Ticket #8135: debugger.external_debug_info.patch.2

diff --git a/src/apps/debugger/dwarf/DwarfFile.cpp b/src/apps/debugger/dwarf/DwarfFile.cpp
index f95d18e..2224f62 100644
--- a/src/apps/debugger/dwarf/DwarfFile.cpp
+++ b/src/apps/debugger/dwarf/DwarfFile.cpp
@@ -11,6 +11,9 @@
 #include <new>
 
 #include <AutoDeleter.h>
+#include <Entry.h>
+#include <FindDirectory.h>
+#include <Path.h>
 
 #include "AttributeClasses.h"
 #include "AttributeValue.h"
@@ -27,6 +30,30 @@
 #include "Variant.h"
 
 
+// #pragma mark - AutoSectionPutter
+
+
+class AutoSectionPutter {
+public:
+   AutoSectionPutter(ElfFile* elfFile, ElfSection* elfSection)
+       :
+       fElfFile(elfFile),
+       fElfSection(elfSection)
+   {
+   }
+
+   ~AutoSectionPutter()
+   {
+       if (fElfSection != NULL)
+           fElfFile->PutSection(fElfSection);
+   }
+
+private:
+   ElfFile*            fElfFile;
+   ElfSection*         fElfSection;
+};
+
+
 // #pragma mark - ExpressionEvaluationContext
 
 
@@ -281,7 +308,9 @@ private:
 DwarfFile::DwarfFile()
    :
    fName(NULL),
+   fAlternateName(NULL),
    fElfFile(NULL),
+   fAlternateElfFile(NULL),
    fDebugInfoSection(NULL),
    fDebugAbbrevSection(NULL),
    fDebugStringSection(NULL),
@@ -305,19 +334,24 @@ DwarfFile::~DwarfFile()
        delete table;
 
    if (fElfFile != NULL) {
-       fElfFile->PutSection(fDebugInfoSection);
-       fElfFile->PutSection(fDebugAbbrevSection);
-       fElfFile->PutSection(fDebugStringSection);
-       fElfFile->PutSection(fDebugRangesSection);
-       fElfFile->PutSection(fDebugLineSection);
-       fElfFile->PutSection(fDebugFrameSection);
+       ElfFile* debugInfoFile = fAlternateElfFile != NULL
+           ? fAlternateElfFile : fElfFile;
+
+       debugInfoFile->PutSection(fDebugInfoSection);
+       debugInfoFile->PutSection(fDebugAbbrevSection);
+       debugInfoFile->PutSection(fDebugStringSection);
+       debugInfoFile->PutSection(fDebugRangesSection);
+       debugInfoFile->PutSection(fDebugLineSection);
+       debugInfoFile->PutSection(fDebugFrameSection);
        fElfFile->PutSection(fEHFrameSection);
-       fElfFile->PutSection(fDebugLocationSection);
-       fElfFile->PutSection(fDebugPublicTypesSection);
+       debugInfoFile->PutSection(fDebugLocationSection);
+       debugInfoFile->PutSection(fDebugPublicTypesSection);
        delete fElfFile;
+       delete fAlternateElfFile;
    }
 
    free(fName);
+   free(fAlternateName);
 }
 
 
@@ -337,23 +371,24 @@ DwarfFile::Load(const char* fileName)
    if (error != B_OK)
        return error;
 
-   // get the interesting sections
-   fDebugInfoSection = fElfFile->GetSection(".debug_info");
-   fDebugAbbrevSection = fElfFile->GetSection(".debug_abbrev");
-   if (fDebugInfoSection == NULL || fDebugAbbrevSection == NULL) {
-       WARNING("DwarfManager::File::Load(\"%s\"): no "
-           ".debug_info or .debug_abbrev.\n", fileName);
-       return B_ERROR;
-   }
+   error = _LocateDebugInfo();
+   if (error != B_OK)
+       return error;
+
+   ElfFile* debugInfoFile = fAlternateElfFile != NULL
+       ? fAlternateElfFile : fElfFile;
 
    // non mandatory sections
-   fDebugStringSection = fElfFile->GetSection(".debug_str");
-   fDebugRangesSection = fElfFile->GetSection(".debug_ranges");
-   fDebugLineSection = fElfFile->GetSection(".debug_line");
-   fDebugFrameSection = fElfFile->GetSection(".debug_frame");
+   fDebugStringSection = debugInfoFile->GetSection(".debug_str");
+   fDebugRangesSection = debugInfoFile->GetSection(".debug_ranges");
+   fDebugLineSection = debugInfoFile->GetSection(".debug_line");
+   fDebugFrameSection = debugInfoFile->GetSection(".debug_frame");
+   // .eh_frame doesn't appear to get copied into separate debug
+   // info files properly, therefore always use it off the main
+   // executable image
    fEHFrameSection = fElfFile->GetSection(".eh_frame");
-   fDebugLocationSection = fElfFile->GetSection(".debug_loc");
-   fDebugPublicTypesSection = fElfFile->GetSection(".debug_pubtypes");
+   fDebugLocationSection = debugInfoFile->GetSection(".debug_loc");
+   fDebugPublicTypesSection = debugInfoFile->GetSection(".debug_pubtypes");
 
