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-rw-r--r--iconv/gconv_db.c538
1 files changed, 538 insertions, 0 deletions
diff --git a/iconv/gconv_db.c b/iconv/gconv_db.c
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+++ b/iconv/gconv_db.c
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+/* Provide access to the collection of available transformation modules.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <gconv.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include <bits/libc-lock.h>
+
+
+/* Simple data structure for alias mapping.  We have two names, `from'
+   and `to'.  */
+void *__gconv_alias_db;
+
+/* Array with available modules.  */
+size_t __gconv_nmodules;
+struct gconv_module **__gconv_modules_db;
+
+
+/* Function for searching alias.  */
+int
+__gconv_alias_compare (const void *p1, const void *p2)
+{
+  struct gconv_alias *s1 = (struct gconv_alias *) p1;
+  struct gconv_alias *s2 = (struct gconv_alias *) p2;
+  return __strcasecmp (s1->fromname, s2->fromname);
+}
+
+
+/* To search for a derivation we create a list of intermediate steps.
+   Each element contains a pointer to the element which precedes it
+   in the derivation order.  */
+struct derivation_step
+{
+  const char *result_set;
+  struct gconv_module *code;
+  struct derivation_step *last;
+  struct derivation_step *next;
+};
+
+#define NEW_STEP(result, module, last_mod) \
+  ({ struct derivation_step *newp = alloca (sizeof (struct derivation_step)); \
+     newp->result_set = result;						      \
+     newp->code = module;						      \
+     newp->last = last_mod;						      \
+     newp->next = NULL;							      \
+     newp; })
+
+
+/* If a specific transformation is used more than once we should not need
+   to start looking for it again.  Instead cache each successful result.  */
+struct known_derivation
+{
+  const char *from;
+  const char *to;
+  struct gconv_step *steps;
+  size_t nsteps;
+};
+
+/* Compare function for database of found derivations.  */
+static int
+derivation_compare (const void *p1, const void *p2)
+{
+  struct known_derivation *s1 = (struct known_derivation *) p1;
+  struct known_derivation *s2 = (struct known_derivation *) p2;
+  int result;
+
+  result = strcmp (s1->from, s2->from);
+  if (result == 0)
+    result = strcmp (s1->to, s2->to);
+  return result;
+}
+
+/* The search tree for known derivations.  */
+static void *known_derivations;
+
+/* Look up whether given transformation was already requested before.  */
+static int
+derivation_lookup (const char *fromset, const char *toset,
+		   struct gconv_step **handle, size_t *nsteps)
+{
+  struct known_derivation key = { fromset, toset, NULL, 0 };
+  struct known_derivation *result;
+
+  result = __tfind (&key, known_derivations, derivation_compare);
+
+  if (result == NULL)
+    return GCONV_NOCONV;
+
+  *handle = result->steps;
+  *nsteps = result->nsteps;
+
+  /* Please note that we return GCONV_OK even if the last search for
+     this transformation was unsuccessful.  */
+  return GCONV_OK;
+}
+
+/* Add new derivation to list of known ones.  */
+static void
+add_derivation (const char *fromset, const char *toset,
+		struct gconv_step *handle, size_t nsteps)
+{
+  struct known_derivation *new_deriv;
+  size_t fromset_len = strlen (fromset) + 1;
+  size_t toset_len = strlen (toset) + 1;
+
+  new_deriv = (struct known_derivation *)
+    malloc (sizeof (struct known_derivation) + fromset_len + toset_len);
+  if (new_deriv != NULL)
+    {
+      new_deriv->from = memcpy ((char *) new_deriv
+				+ sizeof (struct known_derivation),
+				fromset, fromset_len);
+      new_deriv->to = memcpy ((char *) new_deriv->from + fromset_len,
+			      toset, toset_len);
