      only if it isn't a fake PID.  */
-  inf = find_inferior_ptid (ptid);
+  inf = find_inferior_pid (ptid_get_pid (ptid));
   if (inf != NULL && !inf->fake_pid_p)
     return normal_pid_to_str (ptid);
 
@@ -1028,7 +1066,7 @@ init_core_ops (void)
   core_ops.to_doc =
     "Use a core file as a target.  Specify the filename of the core file.";
   core_ops.to_open = core_open;
-  core_ops.to_close = core_close;
+  core_ops.to_xclose = core_xclose;
   core_ops.to_detach = core_detach;
   core_ops.to_fetch_registers = get_core_registers;
   core_ops.to_xfer_partial = core_xfer_partial;
diff --git a/gdb/target.c b/gdb/target.c
index 1a3d417..c791aa5 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -706,6 +706,26 @@ push_target (struct target_ops *t)
   update_current_target ();
 }
 
+/* See target.h.  */
+
+struct target_ops *
+allocate_target (struct target_ops *ops, size_t alloc)
+{
+  char *mem;
+
+  gdb_assert (ops->to_identity != NULL);
+  gdb_assert (ops->to_xclose != NULL);
+  gdb_assert (alloc >= sizeof (struct target_ops));
+
+  mem = xmalloc (alloc);
+  memcpy (mem, ops, sizeof (struct target_ops));
+  if (alloc > sizeof (struct target_ops))
+    memset (&mem[sizeof (struct target_ops)], 0,
+	    alloc - sizeof (struct target_ops));
+
+  return (struct target_ops *) mem;
+}
+
 /* Remove a target_ops vector from the stack, wherever it may be.
    Return how many times it was removed (0 or 1).  */
 
diff --git a/gdb/target.h b/gdb/target.h
index 804b579..fce4046 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -2289,6 +2289,21 @@ extern void push_target (struct target_ops *);
 
 extern int unpush_target (struct target_ops *);
 
+/* Allocate a new target object.  OPS is the "prototype"
+   implementation of the new target; it is copied into the new object.
+   ALLOC is the number of bytes to allocate.  It may be larger than
+   sizeof (struct target_ops) if the target subclasses target_ops to
+   store extra data.  Returns the new target object.  Extra space
+   beyond the initial OPS component of the result is zeroed.  */
+
+extern struct target_ops *allocate_target (struct target_ops *ops,
+					   size_t alloc);
+
+/* A typed convenience wrapper for allocate_target.  T is the type of
+   the subclass of target_ops to allocate.  */
+
+#define TARGET_NEW(T, OPS) ((T *) (allocate_target ((OPS), sizeof (T))))
+
 extern void target_pre_inferior (int);
 
 extern void target_preopen (int);