/* CTF string table management.

   Copyright (C) 2019-2025 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 <assert.h>

#include <ctf-impl.h>

#include <string.h>

static ctf_str_atom_t *

ctf_str_add_ref_internal (ctf_dict_t *fp, const char *str,

        int flags, uint32_t *ref);

/* Convert an encoded CTF string name into a pointer to a C string, possibly

  using an explicit internal provisional strtab rather than the fp-based

  one.  */

const char *

ctf_strraw_explicit (ctf_dict_t *fp, uint32_t name, ctf_strs_t *strtab)

{

  ctf_strs_t *ctsp = &fp->ctf_str[CTF_NAME_STID (name)];

  if ((CTF_NAME_STID (name) == CTF_STRTAB_0) && (strtab != NULL))

    ctsp = strtab;

  /* If this name is in the external strtab, and there is a synthetic

     strtab, use it in preference.  (This is used to add the set of strings

     -- symbol names, etc -- the linker knows about before the strtab is

     written out.)  */

  if (CTF_NAME_STID (name) == CTF_STRTAB_1

      && fp->ctf_syn_ext_strtab != NULL)

    return ctf_dynhash_lookup (fp->ctf_syn_ext_strtab,

             (void *) (uintptr_t) name);

  /* If the name is in the internal strtab, and the name offset is beyond

     the end of the ctsp->cts_len but below the ctf_str_prov_offset, this is

     a provisional string added by ctf_str_add*() but not yet built into a

     real strtab: get the value out of the ctf_prov_strtab.  */

  if (CTF_NAME_STID (name) == CTF_STRTAB_0

      && name >= ctsp->cts_len && name < fp->ctf_str_prov_offset)

      return ctf_dynhash_lookup (fp->ctf_prov_strtab,

         (void *) (uintptr_t) name);

  if (ctsp->cts_strs != NULL && CTF_NAME_OFFSET (name) < ctsp->cts_len)

    return (ctsp->cts_strs + CTF_NAME_OFFSET (name));

  /* String table not loaded or corrupt offset.  */

  return NULL;

}

/* Convert an encoded CTF string name into a pointer to a C string by looking

  up the appropriate string table buffer and then adding the offset.  */

const char *

ctf_strraw (ctf_dict_t *fp, uint32_t name)

{

  return ctf_strraw_explicit (fp, name, NULL);

}

/* Return a guaranteed-non-NULL pointer to the string with the given CTF

   name.  */

const char *

ctf_strptr (ctf_dict_t *fp, uint32_t name)

{

  const char *s = ctf_strraw (fp, name);

  return (s != NULL ? s : "(?)");

}

/* As above, but return info on what is wrong in more detail.

   (Used for type lookups.) */

const char *

ctf_strptr_validate (ctf_dict_t *fp, uint32_t name)

{

  const char *str = ctf_strraw (fp, name);

  if (str == NULL)

    {

      if (CTF_NAME_STID (name) == CTF_STRTAB_1

    && fp->ctf_syn_ext_strtab == NULL

    && fp->ctf_str[CTF_NAME_STID (name)].cts_strs == NULL)

  {

    ctf_set_errno (fp, ECTF_STRTAB);

    return NULL;

  }

      ctf_set_errno (fp, ECTF_BADNAME);

      return NULL;

    }

  return str;

}

/* Remove all refs to a given atom.  */

static void

ctf_str_purge_atom_refs (ctf_str_atom_t *atom)

{

  ctf_str_atom_ref_t *ref, *next;

  ctf_str_atom_ref_movable_t *movref, *movnext;

  for (ref = ctf_list_next (&atom->csa_refs); ref != NULL; ref = next)

    {

      next = ctf_list_next (ref);

      ctf_list_delete (&atom->csa_refs, ref);

      free (ref);

    }

  for (movref = ctf_list_next (&atom->csa_movable_refs);

       movref != NULL; movref = movnext)

    {

      movnext = ctf_list_next (movref);

      ctf_list_delete (&atom->csa_movable_refs, movref);

      ctf_dynhash_remove (movref->caf_movable_refs, movref);

      free (movref);