+
+      new_deriv->steps = handle;
+      new_deriv->nsteps = nsteps;
+
+      __tsearch (new_deriv, &known_derivations, derivation_compare);
+    }
+  /* Please note that we don't complain if the allocation failed.  This
+     is not tragically but in case we use the memory debugging facilities
+     not all memory will be freed.  */
+}
+
+static void
+free_derivation (void *p)
+{
+  struct known_derivation *deriv = (struct known_derivation *) p;
+
+  free ((struct gconv_step *) deriv->steps);
+  free (deriv);
+}
+
+
+static int
+internal_function
+gen_steps (struct derivation_step *best, const char *toset,
+	   const char *fromset, struct gconv_step **handle, size_t *nsteps)
+{
+  size_t step_cnt = 0;
+  struct gconv_step *result;
+  struct derivation_step *current;
+  int status = GCONV_NOMEM;
+
+  /* First determine number of steps.  */
+  for (current = best; current->last != NULL; current = current->last)
+    ++step_cnt;
+
+  result = (struct gconv_step *) malloc (sizeof (struct gconv_step)
+					 * step_cnt);
+  if (result != NULL)
+    {
+      current = best;
+      while (step_cnt-- > 0)
+	{
+	  result[step_cnt].from_name = current->last->result_set;
+	  result[step_cnt].to_name = current->result_set;
+
+	  if (current->code->module_name[0] == '/')
+	    {
+	      /* Load the module, return handle for it.  */
+	      void *shlib_handle =
+		__gconv_find_shlib (current->code->module_name);
+
+	      if (shlib_handle == NULL)
+		break;
+
+	      result[step_cnt].shlib_handle = shlib_handle;
+
+	      result[step_cnt].fct = __gconv_find_func (shlib_handle, "gconv");
+	      if (result[step_cnt].fct == NULL)
+		{
+		  /* Argh, no conversion function.  There is something
+		     wrong here.  */
+		  __gconv_release_shlib (result[step_cnt].shlib_handle);
+		  break;
+		}
+
+	      result[step_cnt].init_fct = __gconv_find_func (shlib_handle,
+							     "gconv_init");
+	      result[step_cnt].end_fct = __gconv_find_func (shlib_handle,
+							    "gconv_end");
+	    }
+	  else
+	    /* It's a builtin transformation.  */
+	    __gconv_get_builtin_trans (current->code->module_name,
+				       &result[step_cnt]);
+
+	  current = current->last;
+	}
+
+      if (step_cnt != 0)
+	{
+	  /* Something went wrong while initializing the modules.  */
+	  while (step_cnt-- > 0)
+	    __gconv_release_shlib (result[step_cnt].shlib_handle);
+	  free (result);
+	  status = GCONV_NOCONV;
+	}
+      else
+	{
+	  *handle = result;
+	  *nsteps = step_cnt;
+	  status = GCONV_OK;
+	}
+    }
+
+  return status;
+}
+
+
+/* The main function: find a possible derivation from the `fromset' (either
+   the given name or the alias) to the `toset' (again with alias).  */
+static int
+find_derivation (const char *toset, const char *toset_expand,
+		 const char *fromset, const char *fromset_expand,
+		 struct gconv_step **handle, size_t *nsteps)
+{
+  __libc_lock_define_initialized (static, lock)
+  struct derivation_step *current, **lastp, *best = NULL;
+  int best_cost = 0;
+  int result;
+
+  result = derivation_lookup (fromset_expand ?: fromset, toset_expand ?: toset,
+			      handle, nsteps);
+  if (result == GCONV_OK)
+    return result;
+
+  __libc_lock_lock (lock);
+
+  /* There is a small chance that this derivation is meanwhile found.  This
+     can happen if in `find_derivation' we look for this derivation, didn't
+     find it but at the same time another thread looked for this derivation. */
+  result = derivation_lookup (fromset_expand ?: fromset, toset_expand ?: toset,
+			      handle, nsteps);
+  if (result == GCONV_OK)
+    return result;
+
+  /* ### TODO
+     For now we use a simple algorithm with quadratic runtime behaviour.
