Security-55163.44.tar.gz

[apple/security.git] / libsecurity_utilities / lib / dyldcache.cpp

diff --git a/libsecurity_utilities/lib/dyldcache.cpp b/libsecurity_utilities/lib/dyldcache.cpp
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+/*
+ * Copyright (c) 2009 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@
+ */
+
+//
+// dyldcache - access layer to the DYLD Shared Library Cache file
+//
+#include "dyldcache.h"
+
+
+//
+// Table of supported architectures.
+// The cache file header has no direct architecture information, so we need to deduce it like this.
+//
+static const uint16_t bigEndian = 0x1200;
+static const uint16_t littleEndian = 0x0012;
+
+const DYLDCache::ArchType DYLDCache::architectures[] = {
+       { CPU_TYPE_X86_64, CPU_SUBTYPE_MULTIPLE,        "dyld_v1  x86_64", "x86_64", littleEndian },
+       { CPU_TYPE_X86, CPU_SUBTYPE_MULTIPLE,           "dyld_v1    i386", "i386", littleEndian },
+       { CPU_TYPE_POWERPC, CPU_SUBTYPE_MULTIPLE,       "dyld_v1     ppc", "rosetta", bigEndian },
+       { CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V6,                     "dyld_v1   armv6", "armv6", littleEndian },
+       { CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V7,                     "dyld_v1   armv7", "armv7", littleEndian },
+       { 0 }
+};
+
+
+//
+// Architecture matching and lookup
+//
+std::string DYLDCache::pathFor(const Architecture &arch)
+{
+       for (const ArchType *it = architectures; it->cpu; it++)
+               if (arch.matches(it->architecture()))
+                       return it->path();
+       UnixError::throwMe(ENOEXEC);
+}
+
+const DYLDCache::ArchType *DYLDCache::matchArchitecture(const dyld_cache_header &header)
+{
+       for (const ArchType *arch = architectures; arch->cpu; arch++)
+               if (!strcmp(header.magic, arch->magic))
+                       return arch;
+       return NULL;
+}
+
+
+//
+// Construction and teardown
+//
+DYLDCache::DYLDCache(const std::string &path)
+{
+       this->open(path);
+       mLength = this->fileSize();
+       mBase = this->mmap(PROT_READ, mLength);
+       mHeader = at<dyld_cache_header>(0);
+
+       if ((mArch = matchArchitecture(*mHeader)) == NULL)
+               UnixError::throwMe(ENOEXEC);
+       mFlip = *((const uint8_t *)&mArch->order) != 0x12;
+       
+       mSigStart = flip(mHeader->codeSignatureOffset);
+       mSigLength = flip(mHeader->codeSignatureSize);
+}
+
+
+DYLDCache::~DYLDCache()
+{
+       ::munmap((void *)mBase, mLength);
+}
+
+
+//
+// Preflight a file for file type
+//
+bool DYLDCache::validate(UnixPlusPlus::FileDesc &fd)
+{
+       dyld_cache_header header;
+       return fd.read(&header, sizeof(header), 0) == sizeof(header)
+               && matchArchitecture(header) != NULL;
+}
+
+
+//
+// Locate a mapping in the cache
+//
+DYLDCache::Mapping DYLDCache::mapping(unsigned ix) const
+{
+       assert(ix < this->mappingCount());
+       return Mapping(*this, flip(mHeader->mappingOffset) + ix * sizeof(shared_file_mapping_np));
+}
+
+
+//
+// Locate an image in the cache
+//
+DYLDCache::Image DYLDCache::image(unsigned ix) const
+{
+       assert(ix < this->imageCount());
+       return Image(*this, flip(mHeader->imagesOffset) + ix * sizeof(dyld_cache_image_info));
+}
+
+
+
+DYLDCache::Mapping DYLDCache::findMap(uint64_t address) const
+{
+       for (unsigned ix = 0; ix < mappingCount(); ix++) {
+               Mapping map = this->mapping(ix);
+               if (map.contains(address))
+                       return map;
+       }
+       UnixError::throwMe(EINVAL);
+}
+
+uint64_t DYLDCache::mapAddress(uint64_t address) const
+{
+       Mapping map = this->findMap(address);
+       return (address - map.address()) + map.offset();
+}