libctf/ctf-serialize.c

/* CTF dict creation.
   Copyright (C) 2019-2024 Free Software Foundation, Inc.

   This file is part of libctf.

   libctf 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, 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; see the file COPYING.  If not see
   <http://www.gnu.org/licenses/>.  */

#include <ctf-impl.h>
#include <assert.h>
#include <string.h>
#include <unistd.h>
#include <zlib.h>

#include <elf.h>
#include "elf-bfd.h"

/* Symtypetab sections.  */

/* Symtypetab emission flags.  */

#define CTF_SYMTYPETAB_EMIT_FUNCTION 0x1
#define CTF_SYMTYPETAB_EMIT_PAD 0x2
#define CTF_SYMTYPETAB_FORCE_INDEXED 0x4

/* Properties of symtypetab emission, shared by symtypetab section
   sizing and symtypetab emission itself.  */

typedef struct emit_symtypetab_state
{
  /* True if linker-reported symbols are being filtered out.  symfp is set if
     this is true: otherwise, indexing is forced and the symflags indicate as
     much. */
  int filter_syms;

  /* True if symbols are being sorted.  */
  int sort_syms;

  /* Flags for symtypetab emission.  */
  int symflags;

  /* The dict to which the linker has reported symbols.  */
  ctf_dict_t *symfp;

  /* The maximum number of objects seen.  */
  size_t maxobjt;

  /* The maximum number of func info entris seen.  */
  size_t maxfunc;
} emit_symtypetab_state_t;

/* Determine if a symbol is "skippable" and should never appear in the
   symtypetab sections.  */

int
ctf_symtab_skippable (ctf_link_sym_t *sym)
{
  /* Never skip symbols whose name is not yet known.  */
  if (sym->st_nameidx_set)
    return 0;

  return (sym->st_name == NULL || sym->st_name[0] == 0
	  || sym->st_shndx == SHN_UNDEF
	  || strcmp (sym->st_name, "_START_") == 0
	  || strcmp (sym->st_name, "_END_") == 0
	  || (sym->st_type == STT_OBJECT && sym->st_shndx == SHN_EXTABS
	      && sym->st_value == 0));
}

/* Get the number of symbols in a symbol hash, the count of symbols, the maximum
   seen, the eventual size, without any padding elements, of the func/data and
   (if generated) index sections, and the size of accumulated padding elements.
   The linker-reported set of symbols is found in SYMFP: it may be NULL if
   symbol filtering is not desired, in which case CTF_SYMTYPETAB_FORCE_INDEXED
   will always be set in the flags.

   Also figure out if any symbols need to be moved to the variable section, and
   add them (if not already present).  */

_libctf_nonnull_ ((1,3,4,5,6,7,8))
static int
symtypetab_density (ctf_dict_t *fp, ctf_dict_t *symfp, ctf_dynhash_t *symhash,
		    size_t *count, size_t *max, size_t *unpadsize,
		    size_t *padsize, size_t *idxsize, int flags)
{
  ctf_next_t *i = NULL;
  const void *name;
  const void *ctf_sym;
  ctf_dynhash_t *linker_known = NULL;
  int err;
  int beyond_max = 0;

  *count = 0;
  *max = 0;
  *unpadsize = 0;
  *idxsize = 0;
  *padsize = 0;

  if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
    {
      /* Make a dynhash citing only symbols reported by the linker of the
	 appropriate type, then traverse all potential-symbols we know the types
	 of, removing them from linker_known as we go.  Once this is done, the
	 only symbols remaining in linker_known are symbols we don't know the
	 types of: we must emit pads for those symbols that are below the
	 maximum symbol we will emit (any beyond that are simply skipped).

	 If there are none, this symtypetab will be empty: just report that.  */

      if (!symfp->ctf_dynsyms)
	return 0;

      if ((linker_known = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,
					      NULL, NULL)) == NULL)
	return (ctf_set_errno (fp, ENOMEM));

      while ((err = ctf_dynhash_cnext (symfp->ctf_dynsyms, &i,
				       &name, &ctf_sym)) == 0)
	{
	  ctf_link_sym_t *sym = (ctf_link_sym_t *) ctf_sym;

	  if (((flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
	       && sym->st_type != STT_FUNC)
	      || (!(flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
		  && sym->st_type != STT_OBJECT))
	    continue;

	  if (ctf_symtab_skippable (sym))
	    continue;

	  /* This should only be true briefly before all the names are
	     finalized, long before we get this far.  */
	  if (!ctf_assert (fp, !sym->st_nameidx_set))
	    return -1;				/* errno is set for us.  */

	  if (ctf_dynhash_cinsert (linker_known, name, ctf_sym) < 0)
	    {
	      ctf_dynhash_destroy (linker_known);
	      return (ctf_set_errno (fp, ENOMEM));
	    }
	}
      if (err != ECTF_NEXT_END)
	{
	  ctf_err_warn (fp, 0, err, _("iterating over linker-known symbols during "
				  "serialization"));
	  ctf_dynhash_destroy (linker_known);
	  return (ctf_set_errno (fp, err));
	}
    }

  while ((err = ctf_dynhash_cnext (symhash, &i, &name, NULL)) == 0)
    {
      ctf_link_sym_t *sym;

      if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
	{
	  /* Linker did not report symbol in symtab.  Remove it from the
	     set of known data symbols and continue.  */
	  if ((sym = ctf_dynhash_lookup (symfp->ctf_dynsyms, name)) == NULL)
	    {
	      ctf_dynhash_remove (symhash, name);
	      continue;
	    }

