Applied patch series for LD plugin interface (six parts).

[PATCH] Add infrastructure for plugin API; functionality to follow.

    include/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 1/6).
	* plugin-api.h (LDPT_GNU_LD_VERSION): New ld_plugin_tag enum member.

    ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 1/6).
	* configure.in: Add AC_CHECKs for file io and dlfcn headers and
	functions and AC_SEARCH for -ldl.
	(enable_plugins): New shell variable set if above tests find dlopen
	functionality.
	(ENABLE_PLUGINS): Add related automake conditional.
	* configure: Regenerate.
	* config.in: Likewise.
	* Makefile.am (PLUGIN_C): Declare plugin C source file, conditional
	on ENABLE_PLUGINS being defined.
	(PLUGIN_H): Likewise for header file.
	(PLUGIN_OBJECT): Likewise for object file.
	(PLUGIN_CFLAGS): Likewise -D flag required to compile plugin support.
	(AM_CPPFLAGS): Use PLUGIN_CFLAGS.
	(CFILES): Use PLUGIN_C.
	(HFILES): Use PLUGIN_H.
	(OFILES): Use PLUGIN_OBJECT.
	(ld_new_SOURCES): Use PLUGIN_C.
	(noinst_LTLIBRARIES)[ENABLE_PLUGINS]: Declare test plugin.
	(libldtestplug_la_SOURCES)[ENABLE_PLUGINS]: Add automake definition
	for test plugin.
	(libldtestplug_la_CFLAGS)[ENABLE_PLUGINS]: Likewise.
	(libldtestplug_la_LDFLAGS)[ENABLE_PLUGINS]: Likewise.
	* Makefile.in: Regenerate.
	* sysdep.h: Include stdarg.h, unistd.h and one of fcntl.h or
	sys/file.h where available.  Include dlfcn.h when ENABLE_PLUGINS.
	(O_RDONLY): Supply default definition likewise to bfd's sysdep.h
	(O_WRONLY): Likewise.
	(O_RDWR): Likewise.
	(O_ACCMODE): Likewise.
	(O_BINARY): Likewise.
	(SEEK_SET): Likewise.
	(SEEK_CUR): Likewise.
	(SEEK_END): Likewise.
	* ldmisc.c (vfinfo): Make non-static.  Add %p format char.
	* ldmisc.h (vfinfo): Declare extern prototype.
	* lexsup.c (enum option_values)[ENABLE_PLUGINS]: Add new entries for
	OPTION_PLUGIN and OPTION_PLUGIN_OPT.
	(ld_options[])[ENABLE_PLUGINS]: Add option data for the above two.
	(parse_args)[ENABLE_PLUGINS]: Handle them, and load all plugins once
	option parsing is complete.
	* ldmain.c (main)[ENABLE_PLUGINS]: Call plugin cleanup hooks just
	after lang_finish.
	* plugin.c: New source file.
	* plugin.h: Likewise new header.
	* testplug.c: New source file.

    ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 1/6).
	* ld-bootstrap/bootstrap.exp: Skip static tests also if LD plugins
	are enabled.
	* lib/ld-lib.exp (proc regexp_diff): Extend verbose debug output.
	(proc set_file_contents): Write a file with the supplied content.
	(run_ld_link_tests): Add new 'ld' action to test linker output.
	(proc check_plugin_api_available): Return true if linker under test
	supports the plugin API.
	* ld-plugin/func.c: New test source file.
	* ld-plugin/main.c: Likewise.
	* ld-plugin/text.c: Likewise.
	* ld-plugin/plugin-1.d: New dump test output pattern script.
	* ld-plugin/plugin-2.d: Likewise.
	* ld-plugin/plugin-3.d: Likewise.
	* ld-plugin/plugin-4.d: Likewise.
	* ld-plugin/plugin-5.d: Likewise.
	* ld-plugin/plugin.exp: New test control script.
---
[PATCH] Implement claim file and all symbols read hooks and add symbols callback.

  ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 2/6).
	* ldfile.c (ldfile_try_open_bfd)[ENABLE_PLUGINS]: Don't return early
	during compat checks if they pass, instead offer any successfully
	opened and accepted file to the plugin claim file hooks chain.  Create
	a dummy bfd to accept symbols added by the plugin, if the plugin
	claims the file.
	* ldlang.c (lang_process)[ENABLE_PLUGINS]: Call plugin all symbols
	read hook chain before ldemul_after_open.
	* ldlang.h (struct lang_input_statement_struct): Add new single-bit
	'claimed' flag.
	* plugin.c (IRONLY_SUFFIX): New macro for dummy bfd file suffix.
	(IRONLY_SUFFIX_LEN): Length of the above string.
	(plugin_get_ir_dummy_bfd): New function to create the dummy bfd used
	to store symbols for ir-only files.
	(is_ir_dummy_bfd): New function to check if a bfd is ir-only.
	(asymbol_from_plugin_symbol): New function converts symbol formats.
	(add_symbols): Call it to convert plugin syms to bfd syms and add
	them to the dummy bfd.
	* plugin.h: Add missing include guards.
	(plugin_get_ir_dummy_bfd): Add prototype.
	(is_ir_dummy_bfd): Likewise.
	* testplug.c (TV_MESSAGE): New helper macro.
	(struct claim_file): New struct.
	(claim_file_t): New typedef.
	(tag_names[]): Make static and const.
	(claimfiles_list): New variable.
	(claimfiles_tail_chain_ptr): Likewise.
	(last_claimfile): Likewise.
	(record_claim_file): Record a file to claim on a singly-linked list.
	(parse_symdefstr): Parse an ASCII representation of a symbol from a
	plugin option into the fields of a struct ld_plugin_symbol.
	(record_claimed_file_symbol):  Use it to parse plugin option for
	adding a symbol.
	(parse_option): Parse claim file and add symbol options.
	(dump_tv_tag): Use TV_MESSAGE.
	(onload): Likewise.
	(onclaim_file): Make static.  Use TV_MESSAGE.  Scan list of files to
	claim and claim this file if required, adding any symbols specified.
	(onall_symbols_read): Make static and use TV_MESSAGE.
	(oncleanup): Likewise.

  ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 2/6).
	* ld-plugin/plugin-3.d: Enable regexes for new functionality.
	* ld-plugin/plugin-5.d: Likewise.
	* ld-plugin/plugin-6.d: New testcase.
	* ld-plugin/plugin-7.d: Likewise.
	* ld-plugin/plugin.exp: Use 'nm' on compiled test objects to determine
	whether symbols in plugin arguments need an underscore prefix.  Add
	new plugin-6.d and plugin-7.d testcases.
---
[PATCH] Implement get symbols callback.

  ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 3/6).
	* ldmain.c (notice)[ENABLE_PLUGINS]: Call plugin_notice.
	* plugin.c (non_ironly_hash): Add new bfd hash table.
	(plugin_load_plugins): Exit early if no plugins to load.  If plugins
	do load successfully, set notice_all flag in link info.
	(get_symbols): Implement.
	(plugin_load_plugins): Exit early if no plugins to load, else after
	loading plugins successfully enable notice_all mode.
	(init_non_ironly_hash): Lazily init non_ironly_hash table.
	(plugin_notice): Record symbols referenced from non-IR files in the
	non_ironly_hash.  Suppress tracing, cref generation and nocrossrefs
	tracking for symbols from dummy IR bfds.
	* plugin.h: Fix formatting.
	(plugin_notice): Add prototype.
	* testplug.c (dumpresolutions): New global var.
	(parse_options): Accept "dumpresolutions".
	(onall_symbols_read): Get syms and dump resolutions if it was given.

  ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 3/6).
	* ld-plugin/plugin-8.d: New testcase.
	* ld-plugin/plugin.exp: Invoke it.
---
[PATCH] Implement add input file, add input lib and set extra lib path callbacks.

  ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 4/6).
	* ldlang.c (lang_process)[ENABLE_PLUGINS]: Move invocation of
	plugin_call_all_symbols_read to before setting of gc_sym_list, and
	open any new input files that may have been added during it.
	* ldmain.c (multiple_definition)[ENABLE_PLUGINS]: Call out to
	plugin_multiple_definition and let it have first say over what to do
	with the clashing definitions.
	* plugin.c (no_more_claiming): New boolean variable.
	(plugin_cached_allow_multiple_defs): Likewise.
	(add_input_file): Implement.
	(add_input_library): Likewise.
	(set_extra_library_path): Likewise.
	(plugin_call_claim_file): Don't do anything when no_more_claiming set.
	(plugin_call_all_symbols_read): Set it.  Disable link info
	"allow_multiple_definition" flag, but cache its value.
	(plugin_multiple_definition): New function.
	* plugin.h (plugin_multiple_definition): Add prototype.
	* testplug.c (addfile_enum_t): New enumerated typedef.
	(add_file_t): New struct typedef.
	(addfiles_list): New variable.
	(addfiles_tail_chain_ptr): Likewise.
	(record_add_file): New function.
	(parse_option): Parse "add:", "lib:" and "dir:" options and call it.
	(onall_symbols_read): Iterate the list of new files, libs and dirs,
	adding them.

  ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 4/6).
	* ld-plugin/plugin-9.d: New testcase.
	* ld-plugin/plugin.exp: Invoke it.
---
[PATCH] Add ELF symbol visibility support to plugin interface.

  ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 5/6).
	* plugin.c (asymbol_from_plugin_symbol): If the bfd is an ELF bfd,
	find the elf symbol data and set the visibility in the st_other field.

  ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 5/6).
	* ld-plugin/plugin-ignore.d: New dump test control script.
	* ld-plugin/plugin-vis-1.d: Likewise.
	* ld-plugin/plugin.exp: Add list of ELF-only tests and run them if
	testing on an ELF target.
---
[PATCH] Add archive support to plugin interface.

  bfd/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 6/6).
	* aoutx.h (aout_link_check_ar_symbols): Take new "subsbfd" reference
	parameter and pass it when invoking add_archive_element callback.
	(aout_link_check_archive_element): Handle substitute bfd if it
	was set during add_archive_element callback in the above.
	* cofflink.c (coff_link_check_ar_symbols): Take new "subsbfd" reference
	parameter and pass it when invoking add_archive_element callback.
	(coff_link_check_archive_element): Handle substitute bfd if it
	was set during add_archive_element callback in the above.
	* ecoff.c (read_ext_syms_and_strs): New function holds symbol-reading
	code factored-out from ecoff_link_check_archive_element.
	(reread_ext_syms_and_strs): Clear old symbols and call it.
	(ecoff_link_check_archive_element):  Use the above.  Handle substitute
	BFD if one is set by add_archive_element callback.
	(ecoff_link_add_archive_symbols): Likewise allow bfd substitution.
	* elflink.c (elf_link_add_archive_symbols): Likewise.
	* linker.c (generic_link_check_archive_element): Likewise.
	* pdp11.c (aout_link_check_ar_symbols): Take new "subsbfd" reference
	parameter and pass it when invoking add_archive_element callback.
	(aout_link_check_archive_element): Handle substitute bfd if it was
	set during add_archive_element callback in the above.
	* vms-alpha.c (alpha_vms_link_add_archive_symbols): Handle substitute
	BFD if one is set by add_archive_element callback.
	* xcofflink.c (xcoff_link_check_dynamic_ar_symbols): Take new "subsbfd"
	reference parameter and pass it when invoking add_archive_element
	callback.
	(xcoff_link_check_ar_symbols): Likewise.
	(xcoff_link_check_archive_element): Handle bfd substitution if it was
	set by callback in the above.

  include/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 6/6).
	* bfdlink.h (struct_bfd_link_callbacks): Document new argument
	to add_archive_element callback used to return a replacement bfd which
	is to be added to the hash table in place of the original element.

  ld/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 6/6).
	* ldlang.c (load_symbols): Handle bfd subsitution when calling the
	add_archive_element callback.
	* ldmain.c (add_archive_element)[ENABLE_PLUGINS]: Offer the archive
	member to the plugins and if claimed set "subsbfd" output parameter to
	point to the dummy IR-only BFD.

  ld/testsuite/ChangeLog:

2010-10-14  Dave Korn  <dave.korn.cygwin@gmail.com>

	Apply LD plugin patch series (part 6/6).
	* ld-plugin/plugin-10.d: New dump test control script.
	* ld-plugin/plugin-11.d: Likewise.
	* ld-plugin/plugin.exp: Run them.
---

