ld/testplug.c

/* Test plugin for the GNU linker.
   Copyright (C) 2010-2021 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 "bfd.h"
#if BFD_SUPPORTS_PLUGINS
#include "plugin-api.h"
/* For ARRAY_SIZE macro only - we don't link the library itself.  */
#include "libiberty.h"

#include <ctype.h> /* For isdigit.  */

extern enum ld_plugin_status onload (struct ld_plugin_tv *tv);
static enum ld_plugin_status onclaim_file (const struct ld_plugin_input_file *file,
				int *claimed);
static enum ld_plugin_status onall_symbols_read (void);
static enum ld_plugin_status oncleanup (void);

/* Helper for calling plugin api message function.  */
#define TV_MESSAGE if (tv_message) (*tv_message)

/* Struct for recording files to claim / files claimed.  */
typedef struct claim_file
{
  struct claim_file *next;
  struct ld_plugin_input_file file;
  bool claimed;
  struct ld_plugin_symbol *symbols;
  int n_syms_allocated;
  int n_syms_used;
} claim_file_t;

/* Types of things that can be added at all symbols read time.  */
typedef enum addfile_enum
{
  ADD_FILE,
  ADD_LIB,
  ADD_DIR
} addfile_enum_t;

/* Struct for recording files to add to final link.  */
typedef struct add_file
{
  struct add_file *next;
  const char *name;
  addfile_enum_t type;
} add_file_t;

/* Helper macro for defining array of transfer vector tags and names.  */
#define ADDENTRY(tag) { tag, #tag }

/* Struct for looking up human-readable versions of tag names.  */
typedef struct tag_name
{
  enum ld_plugin_tag tag;
  const char *name;
} tag_name_t;

/* Array of all known tags and their names.  */
static const tag_name_t tag_names[] =
{
  ADDENTRY(LDPT_NULL),
  ADDENTRY(LDPT_API_VERSION),
  ADDENTRY(LDPT_GOLD_VERSION),
  ADDENTRY(LDPT_LINKER_OUTPUT),
  ADDENTRY(LDPT_OPTION),
  ADDENTRY(LDPT_REGISTER_CLAIM_FILE_HOOK),
  ADDENTRY(LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK),
  ADDENTRY(LDPT_REGISTER_CLEANUP_HOOK),
  ADDENTRY(LDPT_ADD_SYMBOLS),
  ADDENTRY(LDPT_GET_SYMBOLS),
  ADDENTRY(LDPT_GET_SYMBOLS_V2),
  ADDENTRY(LDPT_ADD_INPUT_FILE),
  ADDENTRY(LDPT_MESSAGE),
  ADDENTRY(LDPT_GET_INPUT_FILE),
  ADDENTRY(LDPT_GET_VIEW),
  ADDENTRY(LDPT_RELEASE_INPUT_FILE),
  ADDENTRY(LDPT_ADD_INPUT_LIBRARY),
  ADDENTRY(LDPT_OUTPUT_NAME),
  ADDENTRY(LDPT_SET_EXTRA_LIBRARY_PATH),
  ADDENTRY(LDPT_GNU_LD_VERSION)
};

/* Function pointers to cache hooks passed at onload time.  */
static ld_plugin_register_claim_file tv_register_claim_file = 0;
static ld_plugin_register_all_symbols_read tv_register_all_symbols_read = 0;
static ld_plugin_register_cleanup tv_register_cleanup = 0;
static ld_plugin_add_symbols tv_add_symbols = 0;
static ld_plugin_get_symbols tv_get_symbols = 0;
static ld_plugin_get_symbols tv_get_symbols_v2 = 0;
static ld_plugin_add_input_file tv_add_input_file = 0;
static ld_plugin_message tv_message = 0;
static ld_plugin_get_input_file tv_get_input_file = 0;
static ld_plugin_get_view tv_get_view = 0;
static ld_plugin_release_input_file tv_release_input_file = 0;
static ld_plugin_add_input_library tv_add_input_library = 0;
static ld_plugin_set_extra_library_path tv_set_extra_library_path = 0;

