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Add OMF read support #807

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ba4f5d6
Initial read support for OMF
encounter Sep 24, 2025
cbfb7e2
Remove WKEXT handling and handle ABS symbols
encounter Sep 24, 2025
3ceabdf
Rework internal symbol layout; support local records
encounter Sep 24, 2025
fe36b32
Check for LEDATA/LIDATA before FIXUPP/FIXUPP32
encounter Sep 25, 2025
d24826e
OMF module reorganization
encounter Sep 25, 2025
be97f1a
Improve LIDATA expansion
encounter Sep 25, 2025
a6a04f5
Refactoring & improvements
encounter Sep 25, 2025
958fd5b
Update testfiles
encounter Sep 25, 2025
aa88ee5
Adapt OMF to upstream API changes (permissions, subtractor)
encounter Jun 11, 2026
ebd9c41
Rework OMF sections to include COMDATs; fix Borland/Watcom parsing
encounter Jun 11, 2026
b1b72c6
Add OMF objdump snapshot tests and strengthen handwritten tests
encounter Jun 11, 2026
d45abb6
OMF quality pass
encounter Jun 11, 2026
1659fc2
Harden OMF parsing against malformed input
encounter Jun 11, 2026
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3 changes: 2 additions & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@ alloc = { version = '1.0.0', optional = true, package = 'rustc-std-workspace-all
# Core read support. You will need to enable some file formats too.
read_core = []
# Read support for most file formats.
read = ["read_core", "archive", "coff", "elf", "macho", "pe", "xcoff"]
read = ["read_core", "archive", "coff", "elf", "macho", "pe", "xcoff", "omf"]
# Core write support. You will need to enable some file formats too.
write_core = ["dep:crc32fast", "dep:indexmap", "dep:hashbrown"]
# Core write support with libstd features. You will need to enable some file formats too.
Expand Down Expand Up @@ -73,6 +73,7 @@ macho = []
pe = ["coff"]
wasm = ["dep:wasmparser"]
xcoff = []
omf = []

#=======================================
# By default, support all read features.
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3 changes: 2 additions & 1 deletion crates/examples/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -11,10 +11,11 @@ object = { path = "../..", default-features = false }
[features]
read = ["object/read"]
write = ["object/write"]
omf = ["object/omf"]
wasm = ["object/wasm"]
xcoff = ["object/xcoff"]
names = ["object/names"]
all = ["read", "write", "wasm", "xcoff", "names"]
all = ["read", "write", "omf", "wasm", "xcoff", "names"]
unstable-all = ["all"]
default = ["read"]

Expand Down
38 changes: 38 additions & 0 deletions crates/examples/testfiles/omf/base-borland-debug.obj.objdump
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Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: 12, permissions: R-X }
Segment { name: "_DATA", address: 0, size: 10, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
Segment { name: "$$BSYMS", address: 0, size: 85, permissions: R-- }
Segment { name: "$$BTYPES", address: 0, size: 4c, permissions: R-- }
Segment { name: "$$BNAMES", address: 0, size: 1a, permissions: R-- }
Segment { name: "$$BROWSE", address: 0, size: 0, permissions: R-- }
Segment { name: "$$BROWFILE", address: 0, size: 0, permissions: R-- }
1: Section { name: "_TEXT", address: 0, size: 12, align: 4, kind: Text, flags: None }
2: Section { name: "_DATA", address: 0, size: 10, align: 4, kind: Data, flags: None }
3: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }
4: Section { name: "$$BSYMS", address: 0, size: 85, align: 1, kind: Debug, flags: None }
5: Section { name: "$$BTYPES", address: 0, size: 4c, align: 1, kind: Debug, flags: None }
6: Section { name: "$$BNAMES", address: 0, size: 1a, align: 1, kind: Debug, flags: None }
7: Section { name: "$$BROWSE", address: 0, size: 0, align: 1, kind: Debug, flags: None }
8: Section { name: "$$BROWFILE", address: 0, size: 0, align: 1, kind: Debug, flags: None }