    }

}

/* Free an atom.  */

static void

ctf_str_free_atom (void *a)

{

  ctf_str_atom_t *atom = a;

  ctf_str_purge_atom_refs (atom);

  if (atom->csa_flags & CTF_STR_ATOM_FREEABLE)

    free (atom->csa_str);

  free (atom);

}

/* Create the atoms table.  There is always at least one atom in it, the null

   string: but also pull in atoms from the internal strtab.  (We rely on

   calls to ctf_str_add_external to populate external strtab entries, since

   these are often not quite the same as what appears in any external

   strtab, and the external strtab is often huge and best not aggressively

   pulled in.)  */

int

ctf_str_create_atoms (ctf_dict_t *fp)

{

  size_t i;

  fp->ctf_str_atoms = ctf_dynhash_create (ctf_hash_string, ctf_hash_eq_string,

            NULL, ctf_str_free_atom);

  if (!fp->ctf_str_atoms)

    return -ENOMEM;

  if (!fp->ctf_prov_strtab)

    fp->ctf_prov_strtab = ctf_dynhash_create (ctf_hash_integer,

                ctf_hash_eq_integer,

                NULL, NULL);

  if (!fp->ctf_prov_strtab)

    goto oom_prov_strtab;

  fp->ctf_str_movable_refs = ctf_dynhash_create (ctf_hash_integer,

             ctf_hash_eq_integer,

             NULL, NULL);

  if (!fp->ctf_str_movable_refs)

    goto oom_movable_refs;

  errno = 0;

  ctf_str_add (fp, "");

  if (errno == ENOMEM)

    goto oom_str_add;

  /* Pull in all the strings in the strtab as new atoms.  The provisional

     strtab must be empty at this point, so there is no need to populate

     atoms from it as well.  Types in this subset are frozen and readonly,

     so the refs list and movable refs list need not be populated.  */

  for (i = 0; i < fp->ctf_str[CTF_STRTAB_0].cts_len;

       i += strlen (&fp->ctf_str[CTF_STRTAB_0].cts_strs[i]) + 1)

    {

      ctf_str_atom_t *atom;

      if (fp->ctf_str[CTF_STRTAB_0].cts_strs[i] == 0)

  continue;

      atom = ctf_str_add_ref_internal (fp, &fp->ctf_str[CTF_STRTAB_0].cts_strs[i],

               0, 0);

      if (!atom)

  goto oom_str_add;

      atom->csa_offset = i;

    }

  fp->ctf_str_prov_offset = fp->ctf_str[CTF_STRTAB_0].cts_len + 1;

  return 0;

 oom_str_add:

  ctf_dynhash_destroy (fp->ctf_str_movable_refs);

  fp->ctf_str_movable_refs = NULL;

 oom_movable_refs:

  ctf_dynhash_destroy (fp->ctf_prov_strtab);

  fp->ctf_prov_strtab = NULL;

 oom_prov_strtab:

  ctf_dynhash_destroy (fp->ctf_str_atoms);

  fp->ctf_str_atoms = NULL;

  return -ENOMEM;

}

/* Destroy the atoms table and associated refs.  */

void

ctf_str_free_atoms (ctf_dict_t *fp)

{

  ctf_dynhash_destroy (fp->ctf_prov_strtab);

  ctf_dynhash_destroy (fp->ctf_str_atoms);

  ctf_dynhash_destroy (fp->ctf_str_movable_refs);

  if (fp->ctf_dynstrtab)

    {

      free (fp->ctf_dynstrtab->cts_strs);

      free (fp->ctf_dynstrtab);

    }

}

#define CTF_STR_ADD_REF 0x1

#define CTF_STR_PROVISIONAL 0x2

#define CTF_STR_MOVABLE 0x4

/* Allocate a ref and bind it into a ref list.  */

static ctf_str_atom_ref_t *

aref_create (ctf_dict_t *fp, ctf_str_atom_t *atom, uint32_t *ref, int flags)

