Fix bug with mach-o walker not properly walking universal binary (Issue #125)

Fix exception handler so that it will properly forward exceptions (Issue #126)
r=mmentovai



git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@119 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/mac/macho_id.cc

@@ -39,6 +39,7 @@
 #include <openssl/md5.h>
 #include <openssl/sha.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
@@ -246,6 +247,12 @@ bool MachoID::WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
     if (swap)
       swap_segment_command(&seg, NXHostByteOrder());
 
+    struct mach_header_64 header;
+    off_t header_offset;
+    
+    if (!walker->CurrentHeader(&header, &header_offset))
+      return false;
+        
     // Process segments that have sections:
     // (e.g., __TEXT, __DATA, __IMPORT, __OBJC)
     offset += sizeof(struct segment_command);
@@ -257,7 +264,7 @@ bool MachoID::WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
       if (swap)
         swap_section(&sec, 1, NXHostByteOrder());
 
-      macho_id->Update(walker, sec.offset, sec.size);
+      macho_id->Update(walker, header_offset + sec.offset, sec.size);
       offset += sizeof(struct section);
     }
   } else if (cmd->cmd == LC_SEGMENT_64) {
@@ -269,6 +276,12 @@ bool MachoID::WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
     if (swap)
       swap_segment_command_64(&seg64, NXHostByteOrder());
 
+    struct mach_header_64 header;
+    off_t header_offset;
+    
+    if (!walker->CurrentHeader(&header, &header_offset))
+      return false;
+    
     // Process segments that have sections:
     // (e.g., __TEXT, __DATA, __IMPORT, __OBJC)
     offset += sizeof(struct segment_command_64);
@@ -280,7 +293,7 @@ bool MachoID::WalkerCB(MachoWalker *walker, load_command *cmd, off_t offset,
       if (swap)
         swap_section_64(&sec64, 1, NXHostByteOrder());
 
-      macho_id->Update(walker, sec64.offset, sec64.size);
+      macho_id->Update(walker, header_offset + sec64.offset, sec64.size);
       offset += sizeof(struct section_64);
     }
   }

src/common/mac/macho_walker.cc

@@ -38,6 +38,7 @@
 #include <mach-o/arch.h>
 #include <mach-o/loader.h>
 #include <mach-o/swap.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "common/mac/macho_walker.h"
@@ -93,6 +94,16 @@ bool MachoWalker::ReadBytes(void *buffer, size_t size, off_t offset) {
   return pread(file_, buffer, size, offset) == (ssize_t)size;
 }
 
+bool MachoWalker::CurrentHeader(struct mach_header_64 *header, off_t *offset) {
+  if (current_header_) {
+    memcpy(header, current_header_, sizeof(mach_header_64));
+    *offset = current_header_offset_;
+    return true;
+  }
+  
+  return false;
+}
+
 bool MachoWalker::FindHeader(int cpu_type, off_t &offset) {
   int valid_cpu_type = ValidateCPUType(cpu_type);
   // Read the magic bytes that's common amongst all mach-o files
@@ -165,8 +176,22 @@ bool MachoWalker::WalkHeaderAtOffset(off_t offset) {
   bool swap = (header.magic == MH_CIGAM);
   if (swap)
     swap_mach_header(&header, NXHostByteOrder());
-
-  return WalkHeaderCore(offset + sizeof(header), header.ncmds, swap);
+  
+  // Copy the data into the mach_header_64 structure.  Since the 32-bit and
+  // 64-bit only differ in the last field (reserved), this is safe to do.
+  struct mach_header_64 header64;
+  memcpy((void *)&header64, (const void *)&header, sizeof(header));
+  header64.reserved = 0;
+  
+  current_header_ = &header64;
+  current_header_size_ = sizeof(header); // 32-bit, not 64-bit
+  current_header_offset_ = offset;
+  offset += current_header_size_;
+  bool result = WalkHeaderCore(offset, header.ncmds, swap);
+  current_header_ = NULL;
+  current_header_size_ = 0;
+  current_header_offset_ = 0;
+  return result;
 }
 
 bool MachoWalker::WalkHeader64AtOffset(off_t offset) {
@@ -178,7 +203,15 @@ bool MachoWalker::WalkHeader64AtOffset(off_t offset) {
   if (swap)
     swap_mach_header_64(&header, NXHostByteOrder());
 
-  return WalkHeaderCore(offset + sizeof(header), header.ncmds, swap);
+  current_header_ = &header;
+  current_header_size_ = sizeof(header);
+  current_header_offset_ = offset;
+  offset += current_header_size_;
+  bool result = WalkHeaderCore(offset, header.ncmds, swap);
+  current_header_ = NULL;
+  current_header_size_ = 0;
+  current_header_offset_ = 0;
+  return result;
 }
 
 bool MachoWalker::WalkHeaderCore(off_t offset, uint32_t number_of_commands,

src/common/mac/macho_walker.h

@@ -68,6 +68,9 @@ class MachoWalker {
 
   // Read |size| bytes from the opened file at |offset| into |buffer|
   bool ReadBytes(void *buffer, size_t size, off_t offset);
+  
+  // Return the current header and header offset
+  bool CurrentHeader(struct mach_header_64 *header, off_t *offset);
 
  private:
   // Validate the |cpu_type|
@@ -87,6 +90,15 @@ class MachoWalker {
   // User specified callback & context
   LoadCommandCallback callback_;
   void *callback_context_;
+  
+  // Current header, size, and offset.  The mach_header_64 is used for both
+  // 32-bit and 64-bit headers because they only differ in their last field
+  // (reserved).  By adding the |current_header_size_| and the 
+  // |current_header_offset_|, you can determine the offset in the file just
+  // after the header.
+  struct mach_header_64 *current_header_;
+  unsigned long current_header_size_;
+  off_t current_header_offset_;
 };
 
 }  // namespace MacFileUtilities