Produce the first specific error message for a malformed Mach-O file describing
the problem instead of the generic message for object_error::parse_failed of
"Invalid data was encountered while parsing the file”. Many more good error
messages will follow after this first one.
This is built on Lang Hames’ great work of adding the ’Error' class for
structured error handling and threading Error through MachOObjectFile
construction. And making createMachOObjectFile return Expected<...> .
So to to get the error to the llvm-obdump tool, I changed the stack of
these methods to also return Expected<...> :
object::ObjectFile::createObjectFile()
object::SymbolicFile::createSymbolicFile()
object::createBinary()
Then finally in ParseInputMachO() in MachODump.cpp the error can
be reported and the specific error message can be printed in llvm-objdump
and can be seen in the existing test case for the existing malformed binary
but with the updated error message.
Converting these interfaces to Expected<> from ErrorOr<> does involve
touching a number of places. To contain the changes for now use of
errorToErrorCode() and errorOrToExpected() are used where the callers
are yet to be converted.
Also there some were bugs in the existing code that did not deal with the
old ErrorOr<> return values. So now with Expected<> since they must be
checked and the error handled, I added a TODO and a comment:
“// TODO: Actually report errors helpfully” and a call something like
consumeError(ObjOrErr.takeError()) so the buggy code will not crash
since needed to deal with the Error.
Note there is one fix also needed to lld/COFF/InputFiles.cpp that goes along
with this that I will commit right after this. So expect lld not to built
after this commit and before the next one.
llvm-svn: 265606
in the test suite. While this is not really an interesting tool and option to run
on a Mach-O file to show the symbol table in a generic libObject format
it shouldn’t crash.
The reason for the crash was in MachOObjectFile::getSymbolType() when it was
calling MachOObjectFile::getSymbolSection() without checking its return value
for the error case.
What makes this fix require a fair bit of diffs is that the method getSymbolType() is
in the class ObjectFile defined without an ErrorOr<> so I needed to add that all
the sub classes. And all of the uses needed to be updated and the return value
needed to be checked for the error case.
The MachOObjectFile version of getSymbolType() “can” get an error in trying to
come up with the libObject’s internal SymbolRef::Type when the Mach-O symbol
symbol type is an N_SECT type because the code is trying to select from the
SymbolRef::ST_Data or SymbolRef::ST_Function values for the SymbolRef::Type.
And it needs the Mach-O section to use isData() and isBSS to determine if
it will return SymbolRef::ST_Data.
One other possible fix I considered is to simply return SymbolRef::ST_Other
when MachOObjectFile::getSymbolSection() returned an error. But since in
the past when I did such changes that “ate an error in the libObject code” I
was asked instead to push the error out of the libObject code I chose not
to implement the fix this way.
As currently written both the COFF and ELF versions of getSymbolType()
can’t get an error. But if isReservedSectionNumber() wanted to check for
the two known negative values rather than allowing all negative values or
the code wanted to add the same check as in getSymbolAddress() to use
getSection() and check for the error then these versions of getSymbolType()
could return errors.
At the end of the day the error printed now is the generic “Invalid data was
encountered while parsing the file” for object_error::parse_failed. In the
future when we thread Lang’s new TypedError for recoverable error handling
though libObject this will improve. And where the added // Diagnostic(…
comment is, it would be changed to produce and error message
like “bad section index (42) for symbol at index 8” for this case.
llvm-svn: 264187
Summary:
Rename the section embeds bitcode from ".llvmbc,.llvmbc" to "__LLVM,__bitcode".
The new name matches MachO section naming convention.
Reviewers: rafael, pcc
Subscribers: davide, llvm-commits, joker.eph
Differential Revision: http://reviews.llvm.org/D17388
llvm-svn: 262245
getSymbolValue now returns a value that in convenient for most callers:
* 0 for undefined
* symbol size for common symbols
* offset/address for symbols the rest
Code that needs something more specific can check getSymbolFlags.
llvm-svn: 241605
Originally added in r139314.
Back then it didn't actually get the address, it got whatever value the
relocation used: address or offset.
The values in different object formats are:
* MachO: Always an offset.
* COFF: Always an address, but when talking about the virtual address of
sections it says: "for simplicity, compilers should set this to zero".
* ELF: An offset for .o files and and address for .so files. In the case of the
.so, the relocation in not linked to any section (sh_info is 0). We can't
really compute an offset.
Some API mappings would be:
* Use getAddress for everything. It would be quite cumbersome. To compute the
address elf has to follow sh_info, which can be corrupted and therefore the
method has to return an ErrorOr. The address of the section is also the same
for every relocation in a section, so we shouldn't have to check the error
and fetch the value for every relocation.
* Use a getValue and make it up to the user to know what it is getting.
* Use a getOffset and:
* Assert for dynamic ELF objects. That is a very peculiar case and it is
probably fair to ask any tool that wants to support it to use ELF.h. The
only tool we have that reads those (llvm-readobj) already does that. The
only other use case I can think of is a dynamic linker.
* Check that COFF .obj files have sections with zero virtual address spaces. If
it turns out that some assembler/compiler produces these, we can change
COFFObjectFile::getRelocationOffset to subtract it. Given COFF format,
this can be done without the need for ErrorOr.
The getRelocationAddress method was never implemented for COFF. It also
had exactly one use in a very peculiar case: a shortcut for adding the
section value to a pcrel reloc on MachO.