/* Other cached info from the transfer vector.  */
static enum ld_plugin_output_file_type linker_output;
static const char *output_name;

/* Behaviour control flags set by plugin options.  */
static enum ld_plugin_status onload_ret = LDPS_OK;
static enum ld_plugin_status claim_file_ret = LDPS_OK;
static enum ld_plugin_status all_symbols_read_ret = LDPS_OK;
static enum ld_plugin_status cleanup_ret = LDPS_OK;
static bool register_claimfile_hook = false;
static bool register_allsymbolsread_hook = false;
static bool register_cleanup_hook = false;
static bool dumpresolutions = false;

/* The master list of all claimable/claimed files.  */
static claim_file_t *claimfiles_list = NULL;

/* We keep a tail pointer for easy linking on the end.  */
static claim_file_t **claimfiles_tail_chain_ptr = &claimfiles_list;

/* The last claimed file added to the list, for receiving syms.  */
static claim_file_t *last_claimfile = NULL;

/* The master list of all files to add to the final link.  */
static add_file_t *addfiles_list = NULL;

/* We keep a tail pointer for easy linking on the end.  */
static add_file_t **addfiles_tail_chain_ptr = &addfiles_list;

/* Number of bytes read in claim file before deciding if the file can be
   claimed.  */
static int bytes_to_read_before_claim = 0;

/* Add a new claimfile on the end of the chain.  */
static enum ld_plugin_status
record_claim_file (const char *file)
{
  claim_file_t *newfile;

  newfile = malloc (sizeof *newfile);
  if (!newfile)
    return LDPS_ERR;
  memset (newfile, 0, sizeof *newfile);
  /* Only setup for now is remembering the name to look for.  */
  newfile->file.name = file;
  /* Chain it on the end of the list.  */
  *claimfiles_tail_chain_ptr = newfile;
  claimfiles_tail_chain_ptr = &newfile->next;
  /* Record it as active for receiving symbols to register.  */
  last_claimfile = newfile;
  return LDPS_OK;
}

/* How many bytes to read before claiming (or not) an input file.  */
static enum ld_plugin_status
record_read_length (const char *length)
{
  const char *tmp;

  tmp = length;
  while (*tmp != '\0' && isdigit (*tmp))
    ++tmp;
  if (*tmp != '\0' || *length == '\0')
    return LDPS_ERR;

  bytes_to_read_before_claim = atoi (length);
  return LDPS_OK;
}

/* Add a new addfile on the end of the chain.  */
static enum ld_plugin_status
record_add_file (const char *file, addfile_enum_t type)
{
  add_file_t *newfile;

  newfile = malloc (sizeof *newfile);
  if (!newfile)
    return LDPS_ERR;
  newfile->next = NULL;
  newfile->name = file;
  newfile->type = type;
  /* Chain it on the end of the list.  */
  *addfiles_tail_chain_ptr = newfile;
  addfiles_tail_chain_ptr = &newfile->next;
  return LDPS_OK;
}

/* Parse a command-line argument string into a symbol definition.
   Symbol-strings follow the colon-separated format:
	NAME:VERSION:def:vis:size:COMDATKEY
   where the fields in capitals are strings and those in lower
   case are integers.  We don't allow to specify a resolution as
   doing so is not meaningful when calling the add symbols hook.  */
static enum ld_plugin_status
parse_symdefstr (const char *str, struct ld_plugin_symbol *sym)
{
  int n;
  long long size;
  const char *colon1, *colon2, *colon5;

  /* Locate the colons separating the first two strings.  */
  colon1 = strchr (str, ':');
  if (!colon1)
    return LDPS_ERR;
  colon2 = strchr (colon1+1, ':');
  if (!colon2)
    return LDPS_ERR;
  /* Name must not be empty (version may be).  */
  if (colon1 == str)
    return LDPS_ERR;

  /* The fifth colon and trailing comdat key string are optional,
     but the intermediate ones must all be present.  */
  colon5 = strchr (colon2+1, ':');	/* Actually only third so far.  */
  if (!colon5)
    return LDPS_ERR;
  colon5 = strchr (colon5+1, ':');	/* Hopefully fourth now.  */
  if (!colon5)
    return LDPS_ERR;
  colon5 = strchr (colon5+1, ':');	/* Optional fifth now.  */