	  /* We don't remove skippable symbols from the symhash because we don't
	     want them to be migrated into variables.  */
	  if (ctf_symtab_skippable (sym))
	    continue;

	  if ((flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
	      && sym->st_type != STT_FUNC)
	    {
	      ctf_err_warn (fp, 1, 0, _("symbol %s (%x) added to CTF as a "
					"function but is of type %x.  "
					"The symbol type lookup tables "
					"are probably corrupted"),
			    sym->st_name, sym->st_symidx, sym->st_type);
	      ctf_dynhash_remove (symhash, name);
	      continue;
	    }
	  else if (!(flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
		   && sym->st_type != STT_OBJECT)
	    {
	      ctf_err_warn (fp, 1, 0, _("symbol %s (%x) added to CTF as a "
					"data object but is of type %x.  "
					"The symbol type lookup tables "
					"are probably corrupted"),
			    sym->st_name, sym->st_symidx, sym->st_type);
	      ctf_dynhash_remove (symhash, name);
	      continue;
	    }

	  ctf_dynhash_remove (linker_known, name);

	  if (*max < sym->st_symidx)
	    *max = sym->st_symidx;
	}
      else
	(*max)++;

      *unpadsize += sizeof (uint32_t);
      (*count)++;
    }
  if (err != ECTF_NEXT_END)
    {
      ctf_err_warn (fp, 0, err, _("iterating over CTF symtypetab during "
				  "serialization"));
      ctf_dynhash_destroy (linker_known);
      return (ctf_set_errno (fp, err));
    }

  if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
    {
      while ((err = ctf_dynhash_cnext (linker_known, &i, NULL, &ctf_sym)) == 0)
	{
	  ctf_link_sym_t *sym = (ctf_link_sym_t *) ctf_sym;

	  if (sym->st_symidx > *max)
	    beyond_max++;
	}
      if (err != ECTF_NEXT_END)
	{
	  ctf_err_warn (fp, 0, err, _("iterating over linker-known symbols "
				      "during CTF serialization"));
	  ctf_dynhash_destroy (linker_known);
	  return (ctf_set_errno (fp, err));
	}
    }

  *idxsize = *count * sizeof (uint32_t);
  if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
    *padsize = (ctf_dynhash_elements (linker_known) - beyond_max) * sizeof (uint32_t);

  ctf_dynhash_destroy (linker_known);
  return 0;
}

/* Emit an objt or func symtypetab into DP in a particular order defined by an
   array of ctf_link_sym_t or symbol names passed in.  The index has NIDX
   elements in it: unindexed output would terminate at symbol OUTMAX and is in
   any case no larger than SIZE bytes.  Some index elements are expected to be
   skipped: see symtypetab_density.  The linker-reported set of symbols (if any)
   is found in SYMFP. */
static int
emit_symtypetab (ctf_dict_t *fp, ctf_dict_t *symfp, uint32_t *dp,
		 ctf_link_sym_t **idx, const char **nameidx, uint32_t nidx,
		 uint32_t outmax, int size, int flags)
{
  uint32_t i;
  uint32_t *dpp = dp;
  ctf_dynhash_t *symhash;

  ctf_dprintf ("Emitting table of size %i, outmax %u, %u symtypetab entries, "
	       "flags %i\n", size, outmax, nidx, flags);

  /* Empty table? Nothing to do.  */
  if (size == 0)
    return 0;

  if (flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
    symhash = fp->ctf_funchash;
  else
    symhash = fp->ctf_objthash;

  for (i = 0; i < nidx; i++)
    {
      const char *sym_name;
      void *type;

      /* If we have a linker-reported set of symbols, we may be given that set
	 to work from, or a set of symbol names.  In both cases we want to look
	 at the corresponding linker-reported symbol (if any).  */
      if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
	{
	  ctf_link_sym_t *this_link_sym;

	  if (idx)
	    this_link_sym = idx[i];
	  else
	    this_link_sym = ctf_dynhash_lookup (symfp->ctf_dynsyms, nameidx[i]);

	  /* Unreported symbol number.  No pad, no nothing.  */
	  if (!this_link_sym)
	    continue;

	  /* Symbol of the wrong type, or skippable?  This symbol is not in this
	     table.  */
	  if (((flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
	       && this_link_sym->st_type != STT_FUNC)
	      || (!(flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
		  && this_link_sym->st_type != STT_OBJECT))
	    continue;

	  if (ctf_symtab_skippable (this_link_sym))
	    continue;

	  sym_name = this_link_sym->st_name;

	  /* Linker reports symbol of a different type to the symbol we actually
	     added?  Skip the symbol.  No pad, since the symbol doesn't actually
	     belong in this table at all.  (Warned about in
	     symtypetab_density.)  */
	  if ((this_link_sym->st_type == STT_FUNC)
	      && (ctf_dynhash_lookup (fp->ctf_objthash, sym_name)))
	    continue;

	  if ((this_link_sym->st_type == STT_OBJECT)
	      && (ctf_dynhash_lookup (fp->ctf_funchash, sym_name)))
	    continue;
	}
      else
	sym_name = nameidx[i];

      /* Symbol in index but no type set? Silently skip and (optionally)
	 pad.  (In force-indexed mode, this is also where we track symbols of
	 the wrong type for this round of insertion.)  */
      if ((type = ctf_dynhash_lookup (symhash, sym_name)) == NULL)
	{
	  if (flags & CTF_SYMTYPETAB_EMIT_PAD)
	    *dpp++ = 0;
	  continue;
	}

      if (!ctf_assert (fp, (((char *) dpp) - (char *) dp) < size))
	return -1;				/* errno is set for us.  */

      *dpp++ = (ctf_id_t) (uintptr_t) type;

      /* When emitting unindexed output, all later symbols are pads: stop
	 early.  */
      if ((flags & CTF_SYMTYPETAB_EMIT_PAD) && idx[i]->st_symidx == outmax)
	break;
    }

  return 0;
}

/* Emit an objt or func symtypetab index into DP in a paticular order defined by
   an array of symbol names passed in.  Stop at NIDX.  The linker-reported set
   of symbols (if any) is found in SYMFP. */
static int
emit_symtypetab_index (ctf_dict_t *fp, ctf_dict_t *symfp, uint32_t *dp,
		       const char **idx, uint32_t nidx, int size, int flags)
{
  uint32_t i;
  uint32_t *dpp = dp;
  ctf_dynhash_t *symhash;

  ctf_dprintf ("Emitting index of size %i, %u entries reported by linker, "
	       "flags %i\n", size, nidx, flags);

