ld64-95.2.12.tar.gz

[apple/ld64.git] / src / other / PruneTrie.cpp

diff --git a/src/other/PruneTrie.cpp b/src/other/PruneTrie.cpp
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+/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- 
+ *
+ * Copyright (c) 2008 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+#include <vector>
+
+#include "MachOFileAbstraction.hpp"
+#include "MachOTrie.hpp"
+#include "prune_trie.h"
+
+
+
+
+/*
+ * prune_trie() is a C vended function that is used by strip(1) to prune out
+ * defined exported symbols from the export trie.  It is passed a pointer to
+ * the start of bytes of the the trie and the size.  The prune() funciton
+ * passed is called with each symbol name in the trie to determine if it is
+ * to be pruned (retuning 1) or not (returning 0).  It writes the new trie
+ * back into the trie buffer and returns the new size in trie_new_size.
+ * If the pruning succeeds, NULL is returned.  If there was an error processing
+ * the trie (e.f. it is malformed), then an error message string is returned.
+ * The error string can be freed.
+ */
+const char*
+prune_trie(
+       uint8_t*        trie_start,
+       uint32_t        trie_start_size,
+       int                     (*prune)(const char *name),
+       uint32_t*       trie_new_size)
+{
+       // convert trie to vector of entries
+       std::vector<mach_o::trie::Entry> originalExports;
+       try {
+               parseTrie(trie_start, trie_start+trie_start_size, originalExports);
+       }
+       catch (const char* msg) {
+               return strdup(msg);
+       }
+       catch (...) {
+               return strdup("unexpected exception processing trie");
+       }
+       
+       // prune entries into new vector of entries
+       std::vector<mach_o::trie::Entry> newExports;
+       newExports.reserve(originalExports.size());
+       for(std::vector<mach_o::trie::Entry>::iterator it = originalExports.begin(); it != originalExports.end(); ++it) {
+               if ( prune(it->name) == 0 ) 
+                       newExports.push_back(*it);
+       }
+
+       // create new export trie
+       std::vector<uint8_t> newExportTrieBytes;
+       newExportTrieBytes.reserve(trie_start_size);
+       mach_o::trie::makeTrie(newExports, newExportTrieBytes);
+       // Need to align trie to 8 or 4 bytes.  We don't know the arch, but if the incoming trie
+       // was not 8-byte aligned, then it can't be a 64-bit arch, so use 4-byte alignement.
+       if ( (trie_start_size % 8) != 0 ) {
+               // 4-byte align 
+               while ( (newExportTrieBytes.size() % 4 ) != 0)
+                       newExportTrieBytes.push_back(0);
+       }
+       else {
+               // 8-byte align 
+               while ( (newExportTrieBytes.size() % 8 ) != 0)
+                       newExportTrieBytes.push_back(0);
+       }
+       
+       // copy into place, zero pad
+       *trie_new_size = newExportTrieBytes.size();
+       if ( *trie_new_size > trie_start_size ) {
+               char* msg;
+               asprintf(&msg, "new trie is larger (%d) than original (%d)", *trie_new_size, trie_start_size);
+               return msg;
+       }
+       memcpy(trie_start, &newExportTrieBytes[0], *trie_new_size);
+       bzero(trie_start+*trie_new_size, trie_start_size - *trie_new_size);
+       
+       // success
+       return NULL;
+}