  /* Finally we'll use sscanf to parse the numeric fields, then
     we'll split out the strings which we need to allocate separate
     storage for anyway so that we can add nul termination.  */
  n = sscanf (colon2 + 1, "%hhi:%i:%lli", &sym->def, &sym->visibility, &size);
  if (n != 3)
    return LDPS_ERR;

  /* Parsed successfully, so allocate strings and fill out fields.  */
  sym->size = size;
  sym->unused = 0;
  sym->section_kind = 0;
  sym->symbol_type = 0;
  sym->resolution = LDPR_UNKNOWN;
  sym->name = malloc (colon1 - str + 1);
  if (!sym->name)
    return LDPS_ERR;
  memcpy (sym->name, str, colon1 - str);
  sym->name[colon1 - str] = '\0';
  if (colon2 > (colon1 + 1))
    {
      sym->version = malloc (colon2 - colon1);
      if (!sym->version)
	return LDPS_ERR;
      memcpy (sym->version, colon1 + 1, colon2 - (colon1 + 1));
      sym->version[colon2 - (colon1 + 1)] = '\0';
    }
  else
    sym->version = NULL;
  if (colon5 && colon5[1])
    {
      sym->comdat_key = malloc (strlen (colon5 + 1) + 1);
      if (!sym->comdat_key)
	return LDPS_ERR;
      strcpy (sym->comdat_key, colon5 + 1);
    }
  else
    sym->comdat_key = 0;
  return LDPS_OK;
}

/* Record a symbol to be added for the last-added claimfile.  */
static enum ld_plugin_status
record_claimed_file_symbol (const char *symdefstr)
{
  struct ld_plugin_symbol sym;

  /* Can't add symbols except as belonging to claimed files.  */
  if (!last_claimfile)
    return LDPS_ERR;

  /* If string doesn't parse correctly, give an error.  */
  if (parse_symdefstr (symdefstr, &sym) != LDPS_OK)
    return LDPS_ERR;

  /* Check for enough space, resize array if needed, and add it.  */
  if (last_claimfile->n_syms_allocated == last_claimfile->n_syms_used)
    {
      int new_n_syms = last_claimfile->n_syms_allocated
			? 2 * last_claimfile->n_syms_allocated
			: 10;
      last_claimfile->symbols = realloc (last_claimfile->symbols,
			new_n_syms * sizeof *last_claimfile->symbols);
      if (!last_claimfile->symbols)
	return LDPS_ERR;
      last_claimfile->n_syms_allocated = new_n_syms;
    }
  last_claimfile->symbols[last_claimfile->n_syms_used++] = sym;

  return LDPS_OK;
}

/* Records the status to return from one of the registered hooks.  */
static enum ld_plugin_status
set_ret_val (const char *whichval, enum ld_plugin_status retval)
{
  if (!strcmp ("onload", whichval))
    onload_ret = retval;
  else if (!strcmp ("claimfile", whichval))
    claim_file_ret = retval;
  else if (!strcmp ("allsymbolsread", whichval))
    all_symbols_read_ret = retval;
  else if (!strcmp ("cleanup", whichval))
    cleanup_ret = retval;
  else
    return LDPS_ERR;
  return LDPS_OK;
}

/* Records hooks which should be registered.  */
static enum ld_plugin_status
set_register_hook (const char *whichhook, bool yesno)
{
  if (!strcmp ("claimfile", whichhook))
    register_claimfile_hook = yesno;
  else if (!strcmp ("allsymbolsread", whichhook))
    register_allsymbolsread_hook = yesno;
  else if (!strcmp ("cleanup", whichhook))
    register_cleanup_hook = yesno;
  else
    return LDPS_ERR;
  return LDPS_OK;
}