{

  ctf_str_atom_ref_t *aref;

  size_t s = sizeof (struct ctf_str_atom_ref);

  if (flags & CTF_STR_MOVABLE)

    s = sizeof (struct ctf_str_atom_ref_movable);

  aref = malloc (s);

  if (!aref)

    return NULL;

  aref->caf_ref = ref;

  /* Movable refs get a backpointer to them in ctf_str_movable_refs, and a

     pointer to ctf_str_movable_refs itself in the ref, for use when freeing

     refs: they can be moved later in batches via a call to

     ctf_str_move_refs.  */

  if (flags & CTF_STR_MOVABLE)

    {

      ctf_str_atom_ref_movable_t *movref = (ctf_str_atom_ref_movable_t *) aref;

      movref->caf_movable_refs = fp->ctf_str_movable_refs;

      if (ctf_dynhash_insert (fp->ctf_str_movable_refs, ref, aref) < 0)

  {

    free (aref);

    return NULL;

  }

      ctf_list_append (&atom->csa_movable_refs, movref);

    }

  else

    ctf_list_append (&atom->csa_refs, aref);

  return aref;

}

/* Add a string to the atoms table, copying the passed-in string if

   necessary.  Return the atom added. Return NULL only when out of memory

   (and do not touch the passed-in string in that case).

   Possibly add a provisional entry for this string to the provisional

   strtab.  If the string is in the provisional strtab, update its ref list

   with the passed-in ref, causing the ref to be updated when the strtab is

   written out.  */

static ctf_str_atom_t *

ctf_str_add_ref_internal (ctf_dict_t *fp, const char *str,

        int flags, uint32_t *ref)

{

  char *newstr = NULL;

  ctf_str_atom_t *atom = NULL;

  int added = 0;

  atom = ctf_dynhash_lookup (fp->ctf_str_atoms, str);

  /* Existing atoms get refs added only if they are provisional:

     non-provisional strings already have a fixed strtab offset, and just

     get their ref updated immediately, since its value cannot change.  */

  if (atom)

    {

      if (!ctf_dynhash_lookup (fp->ctf_prov_strtab, (void *) (uintptr_t)

             atom->csa_offset))

  {

    if (flags & CTF_STR_ADD_REF)

      {

        if (atom->csa_external_offset)

    *ref = atom->csa_external_offset;

        else

    *ref = atom->csa_offset;

      }

    return atom;

  }

      if (flags & CTF_STR_ADD_REF)

  {

    if (!aref_create (fp, atom, ref, flags))

      {

        ctf_set_errno (fp, ENOMEM);

        return NULL;

      }

  }

      return atom;

    }

  /* New atom.  */

  if ((atom = malloc (sizeof (struct ctf_str_atom))) == NULL)

    goto oom;

  memset (atom, 0, sizeof (struct ctf_str_atom));

  /* Don't allocate new strings if this string is within an mmapped

     strtab.  */

  if ((unsigned char *) str < (unsigned char *) fp->ctf_data_mmapped

      || (unsigned char *) str > (unsigned char *) fp->ctf_data_mmapped + fp->ctf_data_mmapped_len)

    {

      if ((newstr = strdup (str)) == NULL)

  goto oom;

      atom->csa_flags |= CTF_STR_ATOM_FREEABLE;

      atom->csa_str = newstr;

    }

  else

    atom->csa_str = (char *) str;

  if (ctf_dynhash_insert (fp->ctf_str_atoms, atom->csa_str, atom) < 0)

    goto oom;

  added = 1;

  atom->csa_snapshot_id = fp->ctf_snapshots;

  /* New atoms marked provisional go into the provisional strtab, and get a

     ref added.  */

  if (flags & CTF_STR_PROVISIONAL)

    {

      atom->csa_offset = fp->ctf_str_prov_offset;

      if (ctf_dynhash_insert (fp->ctf_prov_strtab, (void *) (uintptr_t)

            atom->csa_offset, (void *) atom->csa_str) < 0)

  goto oom;

      fp->ctf_str_prov_offset += strlen (atom->csa_str) + 1;

      if (flags & CTF_STR_ADD_REF)

