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(".debug");
26}
27
28static bool isLinkerSection(const Section &Sec) {
29  return Sec.Name.starts_with("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                               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(Filename, Contents.size());
47      if (!BufferOrErr)
48        return BufferOrErr.takeError();
49      std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr);
50      std::copy(Contents.begin(), Contents.end(), Buf->getBufferStart());
51      if (Error E = Buf->commit())
52        return E;
53      return Error::success();
54    }
55  }
56  return createStringError(errc::invalid_argument, "section '%s' not found",
57                           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(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(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(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(Sec.Name))
103        return false;
104      // Otherwise defer to RemovePred.
105      return RemovePred(Sec);
106    };
107  }
108
109  Obj.removeSections(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(SecName, FileName) = Flag.split("=");
118    if (Error E = dumpSectionToFile(SecName, FileName, Obj))
119      return createFileError(FileName, std::move(E));
120  }
121
122  removeSections(Config, Obj);
123
124  for (const NewSectionInfo &NewSection : Config.AddSection) {
125    Section Sec;
126    Sec.SectionType = llvm::wasm::WASM_SEC_CUSTOM;
127    Sec.Name = NewSection.SectionName;
128
129    llvm::StringRef InputData =
130        llvm::StringRef(NewSection.SectionData->getBufferStart(),
131                        NewSection.SectionData->getBufferSize());
132    std::unique_ptr<MemoryBuffer> BufferCopy = MemoryBuffer::getMemBufferCopy(
133        InputData, NewSection.SectionData->getBufferIdentifier());
134    Sec.Contents = ArrayRef<uint8_t>(
135        reinterpret_cast<const uint8_t *>(BufferCopy->getBufferStart()),
136        BufferCopy->getBufferSize());
137
138    Obj.addSectionWithOwnedContents(Sec, std::move(BufferCopy));
139  }
140
141  return Error::success();
142}
143
144Error executeObjcopyOnBinary(const CommonConfig &Config, const WasmConfig &,
145                             object::WasmObjectFile &In, raw_ostream &Out) {
146  Reader TheReader(In);
147  Expected<std::unique_ptr<Object>> ObjOrErr = TheReader.create();
148  if (!ObjOrErr)
149    return createFileError(Config.InputFilename, ObjOrErr.takeError());
150  Object *Obj = ObjOrErr->get();
151  assert(Obj && "Unable to deserialize Wasm object");
152  if (Error E = handleArgs(Config, *Obj))
153    return E;
154  Writer TheWriter(*Obj, Out);
155  if (Error E = TheWriter.write())
156    return createFileError(Config.OutputFilename, std::move(E));
157  return Error::success();
158}
159
160} // end namespace wasm
161} // end namespace objcopy
162} // end namespace llvm
163