| Zachary Turner | ab792ca | 2016-11-10 19:24:21 +0000 | [diff] [blame] | 1 | =====================================
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| 2 | The Module Information Stream
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| 3 | =====================================
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| Zachary Turner | 29916a1 | 2016-11-29 22:14:56 +0000 | [diff] [blame] | 4 |
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| 5 | .. contents::
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| 6 | :local:
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| 7 |
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| 8 | .. _modi_stream_intro:
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| 9 |
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| 10 | Introduction
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| 11 | ============
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| 12 |
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| 13 | The Module Info Stream (henceforth referred to as the Modi stream) contains
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| 14 | information about a single module (object file, import library, etc that
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| 15 | contributes to the binary this PDB contains debug information about. There
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| 16 | is one modi stream for each module, and the mapping between modi stream index
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| 17 | and module is contained in the :doc:`DBI Stream <DbiStream>`. The modi stream
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| 18 | for a single module contains line information for the compiland, as well as
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| 19 | all CodeView information for the symbols defined in the compiland. Finally,
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| 20 | there is a "global refs" substream which is not well understood.
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| 21 |
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| 22 | .. _modi_stream_layout:
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| 23 |
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| 24 | Stream Layout
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| 25 | =============
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| 26 |
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| 27 | A modi stream is laid out as follows:
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| 28 |
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| 29 |
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| 30 | .. code-block:: c++
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| 31 |
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| 32 | struct ModiStream {
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| 33 | uint32_t Signature;
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| 34 | uint8_t Symbols[SymbolSize-4];
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| 35 | uint8_t C11LineInfo[C11Size];
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| 36 | uint8_t C13LineInfo[C13Size];
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| 37 |
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| 38 | uint32_t GlobalRefsSize;
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| 39 | uint8_t GlobalRefs[GlobalRefsSize];
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| 40 | };
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| 41 |
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| 42 | - **Signature** - Unknown. In practice only the value of ``4`` has been
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| 43 | observed. It is hypothesized that this value corresponds to the set of
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| 44 | ``CV_SIGNATURE_xx`` defines in ``cvinfo.h``, with the value of ``4``
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| 45 | meaning that this module has C13 line information (as opposed to C11 line
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| 46 | information). A corollary of this is that we expect to only ever see
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| 47 | C13 line info, and that we do not understand the format of C11 line info.
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| 48 |
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| 49 | - **Symbols** - The :ref:`CodeView Symbol Substream <modi_symbol_substream>`.
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| 50 | ``SymbolSize`` is equal to the value of ``SymByteSize`` for the
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| 51 | corresponding module's entry in the :ref:`Module Info Substream <dbi_mod_info_substream>`
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| 52 | of the :doc:`DBI Stream <DbiStream>`.
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| 53 |
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| 54 | - **C11LineInfo** - A block containing CodeView line information in C11
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| 55 | format. ``C11Size`` is equal to the value of ``C11ByteSize`` from the
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| 56 | :ref:`Module Info Substream <dbi_mod_info_substream>` of the
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| 57 | :doc:`DBI Stream <DbiStream>`. If this value is ``0``, then C11 line
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| 58 | information is not present. As mentioned previously, the format of
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| 59 | C11 line info is not understood and we assume all line in modern PDBs
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| 60 | to be in C13 format.
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| 61 |
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| 62 | - **C13LineInfo** - A block containing CodeView line information in C13
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| 63 | format. ``C13Size`` is equal to the value of ``C13ByteSize`` from the
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| 64 | :ref:`Module Info Substream <dbi_mod_info_substream>` of the
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| 65 | :doc:`DBI Stream <DbiStream>`. If this value is ``0``, then C13 line
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| 66 | information is not present.
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| 67 |
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| 68 | - **GlobalRefs** - The meaning of this substream is not understood.
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| 69 |
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| 70 | .. _modi_symbol_substream:
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| 71 |
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| 72 | The CodeView Symbol Substream
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| 73 | =============================
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| 74 |
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| 75 | The CodeView Symbol Substream. This is an array of variable length
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| 76 | records describing the functions, variables, inlining information,
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| 77 | and other symbols defined in the compiland. The entire array consumes
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| 78 | ``SymbolSize-4`` bytes. The format of a CodeView Symbol Record (and
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| 79 | thusly, an array of CodeView Symbol Records) is described in
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| 80 | :doc:`CodeViewSymbols`.
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