1 files changed, 795 insertions, 0 deletions

diff --git a/ld/plugin.c b/ld/plugin.c
new file mode 100644
index 0000000..b484bd0
--- /dev/null
+++ b/ld/plugin.c
@@ -0,0 +1,795 @@
+/* Plugin control for the GNU linker.
+   Copyright 2010 Free Software Foundation, Inc.
+
+   This file is part of the GNU Binutils.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+   MA 02110-1301, USA.  */
+
+#include "sysdep.h"
+#include "libiberty.h"
+#include "bfd.h"
+#include "bfdlink.h"
+#include "bfdver.h"
+#include "ld.h"
+#include "ldmain.h"
+#include "ldmisc.h"
+#include "ldexp.h"
+#include "ldlang.h"
+#include "ldfile.h"
+#include "plugin.h"
+#include "plugin-api.h"
+#include "elf-bfd.h"
+
+/* The suffix to append to the name of the real (claimed) object file
+   when generating a dummy BFD to hold the IR symbols sent from the
+   plugin.  */
+#define IRONLY_SUFFIX		".ironly\004"
+
+/* This is sizeof an array of chars, not sizeof a const char *.  We
+   also have to avoid inadvertently counting the trailing NUL.  */
+#define IRONLY_SUFFIX_LEN	(sizeof (IRONLY_SUFFIX) - 1)
+
+/* Stores a single argument passed to a plugin.  */
+typedef struct plugin_arg
+{
+  struct plugin_arg *next;
+  const char *arg;
+} plugin_arg_t;
+
+/* Holds all details of a single plugin.  */
+typedef struct plugin
+{
+  /* Next on the list of plugins, or NULL at end of chain.  */
+  struct plugin *next;
+  /* The argument string given to --plugin.  */
+  const char *name;
+  /* The shared library handle returned by dlopen.  */
+  void *dlhandle;
+  /* The list of argument string given to --plugin-opt.  */
+  plugin_arg_t *args;
+  /* Number of args in the list, for convenience.  */
+  size_t n_args;
+  /* The plugin's event handlers.  */
+  ld_plugin_claim_file_handler claim_file_handler;
+  ld_plugin_all_symbols_read_handler all_symbols_read_handler;
+  ld_plugin_cleanup_handler cleanup_handler;
+  /* TRUE if the cleanup handlers have been called.  */
+  bfd_boolean cleanup_done;
+} plugin_t;
+
+/* The master list of all plugins.  */
+static plugin_t *plugins_list = NULL;
+
+/* We keep a tail pointer for easy linking on the end.  */
+static plugin_t **plugins_tail_chain_ptr = &plugins_list;
+
+/* The last plugin added to the list, for receiving args.  */
+static plugin_t *last_plugin = NULL;
+
+/* The tail of the arg chain of the last plugin added to the list.  */
+static plugin_arg_t **last_plugin_args_tail_chain_ptr = NULL;
+
+/* The plugin which is currently having a callback executed.  */
+static plugin_t *called_plugin = NULL;
+
+/* Last plugin to cause an error, if any.  */
+static const char *error_plugin = NULL;
+
+/* A hash table that records symbols referenced by non-IR files.  Used
+   at get_symbols time to determine whether any prevailing defs from
+   IR files are referenced only from other IR files, so tthat we can
+   we can distinguish the LDPR_PREVAILING_DEF and LDPR_PREVAILING_DEF_IRONLY
+   cases when establishing symbol resolutions.  */
+static struct bfd_hash_table *non_ironly_hash = NULL;
+
+/* Set at all symbols read time, to avoid recursively offering the plugin
+   its own newly-added input files and libs to claim.  */
+static bfd_boolean no_more_claiming = FALSE;
+
+/* If the --allow-multiple-definition command-line option is active, we
+   have to disable it so that BFD always calls our hook, and simulate the
+   effect (when not resolving IR vs. real symbols) ourselves by ensuring
+   TRUE is returned from the hook.  */
+static bfd_boolean plugin_cached_allow_multiple_defs = FALSE;
+
+/* List of tags to set in the constant leading part of the tv array. */
+static const enum ld_plugin_tag tv_header_tags[] =
+{
+  LDPT_MESSAGE,
+  LDPT_API_VERSION,
+  LDPT_GNU_LD_VERSION,
+  LDPT_LINKER_OUTPUT,
+  LDPT_OUTPUT_NAME,
+  LDPT_REGISTER_CLAIM_FILE_HOOK,
+  LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK,
+  LDPT_REGISTER_CLEANUP_HOOK,
+  LDPT_ADD_SYMBOLS,
+  LDPT_GET_INPUT_FILE,
+  LDPT_RELEASE_INPUT_FILE,
+  LDPT_GET_SYMBOLS,
+  LDPT_ADD_INPUT_FILE,
+  LDPT_ADD_INPUT_LIBRARY,
+  LDPT_SET_EXTRA_LIBRARY_PATH
+};
+
+/* How many entries in the constant leading part of the tv array.  */
+static const size_t tv_header_size = ARRAY_SIZE (tv_header_tags);
+
+/* Helper function for exiting with error status.  */
+static int
+set_plugin_error (const char *plugin)
+{
+  error_plugin = plugin;
+  return -1;
+}
+
+/* Test if an error occurred.  */
+static bfd_boolean
+plugin_error_p (void)
+{
+  return error_plugin != NULL;
+}
+
+/* Return name of plugin which caused an error if any.  */
+const char *plugin_error_plugin (void)
+{
+  return error_plugin ? error_plugin : _("<no plugin>");
+}
+
+/* Handle -plugin arg: find and load plugin, or return error.  */