  /* Empty table? Nothing to do.  */
  if (size == 0)
    return 0;

  if (flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
    symhash = fp->ctf_funchash;
  else
    symhash = fp->ctf_objthash;

  /* Indexes should always be unpadded.  */
  if (!ctf_assert (fp, !(flags & CTF_SYMTYPETAB_EMIT_PAD)))
    return -1;					/* errno is set for us.  */

  for (i = 0; i < nidx; i++)
    {
      const char *sym_name;
      void *type;

      if (!(flags & CTF_SYMTYPETAB_FORCE_INDEXED))
	{
	  ctf_link_sym_t *this_link_sym;

	  this_link_sym = ctf_dynhash_lookup (symfp->ctf_dynsyms, idx[i]);

	  /* This is an index: unreported symbols should never appear in it.  */
	  if (!ctf_assert (fp, this_link_sym != NULL))
	    return -1;				/* errno is set for us.  */

	  /* Symbol of the wrong type, or skippable?  This symbol is not in this
	     table.  */
	  if (((flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
	       && this_link_sym->st_type != STT_FUNC)
	      || (!(flags & CTF_SYMTYPETAB_EMIT_FUNCTION)
		  && this_link_sym->st_type != STT_OBJECT))
	    continue;

	  if (ctf_symtab_skippable (this_link_sym))
	    continue;

	  sym_name = this_link_sym->st_name;

	  /* Linker reports symbol of a different type to the symbol we actually
	     added?  Skip the symbol.  */
	  if ((this_link_sym->st_type == STT_FUNC)
	      && (ctf_dynhash_lookup (fp->ctf_objthash, sym_name)))
	    continue;

	  if ((this_link_sym->st_type == STT_OBJECT)
	      && (ctf_dynhash_lookup (fp->ctf_funchash, sym_name)))
	    continue;
	}
      else
	sym_name = idx[i];

      /* Symbol in index and reported by linker, but no type set? Silently skip
	 and (optionally) pad.  (In force-indexed mode, this is also where we
	 track symbols of the wrong type for this round of insertion.)  */
      if ((type = ctf_dynhash_lookup (symhash, sym_name)) == NULL)
	continue;

      ctf_str_add_ref (fp, sym_name, dpp++);

      if (!ctf_assert (fp, (((char *) dpp) - (char *) dp) <= size))
	return -1;				/* errno is set for us.  */
    }

  return 0;
}

/* Delete symbols that have been assigned names from the variable section.  Must
   be called from within ctf_serialize, because that is the only place you can
   safely delete variables without messing up ctf_rollback.  */

static int
symtypetab_delete_nonstatics (ctf_dict_t *fp, ctf_dict_t *symfp)
{
  ctf_dvdef_t *dvd, *nvd;
  ctf_id_t type;

  for (dvd = ctf_list_next (&fp->ctf_dvdefs); dvd != NULL; dvd = nvd)
    {
      nvd = ctf_list_next (dvd);

      if ((((type = (ctf_id_t) (uintptr_t)
	     ctf_dynhash_lookup (fp->ctf_objthash, dvd->dvd_name)) > 0)
	   || (type = (ctf_id_t) (uintptr_t)
	       ctf_dynhash_lookup (fp->ctf_funchash, dvd->dvd_name)) > 0)
	  && ctf_dynhash_lookup (symfp->ctf_dynsyms, dvd->dvd_name) != NULL
	  && type == dvd->dvd_type)
	ctf_dvd_delete (fp, dvd);
    }

  return 0;
}

/* Figure out the sizes of the symtypetab sections, their indexed state,
   etc.  */
static int
ctf_symtypetab_sect_sizes (ctf_dict_t *fp, emit_symtypetab_state_t *s,
			   ctf_header_t *hdr, size_t *objt_size,
			   size_t *func_size, size_t *objtidx_size,
			   size_t *funcidx_size)
{
  size_t nfuncs, nobjts;
  size_t objt_unpadsize, func_unpadsize, objt_padsize, func_padsize;

  /* If doing a writeout as part of linking, and the link flags request it,
     filter out reported symbols from the variable section, and filter out all
     other symbols from the symtypetab sections.  (If we are not linking, the
     symbols are sorted; if we are linking, don't bother sorting if we are not
     filtering out reported symbols: this is almost certainly an ld -r and only
     the linker is likely to consume these symtypetabs again.  The linker
     doesn't care what order the symtypetab entries are in, since it only
     iterates over symbols and does not use the ctf_lookup_by_symbol* API.)  */

  s->sort_syms = 1;
  if (fp->ctf_flags & LCTF_LINKING)
    {
      s->filter_syms = !(fp->ctf_link_flags & CTF_LINK_NO_FILTER_REPORTED_SYMS);
      if (!s->filter_syms)
	s->sort_syms = 0;
    }

  /* Find the dict to which the linker has reported symbols, if any.  */

  if (s->filter_syms)
    {
      if (!fp->ctf_dynsyms && fp->ctf_parent && fp->ctf_parent->ctf_dynsyms)
	s->symfp = fp->ctf_parent;
      else
	s->symfp = fp;
    }

  /* If not filtering, keep all potential symbols in an unsorted, indexed
     dict.  */
  if (!s->filter_syms)
    s->symflags = CTF_SYMTYPETAB_FORCE_INDEXED;
  else
    hdr->cth_flags |= CTF_F_IDXSORTED;

  if (!ctf_assert (fp, (s->filter_syms && s->symfp)
		   || (!s->filter_syms && !s->symfp
		       && ((s->symflags & CTF_SYMTYPETAB_FORCE_INDEXED) != 0))))
    return -1;

