/* Provide access to the collection of available transformation modules. Copyright (C) 1997-2021 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #include #include #include #include #include #include #include #include #include #include #include /* Simple data structure for alias mapping. We have two names, `from' and `to'. */ void *__gconv_alias_db; /* Array with available modules. */ struct gconv_module *__gconv_modules_db; /* We modify global data. */ __libc_lock_define_initialized (, __gconv_lock) /* Provide access to module database. */ struct gconv_module * __gconv_get_modules_db (void) { return __gconv_modules_db; } void * __gconv_get_alias_db (void) { return __gconv_alias_db; } /* Function for searching alias. */ int __gconv_alias_compare (const void *p1, const void *p2) { const struct gconv_alias *s1 = (const struct gconv_alias *) p1; const struct gconv_alias *s2 = (const struct gconv_alias *) p2; return strcmp (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; size_t result_set_len; int cost_lo; int cost_hi; struct gconv_module *code; struct derivation_step *last; struct derivation_step *next; }; #define NEW_STEP(result, hi, lo, module, last_mod) \ ({ struct derivation_step *newp = alloca (sizeof (struct derivation_step)); \ newp->result_set = result; \ newp->result_set_len = strlen (result); \ newp->cost_hi = hi; \ newp->cost_lo = lo; \ 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) { const struct known_derivation *s1 = (const struct known_derivation *) p1; const struct known_derivation *s2 = (const 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 = (char *) (new_deriv + 1); new_deriv->to = memcpy (__mempcpy (new_deriv + 1, fromset, fromset_len), toset, toset_len); new_deriv->steps = handle; new_deriv->nsteps = nsteps; if (__tsearch (new_deriv, &known_derivations, derivation_compare) == NULL) /* There is some kind of memory allocation problem. */ free (new_deriv); } /* 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 __libc_freeres_fn_section free_derivation (void *p) { struct known_derivation *deriv = (struct known_derivation *) p; size_t cnt; for (cnt = 0; cnt < deriv->nsteps; ++cnt) if (deriv->steps[cnt].__counter > 0 && deriv->steps[cnt].__shlib_handle != NULL) { __gconv_end_fct end_fct = deriv->steps[cnt].__end_fct; #ifdef PTR_DEMANGLE PTR_DEMANGLE (end_fct); #endif if (end_fct != NULL) DL_CALL_FCT (end_fct, (&deriv->steps[cnt])); } /* Free the name strings. */ if (deriv->steps != NULL) { free ((char *) deriv->steps[0].__from_name); free ((char *) deriv->steps[deriv->nsteps - 1].__to_name); free ((struct __gconv_step *) deriv->steps); } free (deriv); } /* Decrement the reference count for a single step in a steps array. */ void __gconv_release_step (struct __gconv_step *step) { /* Skip builtin modules; they are not reference counted. */ if (step->__shlib_handle != NULL && --step->__counter == 0) { /* Call the destructor. */ __gconv_end_fct end_fct = step->__end_fct; #ifdef PTR_DEMANGLE PTR_DEMANGLE (end_fct); #endif if (end_fct != NULL) DL_CALL_FCT (end_fct, (step)); #ifndef STATIC_GCONV /* Release the loaded module. */ __gconv_release_shlib (step->__shlib_handle); step->__shlib_handle = NULL; #endif } else if (step->__shlib_handle == NULL) /* Builtin modules should not have end functions. */ assert (step->__end_fct == NULL); } static int 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; char *from_name = NULL; char *to_name = NULL; /* 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) { int failed = 0; status = __GCONV_OK; *nsteps = step_cnt; current = best; while (step_cnt-- > 0) { if (step_cnt == 0) { result[step_cnt].__from_name = from_name = __strdup (fromset); if (from_name == NULL) { failed = 1; break; } } else result[step_cnt].__from_name = (char *)current->last->result_set; if (step_cnt + 1 == *nsteps) { result[step_cnt].__to_name = to_name = __strdup (current->result_set); if (to_name == NULL) { failed = 1; break; } } else result[step_cnt].__to_name = result[step_cnt + 1].__from_name; result[step_cnt].__counter = 1; result[step_cnt].__data = NULL; #ifndef STATIC_GCONV if (current->code->module_name[0] == '/') { /* Load the module, return handle for it. */ struct __gconv_loaded_object *shlib_handle = __gconv_find_shlib (current->code->module_name); if (shlib_handle == NULL) { failed = 1; break; } result[step_cnt].