+     The task is to match the `toset' with any of the available.  */
+  if (fromset_expand != NULL)
+    {
+      current = NEW_STEP (fromset_expand, NULL, NULL);
+      current->next = NEW_STEP (fromset, NULL, NULL);
+      lastp = &current->next->next;
+    }
+  else
+    {
+      current = NEW_STEP (fromset, NULL, NULL);
+      lastp = &current->next;
+    }
+
+  while (current != NULL)
+    {
+      /* Now match all the available module specifications against the
+         current charset name.  If any of them matches check whether
+         we already have a derivation for this charset.  If yes, use the
+         one with the lower costs.  Otherwise add the new charset at the
+         end.  */
+      size_t cnt;
+
+      for (cnt = 0; cnt < __gconv_nmodules; ++cnt)
+        {
+	  const char *result_set = NULL;
+
+	  if (__gconv_modules_db[cnt]->from_pattern == NULL)
+	    {
+	      if (__strcasecmp (current->result_set,
+				__gconv_modules_db[cnt]->from_constpfx) == 0)
+		{
+		  if (strcmp (__gconv_modules_db[cnt]->to_string, "-") == 0)
+		    result_set = toset_expand ?: toset;
+		  else
+		    result_set = __gconv_modules_db[cnt]->to_string;
+		}
+	    }
+	  else
+	    /* We have a regular expression.  First see if the prefix
+	       matches.  */
+	    if (__strncasecmp (current->result_set,
+			       __gconv_modules_db[cnt]->from_constpfx,
+			       __gconv_modules_db[cnt]->from_constpfx_len)
+		== 0)
+	      {
+		/* First compile the regex if not already done.  */
+		if (__gconv_modules_db[cnt]->from_regex == NULL)
+		  {
+		    regex_t *newp = (regex_t *) malloc (sizeof (regex_t));
+
+		    if (regcomp (newp, __gconv_modules_db[cnt]->from_pattern,
+				 REG_EXTENDED | REG_ICASE) != 0)
+		      {
+			/* Something is wrong.  Remember this.  */
+			free (newp);
+			__gconv_modules_db[cnt]->from_regex = (regex_t *) -1L;
+		      }
+		    else
+		      __gconv_modules_db[cnt]->from_regex = newp;
+		  }
+
+		if (__gconv_modules_db[cnt]->from_regex != (regex_t *) -1L)
+		  {
+		    /* Try to match the from name.  */
+		    regmatch_t match[4];
+
+		    if (regexec (__gconv_modules_db[cnt]->from_regex,
+				 current->result_set, 4, match, 0) == 0
+			&& match[0].rm_so == 0
+			&& current->result_set[match[0].rm_eo] == '\0')
+		      {
+			/* At least the whole <from> string is matched.
+			   We must now match sed-like possible
+			   subexpressions from the match to the
+			   toset expression.  */
+#define ENSURE_LEN(LEN) \
+  if (wp + (LEN) >= constr + len - 1)					      \
+    {									      \
+      char *newp = alloca (len += 128);					      \
+      memcpy (newp, constr, wp - constr);				      \
+      wp = newp + (wp - constr);					      \
+      constr = newp;							      \
+    }
+			size_t len = 128;
+			char *constr = alloca (len);
+			char *wp = constr;
+			const char *cp = __gconv_modules_db[cnt]->to_string;
+
+			while (*cp != '\0')
+			  {
+			    if (*cp != '\\')
+			      {
+				ENSURE_LEN (1);
+				*wp++ = *cp++;
+			      }
+			    else if (cp[1] == '\0')
+			      /* Backslash at end of string.  */
+			      break;
+			    else
+			      {
+				++cp;
+				if (*cp == '\\')
+				  {
+				    *wp++ = *cp++;
+				    ENSURE_LEN (1);
+				  }
+				else if (*cp < '1' || *cp > '3')
+				  break;
+				else
+				  {
+				    int idx = *cp - '0';
+				    if (match[idx].rm_so == -1)
+				      /* No match.  */
+				      break;
+
+				    ENSURE_LEN (match[idx].rm_eo
+						- match[idx].rm_so);
+				    wp = __mempcpy (wp,
+						    &current->result_set[match[idx].rm_so],
+						    match[idx].rm_eo
+						    - match[idx].rm_so);
+				    ++cp;
+				  }
+			      }
+			  }
+			if (*cp == '\0' && wp != constr)
+			  {
+                                /* Terminate the constructed string.  */
+			    *wp = '\0';
+			    result_set = constr;
+			  }
+		      }
+		  }
+	      }
+
+	  if (result_set != NULL)
+	    {
+	      /* We managed to find a derivation.  First see whether
+		 this is what we are looking for.  */
