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Diffstat (limited to 'iconv/gconv_db.c')
-rw-r--r--iconv/gconv_db.c255
1 files changed, 167 insertions, 88 deletions
diff --git a/iconv/gconv_db.c b/iconv/gconv_db.c
index ed2698a628..dd51670af1 100644
--- a/iconv/gconv_db.c
+++ b/iconv/gconv_db.c
@@ -163,7 +163,8 @@ free_derivation (void *p)
size_t cnt;
for (cnt = 0; cnt < deriv->nsteps; ++cnt)
- if (deriv->steps[cnt].__end_fct)
+ if (deriv->steps[cnt].__counter > 0
+ && deriv->steps[cnt].__end_fct != NULL)
DL_CALL_FCT (deriv->steps[cnt].__end_fct, (&deriv->steps[cnt]));
/* Free the name strings. */
@@ -175,6 +176,28 @@ free_derivation (void *p)
}
+/* Decrement the reference count for a single step in a steps array. */
+static inline void
+release_step (struct __gconv_step *step)
+{
+ if (--step->__counter == 0)
+ {
+ /* Call the destructor. */
+ if (step->__end_fct != NULL)
+ DL_CALL_FCT (step->__end_fct, (step));
+
+#ifndef STATIC_GCONV
+ /* Skip builtin modules; they are not reference counted. */
+ if (step->__shlib_handle != NULL)
+ {
+ /* Release the loaded module. */
+ __gconv_release_shlib (step->__shlib_handle);
+ step->__shlib_handle = NULL;
+ }
+#endif
+ }
+}
+
static int
internal_function
gen_steps (struct derivation_step *best, const char *toset,
@@ -222,7 +245,6 @@ gen_steps (struct derivation_step *best, const char *toset,
result[step_cnt].__shlib_handle = shlib_handle;
result[step_cnt].__modname = shlib_handle->name;
- result[step_cnt].__counter = 1;
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;
@@ -233,6 +255,8 @@ gen_steps (struct derivation_step *best, const char *toset,
__gconv_get_builtin_trans (current->code->module_name,
&result[step_cnt]);
+ result[step_cnt].__counter = 1;
+
/* Call the init function. */
result[step_cnt].__data = NULL;
if (result[step_cnt].__init_fct != NULL)
@@ -245,6 +269,7 @@ gen_steps (struct derivation_step *best, const char *toset,
failed = 1;
/* Make sure we unload this modules. */
--step_cnt;
+ result[step_cnt].__end_fct = NULL;
break;
}
}
@@ -256,13 +281,7 @@ gen_steps (struct derivation_step *best, const char *toset,
{
/* Something went wrong while initializing the modules. */
while (++step_cnt < *nsteps)
- {
- if (result[step_cnt].__end_fct != NULL)
- DL_CALL_FCT (result[step_cnt].__end_fct, (&result[step_cnt]));
-#ifndef STATIC_GCONV
- __gconv_release_shlib (result[step_cnt].__shlib_handle);
-#endif
- }
+ release_step (&result[step_cnt]);
free (result);
*nsteps = 0;
*handle = NULL;
@@ -292,29 +311,38 @@ increment_counter (struct __gconv_step *steps, size_t nsteps)
int result = __GCONV_OK;
while (cnt-- > 0)
- if (steps[cnt].__counter++ == 0)
- {
- steps[cnt].__shlib_handle =
- __gconv_find_shlib (steps[cnt].__modname);
- if (steps[cnt].__shlib_handle == NULL)
- {
- /* Oops, this is the second time we use this module (after
- unloading) and this time loading failed!? */
- while (++cnt < nsteps)
- __gconv_release_shlib (steps[cnt].__shlib_handle);
- result = __GCONV_NOCONV;
- break;
- }
-
- steps[cnt].__init_fct = steps[cnt].__shlib_handle->init_fct;
- steps[cnt].__fct = steps[cnt].__shlib_handle->fct;
- steps[cnt].__end_fct = steps[cnt].__shlib_handle->end_fct;
-
- if (steps[cnt].__end_fct != NULL)
- DL_CALL_FCT (steps[cnt].__end_fct, (&steps[cnt]));
- if (steps[cnt].__init_fct != NULL)
- DL_CALL_FCT (steps[cnt].__init_fct, (&steps[cnt]));
- }
+ {
+ 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)
+ 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;
+ }
+
+ if (step->__init_fct != NULL)
+ DL_CALL_FCT (step->__init_fct, (step));
+ }
+ }
return result;
}
#endif
@@ -333,9 +361,8 @@ find_derivation (const char *toset, const char *toset_expand,
int best_cost_lo = INT_MAX;
int result;
- /* 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. */
+ /* 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)
@@ -346,9 +373,32 @@ find_derivation (const char *toset, const char *toset_expand,
return result;
}
- /* For now we use a simple algorithm with quadratic runtime behaviour.