+int plugin_opt_plugin (const char *plugin)
+{
+  plugin_t *newplug;
+
+  newplug = xmalloc (sizeof *newplug);
+  memset (newplug, 0, sizeof *newplug);
+  newplug->name = plugin;
+  newplug->dlhandle = dlopen (plugin, RTLD_NOW);
+  if (!newplug->dlhandle)
+    return set_plugin_error (plugin);
+
+  /* Chain on end, so when we run list it is in command-line order.  */
+  *plugins_tail_chain_ptr = newplug;
+  plugins_tail_chain_ptr = &newplug->next;
+
+  /* Record it as current plugin for receiving args.  */
+  last_plugin = newplug;
+  last_plugin_args_tail_chain_ptr = &newplug->args;
+  return 0;
+}
+
+/* Accumulate option arguments for last-loaded plugin, or return
+   error if none.  */
+int plugin_opt_plugin_arg (const char *arg)
+{
+  plugin_arg_t *newarg;
+
+  if (!last_plugin)
+    return set_plugin_error (_("<no plugin>"));
+
+  newarg = xmalloc (sizeof *newarg);
+  newarg->arg = arg;
+  newarg->next = NULL;
+
+  /* Chain on end to preserve command-line order.  */
+  *last_plugin_args_tail_chain_ptr = newarg;
+  last_plugin_args_tail_chain_ptr = &newarg->next;
+  last_plugin->n_args++;
+  return 0;
+}
+
+/* Create a dummy BFD.  */
+bfd *
+plugin_get_ir_dummy_bfd (const char *name, bfd *srctemplate)
+{
+  asection *sec;
+  bfd *abfd = bfd_create (
+		concat (name, IRONLY_SUFFIX, (const char *)NULL),
+		srctemplate);
+  bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate));
+  bfd_make_writable (abfd);
+  /* Create a minimal set of sections to own the symbols.  */
+  sec = bfd_make_section_old_way (abfd, ".text");
+  bfd_set_section_flags (abfd, sec,
+	SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY
+	| SEC_ALLOC | SEC_LOAD | SEC_KEEP);
+  sec->output_section = sec;
+  sec->output_offset = 0;
+  return abfd;
+}
+
+/* Check if the BFD is an IR dummy.  */
+bfd_boolean
+is_ir_dummy_bfd (const bfd *abfd)
+{
+  size_t namlen = strlen (abfd->filename);
+  if (namlen < IRONLY_SUFFIX_LEN)
+    return FALSE;
+  return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX);
+}
+
+/* Helpers to convert between BFD and GOLD symbol formats.  */
+static enum ld_plugin_status
+asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym,
+				const struct ld_plugin_symbol *ldsym)
+{
+  flagword flags = BSF_NO_FLAGS;
+  struct bfd_section *section;
+
+  asym->the_bfd = abfd;
+  asym->name = ldsym->version
+		? concat (ldsym->name, "@", ldsym->version, NULL)
+		: ldsym->name;
+  asym->value = 0;
+  switch (ldsym->def)
+    {
+    case LDPK_WEAKDEF:
+      flags = BSF_WEAK;
+      /* FALLTHRU */
+    case LDPK_DEF:
+      flags |= BSF_GLOBAL;
+      section = bfd_get_section_by_name (abfd, ".text");
+      break;
+
+    case LDPK_WEAKUNDEF:
+      flags = BSF_WEAK;
+      /* FALLTHRU */
+    case LDPK_UNDEF:
+      section = bfd_und_section_ptr;
+      break;
+
+    case LDPK_COMMON:
+      flags = BSF_GLOBAL;
+      section = bfd_com_section_ptr;
+      asym->value = ldsym->size;
+      break;
+
+    default:
+      return LDPS_ERR;
+    }
+  asym->flags = flags;
+  asym->section = section;
+
+  /* Visibility only applies on ELF targets.  */
+  if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
+    {
+      elf_symbol_type *elfsym = elf_symbol_from (abfd, asym);
+      if (!elfsym)
+	einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!"), asym->name);
+      elfsym->internal_elf_sym.st_other &= ~3;
+      elfsym->internal_elf_sym.st_other |= ldsym->visibility;
+    }
+
+  return LDPS_OK;
+}
+
+/* Register a claim-file handler.  */
+static enum ld_plugin_status
+register_claim_file (ld_plugin_claim_file_handler handler)
+{
+  ASSERT (called_plugin);
+  called_plugin->claim_file_handler = handler;
+  return LDPS_OK;
+}
+
+/* Register an all-symbols-read handler.  */
+static enum ld_plugin_status
+register_all_symbols_read (ld_plugin_all_symbols_read_handler handler)
+{
+  ASSERT (called_plugin);
+  called_plugin->all_symbols_read_handler = handler;
+  return LDPS_OK;
+}
+
+/* Register a cleanup handler.  */
+static enum ld_plugin_status
+register_cleanup (ld_plugin_cleanup_handler handler)
+{
+  ASSERT (called_plugin);
+  called_plugin->cleanup_handler = handler;
+  return LDPS_OK;
+}
+
+/* Add symbols from a plugin-claimed input file.  */
+static enum ld_plugin_status
+add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms)
+{
+  asymbol **symptrs;
+  bfd *abfd = handle;
+  int n;
+  ASSERT (called_plugin);
+  symptrs = xmalloc (nsyms * sizeof *symptrs);
+  for (n = 0; n < nsyms; n++)
+    {
+      enum ld_plugin_status rv;
+      asymbol *bfdsym = bfd_make_empty_symbol (abfd);
+      symptrs[n] = bfdsym;
+      rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n);
+      if (rv != LDPS_OK)
+	return rv;
+    }
+  bfd_set_symtab (abfd, symptrs, nsyms);