/* Determine type of plugin option and pass to individual parsers.  */
static enum ld_plugin_status
parse_option (const char *opt)
{
  if (!strncmp ("fail", opt, 4))
    return set_ret_val (opt + 4, LDPS_ERR);
  else if (!strncmp ("pass", opt, 4))
    return set_ret_val (opt + 4, LDPS_OK);
  else if (!strncmp ("register", opt, 8))
    return set_register_hook (opt + 8, true);
  else if (!strncmp ("noregister", opt, 10))
    return set_register_hook (opt + 10, false);
  else if (!strncmp ("claim:", opt, 6))
    return record_claim_file (opt + 6);
  else if (!strncmp ("read:", opt, 5))
    return record_read_length (opt + 5);
  else if (!strncmp ("sym:", opt, 4))
    return record_claimed_file_symbol (opt + 4);
  else if (!strncmp ("add:", opt, 4))
    return record_add_file (opt + 4, ADD_FILE);
  else if (!strncmp ("lib:", opt, 4))
    return record_add_file (opt + 4, ADD_LIB);
  else if (!strncmp ("dir:", opt, 4))
    return record_add_file (opt + 4, ADD_DIR);
  else if (!strcmp ("dumpresolutions", opt))
    dumpresolutions = true;
  else
    return LDPS_ERR;
  return LDPS_OK;
}

/* Output contents of transfer vector array entry in human-readable form.  */
static void
dump_tv_tag (size_t n, struct ld_plugin_tv *tv)
{
  size_t tag;
  char unknownbuf[40];
  const char *name;

  for (tag = 0; tag < ARRAY_SIZE (tag_names); tag++)
    if (tag_names[tag].tag == tv->tv_tag)
      break;
  sprintf (unknownbuf, "unknown tag #%d", tv->tv_tag);
  name = (tag < ARRAY_SIZE (tag_names)) ? tag_names[tag].name : unknownbuf;
  switch (tv->tv_tag)
    {
      case LDPT_OPTION:
      case LDPT_OUTPUT_NAME:
	TV_MESSAGE (LDPL_INFO, "tv[%d]: %s '%s'", n, name,
		    tv->tv_u.tv_string);
        break;
      case LDPT_REGISTER_CLAIM_FILE_HOOK:
      case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
      case LDPT_REGISTER_CLEANUP_HOOK:
      case LDPT_ADD_SYMBOLS:
      case LDPT_GET_SYMBOLS:
      case LDPT_GET_SYMBOLS_V2:
      case LDPT_ADD_INPUT_FILE:
      case LDPT_MESSAGE:
      case LDPT_GET_INPUT_FILE:
      case LDPT_GET_VIEW:
      case LDPT_RELEASE_INPUT_FILE:
      case LDPT_ADD_INPUT_LIBRARY:
      case LDPT_SET_EXTRA_LIBRARY_PATH:
	TV_MESSAGE (LDPL_INFO, "tv[%d]: %s func@0x%p", n, name,
		    (void *)(tv->tv_u.tv_message));
        break;
      case LDPT_NULL:
      case LDPT_API_VERSION:
      case LDPT_GOLD_VERSION:
      case LDPT_LINKER_OUTPUT:
      case LDPT_GNU_LD_VERSION:
      default:
	TV_MESSAGE (LDPL_INFO, "tv[%d]: %s value %W (%d)", n, name,
		    (bfd_vma)tv->tv_u.tv_val, tv->tv_u.tv_val);
	break;
    }
}