Symbols
0: Symbol { name: "_printf", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
1: Symbol { name: "_main", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }

_TEXT relocations
(4, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(2)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(2) } })
(9, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(0)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Target, target: External(1) } })

$$BSYMS relocations
(20, Relocation { kind: Absolute, encoding: Generic, size: 30, target: Section(SectionIndex(1)), addend: 0, implicit_addend: false, flags: Omf { location: Pointer48, mode: SegmentRelative, frame: Target, target: Segment(1) } })

Dynamic symbols

Symbol map
0x0-0x10 "_main"
25 changes: 25 additions & 0 deletions crates/examples/testfiles/omf/base-borland.obj.objdump
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@@ -0,0 +1,25 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: 12, permissions: R-X }
Segment { name: "_DATA", address: 0, size: 10, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
1: Section { name: "_TEXT", address: 0, size: 12, align: 4, kind: Text, flags: None }
2: Section { name: "_DATA", address: 0, size: 10, align: 4, kind: Data, flags: None }
3: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }

Symbols
0: Symbol { name: "_printf", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
1: Symbol { name: "_main", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }

_TEXT relocations
(4, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(2)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(2) } })
(9, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(0)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Target, target: External(1) } })

Dynamic symbols

Symbol map
0x0-0x10 "_main"
41 changes: 41 additions & 0 deletions crates/examples/testfiles/omf/base-watcom-debug.obj.objdump
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Original file line number Diff line number Diff line change
@@ -0,0 +1,41 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: 39, permissions: R-X }
Segment { name: "CONST", address: 0, size: d, permissions: R-- }
Segment { name: "CONST2", address: 0, size: 0, permissions: R-- }
Segment { name: "_DATA", address: 0, size: 0, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
Segment { name: "$$SYMBOLS", address: 0, size: 22, permissions: R-- }
Segment { name: "$$TYPES", address: 0, size: fa, permissions: R-- }
Segment { name: "$$TYPES", address: 0, size: c7, permissions: R-- }
1: Section { name: "_TEXT", address: 0, size: 39, align: 1, kind: Text, flags: None }
2: Section { name: "CONST", address: 0, size: d, align: 4, kind: ReadOnlyData, flags: None }
3: Section { name: "CONST2", address: 0, size: 0, align: 4, kind: ReadOnlyData, flags: None }
4: Section { name: "_DATA", address: 0, size: 0, align: 4, kind: Data, flags: None }
5: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }
6: Section { name: "$$SYMBOLS", address: 0, size: 22, align: 1, kind: Debug, flags: None }
7: Section { name: "$$TYPES", address: 0, size: fa, align: 1, kind: Debug, flags: None }
8: Section { name: "$$TYPES", address: 0, size: c7, align: 1, kind: Debug, flags: None }

Symbols
0: Symbol { name: "__CHK", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
1: Symbol { name: "_printf", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
2: Symbol { name: "main_", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
3: Symbol { name: "_cstart_", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }

_TEXT relocations
(6, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(0)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Group(2), target: External(1) } })
(19, Relocation { kind: Absolute, encoding: Generic, size: 20, target: Section(SectionIndex(2)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Group(2), target: Segment(2) } })
(1f, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(1)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Group(2), target: External(2) } })

$$SYMBOLS relocations
(2, Relocation { kind: Absolute, encoding: Generic, size: 30, target: Section(SectionIndex(1)), addend: 0, implicit_addend: false, flags: Omf { location: Pointer48, mode: SegmentRelative, frame: Group(2), target: Segment(1) } })