+  return LDPS_OK;
+}
+
+/* Get the input file information with an open (possibly re-opened)
+   file descriptor.  */
+static enum ld_plugin_status
+get_input_file (const void *handle, struct ld_plugin_input_file *file)
+{
+  ASSERT (called_plugin);
+  handle = handle;
+  file = file;
+  return LDPS_ERR;
+}
+
+/* Release the input file.  */
+static enum ld_plugin_status
+release_input_file (const void *handle)
+{
+  ASSERT (called_plugin);
+  handle = handle;
+  return LDPS_ERR;
+}
+
+/* Get the symbol resolution info for a plugin-claimed input file.  */
+static enum ld_plugin_status
+get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms)
+{
+  const bfd *abfd = handle;
+  int n;
+  ASSERT (called_plugin);
+  for (n = 0; n < nsyms; n++)
+    {
+      struct bfd_link_hash_entry *blhe;
+      bfd_boolean ironly;
+
+      blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name,
+				FALSE, FALSE, TRUE);
+      if (!blhe)
+	{
+	  syms[n].resolution = LDPR_UNKNOWN;
+	  continue;
+	}
+
+      /* Determine resolution from blhe type and symbol's original type.  */
+      if (blhe->type == bfd_link_hash_undefined
+		|| blhe->type == bfd_link_hash_undefweak)
+	{
+	  syms[n].resolution = LDPR_UNDEF;
+	  continue;
+	}
+      if (blhe->type != bfd_link_hash_defined
+		&& blhe->type != bfd_link_hash_defweak
+		&& blhe->type != bfd_link_hash_common)
+	{
+	  /* We should not have a new, indirect or warning symbol here.  */
+	  einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)",
+		called_plugin->name, blhe->type);
+	}
+
+      /* We need to know if the sym is referenced from non-IR files.  */
+      ironly = !bfd_hash_lookup (non_ironly_hash, syms[n].name, FALSE, FALSE);
+
+      /* If it was originally undefined or common, then it has been
+         resolved; determine how.  */
+      if (syms[n].def == LDPK_UNDEF || syms[n].def == LDPK_WEAKUNDEF
+	  || syms[n].def == LDPK_COMMON)
+	{
+	  asection *owner_sec = (syms[n].def == LDPK_COMMON)
+				? blhe->u.c.p->section
+				: blhe->u.def.section;
+	  if (owner_sec->owner == link_info.output_bfd)
+	    syms[n].resolution = LDPR_RESOLVED_EXEC;
+	  else if (owner_sec->owner == abfd)
+	    syms[n].resolution = (ironly)
+				? LDPR_PREVAILING_DEF_IRONLY
+				: LDPR_PREVAILING_DEF;
+	  else if (is_ir_dummy_bfd (owner_sec->owner))
+	    syms[n].resolution = LDPR_RESOLVED_IR;
+	  else if (owner_sec->owner->flags & DYNAMIC)
+	    syms[n].resolution =  LDPR_RESOLVED_DYN;
+	  else
+	    syms[n].resolution = LDPR_RESOLVED_EXEC;
+	  continue;
+	}
+
+      /* Was originally def, or weakdef.  Does it prevail?  If the
+         owner is the original dummy bfd that supplied it, then this
+	 is the definition that has prevailed.  */
+      if (blhe->u.def.section->owner == link_info.output_bfd)
+	syms[n].resolution = LDPR_PREEMPTED_REG;
+      else if (blhe->u.def.section->owner == abfd)
+	{
+	  syms[n].resolution = (ironly)
+				? LDPR_PREVAILING_DEF_IRONLY
+				: LDPR_PREVAILING_DEF;
+	  continue;
+	}
+
+      /* Was originally def, weakdef, or common, but has been pre-empted.  */
+      syms[n].resolution = is_ir_dummy_bfd (blhe->u.def.section->owner)
+				? LDPR_PREEMPTED_IR
+				: LDPR_PREEMPTED_REG;
+    }
+  return LDPS_OK;
+}
+
+/* Add a new (real) input file generated by a plugin.  */
+static enum ld_plugin_status
+add_input_file (const char *pathname)
+{
+  ASSERT (called_plugin);
+  if (!lang_add_input_file (pathname, lang_input_file_is_file_enum, NULL))
+    return LDPS_ERR;
+  return LDPS_OK;
+}
+
+/* Add a new (real) library required by a plugin.  */
+static enum ld_plugin_status
+add_input_library (const char *pathname)
+{
+  ASSERT (called_plugin);
+  if (!lang_add_input_file (pathname, lang_input_file_is_l_enum, NULL))
+    return LDPS_ERR;
+  return LDPS_OK;
+}
+
+/* Set the extra library path to be used by libraries added via
+   add_input_library.  */
+static enum ld_plugin_status
+set_extra_library_path (const char *path)
+{
+  ASSERT (called_plugin);
+  ldfile_add_library_path (path, FALSE);
+  return LDPS_OK;
+}
+
+/* Issue a diagnostic message from a plugin.  */
+static enum ld_plugin_status
+message (int level, const char *format, ...)
+{
+  va_list args;
+  va_start (args, format);
+
+  switch (level)
+    {
+    case LDPL_INFO:
+      vfinfo (stdout, format, args, FALSE);
+      break;
+    case LDPL_WARNING:
+      vfinfo (stdout, format, args, TRUE);
+      break;
+    case LDPL_FATAL:
+    case LDPL_ERROR:
+    default:
+      {
+	char *newfmt = ACONCAT ((level == LDPL_FATAL ? "%F" : "%X",
+				format, NULL));
+	vfinfo (stderr, newfmt, args, TRUE);
+      }
+      break;
+    }
+
+  va_end (args);
+  return LDPS_OK;
+}
+
+/* Helper to size leading part of tv array and set it up. */