    // iterate through the debug info section
    DataReader dataReader(fDebugInfoSection->Data(),
@@ -2224,3 +2259,106 @@ DwarfFile::_FindLocationExpression(CompilationUnit* unit, uint64 offset,
        }
    }
 }
+
+
+status_t
+DwarfFile::_LocateDebugInfo()
+{
+   ElfFile* debugInfoFile = fElfFile;
+   ElfSection* debugLinkSection = fElfFile->GetSection(".gnu_debuglink");
+   if (debugLinkSection != NULL) {
+       AutoSectionPutter putter(fElfFile, debugLinkSection);
+
+       // the file specifies a debug link, look at its target instead
+       // for debug information.
+       // Format: null-terminated filename, as many 0 padding bytes as
+       // needed to reach the next 32-bit address boundary, followed
+       // by a 32-bit CRC
+
+       BString debugPath;
+       status_t result = _GetDebugInfoPath(debugPath,
+           (const char*)debugLinkSection->Data());
+       if (result != B_OK)
+           return result;
+
+       fAlternateName = strdup(debugPath.String());
+
+       if (fAlternateName == NULL)
+           return B_NO_MEMORY;
+
+/*
+       // TODO: validate CRC
+       int32 debugCRC = *(int32*)((char*)debugLinkSection->Data()
+           + debugLinkSection->Size() - sizeof(int32));
+*/
+       fAlternateElfFile = new(std::nothrow) ElfFile;
+       if (fAlternateElfFile == NULL)
+           return B_NO_MEMORY;
+
+       result = fAlternateElfFile->Init(fAlternateName);
+       if (result != B_OK)
+           return result;
+
+       debugInfoFile = fAlternateElfFile;
+   }
+
+   // get the interesting sections
+   fDebugInfoSection = debugInfoFile->GetSection(".debug_info");
+   fDebugAbbrevSection = debugInfoFile->GetSection(".debug_abbrev");
+   if (fDebugInfoSection == NULL || fDebugAbbrevSection == NULL) {
+       WARNING("DwarfManager::File::Load(\"%s\"): no "
+           ".debug_info or .debug_abbrev.\n", fName);
+       return B_ERROR;
+   }
+
+   return B_OK;
+}
+
+
+status_t
+DwarfFile::_GetDebugInfoPath(BString& _infoPath, const char* debugFileName)
+{
+   int16 dirLocations[] = { B_SYSTEM_DIRECTORY, B_COMMON_DIRECTORY,
+       B_USER_CONFIG_DIRECTORY, -1 };
+
+   // first, see if we have a relative match to our local directory
+   BPath basePath;
+   status_t result = basePath.SetTo(fName);
+   if (result != B_OK)
+       return result;
+   basePath.GetParent(&basePath);
+   if (strcmp(basePath.Leaf(), "lib") == 0 || strcmp(basePath.Leaf(),
+           "add-ons") == 0) {
+       _infoPath.SetToFormat("%s/../debug/%s", basePath.Path(),
+           debugFileName);
+   } else
+       _infoPath.SetToFormat("%s/debug/%s", basePath.Path(), debugFileName);
+
+   BEntry entry(_infoPath.String());
+   result = entry.InitCheck();
+   if (result != B_OK && result != B_ENTRY_NOT_FOUND)
+       return result;
+   if (entry.Exists())
+       return B_OK;
+
+   // See if our image is in any of the system locations.
+   // if so, look for its debug info in the corresponding location.
+   for (int16 i = 0; dirLocations[i] >= 0; i++) {
+       result = find_directory((directory_which)dirLocations[i], &basePath);
+       if (result != B_OK)
+           return result;
+
+       if (strncmp(fName, basePath.Path(), strlen(basePath.Path())) == 0) {
+           _infoPath.SetToFormat("%s/develop/debug/%s", basePath.Path(),
+               debugFileName);
+           entry.SetTo(_infoPath.String());
+           result = entry.InitCheck();
+           if (result != B_OK && result != B_ENTRY_NOT_FOUND)
+               return result;
+           return entry.Exists() ? B_OK : B_ENTRY_NOT_FOUND;
+       }
+   }
+
+   return B_ENTRY_NOT_FOUND;
+}
+
diff --git a/src/apps/debugger/dwarf/DwarfFile.h b/src/apps/debugger/dwarf/DwarfFile.h
index b7d53b8..e060469 100644
--- a/src/apps/debugger/dwarf/DwarfFile.h
+++ b/src/apps/debugger/dwarf/DwarfFile.h
@@ -150,12 +150,18 @@ private:
                                    const void*& _expression,
                                    off_t& _length) const;
 
+           status_t            _LocateDebugInfo();
+           status_t            _GetDebugInfoPath(BString& _infoPath,
+                                   const char* fileName);
+
 private:
            friend class        DwarfFile::ExpressionEvaluationContext;
 
 private:
            char*               fName;
+           char*               fAlternateName;
            ElfFile*            fElfFile;
+           ElfFile*            fAlternateElfFile;
            ElfSection*         fDebugInfoSection;
            ElfSection*         fDebugAbbrevSection;
            ElfSection*         fDebugStringSection;