/* Handle/record information received in a transfer vector entry.  */
static enum ld_plugin_status
parse_tv_tag (struct ld_plugin_tv *tv)
{
#define SETVAR(x) x = tv->tv_u.x
  switch (tv->tv_tag)
    {
      case LDPT_OPTION:
	return parse_option (tv->tv_u.tv_string);
      case LDPT_NULL:
      case LDPT_GOLD_VERSION:
      case LDPT_GNU_LD_VERSION:
      case LDPT_API_VERSION:
      default:
	break;
      case LDPT_OUTPUT_NAME:
	output_name = tv->tv_u.tv_string;
	break;
      case LDPT_LINKER_OUTPUT:
	linker_output = tv->tv_u.tv_val;
	break;
      case LDPT_REGISTER_CLAIM_FILE_HOOK:
	SETVAR(tv_register_claim_file);
	break;
      case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
	SETVAR(tv_register_all_symbols_read);
	break;
      case LDPT_REGISTER_CLEANUP_HOOK:
	SETVAR(tv_register_cleanup);
	break;
      case LDPT_ADD_SYMBOLS:
	SETVAR(tv_add_symbols);
	break;
      case LDPT_GET_SYMBOLS:
	SETVAR(tv_get_symbols);
	break;
      case LDPT_GET_SYMBOLS_V2:
	tv_get_symbols_v2 = tv->tv_u.tv_get_symbols;
	break;
      case LDPT_ADD_INPUT_FILE:
	SETVAR(tv_add_input_file);
	break;
      case LDPT_MESSAGE:
	SETVAR(tv_message);
	break;
      case LDPT_GET_INPUT_FILE:
	SETVAR(tv_get_input_file);
	break;
      case LDPT_GET_VIEW:
	SETVAR(tv_get_view);
	break;
      case LDPT_RELEASE_INPUT_FILE:
	SETVAR(tv_release_input_file);
	break;
      case LDPT_ADD_INPUT_LIBRARY:
	SETVAR(tv_add_input_library);
	break;
      case LDPT_SET_EXTRA_LIBRARY_PATH:
	SETVAR(tv_set_extra_library_path);
	break;
    }
#undef SETVAR
  return LDPS_OK;
}

/* Record any useful information in transfer vector entry and display
   it in human-readable form using the plugin API message() callback.  */
enum ld_plugin_status
parse_and_dump_tv_tag (size_t n, struct ld_plugin_tv *tv)
{
  enum ld_plugin_status rv = parse_tv_tag (tv);
  dump_tv_tag (n, tv);
  return rv;
}

/* Standard plugin API entry point.  */
enum ld_plugin_status
onload (struct ld_plugin_tv *tv)
{
  size_t n = 0;
  enum ld_plugin_status rv;

  /* This plugin does nothing but dump the tv array.  It would
     be an error if this function was called without one.  */
  if (!tv)
    return LDPS_ERR;

  /* First entry should always be LDPT_MESSAGE, letting us get
     hold of it easily so we can send output straight away.  */
  if (tv[0].tv_tag == LDPT_MESSAGE)
    tv_message = tv[0].tv_u.tv_message;

  fflush (NULL);
  TV_MESSAGE (LDPL_INFO, "Hello from testplugin.");

  do
    if ((rv = parse_and_dump_tv_tag (n++, tv)) != LDPS_OK)
      return rv;
  while ((tv++)->tv_tag != LDPT_NULL);

  /* Register hooks only if instructed by options.  */
  if (register_claimfile_hook)
    {
      if (!tv_register_claim_file)
	{
	  TV_MESSAGE (LDPL_FATAL, "No register_claim_file hook");
	  fflush (NULL);
	  return LDPS_ERR;
	}
      (*tv_register_claim_file) (onclaim_file);
    }
  if (register_allsymbolsread_hook)
    {
      if (!tv_register_all_symbols_read)
	{
	  TV_MESSAGE (LDPL_FATAL, "No register_all_symbols_read hook");
	  fflush (NULL);
	  return LDPS_ERR;
	}
      (*tv_register_all_symbols_read) (onall_symbols_read);
    }
  if (register_cleanup_hook)
    {
      if (!tv_register_cleanup)
	{
	  TV_MESSAGE (LDPL_FATAL, "No register_cleanup hook");
	  fflush (NULL);
	  return LDPS_ERR;
	}
      (*tv_register_cleanup) (oncleanup);
    }
  fflush (NULL);
  return onload_ret;
}

/* Standard plugin API registerable hook.  */
static enum ld_plugin_status
onclaim_file (const struct ld_plugin_input_file *file, int *claimed)
{
  /* Possible read of some bytes out of the input file into a buffer.  This
     simulates a plugin that reads some file content in order to decide if
     the file should be claimed or not.  */
  if (bytes_to_read_before_claim > 0)
    {
      char *buffer = malloc (bytes_to_read_before_claim);

      if (buffer == NULL)
        return LDPS_ERR;
      if (read (file->fd, buffer, bytes_to_read_before_claim) < 0)
        return LDPS_ERR;
      free (buffer);
    }