+static size_t
+set_tv_header (struct ld_plugin_tv *tv)
+{
+  size_t i;
+
+  /* Version info.  */
+  static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL);
+  static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100;
+
+  if (!tv)
+    return tv_header_size;
+
+  for (i = 0; i < tv_header_size; i++)
+    {
+      tv[i].tv_tag = tv_header_tags[i];
+#define TVU(x) tv[i].tv_u.tv_ ## x
+      switch (tv[i].tv_tag)
+	{
+	  case LDPT_MESSAGE:
+	    TVU(message) = message;
+	    break;
+	  case LDPT_API_VERSION:
+	    TVU(val) = LD_PLUGIN_API_VERSION;
+	    break;
+	  case LDPT_GNU_LD_VERSION:
+	    TVU(val) = major * 100 + minor;
+	    break;
+	  case LDPT_LINKER_OUTPUT:
+	    TVU(val) = link_info.relocatable ? LDPO_REL
+			: (link_info.shared ? LDPO_DYN : LDPO_EXEC);
+	    break;
+	  case LDPT_OUTPUT_NAME:
+	    TVU(string) = output_filename;
+	    break;
+	  case LDPT_REGISTER_CLAIM_FILE_HOOK:
+	    TVU(register_claim_file) = register_claim_file;
+	    break;
+	  case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
+	    TVU(register_all_symbols_read) = register_all_symbols_read;
+	    break;
+	  case LDPT_REGISTER_CLEANUP_HOOK:
+	    TVU(register_cleanup) = register_cleanup;
+	    break;
+	  case LDPT_ADD_SYMBOLS:
+	    TVU(add_symbols) = add_symbols;
+	    break;
+	  case LDPT_GET_INPUT_FILE:
+	    TVU(get_input_file) = get_input_file;
+	    break;
+	  case LDPT_RELEASE_INPUT_FILE:
+	    TVU(release_input_file) = release_input_file;
+	    break;
+	  case LDPT_GET_SYMBOLS:
+	    TVU(get_symbols) = get_symbols;
+	    break;
+	  case LDPT_ADD_INPUT_FILE:
+	    TVU(add_input_file) = add_input_file;
+	    break;
+	  case LDPT_ADD_INPUT_LIBRARY:
+	    TVU(add_input_library) = add_input_library;
+	    break;
+	  case LDPT_SET_EXTRA_LIBRARY_PATH:
+	    TVU(set_extra_library_path) = set_extra_library_path;
+	    break;
+	  default:
+	    /* Added a new entry to the array without adding
+	       a new case to set up its value is a bug.  */
+	    FAIL ();
+	}
+#undef TVU
+    }
+  return tv_header_size;
+}
+
+/* Append the per-plugin args list and trailing LDPT_NULL to tv.  */
+static void
+set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv)
+{
+  plugin_arg_t *arg = plugin->args;
+  while (arg)
+    {
+      tv->tv_tag = LDPT_OPTION;
+      tv->tv_u.tv_string = arg->arg;
+      arg = arg->next;
+      tv++;
+    }
+  tv->tv_tag = LDPT_NULL;
+  tv->tv_u.tv_val = 0;
+}
+
+/* Load up and initialise all plugins after argument parsing.  */
+int plugin_load_plugins (void)
+{
+  struct ld_plugin_tv *my_tv;
+  unsigned int max_args = 0;
+  plugin_t *curplug = plugins_list;
+
+  /* If there are no plugins, we need do nothing this run.  */
+  if (!curplug)
+    return 0;
+
+  /* First pass over plugins to find max # args needed so that we
+     can size and allocate the tv array.  */
+  while (curplug)
+    {
+      if (curplug->n_args > max_args)
+	max_args = curplug->n_args;
+      curplug = curplug->next;
+    }
+
+  /* Allocate tv array and initialise constant part.  */
+  my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv);
+  set_tv_header (my_tv);
+
+  /* Pass over plugins again, activating them.  */
+  curplug = plugins_list;
+  while (curplug)
+    {
+      enum ld_plugin_status rv;
+      ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload");
+      if (!onloadfn)
+	onloadfn = dlsym (curplug->dlhandle, "_onload");
+      if (!onloadfn)
+        return set_plugin_error (curplug->name);
+      set_tv_plugin_args (curplug, &my_tv[tv_header_size]);
+      called_plugin = curplug;
+      rv = (*onloadfn) (my_tv);
+      called_plugin = NULL;
+      if (rv != LDPS_OK)
+        return set_plugin_error (curplug->name);
+      curplug = curplug->next;
+    }
+
+  /* Since plugin(s) inited ok, assume they're going to want symbol
+     resolutions, which needs us to track which symbols are referenced
+     by non-IR files using the linker's notice callback.  */
+  link_info.notice_all = TRUE;
+
+  return 0;
+}
+
+/* Call 'claim file' hook for all plugins.  */
+int
+plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed)
+{
+  plugin_t *curplug = plugins_list;
+  *claimed = FALSE;
+  if (no_more_claiming)
+    return 0;
+  while (curplug && !*claimed)
+    {
+      if (curplug->claim_file_handler)
+	{
+	  enum ld_plugin_status rv;
+	  called_plugin = curplug;
+	  rv = (*curplug->claim_file_handler) (file, claimed);
+	  called_plugin = NULL;
+	  if (rv != LDPS_OK)
+	    set_plugin_error (curplug->name);
+	}
+      curplug = curplug->next;
+    }
+  return plugin_error_p () ? -1 : 0;
+}
+
+/* Call 'all symbols read' hook for all plugins.  */
+int
+plugin_call_all_symbols_read (void)
+{
+  plugin_t *curplug = plugins_list;
+
