Use double linked list instead of static array of 255 global objects.

1 files changed, 68 insertions, 35 deletions

diff --git a/dlfcn.c b/dlfcn.c
index 4c82304..f0efc22 100644
--- a/dlfcn.c
+++ b/dlfcn.c
@@ -27,43 +27,76 @@
  * any kind of thread safety.

  */

 

-/* I have no special reason to have set MAX_GLOBAL_OBJECTS to this value. Any

- * comments are welcome.

- */

-#define MAX_OBJECTS 255

+typedef struct global_object {

+    HMODULE hModule;

+    struct global_object *previous;

+    struct global_object *next;

+} global_object;

 

-static HMODULE global_objects[MAX_OBJECTS];

+static global_object first_object;

 

-/* This function adds an object to the list of global objects.

- * The implementation is very simple and slow.

- * TODO: should failing this function be enough to fail the call to dlopen( )?

- */

-static void global_object_add( HMODULE hModule )

+/* These functions implement a double linked list for the global objects. */

+static global_object *global_search( HMODULE hModule )

 {

-    int i;

+    global_object *pobject;

 

-    for( i = 0 ; i < MAX_OBJECTS ; i++ )

-    {

-        if( !global_objects[i] )

-        {

-            global_objects[i] = hModule;

-            break;

-        }

-    }

+    if( hModule == NULL )

+        return NULL;

+

+    for( pobject = &first_object; pobject ; pobject = pobject->next )

+        if( pobject->hModule == hModule )

+            return pobject;

+

+    return NULL;

 }

 

-static void global_object_rem( HMODULE hModule )

+static void global_add( HMODULE hModule )

 {

-    int i;

+    global_object *pobject;

+    global_object *nobject;

 

-    for( i = 0 ; i < MAX_OBJECTS ; i++ )

-    {

-        if( global_objects[i] == hModule )

-        {

-            global_objects[i] = 0;

-            break;

-        }

-    }

+    if( hModule == NULL )

+        return;

+

+    pobject = global_search( hModule );

+

+    /* Do not add object again if it's already on the list */

+    if( pobject )

+        return;

+

+    for( pobject = &first_object; pobject->next ; pobject = pobject->next );

+

+    nobject = malloc( sizeof(global_object) );

+

+    /* Should this be enough to fail global_add, and therefore also fail

+     * dlopen?

+     */

+    if( !nobject )

+        return;

+

+    pobject->next = nobject;

+    nobject->previous = pobject;

+    nobject->hModule = hModule;

+}

+

+static void global_rem( HMODULE hModule )

+{

+    global_object *pobject;

+

+    if( hModule == NULL )

+        return;

+

+    pobject = global_search( hModule );

+

+    if( !pobject )

+        return;

+

+    if( pobject->next )

+        pobject->next->previous = pobject->previous;

+    if( pobject->previous )

+        pobject->previous->next = pobject->next;

+

+    free( pobject );

 }

 

 /* POSIX says dlerror( ) doesn't have to be thread-safe, so we use one

@@ -191,7 +224,7 @@ void *dlopen( const char *file, int mode )
         if( !hModule )

             save_err_str( lpFileName );

         else if( (mode & RTLD_GLOBAL) )

-            global_object_add( hModule );

+            global_add( hModule );

     }

 

     /* Return to previous state of the error-mode bit flags. */

@@ -213,7 +246,7 @@ int dlclose( void *handle )
      * objects.

      */

     if( ret )

-        global_object_rem( hModule );

+        global_rem( hModule );

     else

         save_err_ptr( handle );

 

@@ -243,13 +276,13 @@ void *dlsym( void *handle, const char *name )
 

         if( hModule == handle )

         {

-            int i;

+            global_object *pobject;

 

-            for( i = 0 ; i < MAX_OBJECTS ; i++ )

+            for( pobject = &first_object; pobject ; pobject = pobject->next )

             {

-                if( global_objects[i] != 0 )

+                if( pobject->hModule )

                 {

-                    symbol = GetProcAddress( global_objects[i], name );

+                    symbol = GetProcAddress( pobject->hModule, name );

                     if( symbol != NULL )

                         break;

                 }