1 //===-- ObjDumper.cpp - Base dumper class -----------------------*- C++ -*-===//
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 /// \file
10 /// This file implements ObjDumper.
11 ///
12 //===----------------------------------------------------------------------===//
13 
14 #include "ObjDumper.h"
15 #include "Error.h"
16 #include "llvm-readobj.h"
17 #include "llvm/Object/ObjectFile.h"
18 #include "llvm/Support/Error.h"
19 #include "llvm/Support/FormatVariadic.h"
20 #include "llvm/Support/ScopedPrinter.h"
21 #include "llvm/Support/raw_ostream.h"
22 
23 namespace llvm {
24 
25 ObjDumper::ObjDumper(ScopedPrinter &Writer) : W(Writer) {}
26 
27 ObjDumper::~ObjDumper() {
28 }
29 
30 static void printAsPrintable(raw_ostream &W, const uint8_t *Start, size_t Len) {
31   for (size_t i = 0; i < Len; i++)
32     W << (isPrint(Start[i]) ? static_cast<char>(Start[i]) : '.');
33 }
34 
35 static Expected<object::SectionRef>
36 getSecNameOrIndexAsSecRef(const object::ObjectFile *Obj, StringRef SecName) {
37   char *StrPtr;
38   long SectionIndex = strtol(SecName.data(), &StrPtr, 10);
39   long SecIndex;
40   if (Obj->isELF())
41     SecIndex = 0;
42   else
43     SecIndex = 1;
44   for (object::SectionRef SecRef : Obj->sections()) {
45     if (*StrPtr) {
46       StringRef SectionName;
47 
48       if (std::error_code E = SecRef.getName(SectionName))
49         return errorCodeToError(E);
50 
51       if (SectionName == SecName)
52         return SecRef;
53     } else if (SecIndex == SectionIndex)
54       return SecRef;
55 
56     SecIndex++;
57   }
58   return make_error<StringError>(
59       formatv("could not find section '{0}'", SecName),
60       object::object_error::parse_failed);
61 }
62 
63 void ObjDumper::printSectionAsString(const object::ObjectFile *Obj,
64                                      StringRef SecName) {
65   Expected<object::SectionRef> SectionRefOrError =
66       getSecNameOrIndexAsSecRef(Obj, SecName);
67   if (!SectionRefOrError)
68     error(std::move(SectionRefOrError));
69   object::SectionRef Section = *SectionRefOrError;
70   StringRef SectionName;
71 
72   if (std::error_code E = Section.getName(SectionName))
73     error(E);
74   W.startLine() << "String dump of section '" << SectionName << "':\n";
75 
76   StringRef SectionContent = unwrapOrError(Section.getContents());
77 
78   const uint8_t *SecContent = SectionContent.bytes_begin();
79   const uint8_t *CurrentWord = SecContent;
80   const uint8_t *SecEnd = SectionContent.bytes_end();
81 
82   while (CurrentWord <= SecEnd) {
83     size_t WordSize = strnlen(reinterpret_cast<const char *>(CurrentWord),
84                               SecEnd - CurrentWord);
85     if (!WordSize) {
86       CurrentWord++;
87       continue;
88     }
89     W.startLine() << format("[%6tx] ", CurrentWord - SecContent);
90     printAsPrintable(W.startLine(), CurrentWord, WordSize);
91     W.startLine() << '\n';
92     CurrentWord += WordSize + 1;
93   }
94 }
95 
96 void ObjDumper::printSectionAsHex(const object::ObjectFile *Obj,
97                                   StringRef SecName) {
98   Expected<object::SectionRef> SectionRefOrError =
99       getSecNameOrIndexAsSecRef(Obj, SecName);
100   if (!SectionRefOrError)
101     error(std::move(SectionRefOrError));
102   object::SectionRef Section = *SectionRefOrError;
103   StringRef SectionName;
104 
105   if (std::error_code E = Section.getName(SectionName))
106     error(E);
107   W.startLine() << "Hex dump of section '" << SectionName << "':\n";
108 
109   StringRef SectionContent = unwrapOrError(Section.getContents());
110   const uint8_t *SecContent = SectionContent.bytes_begin();
111   const uint8_t *SecEnd = SecContent + SectionContent.size();
112 
113   for (const uint8_t *SecPtr = SecContent; SecPtr < SecEnd; SecPtr += 16) {
114     const uint8_t *TmpSecPtr = SecPtr;
115     uint8_t i;
116     uint8_t k;
117 
118     W.startLine() << format_hex(Section.getAddress() + (SecPtr - SecContent),
119                                 10);
120     W.startLine() << ' ';
121     for (i = 0; TmpSecPtr < SecEnd && i < 4; ++i) {
122       for (k = 0; TmpSecPtr < SecEnd && k < 4; k++, TmpSecPtr++) {
123         uint8_t Val = *(reinterpret_cast<const uint8_t *>(TmpSecPtr));
124         W.startLine() << format_hex_no_prefix(Val, 2);
125       }
126       W.startLine() << ' ';
127     }
128 
129     // We need to print the correct amount of spaces to match the format.
130     // We are adding the (4 - i) last rows that are 8 characters each.
131     // Then, the (4 - i) spaces that are in between the rows.
132     // Least, if we cut in a middle of a row, we add the remaining characters,
133     // which is (8 - (k * 2)).
134     if (i < 4)
135       W.startLine() << format("%*c", (4 - i) * 8 + (4 - i) + (8 - (k * 2)),
136                               ' ');
137 
138     TmpSecPtr = SecPtr;
139     for (i = 0; TmpSecPtr + i < SecEnd && i < 16; ++i)
140       W.startLine() << (isPrint(TmpSecPtr[i]) ? static_cast<char>(TmpSecPtr[i])
141                                               : '.');
142 
143     W.startLine() << '\n';
144   }
145 }
146 
147 } // namespace llvm
148