Add dlfcn-win32 to third_party

third_party/dlfcn-win32/dlfcn.c

+/*
+ * dlfcn-win32
+ * Copyright (c) 2007 Ramiro Polla
+ *
+ * This 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.
+ *
+ * This 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <windows.h>
+#include <stdio.h>
+
+#include "dlfcn.h"
+
+/* Note:
+ * MSDN says these functions are not thread-safe. We make no efforts to have
+ * any kind of thread safety.
+ */
+
+typedef struct global_object {
+    HMODULE hModule;
+    struct global_object *previous;
+    struct global_object *next;
+} global_object;
+
+static global_object first_object;
+
+/* These functions implement a double linked list for the global objects. */
+static global_object *global_search( HMODULE hModule )
+{
+    global_object *pobject;
+
+    if( hModule == NULL )
+        return NULL;
+
+    for( pobject = &first_object; pobject ; pobject = pobject->next )
+        if( pobject->hModule == hModule )
+            return pobject;
+
+    return NULL;
+}
+
+static void global_add( HMODULE hModule )
+{
+    global_object *pobject;
+    global_object *nobject;
+
+    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->next = NULL;
+    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
+ * static buffer.
+ * MSDN says the buffer cannot be larger than 64K bytes, so we set it to
+ * the limit.
+ */
+static char error_buffer[65535];
+static char *current_error;
+
+static int copy_string( char *dest, int dest_size, const char *src )
+{
+    int i = 0;
+
+    /* gcc should optimize this out */
+    if( !src || !dest )
+        return 0;
+
+    for( i = 0 ; i < dest_size-1 ; i++ )
+    {
+        if( !src[i] )
+            break;
+        else
+            dest[i] = src[i];
+    }
+    dest[i] = '\0';
+
+    return i;
+}
+
+static void save_err_str( const char *str )
+{
+    DWORD dwMessageId;
+    DWORD pos;
+
+    dwMessageId = GetLastError( );
+
+    if( dwMessageId == 0 )
+        return;
+
+    /* Format error message to:
+     * "<argument to function that failed>": <Windows localized error message>
+     */
+    pos  = copy_string( error_buffer,     sizeof(error_buffer),     "\"" );
+    pos += copy_string( error_buffer+pos, sizeof(error_buffer)-pos, str );
+    pos += copy_string( error_buffer+pos, sizeof(error_buffer)-pos, "\": " );
+    pos += FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM, NULL, dwMessageId,
+                          MAKELANGID( LANG_NEUTRAL, SUBLANG_DEFAULT ),
+                          error_buffer+pos, sizeof(error_buffer)-pos, NULL );
+
+    if( pos > 1 )
+    {
+        /* POSIX says the string must not have trailing <newline> */
+        if( error_buffer[pos-2] == '\r' && error_buffer[pos-1] == '\n' )
+            error_buffer[pos-2] = '\0';
+    }
+
+    current_error = error_buffer;
+}
+
+static void save_err_ptr_str( const void *ptr )
+{
+    char ptr_buf[19]; /* 0x<pointer> up to 64 bits. */
+
+    sprintf( ptr_buf, "0x%p", ptr );
+
+    save_err_str( ptr_buf );
+}
+
+void *dlopen( const char *file, int mode )
+{
+    HMODULE hModule;
+    UINT uMode;
+
+    current_error = NULL;
+
+    /* Do not let Windows display the critical-error-handler message box */
+    uMode = SetErrorMode( SEM_FAILCRITICALERRORS );
+
+    if( file == 0 )
+    {
+        /* POSIX says that if the value of file is 0, a handle on a global
+         * symbol object must be provided. That object must be able to access
+         * all symbols from the original program file, and any objects loaded
+         * with the RTLD_GLOBAL flag.
+         * The return value from GetModuleHandle( ) allows us to retrieve
+         * symbols only from the original program file. For objects loaded with
+         * the RTLD_GLOBAL flag, we create our own list later on.
+         */
+        hModule = GetModuleHandle( NULL );
+
+        if( !hModule )
+            save_err_ptr_str( file );
+    }
+    else
+    {
+        char lpFileName[MAX_PATH];
+        int i;
+
+        /* MSDN says backslashes *must* be used instead of forward slashes. */
+        for( i = 0 ; i < sizeof(lpFileName)-1 ; i++ )
+        {
+            if( !file[i] )
+                break;
+            else if( file[i] == '/' )
+                lpFileName[i] = '\\';
+            else
+                lpFileName[i] = file[i];
+        }
+        lpFileName[i] = '\0';
+
+        /* POSIX says the search path is implementation-defined.
+         * LOAD_WITH_ALTERED_SEARCH_PATH is used to make it behave more closely
+         * to UNIX's search paths (start with system folders instead of current
+         * folder).
+         */
+        hModule = LoadLibraryEx( (LPSTR) lpFileName, NULL, 
+                                 LOAD_WITH_ALTERED_SEARCH_PATH );
+
+        /* If the object was loaded with RTLD_GLOBAL, add it to list of global
+         * objects, so that its symbols may be retrieved even if the handle for
+         * the original program file is passed. POSIX says that if the same
+         * file is specified in multiple invocations, and any of them are
+         * RTLD_GLOBAL, even if any further invocations use RTLD_LOCAL, the
+         * symbols will remain global.
+         */
+        if( !hModule )
+            save_err_str( lpFileName );
+        else if( (mode & RTLD_GLOBAL) )
+            global_add( hModule );
+    }
+
+    /* Return to previous state of the error-mode bit flags. */
+    SetErrorMode( uMode );
+
+    return (void *) hModule;
+}
+
+int dlclose( void *handle )
+{
+    HMODULE hModule = (HMODULE) handle;
+    BOOL ret;
+
+    current_error = NULL;
+
+    ret = FreeLibrary( hModule );
+
+    /* If the object was loaded with RTLD_GLOBAL, remove it from list of global
+     * objects.
+     */
+    if( ret )
+        global_rem( hModule );
+    else
+        save_err_ptr_str( handle );
+
+    /* dlclose's return value in inverted in relation to FreeLibrary's. */
+    ret = !ret;
+
+    return (int) ret;
+}
+
+void *dlsym( void *handle, const char *name )
+{
+    FARPROC symbol;
+
+    current_error = NULL;
+
+    symbol = GetProcAddress( handle, name );
+
+    if( symbol == NULL )
+    {
+        HMODULE hModule;
+
+        /* If the handle for the original program file is passed, also search
+         * in all globally loaded objects.
+         */
+
+        hModule = GetModuleHandle( NULL );
+
+        if( hModule == handle )
+        {
+            global_object *pobject;
+
+            for( pobject = &first_object; pobject ; pobject = pobject->next )
+            {
+                if( pobject->hModule )
+                {
+                    symbol = GetProcAddress( pobject->hModule, name );
+                    if( symbol != NULL )
+                        break;
+                }
+            }
+        }
+    }
+
+    if( symbol == NULL )
+        save_err_str( name );
+
+    return (void*) symbol;
+}
+
+char *dlerror( void )
+{
+    char *error_pointer = current_error;
+
+    /* POSIX says that invoking dlerror( ) a second time, immediately following
+     * a prior invocation, shall result in NULL being returned.
+     */
+    current_error = NULL;
+
+    return error_pointer;
+}