1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
//===- FileUpdate.cpp - Conditionally update a file -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// FileUpdate is a utility for conditionally updating a file from its input
// based on whether the input differs from the output. It is used to avoid
// unnecessary modifications in a build system.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/OwningPtr.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/system_error.h"
using namespace llvm;
static cl::opt<bool>
Quiet("quiet", cl::desc("Don't print unnecessary status information"),
cl::init(false));
static cl::opt<std::string>
InputFilename("input-file", cl::desc("Input file (defaults to stdin)"),
cl::init("-"), cl::value_desc("filename"));
static cl::opt<std::string>
OutputFilename(cl::Positional, cl::desc("<output-file>"), cl::Required);
int main(int argc, char **argv) {
sys::PrintStackTraceOnErrorSignal();
PrettyStackTraceProgram X(argc, argv);
cl::ParseCommandLineOptions(argc, argv);
if (OutputFilename == "-") {
errs() << argv[0] << ": error: Can't update standard output\n";
return 1;
}
// Get the input data.
OwningPtr<MemoryBuffer> In;
if (error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename.c_str(), In)) {
errs() << argv[0] << ": error: Unable to get input '"
<< InputFilename << "': " << ec.message() << '\n';
return 1;
}
// Get the output data.
OwningPtr<MemoryBuffer> Out;
MemoryBuffer::getFile(OutputFilename.c_str(), Out);
// If the output exists and the contents match, we are done.
if (Out && In->getBufferSize() == Out->getBufferSize() &&
memcmp(In->getBufferStart(), Out->getBufferStart(),
Out->getBufferSize()) == 0) {
if (!Quiet)
errs() << argv[0] << ": Not updating '" << OutputFilename
<< "', contents match input.\n";
return 0;
}
// Otherwise, overwrite the output.
if (!Quiet)
errs() << argv[0] << ": Updating '" << OutputFilename
<< "', contents changed.\n";
std::string ErrorStr;
tool_output_file OutStream(OutputFilename.c_str(), ErrorStr,
raw_fd_ostream::F_Binary);
if (!ErrorStr.empty()) {
errs() << argv[0] << ": Unable to write output '"
<< OutputFilename << "': " << ErrorStr << '\n';
return 1;
}
OutStream.os().write(In->getBufferStart(), In->getBufferSize());
// Declare success.
OutStream.keep();
return 0;
}
|