+	      if (__strcasecmp (result_set, toset) == 0
+		  || (toset_expand != NULL
+		      && __strcasecmp (result_set, toset_expand) == 0))
+		{
+		  /* Determine the costs.  If they are lower than the
+		     previous solution (or this is the first solution)
+		     remember this solution.  */
+		  int cost = __gconv_modules_db[cnt]->cost;
+		  struct derivation_step *runp = current;
+		  while (runp->code != NULL)
+		    {
+		      cost += runp->code->cost;
+		      runp = runp->last;
+		    }
+		  if (best == NULL || cost < best_cost)
+		    {
+		      best = NEW_STEP (result_set, __gconv_modules_db[cnt],
+				       current);
+		      best_cost = cost;
+		    }
+		}
+	      else
+		{
+		  /* Append at the end.  */
+		  *lastp = NEW_STEP (result_set, __gconv_modules_db[cnt],
+				     current);
+		  lastp = &(*lastp)->next;
+                }
+	    }
+	}
+    }
+
+  if (best != NULL)
+    /* We really found a way to do the transformation.  Now build a data
+       structure describing the transformation steps.*/
+    result = gen_steps (best, toset_expand ?: toset, fromset_expand ?: fromset,
+			handle, nsteps);
+  else
+    {
+      /* We haven't found a transformation.  Clear the result values.  */
+      *handle = NULL;
+      *nsteps = 0;
+    }
+
+  /* Add result in any case to list of known derivations.  */
+  add_derivation (fromset_expand ?: fromset, toset_expand ?: toset,
+		  *handle, *nsteps);
+
+  __libc_lock_unlock (lock);
+
+  return result;
+}
+
+
+int
+__gconv_find_transform (const char *toset, const char *fromset,
+			struct gconv_step **handle, size_t *nsteps)
+{
+  __libc_once_define (static, once);
+  const char *fromset_expand = NULL;
+  const char *toset_expand = NULL;
+  int result;
+
+  /* Ensure that the configuration data is read.  */
+  __libc_once (once, __gconv_read_conf);
+
+  /* If we don't have a module database return with an error.  */
+  if (__gconv_modules_db == NULL)
+    return GCONV_NOCONV;
+
+  /* See whether the names are aliases.  */
+  if (__gconv_alias_db != NULL)
+    {
+      struct gconv_alias key;
+      struct gconv_alias *found;
+
+      key.fromname = fromset;
+      found = __tfind (&key, __gconv_alias_db, __gconv_alias_compare);
+      fromset_expand = found != NULL ? found->toname : NULL;
+
+      key.fromname = toset;
+      found = __tfind (&key, __gconv_alias_db, __gconv_alias_compare);
+      toset_expand = found != NULL ? found->toname : NULL;
+    }
+
+  result = find_derivation (toset, toset_expand, fromset, fromset_expand,
+			    handle, nsteps);
+
+  /* The following code is necessary since `find_derivation' will return
+     GCONV_OK even when no derivation was found but the same request
+     was processed before.  I.e., negative results will also be cached.  */
+  return (result == GCONV_OK
+	  ? (*handle == NULL ? GCONV_NOCONV : GCONV_OK)
+	  : result);
+}
+
+
+/* Release the entries of the modules list.  */
+int
+__gconv_close_transform (struct gconv_step *steps, size_t nsteps)
+{
+  int result = GCONV_OK;
+
+  while (nsteps-- > 0)
+    if (steps[nsteps].shlib_handle != NULL)
+      {
+	result = __gconv_release_shlib (steps[nsteps].shlib_handle);
+	if (result != GCONV_OK)
+	  break;
+      }
+
+  return result;
+}
+
+
+/* Free all resources if necessary.  */
+static void __attribute__ ((unused))
+free_mem (void)
+{
+  size_t cnt;
+
+  if (__gconv_alias_db != NULL)
+    __tdestroy (__gconv_alias_db, free);
+
+  for (cnt = 0; cnt < __gconv_nmodules; ++cnt)
+    {
+      if (__gconv_modules_db[cnt]->from_regex != NULL)
+	regfree ((regex_t *) __gconv_modules_db[cnt]->from_regex);
+
+      /* Modules which names do not start with a slash are builtin
+	 transformations and the memory is not allocated dynamically.  */
+      if (__gconv_modules_db[cnt]->module_name[0] == '/')
+	free (__gconv_modules_db[cnt]);
+    }
+
+  if (known_derivations != NULL)
+    __tdestroy (known_derivations, free_derivation);
+}
+
+text_set_element (__libc_subfreeres, free_mem);