+  /* Disable any further file-claiming.  */
+  no_more_claiming = TRUE;
+
+  /* If --allow-multiple-definition is in effect, we need to disable it,
+     as the plugin infrastructure relies on the multiple_definition
+     callback to swap out the dummy IR-only BFDs for new real ones
+     when it starts opening the files added during this callback.  */
+  plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition;
+  link_info.allow_multiple_definition = FALSE;
+
+  while (curplug)
+    {
+      if (curplug->all_symbols_read_handler)
+	{
+	  enum ld_plugin_status rv;
+	  called_plugin = curplug;
+	  rv = (*curplug->all_symbols_read_handler) ();
+	  called_plugin = NULL;
+	  if (rv != LDPS_OK)
+	    set_plugin_error (curplug->name);
+	}
+      curplug = curplug->next;
+    }
+  return plugin_error_p () ? -1 : 0;
+}
+
+/* Call 'cleanup' hook for all plugins.  */
+int
+plugin_call_cleanup (void)
+{
+  plugin_t *curplug = plugins_list;
+  while (curplug)
+    {
+      if (curplug->cleanup_handler && !curplug->cleanup_done)
+	{
+	  enum ld_plugin_status rv;
+	  curplug->cleanup_done = TRUE;
+	  called_plugin = curplug;
+	  rv = (*curplug->cleanup_handler) ();
+	  called_plugin = NULL;
+	  if (rv != LDPS_OK)
+	    set_plugin_error (curplug->name);
+	  dlclose (curplug->dlhandle);
+	}
+      curplug = curplug->next;
+    }
+  return plugin_error_p () ? -1 : 0;
+}
+
+/* Lazily init the non_ironly hash table.  */
+static void
+init_non_ironly_hash (void)
+{
+  if (non_ironly_hash == NULL)
+    {
+      non_ironly_hash =
+          (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table));
+      if (!bfd_hash_table_init_n (non_ironly_hash,
+				  bfd_hash_newfunc,
+				  sizeof (struct bfd_hash_entry),
+				  61))
+	einfo (_("%P%F: bfd_hash_table_init failed: %E\n"));
+    }
+}
+
+/* To determine which symbols should be resolved LDPR_PREVAILING_DEF
+   and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as
+   the linker adds them to the linker hash table.  If we see a symbol
+   being referenced from a non-IR file, we add it to the non_ironly hash
+   table.  If we can't find it there at get_symbols time, we know that
+   it was referenced only by IR files.  We have to notice_all symbols,
+   because we won't necessarily know until later which ones will be
+   contributed by IR files.  */
+bfd_boolean
+plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED,
+		const char *name, bfd *abfd,
+		asection *section, bfd_vma value ATTRIBUTE_UNUSED)
+{
+  bfd_boolean is_ref = bfd_is_und_section (section);
+  bfd_boolean is_dummy = is_ir_dummy_bfd (abfd);
+  init_non_ironly_hash ();
+  /* We only care about refs, not defs, indicated by section pointing
+     to the undefined section (according to the bfd linker notice callback
+     interface definition).  */
+  if (is_ref && !is_dummy)
+    {
+      /* This is a ref from a non-IR file, so note the ref'd symbol
+         in the non-IR-only hash.  */
+      if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE))
+        einfo (_("%P%X: %s: hash table failure adding symbol %s"),
+		abfd->filename, name);
+    }
+  else if (!is_ref && is_dummy)
+    {
+      /* No further processing since this is a def from an IR dummy BFD.  */
+      return FALSE;
+    }
+
+  /* Continue with cref/nocrossref/trace-sym processing.  */
+  return TRUE;
+}
+
+/* When we add new object files to the link at all symbols read time,
+   these contain the real code and symbols generated from the IR files,
+   and so duplicate all the definitions already supplied by the dummy
+   IR-only BFDs that we created at claim files time.  We use the linker's
+   multiple-definitions callback hook to fix up the clash, discarding
+   the symbol from the IR-only BFD in favour of the symbol from the
+   real BFD.  We return true if this was not-really-a-clash because
+   we've fixed it up, or anyway if --allow-multiple-definition was in
+   effect (before we disabled it to ensure we got called back).  */
+bfd_boolean
+plugin_multiple_definition (struct bfd_link_info *info, const char *name,
+		bfd *obfd, asection *osec ATTRIBUTE_UNUSED,
+		bfd_vma oval ATTRIBUTE_UNUSED,
+		bfd *nbfd, asection *nsec, bfd_vma nval)
+{
+  if (is_ir_dummy_bfd (obfd))
+    {
+      struct bfd_link_hash_entry *blhe = bfd_link_hash_lookup (info->hash,
+					name, FALSE, FALSE, FALSE);
+      if (!blhe)
+	einfo (_("%P%X: %s: can't find IR symbol '%s'"), nbfd->filename,
+		name);
+      else if (blhe->type != bfd_link_hash_defined)
+	einfo (_("%P%x: %s: bad IR symbol type %d"), name, blhe->type);
+      /* Replace it with new details.  */
+      blhe->u.def.section = nsec;
+      blhe->u.def.value = nval;
+      return TRUE;
+    }
+  return plugin_cached_allow_multiple_defs;
+}