1//===- WasmObjcopy.cpp ----------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/ObjCopy/wasm/WasmObjcopy.h"
10#include "WasmObject.h"
11#include "WasmReader.h"
12#include "WasmWriter.h"
13#include "llvm/ObjCopy/CommonConfig.h"
14#include "llvm/Support/Errc.h"
15#include "llvm/Support/FileOutputBuffer.h"
16
17namespace llvm {
18namespace objcopy {
19namespace wasm {
20
21using namespace object;
22using SectionPred = std::function<bool(const Section &Sec)>;
23
24static bool isDebugSection(const Section &Sec) {
25 return Sec.Name.starts_with(Prefix: ".debug") || Sec.Name.starts_with(Prefix: "reloc..debug");
26}
27
28static bool isLinkerSection(const Section &Sec) {
29 return Sec.Name.starts_with(Prefix: "reloc.") || Sec.Name == "linking";
30}
31
32static bool isNameSection(const Section &Sec) { return Sec.Name == "name"; }
33
34// Sections which are known to be "comments" or informational and do not affect
35// program semantics.
36static bool isCommentSection(const Section &Sec) {
37 return Sec.Name == "producers";
38}
39
40static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
41 StringRef InputFilename, Object &Obj) {
42 for (const Section &Sec : Obj.Sections) {
43 if (Sec.Name == SecName) {
44 ArrayRef<uint8_t> Contents = Sec.Contents;
45 Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
46 FileOutputBuffer::create(FilePath: Filename, Size: Contents.size());
47 if (!BufferOrErr)
48 return createFileError(F: Filename, E: BufferOrErr.takeError());
49 std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr);
50 llvm::copy(Range&: Contents, Out: Buf->getBufferStart());
51 if (Error E = Buf->commit())
52 return createFileError(F: Filename, E: std::move(E));
53 return Error::success();
54 }
55 }
56 return createFileError(F: Filename, EC: errc::invalid_argument,
57 Fmt: "section '%s' not found", Vals: SecName.str().c_str());
58}
59
60static void removeSections(const CommonConfig &Config, Object &Obj) {
61 SectionPred RemovePred = [](const Section &) { return false; };
62
63 // Explicitly-requested sections.
64 if (!Config.ToRemove.empty()) {
65 RemovePred = [&Config](const Section &Sec) {
66 return Config.ToRemove.matches(S: Sec.Name);
67 };
68 }
69
70 if (Config.StripDebug) {
71 RemovePred = [RemovePred](const Section &Sec) {
72 return RemovePred(Sec) || isDebugSection(Sec);
73 };
74 }
75
76 if (Config.StripAll) {
77 RemovePred = [RemovePred](const Section &Sec) {
78 return RemovePred(Sec) || isDebugSection(Sec) || isLinkerSection(Sec) ||
79 isNameSection(Sec) || isCommentSection(Sec);
80 };
81 }
82
83 if (Config.OnlyKeepDebug) {
84 RemovePred = [&Config](const Section &Sec) {
85 // Keep debug sections, unless explicitly requested to remove.
86 // Remove everything else, including known sections.
87 return Config.ToRemove.matches(S: Sec.Name) || !isDebugSection(Sec);
88 };
89 }
90
91 if (!Config.OnlySection.empty()) {
92 RemovePred = [&Config](const Section &Sec) {
93 // Explicitly keep these sections regardless of previous removes.
94 // Remove everything else, inluding known sections.
95 return !Config.OnlySection.matches(S: Sec.Name);
96 };
97 }
98
99 if (!Config.KeepSection.empty()) {
100 RemovePred = [&Config, RemovePred](const Section &Sec) {
101 // Explicitly keep these sections regardless of previous removes.
102 if (Config.KeepSection.matches(S: Sec.Name))
103 return false;
104 // Otherwise defer to RemovePred.
105 return RemovePred(Sec);
106 };
107 }
108
109 Obj.removeSections(ToRemove: RemovePred);
110}
111
112static Error handleArgs(const CommonConfig &Config, Object &Obj) {
113 // Only support AddSection, DumpSection, RemoveSection for now.
114 for (StringRef Flag : Config.DumpSection) {
115 StringRef SecName;
116 StringRef FileName;
117 std::tie(args&: SecName, args&: FileName) = Flag.split(Separator: "=");
118 if (Error E =
119 dumpSectionToFile(SecName, Filename: FileName, InputFilename: Config.InputFilename, Obj))
120 return E;
121 }
122
123 removeSections(Config, Obj);
124
125 for (const NewSectionInfo &NewSection : Config.AddSection) {
126 Section Sec;
127 Sec.SectionType = llvm::wasm::WASM_SEC_CUSTOM;
128 Sec.Name = NewSection.SectionName;
129
130 llvm::StringRef InputData =
131 llvm::StringRef(NewSection.SectionData->getBufferStart(),
132 NewSection.SectionData->getBufferSize());
133 std::unique_ptr<MemoryBuffer> BufferCopy = MemoryBuffer::getMemBufferCopy(
134 InputData, BufferName: NewSection.SectionData->getBufferIdentifier());
135 Sec.Contents = ArrayRef<uint8_t>(
136 reinterpret_cast<const uint8_t *>(BufferCopy->getBufferStart()),
137 BufferCopy->getBufferSize());
138
139 Obj.addSectionWithOwnedContents(NewSection: Sec, Content: std::move(BufferCopy));
140 }
141
142 return Error::success();
143}
144
145Error executeObjcopyOnBinary(const CommonConfig &Config, const WasmConfig &,
146 object::WasmObjectFile &In, raw_ostream &Out) {
147 Reader TheReader(In);
148 Expected<std::unique_ptr<Object>> ObjOrErr = TheReader.create();
149 if (!ObjOrErr)
150 return createFileError(F: Config.InputFilename, E: ObjOrErr.takeError());
151 Object *Obj = ObjOrErr->get();
152 assert(Obj && "Unable to deserialize Wasm object");
153 if (Error E = handleArgs(Config, Obj&: *Obj))
154 return E;
155 Writer TheWriter(*Obj, Out);
156 if (Error E = TheWriter.write())
157 return createFileError(F: Config.OutputFilename, E: std::move(E));
158 return Error::success();
159}
160
161} // end namespace wasm
162} // end namespace objcopy
163} // end namespace llvm
164