__shlib_handle = shlib_handle; result[step_cnt].__modname = shlib_handle->name; result[step_cnt].__fct = shlib_handle->fct; result[step_cnt].__init_fct = shlib_handle->init_fct; result[step_cnt].__end_fct = shlib_handle->end_fct; /* These settings can be overridden by the init function. */ result[step_cnt].__btowc_fct = NULL; /* Call the init function. */ __gconv_init_fct init_fct = result[step_cnt].__init_fct; # ifdef PTR_DEMANGLE PTR_DEMANGLE (init_fct); # endif if (init_fct != NULL) { status = DL_CALL_FCT (init_fct, (&result[step_cnt])); if (__builtin_expect (status, __GCONV_OK) != __GCONV_OK) { failed = 1; /* Do not call the end function because the init function has failed. */ result[step_cnt].__end_fct = NULL; # ifdef PTR_MANGLE PTR_MANGLE (result[step_cnt].__end_fct); # endif /* Make sure we unload this module. */ --step_cnt; break; } } # ifdef PTR_MANGLE PTR_MANGLE (result[step_cnt].__btowc_fct); # endif } else #endif /* It's a builtin transformation. */ __gconv_get_builtin_trans (current->code->module_name, &result[step_cnt]); current = current->last; } if (__builtin_expect (failed, 0) != 0) { /* Something went wrong while initializing the modules. */ while (++step_cnt < *nsteps) __gconv_release_step (&result[step_cnt]); free (result); free (from_name); free (to_name); *nsteps = 0; *handle = NULL; if (status == __GCONV_OK) status = __GCONV_NOCONV; } else *handle = result; } else { *nsteps = 0; *handle = NULL; } return status; } #ifndef STATIC_GCONV static int increment_counter (struct __gconv_step *steps, size_t nsteps) { /* Increment the user counter. */ size_t cnt = nsteps; int result = __GCONV_OK; while (cnt-- > 0) { struct __gconv_step *step = &steps[cnt]; if (step->__counter++ == 0) { /* Skip builtin modules. */ if (step->__modname != NULL) { /* Reopen a previously used module. */ step->__shlib_handle = __gconv_find_shlib (step->__modname); if (step->__shlib_handle == NULL) { /* Oops, this is the second time we use this module (after unloading) and this time loading failed!? */ --step->__counter; while (++cnt < nsteps) __gconv_release_step (&steps[cnt]); result = __GCONV_NOCONV; break; } /* The function addresses defined by the module may have changed. */ step->__fct = step->__shlib_handle->fct; step->__init_fct = step->__shlib_handle->init_fct; step->__end_fct = step->__shlib_handle->end_fct; /* These settings can be overridden by the init function. */ step->__btowc_fct = NULL; /* Call the init function. */ __gconv_init_fct init_fct = step->__init_fct; #ifdef PTR_DEMANGLE PTR_DEMANGLE (init_fct); #endif if (init_fct != NULL) DL_CALL_FCT (init_fct, (step)); #ifdef PTR_MANGLE PTR_MANGLE (step->__btowc_fct); #endif } } } return result; } #endif /* 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) { struct derivation_step *first, *current, **lastp, *solution = NULL; int best_cost_hi = INT_MAX; int best_cost_lo = INT_MAX; int result; /* Look whether an earlier call to `find_derivation' has already computed a possible derivation. If so, return it immediately. */ result = derivation_lookup (fromset_expand ?: fromset, toset_expand ?: toset, handle, nsteps); if (result == __GCONV_OK) { #ifndef STATIC_GCONV result = increment_counter (*handle, *nsteps); #endif return result; } /* The task is to find a sequence of transformations, backed by the existing modules - whether builtin or dynamically loadable -, starting at `fromset' (or `fromset_expand') and ending at `toset' (or `toset_expand'), and with minimal cost. For computer scientists, this is a shortest path search in the graph where the nodes are all possible charsets and the edges are the transformations listed in __gconv_modules_db. For now we use a simple algorithm with quadratic runtime behaviour. A breadth-first search, starting at `fromset' and `fromset_expand'. The list starting at `first' contains all nodes that have been visited up to now, in the order in which they have been visited -- excluding the goal nodes `toset' and `toset_expand' which get managed in the list starting at `solution'. `current' walks through the list starting at `first' and looks which nodes are reachable from the current