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88 lines
2.8 KiB
C++
88 lines
2.8 KiB
C++
//===- FileUpdate.cpp - Conditionally update a file -----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// FileUpdate is a utility for conditionally updating a file from its input
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// based on whether the input differs from the output. It is used to avoid
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// unnecessary modifications in a build system.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/ADT/OwningPtr.h"
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#include "llvm/Support/PrettyStackTrace.h"
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#include "llvm/Support/ToolOutputFile.h"
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#include "llvm/Support/Signals.h"
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#include "llvm/Support/system_error.h"
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using namespace llvm;
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static cl::opt<bool>
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Quiet("quiet", cl::desc("Don't print unnecessary status information"),
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cl::init(false));
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static cl::opt<std::string>
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InputFilename("input-file", cl::desc("Input file (defaults to stdin)"),
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cl::init("-"), cl::value_desc("filename"));
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static cl::opt<std::string>
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OutputFilename(cl::Positional, cl::desc("<output-file>"), cl::Required);
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int main(int argc, char **argv) {
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sys::PrintStackTraceOnErrorSignal();
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PrettyStackTraceProgram X(argc, argv);
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cl::ParseCommandLineOptions(argc, argv);
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if (OutputFilename == "-") {
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errs() << argv[0] << ": error: Can't update standard output\n";
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return 1;
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}
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// Get the input data.
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OwningPtr<MemoryBuffer> In;
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if (error_code ec = MemoryBuffer::getFileOrSTDIN(InputFilename.c_str(), In)) {
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errs() << argv[0] << ": error: Unable to get input '"
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<< InputFilename << "': " << ec.message() << '\n';
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return 1;
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}
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// Get the output data.
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OwningPtr<MemoryBuffer> Out;
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MemoryBuffer::getFile(OutputFilename.c_str(), Out);
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// If the output exists and the contents match, we are done.
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if (Out && In->getBufferSize() == Out->getBufferSize() &&
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memcmp(In->getBufferStart(), Out->getBufferStart(),
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Out->getBufferSize()) == 0) {
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if (!Quiet)
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errs() << argv[0] << ": Not updating '" << OutputFilename
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<< "', contents match input.\n";
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return 0;
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}
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// Otherwise, overwrite the output.
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if (!Quiet)
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errs() << argv[0] << ": Updating '" << OutputFilename
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<< "', contents changed.\n";
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std::string ErrorStr;
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tool_output_file OutStream(OutputFilename.c_str(), ErrorStr,
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raw_fd_ostream::F_Binary);
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if (!ErrorStr.empty()) {
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errs() << argv[0] << ": Unable to write output '"
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<< OutputFilename << "': " << ErrorStr << '\n';
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return 1;
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}
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OutStream.os().write(In->getBufferStart(), In->getBufferSize());
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// Declare success.
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OutStream.keep();
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return 0;
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}
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