  /* Work out the sizes of the object and function sections, and work out the
     number of pad (unassigned) symbols in each, and the overall size of the
     sections.  */

  if (symtypetab_density (fp, s->symfp, fp->ctf_objthash, &nobjts, &s->maxobjt,
			  &objt_unpadsize, &objt_padsize, objtidx_size,
			  s->symflags) < 0)
    return -1;					/* errno is set for us.  */

  ctf_dprintf ("Object symtypetab: %i objects, max %i, unpadded size %i, "
	       "%i bytes of pads, index size %i\n", (int) nobjts,
	       (int) s->maxobjt, (int) objt_unpadsize, (int) objt_padsize,
	       (int) *objtidx_size);

  if (symtypetab_density (fp, s->symfp, fp->ctf_funchash, &nfuncs, &s->maxfunc,
			  &func_unpadsize, &func_padsize, funcidx_size,
			  s->symflags | CTF_SYMTYPETAB_EMIT_FUNCTION) < 0)
    return -1;					/* errno is set for us.  */

  ctf_dprintf ("Function symtypetab: %i functions, max %i, unpadded size %i, "
	       "%i bytes of pads, index size %i\n", (int) nfuncs,
	       (int) s->maxfunc, (int) func_unpadsize, (int) func_padsize,
	       (int) *funcidx_size);

  /* It is worth indexing each section if it would save space to do so, due to
     reducing the number of pads sufficiently.  A pad is the same size as a
     single index entry: but index sections compress relatively poorly compared
     to constant pads, so it takes a lot of contiguous padding to equal one
     index section entry.  It would be nice to be able to *verify* whether we
     would save space after compression rather than guessing, but this seems
     difficult, since it would require complete reserialization.  Regardless, if
     the linker has not reported any symbols (e.g. if this is not a final link
     but just an ld -r), we must emit things in indexed fashion just as the
     compiler does.  */

  *objt_size = objt_unpadsize;
  if (!(s->symflags & CTF_SYMTYPETAB_FORCE_INDEXED)
      && ((objt_padsize + objt_unpadsize) * CTF_INDEX_PAD_THRESHOLD
	  > objt_padsize))
    {
      *objt_size += objt_padsize;
      *objtidx_size = 0;
    }

  *func_size = func_unpadsize;
  if (!(s->symflags & CTF_SYMTYPETAB_FORCE_INDEXED)
      && ((func_padsize + func_unpadsize) * CTF_INDEX_PAD_THRESHOLD
	  > func_padsize))
    {
      *func_size += func_padsize;
      *funcidx_size = 0;
    }

  /* If we are filtering symbols out, those symbols that the linker has not
     reported have now been removed from the ctf_objthash and ctf_funchash.
     Delete entries from the variable section that duplicate newly-added
     symbols.  There's no need to migrate new ones in: we do that (if necessary)
     in ctf_link_deduplicating_variables.  */

  if (s->filter_syms && s->symfp->ctf_dynsyms &&
      symtypetab_delete_nonstatics (fp, s->symfp) < 0)
    return -1;

  return 0;
}

static int
ctf_emit_symtypetab_sects (ctf_dict_t *fp, emit_symtypetab_state_t *s,
			   unsigned char **tptr, size_t objt_size,
			   size_t func_size, size_t objtidx_size,
			   size_t funcidx_size)
{
  unsigned char *t = *tptr;
  size_t nsymtypes = 0;
  const char **sym_name_order = NULL;
  int err;

  /* Sort the linker's symbols into name order if need be.  */

  if ((objtidx_size != 0) || (funcidx_size != 0))
    {
      ctf_next_t *i = NULL;
      void *symname;
      const char **walk;

      if (s->filter_syms)
	{
	  if (s->symfp->ctf_dynsyms)
	    nsymtypes = ctf_dynhash_elements (s->symfp->ctf_dynsyms);
	  else
	    nsymtypes = 0;
	}
      else
	nsymtypes = ctf_dynhash_elements (fp->ctf_objthash)
	  + ctf_dynhash_elements (fp->ctf_funchash);

      if ((sym_name_order = calloc (nsymtypes, sizeof (const char *))) == NULL)
	goto oom;

      walk = sym_name_order;

      if (s->filter_syms)
	{
	  if (s->symfp->ctf_dynsyms)
	    {
	      while ((err = ctf_dynhash_next_sorted (s->symfp->ctf_dynsyms, &i,
						     &symname, NULL,
						     ctf_dynhash_sort_by_name,
						     NULL)) == 0)
		*walk++ = (const char *) symname;
	      if (err != ECTF_NEXT_END)
		goto symerr;
	    }
	}
      else
	{
	  ctf_hash_sort_f sort_fun = NULL;

	  /* Since we partition the set of symbols back into objt and func,
	     we can sort the two independently without harm.  */
	  if (s->sort_syms)
	    sort_fun = ctf_dynhash_sort_by_name;

	  while ((err = ctf_dynhash_next_sorted (fp->ctf_objthash, &i, &symname,
						 NULL, sort_fun, NULL)) == 0)
	    *walk++ = (const char *) symname;
	  if (err != ECTF_NEXT_END)
	    goto symerr;

	  while ((err = ctf_dynhash_next_sorted (fp->ctf_funchash, &i, &symname,
						 NULL, sort_fun, NULL)) == 0)
	    *walk++ = (const char *) symname;
	  if (err != ECTF_NEXT_END)
	    goto symerr;
	}
    }