node, adding them to the end of the list [`first' or `solution' respectively] (if they are visited the first time) or updating them in place (if they have have already been visited). In each node of either list, cost_lo and cost_hi contain the minimum cost over any paths found up to now, starting at `fromset' or `fromset_expand', ending at that node. best_cost_lo and best_cost_hi represent the minimum over the elements of the `solution' list. */ if (fromset_expand != NULL) { first = NEW_STEP (fromset_expand, 0, 0, NULL, NULL); first->next = NEW_STEP (fromset, 0, 0, NULL, NULL); lastp = &first->next->next; } else { first = NEW_STEP (fromset, 0, 0, NULL, NULL); lastp = &first->next; } for (current = first; current != NULL; current = current->next) { /* 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. The module database is organized in a tree form which allows searching for prefixes. So we search for the first entry with a matching prefix and any other matching entry can be found from this place. */ struct gconv_module *node; /* Maybe it is not necessary anymore to look for a solution for this entry since the cost is already as high (or higher) as the cost for the best solution so far. */ if (current->cost_hi > best_cost_hi || (current->cost_hi == best_cost_hi && current->cost_lo >= best_cost_lo)) continue; node = __gconv_modules_db; while (node != NULL) { int cmpres = strcmp (current->result_set, node->from_string); if (cmpres == 0) { /* Walk through the list of modules with this prefix and try to match the name. */ struct gconv_module *runp; /* Check all the modules with this prefix. */ runp = node; do { const char *result_set = (strcmp (runp->to_string, "-") == 0 ? (toset_expand ?: toset) : runp->to_string); int cost_hi = runp->cost_hi + current->cost_hi; int cost_lo = runp->cost_lo + current->cost_lo; struct derivation_step *step; /* We managed to find a derivation. First see whether we have reached one of the goal nodes. */ if (strcmp (result_set, toset) == 0 || (toset_expand != NULL && strcmp (result_set, toset_expand) == 0)) { /* Append to the `solution' list if there is no entry with this name. */ for (step = solution; step != NULL; step = step->next) if (strcmp (result_set, step->result_set) == 0) break; if (step == NULL) { step = NEW_STEP (result_set, cost_hi, cost_lo, runp, current); step->next = solution; solution = step; } else if (step->cost_hi > cost_hi || (step->cost_hi == cost_hi && step->cost_lo > cost_lo)) { /* A better path was found for the node, on the `solution' list. */ step->code = runp; step->last = current; step->cost_hi = cost_hi; step->cost_lo = cost_lo; } /* Update best_cost accordingly. */ if (cost_hi < best_cost_hi || (cost_hi == best_cost_hi && cost_lo < best_cost_lo)) { best_cost_hi = cost_hi; best_cost_lo = cost_lo; } } else if (cost_hi < best_cost_hi || (cost_hi == best_cost_hi && cost_lo < best_cost_lo)) { /* Append at the end of the `first' list if there is no entry with this name. */ for (step = first; step != NULL; step = step->next) if (strcmp (result_set, step->result_set) == 0) break; if (step == NULL) { *lastp = NEW_STEP (result_set, cost_hi, cost_lo, runp, current); lastp = &(*lastp)->next; } else if (step->cost_hi > cost_hi || (step->cost_hi == cost_hi && step->cost_lo > cost_lo)) { /* A better path was found for the node, on the `first' list. */ step->code = runp; step->last = current; /* Update the cost for all steps. */ for (step = first; step != NULL; step = step->next) /* But don't update the start nodes. */ if (step->code != NULL) { struct derivation_step *back; int hi, lo; hi = step->code->cost_hi; lo = step->code->cost_lo; for (back = step->last; back->code != NULL; back = back->last) { hi += back->code->cost_hi; lo += back->code->cost_lo; } step->cost_hi = hi; step->cost_lo = lo; } /* Likewise for the nodes on the solution list. Also update best_cost accordingly. */ for (step = solution; step != NULL; step = step->next) { step->cost_hi = (step->code->cost_hi + step->last->cost_hi); step->cost_lo = (step->code->cost_lo + step->last->cost_lo); if (step->cost_hi < best_cost_hi || (step->cost_hi == best_cost_hi && step->cost_lo < best_cost_lo)) { best_cost_hi = step->cost_hi; best_cost_lo = step->cost_lo; } } } } runp = runp->same; } while (runp != NULL); break; } else if (cmpres < 0) node = node->left; else node = node->right; } } if (solution != NULL) { /* We really found a way to do the transformation. */ /* Choose the best solution. This is easy because we know that the solution list has at most length 2 (one for every possible goal node). */ if (solution->next != NULL) { struct derivation_step *solution2 = solution->next; if (solution2->cost_hi < solution->cost_hi || (solution2->cost_hi == solution->cost_hi && solution2->cost_lo < solution->cost_lo)) solution = solution2; } /* Now build a data structure describing the transformation steps. */ result = gen_steps (solution, 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); return result; } static const char * do_lookup_alias (const char *name) { struct gconv_alias key; struct gconv_alias **found; key.fromname = (char *) name; found = __tfind (&key, &__gconv_alias_db, __gconv_alias_compare); return found != NULL ? (*found)->toname : NULL; } int __gconv_compare_alias (const char *name1, const char *name2) { int result; /* Ensure that the configuration data is read. */ __gconv_load_conf (); if (__gconv_compare_alias_cache (name1, name2, &result) != 0) result = strcmp (do_lookup_alias (name1) ?: name1, do_lookup_alias (name2) ?: name2); return result; } int __gconv_find_transform (const char *toset, const char *fromset, struct __gconv_step **handle, size_t *nsteps, int flags) { const char *fromset_expand; const char *toset_expand; int result; /* Ensure that the configuration data is read. */ __gconv_load_conf (); /* Acquire the lock. */ __libc_lock_lock (__gconv_lock); result = __gconv_lookup_cache (toset, fromset, handle, nsteps, flags); if (result != __GCONV_NODB) { /* We have a cache and could resolve the request, successful or not. */ __libc_lock_unlock (__gconv_lock); return result; } /* If we don't have a module database return with an error. */ if (__gconv_modules_db == NULL) { __libc_lock_unlock (__gconv_lock); return __GCONV_NOCONV; } /* See whether the names are aliases. */ fromset_expand = do_lookup_alias (fromset); toset_expand = do_lookup_alias (toset); if (__builtin_expect (flags & GCONV_AVOID_NOCONV, 0) /* We are not supposed to create a pseudo transformation (means copying) when the input and output character set are the same. */ && (strcmp (toset, fromset) == 0 || (toset_expand != NULL && strcmp (toset_expand, fromset) == 0) || (fromset_expand != NULL && (strcmp (toset, fromset_expand) == 0 || (toset_expand != NULL && strcmp (toset_expand, fromset_expand) == 0))))) { /* Both character sets are the same. */ __libc_lock_unlock (__gconv_lock); return __GCONV_NULCONV; } result = find_derivation (toset, toset_expand, fromset, fromset_expand, handle, nsteps); /* Release the lock. */ __libc_lock_unlock (__gconv_lock); /* 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; size_t cnt; /* Acquire the lock. */ __libc_lock_lock (__gconv_lock); #ifndef STATIC_GCONV cnt = nsteps; while (cnt-- > 0) __gconv_release_step (&steps[cnt]); #endif /* If we use the cache we free a bit more since we don't keep any transformation records around, they are cheap enough to recreate. */ __gconv_release_cache (steps, nsteps); /* Release the lock. */ __libc_lock_unlock (__gconv_lock); return result; } /* Free the modules mentioned. */ static void __libc_freeres_fn_section free_modules_db (struct gconv_module *node) { if (node->left != NULL) free_modules_db (node->left); if (node->right != NULL) free_modules_db (node->right); do { struct gconv_module *act = node; node = node->same; if (act->module_name[0] == '/') free (act); } while (node != NULL); } /* Free all resources if necessary. */ libc_freeres_fn (free_mem) { /* First free locale memory. This needs to be done before freeing derivations, as ctype cleanup functions dereference steps arrays which we free below. */ _nl_locale_subfreeres (); /* finddomain.c has similar problem. */ extern void _nl_finddomain_subfreeres (void) attribute_hidden; _nl_finddomain_subfreeres (); if (__gconv_alias_db != NULL) __tdestroy (__gconv_alias_db, free); if (__gconv_modules_db != NULL) free_modules_db (__gconv_modules_db); if (known_derivations != NULL) __tdestroy (known_derivations, free_derivation); }