      {

  if (!aref_create (fp, atom, ref, flags))

    goto oom;

      }

    }

  return atom;

 oom:

  if (added)

    ctf_dynhash_remove (fp->ctf_str_atoms, atom->csa_str);

  free (atom);

  free (newstr);

  ctf_set_errno (fp, ENOMEM);

  return NULL;

}

/* Add a string to the atoms table, without augmenting the ref list for this

   string: return a 'provisional offset' which can be used to return this string

   until ctf_str_write_strtab is called, or 0 on failure.  (Everywhere the

   provisional offset is assigned to should be added as a ref using

   ctf_str_add_ref() as well.) */

uint32_t

ctf_str_add (ctf_dict_t *fp, const char *str)

{

  ctf_str_atom_t *atom;

  if (!str)

    str = "";

  atom = ctf_str_add_ref_internal (fp, str, CTF_STR_PROVISIONAL, 0);

  if (!atom)

    return 0;

  return atom->csa_offset;

}

/* Like ctf_str_add(), but additionally augment the atom's refs list with the

   passed-in ref, whether or not the string is already present.  There is no

   attempt to deduplicate the refs list (but duplicates are harmless).  */

uint32_t

ctf_str_add_ref (ctf_dict_t *fp, const char *str, uint32_t *ref)

{

  ctf_str_atom_t *atom;

  if (!str)

    str = "";

  atom = ctf_str_add_ref_internal (fp, str, CTF_STR_ADD_REF

           | CTF_STR_PROVISIONAL, ref);

  if (!atom)

    return 0;

  return atom->csa_offset;

}

/* Like ctf_str_add_ref(), but note that the ref may be moved later on.  */

uint32_t

ctf_str_add_movable_ref (ctf_dict_t *fp, const char *str, uint32_t *ref)

{

  ctf_str_atom_t *atom;

  if (!str)

    str = "";

  atom = ctf_str_add_ref_internal (fp, str, CTF_STR_ADD_REF

           | CTF_STR_PROVISIONAL

           | CTF_STR_MOVABLE, ref);

  if (!atom)

    return 0;

  return atom->csa_offset;

}

/* Add an external strtab reference at OFFSET.  Returns zero if the addition

   failed, nonzero otherwise.  */

int

ctf_str_add_external (ctf_dict_t *fp, const char *str, uint32_t offset)

{

  ctf_str_atom_t *atom;

  if (!str)

    str = "";

  atom = ctf_str_add_ref_internal (fp, str, 0, 0);

  if (!atom)

    return 0;

  atom->csa_external_offset = CTF_SET_STID (offset, CTF_STRTAB_1);

  if (!fp->ctf_syn_ext_strtab)

    fp->ctf_syn_ext_strtab = ctf_dynhash_create (ctf_hash_integer,

             ctf_hash_eq_integer,

             NULL, NULL);

  if (!fp->ctf_syn_ext_strtab)

    {

      ctf_set_errno (fp, ENOMEM);

      return 0;

    }

  if (ctf_dynhash_insert (fp->ctf_syn_ext_strtab,

        (void *) (uintptr_t)

        atom->csa_external_offset,

        (void *) atom->csa_str) < 0)

    {

      /* No need to bother freeing the syn_ext_strtab: it will get freed at

   ctf_str_write_strtab time if unreferenced.  */

      ctf_set_errno (fp, ENOMEM);

      return 0;

    }

  return 1;

}

/* Note that refs have moved from (SRC, LEN) to DEST.  We use the movable

   refs backpointer for this, because it is done an amortized-constant

   number of times during structure member and enumerand addition, and if we

   did a linear search this would turn such addition into an O(n^2)

   operation.  Even this is not linear, but it's better than that.  */

int

ctf_str_move_refs (ctf_dict_t *fp, void *src, size_t len, void *dest)

{

  uintptr_t p;

  if (src == dest)

    return 0;

  for (p = (uintptr_t) src; p - (uintptr_t) src < len; p++)