Given that, I don't expect that there is any use out there of the C API. If
that is not the case, let me know and I will add it back with the implementation
inlined and do a proper deprecation.
llvm-svn: 241450
This function can really fail since the string table offset can be out of
bounds.
Using ErrorOr makes sure the error is checked.
Hopefully a lot of the boilerplate code in tools/* can go away once we have
a diagnostic manager in Object.
llvm-svn: 241297
This is still a really odd function. Most calls are in object format specific
contexts and should probably be replaced with a more direct query, but at least
now this is not too obnoxious to use.
llvm-svn: 240777
This returns either the symbol offset or address. Since it is not defined which
one, it never has to lookup the section and so never fails.
I will add users in the next commit.
llvm-svn: 240569
COFF and MachO only define symbol sizes for common symbols. Reflect that
in the class hierarchy by having a method for common symbols only in the base
and a general one in ELF.
This avoids the need of using a magic value for the size, which had a few
problems
* Most callers didn't check for it.
* The ones that did could not tell the magic value from a file actually having
that value.
llvm-svn: 240529
There are 3 types of relocations on MachO
* Scattered
* Section based
* Symbol based
On ELF and COFF relocations are symbol based.
We were in the strange situation that we abstracted over two of them. This makes
section based relocations MachO only.
llvm-svn: 240149
make_error_code(object_error) is slow because object::object_category()
uses a ManagedStatic variable. But the real problem is that the function is
called too frequently. This patch uses std::error_code() instead of
object_error::success. In most cases, we return "success", so this patch
reduces number of function calls to that function.
http://reviews.llvm.org/D10333
llvm-svn: 239409
Summary:
This supersedes http://reviews.llvm.org/D4010, hopefully properly
dealing with the JIT case and also adds an actual test case.
DwarfContext was basically already usable for the JIT (and back when
we were overwriting ELF files it actually worked out of the box by
accident), but in order to resolve relocations correctly it needs
to know the load address of the section.
Rather than trying to get this out of the ObjectFile or requiring
the user to create a new ObjectFile just to get some debug info,
this adds the capability to pass in that info directly.
As part of this I separated out part of the LoadedObjectInfo struct
from RuntimeDyld, since it is now required at a higher layer.
Reviewers: lhames, echristo
Reviewed By: echristo
Subscribers: vtjnash, friss, rafael, llvm-commits
Differential Revision: http://reviews.llvm.org/D6961
llvm-svn: 237961
These methods are only used by MCJIT and are very specific to it. In fact, they
are also fairly specific to the fact that we have a dynamic linker of
relocatable objects.
llvm-svn: 223964
There are two methods in SectionRef that can fail:
* getName: The index into the string table can be invalid.
* getContents: The section might point to invalid contents.
Every other method will always succeed and returning and std::error_code just
complicates the code. For example, a section can have an invalid alignment,
but if we are able to get to the section structure at all and create a
SectionRef, we will always be able to read that invalid alignment.
llvm-svn: 219314
Owning the buffer is somewhat inflexible. Some Binaries have sub Binaries
(like Archive) and we had to create dummy buffers just to handle that. It is
also a bad fit for IRObjectFile where the Module wants to own the buffer too.
Keeping this ownership would make supporting IR inside native objects
particularly painful.
This patch focuses in lib/Object. If something elsewhere used to own an Binary,
now it also owns a MemoryBuffer.
This patch introduces a few new types.
* MemoryBufferRef. This is just a pair of StringRefs for the data and name.
This is to MemoryBuffer as StringRef is to std::string.
* OwningBinary. A combination of Binary and a MemoryBuffer. This is needed
for convenience functions that take a filename and return both the
buffer and the Binary using that buffer.
The C api now uses OwningBinary to avoid any change in semantics. I will start
a new thread to see if we want to change it and how.
llvm-svn: 216002
This patch enables the new ELFv2 ABI in the runtime dynamic loader.
The loader has to implement the following features:
- In the ELFv2 ABI, do not look up a function descriptor in .opd, but
instead use the local entry point when resolving a direct call.
- Update the TOC restore code to use the new TOC slot linkage area
offset.
- Create PLT stubs appropriate for the ELFv2 ABI.
Note that this patch also adds common-code changes. These are necessary
because the loader must check the newly added ELF flags: the e_flags
header bits encoding the ABI version, and the st_other symbol table
entry bits encoding the local entry point offset. There is currently
no way to access these, so I've added ObjectFile::getPlatformFlags and
SymbolRef::getOther accessors.
Reviewed by Hal Finkel.
llvm-svn: 213491
This makes the buffer ownership on error conditions very natural. The buffer
is only moved out of the argument if an object is constructed that now
owns the buffer.
llvm-svn: 211546
This allows us to just use a std::unique_ptr to store the pointer to the buffer.
The flip side is that they have to support releasing the buffer back to the
caller.
Overall this looks like a more efficient and less brittle api.
llvm-svn: 211542
We normally don't drop functions from the C API's, but in this case I think we
can:
* The old implementation of getFileOffset was fairly broken
* The introduction of LLVMGetSymbolFileOffset was itself a C api breaking
change as it removed LLVMGetSymbolOffset.
* It is an incredibly specialized use case. The only reason MCJIT needs it is
because of its odd position of being a dynamic linker of .o files.
llvm-svn: 206750