  /* Let's see if we want to claim this file.  */
  claim_file_t *claimfile = claimfiles_list;
  while (claimfile)
    {
      if (!strcmp (file->name, claimfile->file.name))
	break;
      claimfile = claimfile->next;
    }

  /* Inform the user/testsuite.  */
  TV_MESSAGE (LDPL_INFO, "hook called: claim_file %s [@%ld/%ld] %s",
	      file->name, (long)file->offset, (long)file->filesize,
	      claimfile ? "CLAIMED" : "not claimed");
  fflush (NULL);

  /* If we decided to claim it, record that fact, and add any symbols
     that were defined for it by plugin options.  */
  *claimed = (claimfile != 0);
  if (claimfile)
    {
      claimfile->claimed = true;
      claimfile->file = *file;
      if (claimfile->n_syms_used && !tv_add_symbols)
	return LDPS_ERR;
      else if (claimfile->n_syms_used)
	return (*tv_add_symbols) (claimfile->file.handle,
				claimfile->n_syms_used, claimfile->symbols);
    }

  return claim_file_ret;
}

/* Standard plugin API registerable hook.  */
static enum ld_plugin_status
onall_symbols_read (void)
{
  static const char *resolutions[] =
    {
      "LDPR_UNKNOWN",
      "LDPR_UNDEF",
      "LDPR_PREVAILING_DEF",
      "LDPR_PREVAILING_DEF_IRONLY",
      "LDPR_PREEMPTED_REG",
      "LDPR_PREEMPTED_IR",
      "LDPR_RESOLVED_IR",
      "LDPR_RESOLVED_EXEC",
      "LDPR_RESOLVED_DYN",
      "LDPR_PREVAILING_DEF_IRONLY_EXP",
    };
  claim_file_t *claimfile = dumpresolutions ? claimfiles_list : NULL;
  add_file_t *addfile = addfiles_list;
  TV_MESSAGE (LDPL_INFO, "hook called: all symbols read.");
  for ( ; claimfile; claimfile = claimfile->next)
    {
      enum ld_plugin_status rv;
      int n;
      if (claimfile->n_syms_used && !tv_get_symbols_v2)
	return LDPS_ERR;
      else if (!claimfile->n_syms_used)
        continue;
      rv = tv_get_symbols_v2 (claimfile->file.handle, claimfile->n_syms_used,
			      claimfile->symbols);
      if (rv != LDPS_OK)
	return rv;
      for (n = 0; n < claimfile->n_syms_used; n++)
	TV_MESSAGE (LDPL_INFO, "Sym: '%s%s%s' Resolution: %s",
		    claimfile->symbols[n].name,
		    claimfile->symbols[n].version ? "@" : "",
		    (claimfile->symbols[n].version
		     ? claimfile->symbols[n].version : ""),
		    resolutions[claimfile->symbols[n].resolution]);
    }
  for ( ; addfile ; addfile = addfile->next)
    {
      enum ld_plugin_status rv;
      if (addfile->type == ADD_LIB && tv_add_input_library)
	rv = (*tv_add_input_library) (addfile->name);
      else if (addfile->type == ADD_FILE && tv_add_input_file)
	rv = (*tv_add_input_file) (addfile->name);
      else if (addfile->type == ADD_DIR && tv_set_extra_library_path)
	rv = (*tv_set_extra_library_path) (addfile->name);
      else
	rv = LDPS_ERR;
      if (rv != LDPS_OK)
	return rv;
    }
  fflush (NULL);
  return all_symbols_read_ret;
}

/* Standard plugin API registerable hook.  */
static enum ld_plugin_status
oncleanup (void)
{
  TV_MESSAGE (LDPL_INFO, "hook called: cleanup.");
  fflush (NULL);
  return cleanup_ret;
}
#endif /* BFD_SUPPORTS_PLUGINS */