Dynamic symbols

Symbol map
0x0-0xd "main_"
32 changes: 32 additions & 0 deletions crates/examples/testfiles/omf/base-watcom.obj.objdump
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Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: 1e, permissions: R-X }
Segment { name: "CONST", address: 0, size: d, permissions: R-- }
Segment { name: "CONST2", address: 0, size: 0, permissions: R-- }
Segment { name: "_DATA", address: 0, size: 0, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
1: Section { name: "_TEXT", address: 0, size: 1e, align: 1, kind: Text, flags: None }
2: Section { name: "CONST", address: 0, size: d, align: 4, kind: ReadOnlyData, flags: None }
3: Section { name: "CONST2", address: 0, size: 0, align: 4, kind: ReadOnlyData, flags: None }
4: Section { name: "_DATA", address: 0, size: 0, align: 4, kind: Data, flags: None }
5: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }

Symbols
0: Symbol { name: "__CHK", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
1: Symbol { name: "_printf", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }
2: Symbol { name: "main_", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
3: Symbol { name: "_cstart_", address: 0, size: 0, kind: Unknown, section: Undefined, scope: Unknown, weak: false, flags: None }

_TEXT relocations
(6, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(0)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Group(2), target: External(1) } })
(d, Relocation { kind: Absolute, encoding: Generic, size: 20, target: Section(SectionIndex(2)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Group(2), target: Segment(2) } })
(12, Relocation { kind: Relative, encoding: Generic, size: 20, target: Symbol(SymbolIndex(1)), addend: fffffffffffffffc, implicit_addend: false, flags: Omf { location: Offset32, mode: SelfRelative, frame: Group(2), target: External(2) } })

Dynamic symbols

Symbol map
0x0-0xd "main_"
53 changes: 53 additions & 0 deletions crates/examples/testfiles/omf/comdat-borland-debug.obj.objdump
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Original file line number Diff line number Diff line change
@@ -0,0 +1,53 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: f, permissions: R-X }
Segment { name: "_DATA", address: 0, size: 0, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
Segment { name: "@foo1$qi", address: 0, size: f, permissions: R-X }
Segment { name: "@foo2$qi", address: 0, size: a, permissions: R-X }
Segment { name: "$$BSYMS", address: 0, size: 19b, permissions: R-- }
Segment { name: "$$BTYPES", address: 0, size: 9e, permissions: R-- }
Segment { name: "$$BNAMES", address: 0, size: 1f, permissions: R-- }
Segment { name: "$$BROWSE", address: 0, size: 0, permissions: R-- }
Segment { name: "$$BROWFILE", address: 0, size: 0, permissions: R-- }
1: Section { name: "_TEXT", address: 0, size: f, align: 4, kind: Text, flags: None }
2: Section { name: "_DATA", address: 0, size: 0, align: 4, kind: Data, flags: None }
3: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }
4: Section { name: "@foo1$qi", address: 0, size: f, align: 4, kind: Text, flags: None }
5: Section { name: "@foo2$qi", address: 0, size: a, align: 4, kind: Text, flags: None }
6: Section { name: "$$BSYMS", address: 0, size: 19b, align: 1, kind: Debug, flags: None }
7: Section { name: "$$BTYPES", address: 0, size: 9e, align: 1, kind: Debug, flags: None }
8: Section { name: "$$BNAMES", address: 0, size: 1f, align: 1, kind: Debug, flags: None }
9: Section { name: "$$BROWSE", address: 0, size: 0, align: 1, kind: Debug, flags: None }
10: Section { name: "$$BROWFILE", address: 0, size: 0, align: 1, kind: Debug, flags: None }
Comdat { symbol: SymbolIndex(0), name: "@foo1$qi", kind: Any } Sections: 4
Comdat { symbol: SymbolIndex(1), name: "@foo2$qi", kind: Any } Sections: 5

Symbols
0: Symbol { name: "@foo1$qi", address: 0, size: f, kind: Text, section: Section(SectionIndex(4)), scope: Linkage, weak: false, flags: None }
1: Symbol { name: "@foo2$qi", address: 0, size: a, kind: Text, section: Section(SectionIndex(5)), scope: Linkage, weak: false, flags: None }
2: Symbol { name: "@bar1$qv", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
3: Symbol { name: "@bar2$qv", address: 6, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
4: Symbol { name: "_main", address: c, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }

_TEXT relocations
(1, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(4)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4001) } })
(7, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(5)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4002) } })

$$BSYMS relocations
(20, Relocation { kind: Absolute, encoding: Generic, size: 30, target: Section(SectionIndex(1)), addend: 0, implicit_addend: false, flags: Omf { location: Pointer48, mode: SegmentRelative, frame: Target, target: Segment(1) } })
(5d, Relocation { kind: Absolute, encoding: Generic, size: 30, target: Section(SectionIndex(1)), addend: 0, implicit_addend: false, flags: Omf { location: Pointer48, mode: SegmentRelative, frame: Target, target: Segment(1) } })
(9a, Relocation { kind: Absolute, encoding: Generic, size: 30, target: Section(SectionIndex(1)), addend: 0, implicit_addend: false, flags: Omf { location: Pointer48, mode: SegmentRelative, frame: Target, target: Segment(1) } })
(d4, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(4)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4001) } })
(135, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(5)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4002) } })

Dynamic symbols

Symbol map
0x0-0xa "@foo2$qi"
0x6-0xa "@bar2$qv"
0xc-0xf "_main"
36 changes: 36 additions & 0 deletions crates/examples/testfiles/omf/comdat-borland.obj.objdump
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
Format: Omf Little-endian 32-bit
Kind: Relocatable
Architecture: I386
Flags: None
Relative Address Base: 0
Entry Address: 0
Segment { name: "_TEXT", address: 0, size: f, permissions: R-X }
Segment { name: "_DATA", address: 0, size: 0, permissions: RW- }
Segment { name: "_BSS", address: 0, size: 0, permissions: RW- }
Segment { name: "@foo1$qi", address: 0, size: f, permissions: R-X }
Segment { name: "@foo2$qi", address: 0, size: a, permissions: R-X }
1: Section { name: "_TEXT", address: 0, size: f, align: 4, kind: Text, flags: None }
2: Section { name: "_DATA", address: 0, size: 0, align: 4, kind: Data, flags: None }
3: Section { name: "_BSS", address: 0, size: 0, align: 4, kind: UninitializedData, flags: None }
4: Section { name: "@foo1$qi", address: 0, size: f, align: 4, kind: Text, flags: None }
5: Section { name: "@foo2$qi", address: 0, size: a, align: 4, kind: Text, flags: None }
Comdat { symbol: SymbolIndex(0), name: "@foo1$qi", kind: Any } Sections: 4
Comdat { symbol: SymbolIndex(1), name: "@foo2$qi", kind: Any } Sections: 5

Symbols
0: Symbol { name: "@foo1$qi", address: 0, size: f, kind: Text, section: Section(SectionIndex(4)), scope: Linkage, weak: false, flags: None }
1: Symbol { name: "@foo2$qi", address: 0, size: a, kind: Text, section: Section(SectionIndex(5)), scope: Linkage, weak: false, flags: None }
2: Symbol { name: "@bar1$qv", address: 0, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
3: Symbol { name: "@bar2$qv", address: 6, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }
4: Symbol { name: "_main", address: c, size: 0, kind: Text, section: Section(SectionIndex(1)), scope: Linkage, weak: false, flags: None }

_TEXT relocations
(1, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(4)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4001) } })
(7, Relocation { kind: SectionOffset, encoding: Generic, size: 20, target: Section(SectionIndex(5)), addend: 0, implicit_addend: false, flags: Omf { location: Offset32, mode: SegmentRelative, frame: Target, target: Segment(4002) } })

Dynamic symbols

Symbol map
0x0-0xa "@foo2$qi"
0x6-0xa "@bar2$qv"
0xc-0xf "_main"
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