  /* Emit the object and function sections, and if necessary their indexes.
     Emission is done in symtab order if there is no index, and in index
     (name) order otherwise.  */

  if ((objtidx_size == 0) && s->symfp && s->symfp->ctf_dynsymidx)
    {
      ctf_dprintf ("Emitting unindexed objt symtypetab\n");
      if (emit_symtypetab (fp, s->symfp, (uint32_t *) t,
			   s->symfp->ctf_dynsymidx, NULL,
			   s->symfp->ctf_dynsymmax + 1, s->maxobjt,
			   objt_size, s->symflags | CTF_SYMTYPETAB_EMIT_PAD) < 0)
	goto err;				/* errno is set for us.  */
    }
  else
    {
      ctf_dprintf ("Emitting indexed objt symtypetab\n");
      if (emit_symtypetab (fp, s->symfp, (uint32_t *) t, NULL,
			   sym_name_order, nsymtypes, s->maxobjt,
			   objt_size, s->symflags) < 0)
	goto err;				/* errno is set for us.  */
    }

  t += objt_size;

  if ((funcidx_size == 0) && s->symfp && s->symfp->ctf_dynsymidx)
    {
      ctf_dprintf ("Emitting unindexed func symtypetab\n");
      if (emit_symtypetab (fp, s->symfp, (uint32_t *) t,
			   s->symfp->ctf_dynsymidx, NULL,
			   s->symfp->ctf_dynsymmax + 1, s->maxfunc,
			   func_size, s->symflags | CTF_SYMTYPETAB_EMIT_FUNCTION
			   | CTF_SYMTYPETAB_EMIT_PAD) < 0)
	goto err;				/* errno is set for us.  */
    }
  else
    {
      ctf_dprintf ("Emitting indexed func symtypetab\n");
      if (emit_symtypetab (fp, s->symfp, (uint32_t *) t, NULL, sym_name_order,
			   nsymtypes, s->maxfunc, func_size,
			   s->symflags | CTF_SYMTYPETAB_EMIT_FUNCTION) < 0)
	goto err;				/* errno is set for us.  */
    }

  t += func_size;

  if (objtidx_size > 0)
    if (emit_symtypetab_index (fp, s->symfp, (uint32_t *) t, sym_name_order,
			       nsymtypes, objtidx_size, s->symflags) < 0)
      goto err;

  t += objtidx_size;

  if (funcidx_size > 0)
    if (emit_symtypetab_index (fp, s->symfp, (uint32_t *) t, sym_name_order,
			       nsymtypes, funcidx_size,
			       s->symflags | CTF_SYMTYPETAB_EMIT_FUNCTION) < 0)
      goto err;

  t += funcidx_size;
  free (sym_name_order);
  *tptr = t;

  return 0;

 oom:
  ctf_set_errno (fp, EAGAIN);
  goto err;
symerr:
  ctf_err_warn (fp, 0, err, _("error serializing symtypetabs"));
 err:
  free (sym_name_order);
  return -1;
}

/* Type section.  */

/* Iterate through the static types and the dynamic type definition list and
   compute the size of the CTF type section.  */

static size_t
ctf_type_sect_size (ctf_dict_t *fp)
{
  ctf_dtdef_t *dtd;
  size_t type_size;

  for (type_size = 0, dtd = ctf_list_next (&fp->ctf_dtdefs);
       dtd != NULL; dtd = ctf_list_next (dtd))
    {
      uint32_t kind = LCTF_INFO_KIND (fp, dtd->dtd_data.ctt_info);
      uint32_t vlen = LCTF_INFO_VLEN (fp, dtd->dtd_data.ctt_info);
      size_t type_ctt_size = dtd->dtd_data.ctt_size;

      /* Shrink ctf_type_t-using types from a ctf_type_t to a ctf_stype_t
	 if possible.  */

      if (kind == CTF_K_STRUCT || kind == CTF_K_UNION)
	{
	  size_t lsize = CTF_TYPE_LSIZE (&dtd->dtd_data);

	  if (lsize <= CTF_MAX_SIZE)
	    type_ctt_size = lsize;
	}

      if (type_ctt_size != CTF_LSIZE_SENT)
	type_size += sizeof (ctf_stype_t);
      else
	type_size += sizeof (ctf_type_t);

      switch (kind)
	{
	case CTF_K_INTEGER:
	case CTF_K_FLOAT:
	  type_size += sizeof (uint32_t);
	  break;
	case CTF_K_ARRAY:
	  type_size += sizeof (ctf_array_t);
	  break;
	case CTF_K_SLICE:
	  type_size += sizeof (ctf_slice_t);
	  break;
	case CTF_K_FUNCTION:
	  type_size += sizeof (uint32_t) * (vlen + (vlen & 1));
	  break;
	case CTF_K_STRUCT:
	case CTF_K_UNION:
	  if (type_ctt_size < CTF_LSTRUCT_THRESH)
	    type_size += sizeof (ctf_member_t) * vlen;
	  else
	    type_size += sizeof (ctf_lmember_t) * vlen;
	  break;
	case CTF_K_ENUM:
	  type_size += sizeof (ctf_enum_t) * vlen;
	  break;
	}
    }

  return type_size + fp->ctf_header->cth_stroff - fp->ctf_header->cth_typeoff;
}

/* Take a final lap through the dynamic type definition list and copy the
   appropriate type records to the output buffer, noting down the strings as
   we go.  */

static void
ctf_emit_type_sect (ctf_dict_t *fp, unsigned char **tptr)
{
  unsigned char *t = *tptr;
  ctf_dtdef_t *dtd;

  for (dtd = ctf_list_next (&fp->ctf_dtdefs);
       dtd != NULL; dtd = ctf_list_next (dtd))
    {
      uint32_t kind = LCTF_INFO_KIND (fp, dtd->dtd_data.ctt_info);
      uint32_t vlen = LCTF_INFO_VLEN (fp, dtd->dtd_data.ctt_info);
      size_t type_ctt_size = dtd->dtd_data.ctt_size;
      size_t len;
      ctf_stype_t *copied;
      const char *name;
      size_t i;