- The task is to match the `toset' with any of the available rules,
- starting from FROMSET. */
+ /* 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);
@@ -373,16 +423,17 @@ find_derivation (const char *toset, const char *toset_expand,
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 = __gconv_modules_db;
+ 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 heigher) as
+ 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);
@@ -404,37 +455,52 @@ find_derivation (const char *toset, const char *toset_expand,
struct derivation_step *step;
/* We managed to find a derivation. First see whether
- this is what we are looking for. */
+ we have reached one of the goal nodes. */
if (strcmp (result_set, toset) == 0
|| (toset_expand != NULL
&& strcmp (result_set, toset_expand) == 0))
{
- if (solution == NULL || cost_hi < best_cost_hi
+ /* 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;
}
-
- /* Append this solution to list. */
- if (solution == NULL)
- solution = NEW_STEP (result_set, 0, 0, runp, current);
- else
- {
- while (solution->next != NULL)
- solution = solution->next;
-
- solution->next = NEW_STEP (result_set, 0, 0,
- runp, current);
- }
}
else if (cost_hi < best_cost_hi
|| (cost_hi == best_cost_hi
&& cost_lo < best_cost_lo))
{
- /* Append at the end if there is no entry with
- this name. */
+ /* 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;
@@ -450,31 +516,36 @@ find_derivation (const char *toset, const char *toset_expand,
|| (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)
- {
- struct derivation_step *back;
-
- if (step->code == NULL)
- /* This is one of the entries we started
- from. */
- continue;
-
- step->cost_hi = step->code->cost_hi;
- step->cost_lo = step->code->cost_lo;
-
- for (back = step->last; back->code != NULL;
- back = back->last)
- {
- step->cost_hi += back->code->cost_hi;
- step->cost_lo += back->code->cost_lo;
- }
- }
-
+ /* 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)
{
@@ -487,7 +558,6 @@ find_derivation (const char *toset, const char *toset_expand,
|| (step->cost_hi == best_cost_hi
&& step->cost_lo < best_cost_lo))
{
- solution = step;
best_cost_hi = step->cost_hi;
best_cost_lo = step->cost_lo;
}
@@ -509,10 +579,26 @@ find_derivation (const char *toset, const char *toset_expand,
}
if (solution != NULL)
- /* We really found a way to do the transformation. Now build a data
- structure describing the transformation steps.*/
- result = gen_steps (solution, toset_expand ?: toset,
- fromset_expand ?: fromset, handle, nsteps);
+ {
+ /* 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. */
@@ -609,14 +695,7 @@ __gconv_close_transform (struct __gconv_step *steps, size_t nsteps)
__libc_lock_lock (lock);
while (nsteps-- > 0)
- if (steps[nsteps].__shlib_handle != NULL
- && --steps[nsteps].__counter == 0)
- {
- result = __gconv_release_shlib (steps[nsteps].__shlib_handle);
- if (result != __GCONV_OK)
- break;
- steps[nsteps].__shlib_handle = NULL;
- }
+ release_step (&steps[nsteps]);
/* Release the lock. */
__libc_lock_unlock (lock);