    {

      ctf_str_atom_ref_movable_t *ref;

      if ((ref = ctf_dynhash_lookup (fp->ctf_str_movable_refs,

             (ctf_str_atom_ref_t *) p)) != NULL)

  {

    int out_of_memory;

    ref->caf_ref = (uint32_t *) (((uintptr_t) ref->caf_ref +

          (uintptr_t) dest - (uintptr_t) src));

    ctf_dynhash_remove (fp->ctf_str_movable_refs,

            (ctf_str_atom_ref_t *) p);

    out_of_memory = ctf_dynhash_insert (fp->ctf_str_movable_refs,

                ref->caf_ref, ref);

    assert (out_of_memory == 0);

  }

    }

  return 0;

}

/* Remove a single ref.  */

void

ctf_str_remove_ref (ctf_dict_t *fp, const char *str, uint32_t *ref)

{

  ctf_str_atom_ref_t *aref, *anext;

  ctf_str_atom_ref_movable_t *amovref, *amovnext;

  ctf_str_atom_t *atom = NULL;

  atom = ctf_dynhash_lookup (fp->ctf_str_atoms, str);

  if (!atom)

    return;

  for (aref = ctf_list_next (&atom->csa_refs); aref != NULL; aref = anext)

    {

      anext = ctf_list_next (aref);

      if (aref->caf_ref == ref)

  {

    ctf_list_delete (&atom->csa_refs, aref);

    free (aref);

  }

    }

  for (amovref = ctf_list_next (&atom->csa_movable_refs);

       amovref != NULL; amovref = amovnext)

    {

      amovnext = ctf_list_next (amovref);

      if (amovref->caf_ref == ref)

  {

    ctf_list_delete (&atom->csa_movable_refs, amovref);

    ctf_dynhash_remove (fp->ctf_str_movable_refs, ref);

    free (amovref);

  }

    }

}

/* A ctf_dynhash_iter_remove() callback that removes atoms later than a given

   snapshot ID.  External atoms are never removed, because they came from the

   linker string table and are still present even if you roll back type

   additions.  */

static int

ctf_str_rollback_atom (void *key _libctf_unused_, void *value, void *arg)

{

  ctf_str_atom_t *atom = (ctf_str_atom_t *) value;

  ctf_snapshot_id_t *id = (ctf_snapshot_id_t *) arg;

  return (atom->csa_snapshot_id > id->snapshot_id)

    && (atom->csa_external_offset == 0);

}

/* Roll back, deleting all (internal) atoms created after a particular ID.  */

void

ctf_str_rollback (ctf_dict_t *fp, ctf_snapshot_id_t id)

{

  ctf_dynhash_iter_remove (fp->ctf_str_atoms, ctf_str_rollback_atom, &id);

}

/* An adaptor around ctf_purge_atom_refs.  */

static void

ctf_str_purge_one_atom_refs (void *key _libctf_unused_, void *value,

           void *arg _libctf_unused_)

{

  ctf_str_atom_t *atom = (ctf_str_atom_t *) value;

  ctf_str_purge_atom_refs (atom);

}

/* Remove all the recorded refs from the atoms table.  */

static void

ctf_str_purge_refs (ctf_dict_t *fp)

{

  ctf_dynhash_iter (fp->ctf_str_atoms, ctf_str_purge_one_atom_refs, NULL);

}

/* Update a list of refs to the specified value. */

static void

ctf_str_update_refs (ctf_str_atom_t *refs, uint32_t value)

{

  ctf_str_atom_ref_t *ref;

  ctf_str_atom_ref_movable_t *movref;

  for (ref = ctf_list_next (&refs->csa_refs); ref != NULL;

       ref = ctf_list_next (ref))

    *(ref->caf_ref) = value;

  for (movref = ctf_list_next (&refs->csa_movable_refs);

       movref != NULL; movref = ctf_list_next (movref))

    *(movref->caf_ref) = value;

}

/* Sort the strtab.  */

static int

ctf_str_sort_strtab (const void *a, const void *b)

{

  ctf_str_atom_t **one = (ctf_str_atom_t **) a;

  ctf_str_atom_t **two = (ctf_str_atom_t **) b;

  return (strcmp ((*one)->csa_str, (*two)->csa_str));

}

/* Write out and return a strtab containing all strings with recorded refs,

   adjusting the refs to refer to the corresponding string.  The returned

   strtab is already assigned to strtab 0 in this dict, is owned by this

   dict, and may be NULL on error.  Also populate the synthetic strtab with

   mappings from external strtab offsets to names, so we can look them up

   with ctf_strptr().  Only external strtab offsets with references are

   added.