      /* Shrink ctf_type_t-using types from a ctf_type_t to a ctf_stype_t
	 if possible.  */

      if (kind == CTF_K_STRUCT || kind == CTF_K_UNION)
	{
	  size_t lsize = CTF_TYPE_LSIZE (&dtd->dtd_data);

	  if (lsize <= CTF_MAX_SIZE)
	    type_ctt_size = lsize;
	}

      if (type_ctt_size != CTF_LSIZE_SENT)
	len = sizeof (ctf_stype_t);
      else
	len = sizeof (ctf_type_t);

      memcpy (t, &dtd->dtd_data, len);
      copied = (ctf_stype_t *) t;  /* name is at the start: constant offset.  */
      if (copied->ctt_name
	  && (name = ctf_strraw (fp, copied->ctt_name)) != NULL)
        ctf_str_add_ref (fp, name, &copied->ctt_name);
      copied->ctt_size = type_ctt_size;
      t += len;

      switch (kind)
	{
	case CTF_K_INTEGER:
	case CTF_K_FLOAT:
	  memcpy (t, dtd->dtd_vlen, sizeof (uint32_t));
	  t += sizeof (uint32_t);
	  break;

	case CTF_K_SLICE:
	  memcpy (t, dtd->dtd_vlen, sizeof (struct ctf_slice));
	  t += sizeof (struct ctf_slice);
	  break;

	case CTF_K_ARRAY:
	  memcpy (t, dtd->dtd_vlen, sizeof (struct ctf_array));
	  t += sizeof (struct ctf_array);
	  break;

	case CTF_K_FUNCTION:
	  /* Functions with no args also have no vlen.  */
	  if (dtd->dtd_vlen)
	    memcpy (t, dtd->dtd_vlen, sizeof (uint32_t) * (vlen + (vlen & 1)));
	  t += sizeof (uint32_t) * (vlen + (vlen & 1));
	  break;

	  /* These need to be copied across element by element, depending on
	     their ctt_size.  */
	case CTF_K_STRUCT:
	case CTF_K_UNION:
	  {
	    ctf_lmember_t *dtd_vlen = (ctf_lmember_t *) dtd->dtd_vlen;
	    ctf_lmember_t *t_lvlen = (ctf_lmember_t *) t;
	    ctf_member_t *t_vlen = (ctf_member_t *) t;

	    for (i = 0; i < vlen; i++)
	      {
		const char *name = ctf_strraw (fp, dtd_vlen[i].ctlm_name);

		ctf_str_add_ref (fp, name, &dtd_vlen[i].ctlm_name);

		if (type_ctt_size < CTF_LSTRUCT_THRESH)
		  {
		    t_vlen[i].ctm_name = dtd_vlen[i].ctlm_name;
		    t_vlen[i].ctm_type = dtd_vlen[i].ctlm_type;
		    t_vlen[i].ctm_offset = CTF_LMEM_OFFSET (&dtd_vlen[i]);
		    ctf_str_add_ref (fp, name, &t_vlen[i].ctm_name);
		  }
		else
		  {
		    t_lvlen[i] = dtd_vlen[i];
		    ctf_str_add_ref (fp, name, &t_lvlen[i].ctlm_name);
		  }
	      }
	  }

	  if (type_ctt_size < CTF_LSTRUCT_THRESH)
	    t += sizeof (ctf_member_t) * vlen;
	  else
	    t += sizeof (ctf_lmember_t) * vlen;
	  break;

	case CTF_K_ENUM:
	  {
	    ctf_enum_t *dtd_vlen = (struct ctf_enum *) dtd->dtd_vlen;
	    ctf_enum_t *t_vlen = (struct ctf_enum *) t;

	    memcpy (t, dtd->dtd_vlen, sizeof (struct ctf_enum) * vlen);
	    for (i = 0; i < vlen; i++)
	      {
		const char *name = ctf_strraw (fp, dtd_vlen[i].cte_name);

		ctf_str_add_ref (fp, name, &t_vlen[i].cte_name);
		ctf_str_add_ref (fp, name, &dtd_vlen[i].cte_name);
	      }
	    t += sizeof (struct ctf_enum) * vlen;

	    break;
	  }
	}
    }

  *tptr = t;
}

/* Variable section.  */

/* Sort a newly-constructed static variable array.  */

typedef struct ctf_sort_var_arg_cb
{
  ctf_dict_t *fp;
  ctf_strs_t *strtab;
} ctf_sort_var_arg_cb_t;

static int
ctf_sort_var (const void *one_, const void *two_, void *arg_)
{
  const ctf_varent_t *one = one_;
  const ctf_varent_t *two = two_;
  ctf_sort_var_arg_cb_t *arg = arg_;

  return (strcmp (ctf_strraw_explicit (arg->fp, one->ctv_name, arg->strtab),
		  ctf_strraw_explicit (arg->fp, two->ctv_name, arg->strtab)));
}

/* Overall serialization.  */

/* Emit a new CTF dict which is a serialized copy of this one: also reify
   the string table and update all offsets in the current dict suitably.
   (This simplifies ctf-string.c a little, at the cost of storing a second
   copy of the strtab if this dict was originally read in via ctf_open.)

   Other aspects of the existing dict are unchanged, although some
   static entries may be duplicated in the dynamic state (which should
   have no effect on visible operation).  */

static unsigned char *
ctf_serialize (ctf_dict_t *fp, size_t *bufsiz)
{
  ctf_header_t hdr, *hdrp;
  ctf_dvdef_t *dvd;
  ctf_varent_t *dvarents;
  const ctf_strs_writable_t *strtab;
  int sym_functions = 0;

  unsigned char *t;
  unsigned long i;
  size_t buf_size, type_size, objt_size, func_size;
  size_t funcidx_size, objtidx_size;
  size_t nvars;
  unsigned char *buf = NULL, *newbuf;

  emit_symtypetab_state_t symstate;
  memset (&symstate, 0, sizeof (emit_symtypetab_state_t));

  /* Fill in an initial CTF header.  We will leave the label, object,
     and function sections empty and only output a header, type section,
     and string table.  The type section begins at a 4-byte aligned
     boundary past the CTF header itself (at relative offset zero).  The flag
     indicating a new-style function info section (an array of CTF_K_FUNCTION
     type IDs in the types section) is flipped on.  */

  memset (&hdr, 0, sizeof (hdr));
  hdr.cth_magic = CTF_MAGIC;
  hdr.cth_version = CTF_VERSION;

  /* This is a new-format func info section, and the symtab and strtab come out
     of the dynsym and dynstr these days.  */
  hdr.cth_flags = (CTF_F_NEWFUNCINFO | CTF_F_DYNSTR);