   As a side effect, replaces the strtab of the current dict with the newly-

   generated strtab.  This is an exception to the general rule that

   serialization does not change the dict passed in, because the alternative

   is to copy the entire atoms table on every reserialization just to avoid

   modifying the original, which is excessively costly for minimal gain.

   We use the lazy man's approach and double memory costs by always storing

   atoms as individually allocated entities whenever they come from anywhere

   but a freshly-opened, mmapped dict, even though after serialization there

   is another copy in the strtab; this ensures that ctf_strptr()-returned

   pointers to them remain valid for the lifetime of the dict.

   This is all rendered more complex because if a dict is ctf_open()ed it

   will have a bunch of strings in its strtab already, and their strtab

   offsets can never change (without piles of complexity to rescan the

   entire dict just to get all the offsets to all of them into the atoms

   table).  Entries below the existing strtab limit are just copied into the

   new dict: entries above it are new, and are are sorted first, then

   appended to it.  The sorting is purely a compression-efficiency

   improvement, and we get nearly as good an improvement from sorting big

   chunks like this as we would from sorting the whole thing.  */

const ctf_strs_writable_t *

ctf_str_write_strtab (ctf_dict_t *fp)

{

  ctf_strs_writable_t *strtab;

  size_t strtab_count = 0;

  uint32_t cur_stroff = 0;

  ctf_str_atom_t **sorttab;

  ctf_next_t *it = NULL;

  size_t i;

  void *v;

  int err;

  int new_strtab = 0;

  int any_external = 0;

  strtab = calloc (1, sizeof (ctf_strs_writable_t));

  if (!strtab)

    return NULL;

  /* The strtab contains the existing string table at its start: figure out

     how many new strings we need to add.  We only need to add new strings

     that have no external offset, that have refs, and that are found in the

     provisional strtab.  If the existing strtab is empty we also need to

     add the null string at its start.  */

  strtab->cts_len = fp->ctf_str[CTF_STRTAB_0].cts_len;

  if (strtab->cts_len == 0)

    {

      new_strtab = 1;

      strtab->cts_len++;      /* For the \0.  */

    }

  /* Count new entries in the strtab: i.e. entries in the provisional

     strtab.  Ignore any entry for \0, entries which ended up in the

     external strtab, and unreferenced entries.  */

  while ((err = ctf_dynhash_next (fp->ctf_prov_strtab, &it, NULL, &v)) == 0)

    {

      const char *str = (const char *) v;

      ctf_str_atom_t *atom;

      atom = ctf_dynhash_lookup (fp->ctf_str_atoms, str);

      if (!ctf_assert (fp, atom))

  goto err_strtab;

      if (atom->csa_str[0] == 0 || atom->csa_external_offset

    || (ctf_list_empty_p (&atom->csa_refs)

        && ctf_list_empty_p (&atom->csa_movable_refs)))

  continue;

      strtab->cts_len += strlen (atom->csa_str) + 1;

      strtab_count++;

    }

  if (err != ECTF_NEXT_END)

    {

      ctf_dprintf ("ctf_str_write_strtab: error counting strtab entries: %s\n",

       ctf_errmsg (err));

      goto err_strtab;

    }

  ctf_dprintf ("%lu bytes of strings in strtab: %lu pre-existing.\n",

         (unsigned long) strtab->cts_len,

         (unsigned long) fp->ctf_str[CTF_STRTAB_0].cts_len);

  /* Sort the new part of the strtab.  */

  sorttab = calloc (strtab_count, sizeof (ctf_str_atom_t *));

  if (!sorttab)

    {

      ctf_set_errno (fp, ENOMEM);

      goto err_strtab;

    }

  i = 0;

  while ((err = ctf_dynhash_next (fp->ctf_prov_strtab, &it, NULL, &v)) == 0)

    {

      ctf_str_atom_t *atom;

      atom = ctf_dynhash_lookup (fp->ctf_str_atoms, v);

      if (!ctf_assert (fp, atom))

  goto err_sorttab;

      if (atom->csa_str[0] == 0 || atom->csa_external_offset

    || (ctf_list_empty_p (&atom->csa_refs)

        && ctf_list_empty_p (&atom->csa_movable_refs)))

  continue;

      sorttab[i++] = atom;

    }

  qsort (sorttab, strtab_count, sizeof (ctf_str_atom_t *),

   ctf_str_sort_strtab);

  if ((strtab->cts_strs = malloc (strtab->cts_len)) == NULL)

    goto err_sorttab;

  cur_stroff = fp->ctf_str[CTF_STRTAB_0].cts_len;

  if (new_strtab)

    {

      strtab->cts_strs[0] = 0;

      cur_stroff++;

    }

  else

    memcpy (strtab->cts_strs, fp->ctf_str[CTF_STRTAB_0].cts_strs,

      fp->ctf_str[CTF_STRTAB_0].cts_len);

  /* Work over the sorttab, add its strings to the strtab, and remember

     where they are in the csa_offset for the appropriate atom.  No ref

     updating is done at this point, because refs might well relate to

     already-existing strings, or external strings, which do not need adding

     to the strtab and may not be in the sorttab.  */

  for (i = 0; i < strtab_count; i++)

    {

      sorttab[i]->csa_offset = cur_stroff;

      strcpy (&strtab->cts_strs[cur_stroff], sorttab[i]->csa_str);

      cur_stroff += strlen (sorttab[i]->csa_str) + 1;

    }

  free (sorttab);

  sorttab = NULL;

  /* Update all refs, then purge them as no longer necessary: also update

     the strtab appropriately.  */

  while ((err = ctf_dynhash_next (fp->ctf_str_atoms, &it, NULL, &v)) == 0)

    {

      ctf_str_atom_t *atom = (ctf_str_atom_t *) v;

      uint32_t offset;

      if (ctf_list_empty_p (&atom->csa_refs) &&

    ctf_list_empty_p (&atom->csa_movable_refs))

  continue;

      if (atom->csa_external_offset)

  {

    any_external = 1;

    offset = atom->csa_external_offset;

  }

      else

  offset = atom->csa_offset;

      ctf_str_update_refs (atom, offset);

    }

  if (err != ECTF_NEXT_END)

    {

      ctf_dprintf ("ctf_str_write_strtab: error iterating over atoms while updating refs: %s\n",

       ctf_errmsg (err));

      goto err_strtab;

    }

  ctf_str_purge_refs (fp);

  if (!any_external)

    {

      ctf_dynhash_destroy (fp->ctf_syn_ext_strtab);

      fp->ctf_syn_ext_strtab = NULL;

    }

  /* Replace the old strtab with the new one in this dict.  */

  if (fp->ctf_dynstrtab)

    {

      free (fp->ctf_dynstrtab->cts_strs);

      free (fp->ctf_dynstrtab);

    }

  fp->ctf_dynstrtab = strtab;

  fp->ctf_str[CTF_STRTAB_0].cts_strs = strtab->cts_strs;

  fp->ctf_str[CTF_STRTAB_0].cts_len = strtab->cts_len;

  /* All the provisional strtab entries are now real strtab entries, and

     ctf_strptr() will find them there.  The provisional offset now starts right

     beyond the new end of the strtab.  */

  ctf_dynhash_empty (fp->ctf_prov_strtab);

  fp->ctf_str_prov_offset = strtab->cts_len + 1;

  return strtab;

 err_sorttab:

  free (sorttab);

 err_strtab:

  free (strtab);

  return NULL;

}