  /* Propagate all symbols in the symtypetabs into the dynamic state, so that
     we can put them back in the right order.  Symbols already in the dynamic
     state, likely due to repeated serialization, are left unchanged.  */
  do
    {
      ctf_next_t *it = NULL;
      const char *sym_name;
      ctf_id_t sym;

      while ((sym = ctf_symbol_next_static (fp, &it, &sym_name,
					    sym_functions)) != CTF_ERR)
	if ((ctf_add_funcobjt_sym_forced (fp, sym_functions, sym_name, sym)) < 0)
	  if (ctf_errno (fp) != ECTF_DUPLICATE)
	    return NULL;			/* errno is set for us.  */

      if (ctf_errno (fp) != ECTF_NEXT_END)
	return NULL;				/* errno is set for us.  */
    } while (sym_functions++ < 1);

  /* Figure out how big the symtypetabs are now.  */

  if (ctf_symtypetab_sect_sizes (fp, &symstate, &hdr, &objt_size, &func_size,
				 &objtidx_size, &funcidx_size) < 0)
    return NULL;				/* errno is set for us.  */

  /* Propagate all vars into the dynamic state, so we can put them back later.
     Variables already in the dynamic state, likely due to repeated
     serialization, are left unchanged.  */

  for (i = 0; i < fp->ctf_nvars; i++)
    {
      const char *name = ctf_strptr (fp, fp->ctf_vars[i].ctv_name);

      if (name != NULL && !ctf_dvd_lookup (fp, name))
	if (ctf_add_variable_forced (fp, name, fp->ctf_vars[i].ctv_type) < 0)
	  return NULL;				/* errno is set for us.  */
    }

  for (nvars = 0, dvd = ctf_list_next (&fp->ctf_dvdefs);
       dvd != NULL; dvd = ctf_list_next (dvd), nvars++);

  type_size = ctf_type_sect_size (fp);

  /* Compute the size of the CTF buffer we need, sans only the string table,
     then allocate a new buffer and memcpy the finished header to the start of
     the buffer.  (We will adjust this later with strtab length info.)  */

  hdr.cth_lbloff = hdr.cth_objtoff = 0;
  hdr.cth_funcoff = hdr.cth_objtoff + objt_size;
  hdr.cth_objtidxoff = hdr.cth_funcoff + func_size;
  hdr.cth_funcidxoff = hdr.cth_objtidxoff + objtidx_size;
  hdr.cth_varoff = hdr.cth_funcidxoff + funcidx_size;
  hdr.cth_typeoff = hdr.cth_varoff + (nvars * sizeof (ctf_varent_t));
  hdr.cth_stroff = hdr.cth_typeoff + type_size;
  hdr.cth_strlen = 0;

  buf_size = sizeof (ctf_header_t) + hdr.cth_stroff + hdr.cth_strlen;

  if ((buf = malloc (buf_size)) == NULL)
    {
      ctf_set_errno (fp, EAGAIN);
      return NULL;
    }

  memcpy (buf, &hdr, sizeof (ctf_header_t));
  t = (unsigned char *) buf + sizeof (ctf_header_t) + hdr.cth_objtoff;

  hdrp = (ctf_header_t *) buf;
  if ((fp->ctf_flags & LCTF_CHILD) && (fp->ctf_parname != NULL))
    ctf_str_add_ref (fp, fp->ctf_parname, &hdrp->cth_parname);
  if (fp->ctf_cuname != NULL)
    ctf_str_add_ref (fp, fp->ctf_cuname, &hdrp->cth_cuname);

  if (ctf_emit_symtypetab_sects (fp, &symstate, &t, objt_size, func_size,
				 objtidx_size, funcidx_size) < 0)
    goto err;

  assert (t == (unsigned char *) buf + sizeof (ctf_header_t) + hdr.cth_varoff);

  /* Work over the variable list, translating everything into ctf_varent_t's and
     prepping the string table.  */

  dvarents = (ctf_varent_t *) t;
  for (i = 0, dvd = ctf_list_next (&fp->ctf_dvdefs); dvd != NULL;
       dvd = ctf_list_next (dvd), i++)
    {
      ctf_varent_t *var = &dvarents[i];

      ctf_str_add_ref (fp, dvd->dvd_name, &var->ctv_name);
      var->ctv_type = (uint32_t) dvd->dvd_type;
    }
  assert (i == nvars);

  t += sizeof (ctf_varent_t) * nvars;

  assert (t == (unsigned char *) buf + sizeof (ctf_header_t) + hdr.cth_typeoff);

  /* Copy in existing static types, then emit new dynamic types.  */

  memcpy (t, fp->ctf_buf + fp->ctf_header->cth_typeoff,
	  fp->ctf_header->cth_stroff - fp->ctf_header->cth_typeoff);
  t += fp->ctf_header->cth_stroff - fp->ctf_header->cth_typeoff;
  ctf_emit_type_sect (fp, &t);

  assert (t == (unsigned char *) buf + sizeof (ctf_header_t) + hdr.cth_stroff);

  /* Construct the final string table and fill out all the string refs with the
     final offsets.  */

  strtab = ctf_str_write_strtab (fp);

  if (strtab == NULL)
    goto oom;

  /* Now the string table is constructed, we can sort the buffer of
     ctf_varent_t's.  */
  ctf_sort_var_arg_cb_t sort_var_arg = { fp, (ctf_strs_t *) strtab };
  ctf_qsort_r (dvarents, nvars, sizeof (ctf_varent_t), ctf_sort_var,
	       &sort_var_arg);

  if ((newbuf = realloc (buf, buf_size + strtab->cts_len)) == NULL)
    goto oom;

  buf = newbuf;
  memcpy (buf + buf_size, strtab->cts_strs, strtab->cts_len);
  hdrp = (ctf_header_t *) buf;
  hdrp->cth_strlen = strtab->cts_len;
  buf_size += hdrp->cth_strlen;
  *bufsiz = buf_size;

  return buf;

oom:
  ctf_set_errno (fp, EAGAIN);
err:
  free (buf);
  return NULL;					/* errno is set for us.  */
}

/* File writing.  */

/* Write the compressed CTF data stream to the specified gzFile descriptor.  The
   whole stream is compressed, and cannot be read by CTF opening functions in
   this library until it is decompressed.  (The functions below this one leave
   the header uncompressed, and the CTF opening functions work on them without
   manual decompression.)

   No support for (testing-only) endian-flipping.  */
int
ctf_gzwrite (ctf_dict_t *fp, gzFile fd)
{
  unsigned char *buf;
  unsigned char *p;
  size_t bufsiz;
  size_t len, written = 0;

  if ((buf = ctf_serialize (fp, &bufsiz)) == NULL)
    return -1;					/* errno is set for us.  */

  p = buf;
  while (written < bufsiz)
    {
      if ((len = gzwrite (fd, p, bufsiz - written)) <= 0)
	{
	  free (buf);
	  return (ctf_set_errno (fp, errno));
	}
      written += len;
      p += len;
    }

  free (buf);
  return 0;
}

/* Optionally compress the specified CTF data stream and return it as a new
   dynamically-allocated string.  Possibly write it with reversed
   endianness.  */
unsigned char *
ctf_write_mem (ctf_dict_t *fp, size_t *size, size_t threshold)
{
  unsigned char *rawbuf;
  unsigned char *buf = NULL;
  unsigned char *bp;
  ctf_header_t *rawhp, *hp;
  unsigned char *src;
  size_t rawbufsiz;
  size_t alloc_len = 0;
  int uncompressed = 0;
  int flip_endian;
  int rc;

  flip_endian = getenv ("LIBCTF_WRITE_FOREIGN_ENDIAN") != NULL;

  if ((rawbuf = ctf_serialize (fp, &rawbufsiz)) == NULL)
    return NULL;				/* errno is set for us.  */

  if (!ctf_assert (fp, rawbufsiz >= sizeof (ctf_header_t)))
    goto err;

  if (rawbufsiz >= threshold)
    alloc_len = compressBound (rawbufsiz - sizeof (ctf_header_t))
      + sizeof (ctf_header_t);

  /* Trivial operation if the buffer is incompressible or too small to bother
     compressing, and we're not doing a forced write-time flip.  */

  if (rawbufsiz < threshold || rawbufsiz < alloc_len)
    {
      alloc_len = rawbufsiz;
      uncompressed = 1;
    }

  if (!flip_endian && uncompressed)
    {
      *size = rawbufsiz;
      return rawbuf;
    }

  if ((buf = malloc (alloc_len)) == NULL)
    {
      ctf_set_errno (fp, ENOMEM);
      ctf_err_warn (fp, 0, 0, _("ctf_write_mem: cannot allocate %li bytes"),
		    (unsigned long) (alloc_len));
      goto err;
    }

  rawhp = (ctf_header_t *) rawbuf;
  hp = (ctf_header_t *) buf;
  memcpy (hp, rawbuf, sizeof (ctf_header_t));
  bp = buf + sizeof (ctf_header_t);
  *size = sizeof (ctf_header_t);

  if (!uncompressed)
    hp->cth_flags |= CTF_F_COMPRESS;

  src = rawbuf + sizeof (ctf_header_t);

  if (flip_endian)
    {
      ctf_flip_header (hp);
      if (ctf_flip (fp, rawhp, src, 1) < 0)
	goto err;				/* errno is set for us.  */
    }

  if (!uncompressed)
    {
      size_t compress_len = alloc_len - sizeof (ctf_header_t);

      if ((rc = compress (bp, (uLongf *) &compress_len,
			  src, rawbufsiz - sizeof (ctf_header_t))) != Z_OK)
	{
	  ctf_set_errno (fp, ECTF_COMPRESS);
	  ctf_err_warn (fp, 0, 0, _("zlib deflate err: %s"), zError (rc));
	  goto err;
	}
      *size += compress_len;
    }
  else
    {
      memcpy (bp, src, rawbufsiz - sizeof (ctf_header_t));
      *size += rawbufsiz - sizeof (ctf_header_t);
    }

  free (rawbuf);
  return buf;
err:
  free (buf);
  free (rawbuf);
  return NULL;
}

/* Compress the specified CTF data stream and write it to the specified file
   descriptor.  */
int
ctf_compress_write (ctf_dict_t *fp, int fd)
{
  unsigned char *buf;
  unsigned char *bp;
  size_t tmp;
  ssize_t buf_len;
  ssize_t len;
  int err = 0;

  if ((buf = ctf_write_mem (fp, &tmp, 0)) == NULL)
    return -1;					/* errno is set for us.  */

  buf_len = tmp;
  bp = buf;

  while (buf_len > 0)
    {
      if ((len = write (fd, bp, buf_len)) < 0)
	{
	  err = ctf_set_errno (fp, errno);
	  ctf_err_warn (fp, 0, 0, _("ctf_compress_write: error writing"));
	  goto ret;
	}
      buf_len -= len;
      bp += len;
    }

ret:
  free (buf);
  return err;
}

/* Write the uncompressed CTF data stream to the specified file descriptor.  */
int
ctf_write (ctf_dict_t *fp, int fd)
{
  unsigned char *buf;
  unsigned char *bp;
  size_t tmp;
  ssize_t buf_len;
  ssize_t len;
  int err = 0;

  if ((buf = ctf_write_mem (fp, &tmp, (size_t) -1)) == NULL)
    return -1;					/* errno is set for us.  */

  buf_len = tmp;
  bp = buf;

  while (buf_len > 0)
    {
      if ((len = write (fd, bp, buf_len)) < 0)
	{
	  err = ctf_set_errno (fp, errno);
	  ctf_err_warn (fp, 0, 0, _("ctf_compress_write: error writing"));
	  goto ret;
	}
      buf_len -= len;
      bp += len;
    }

ret:
  free (buf);
  return err;
}