[Debuginfod] Add --debug-file-directory to llvm-debuginfod-find.

[mysterymath]

Summary

This allows llvm-debuginfod-find to locate binaries in local build ID
directories configured via --debug-file-directory, the same flag used
for this purpose by llvm-symbolizer. This provides a consistent lookup
semantics between the two tools when configured the same way, in
particular when debug binaries may be located either locally or
remotely.

[phosek]

LGTM

llvm/test/tools/llvm-debuginfod-find/local.test

+# Test that llvm-debuginfod-find can perform local directory lookups.
+
+# Test depends on POSIX file paths.
+UNSUPPORTED: system-windows
+
+RUN: mkdir -p %t/a/.build-id
+RUN: mkdir -p %t/b/.build-id/00/00000000000000
+RUN: mkdir -p %t/b/.build-id/01/23456789012345.debug
+RUN: mkdir -p %t/b/.build-id/02/22222222222222
+RUN: mkdir -p %t/c/.build-id/
+RUN: llvm-debuginfod-find \
+RUN:   --debug-file-directory %t/a \
+RUN:   --debug-file-directory %t/b \
+RUN:   --debug-file-directory %t/c \
+RUN:   --debuginfo 0123456789012345 > %t.out
+RUN: FileCheck -DT=%t --match-full-lines --implicit-check-not {{.}} %s < %t.out
+
+CHECK: [[T]]/b/.build-id/01/23456789012345.debug

llvm/tools/llvm-debuginfod-find/llvm-debuginfod-find.cpp

 /// This file contains the llvm-debuginfod-find tool. This tool
 /// queries the debuginfod servers in the DEBUGINFOD_URLS environment
 /// variable (delimited by space (" ")) for the executable,
 /// debuginfo, or specified source file of the binary matching the
 /// given build-id.
 ///
 //===----------------------------------------------------------------------===//
 
+#include "llvm/DebugInfo/Symbolize/DIFetcher.h"
 #include "llvm/Debuginfod/Debuginfod.h"
 #include "llvm/Debuginfod/HTTPClient.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/InitLLVM.h"
 
 using namespace llvm;
 
 cl::OptionCategory DebuginfodFindCategory("llvm-debuginfod-find Options");

 
 static cl::opt<bool>
     DumpToStdout("dump", cl::init(false),
                  cl::desc("If set, dumps the contents of the fetched artifact "
                           "to standard output. Otherwise, dumps the absolute "
                           "path to the cached artifact on disk."),
                  cl::cat(DebuginfodFindCategory));
 
+static cl::list<std::string> DebugFileDirectory(
+    "debug-file-directory",
+    cl::desc("Path to directory where to look for debug files."),
+    cl::cat(DebuginfodFindCategory));
+
 [[noreturn]] static void helpExit() {
   errs() << "Must specify exactly one of --executable, "
             "--source=/path/to/file, or --debuginfo.";
   exit(1);
 }
 
 ExitOnError ExitOnErr;
 
+static std::string fetchDebugInfo(ArrayRef<uint8_t> BuildID);
+
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
   HTTPClient::initialize();
 
   cl::HideUnrelatedOptions({&DebuginfodFindCategory});
   cl::ParseCommandLineOptions(
       argc, argv,
       "llvm-debuginfod-find: Fetch debuginfod artifacts\n\n"
int main(int argc, char **argv) {
   BuildID ID(IDString.begin(), IDString.end());
 
   std::string Path;
   if (FetchSource != "")
     Path = ExitOnErr(getCachedOrDownloadSource(ID, FetchSource));
   else if (FetchExecutable)
     Path = ExitOnErr(getCachedOrDownloadExecutable(ID));
   else if (FetchDebuginfo)
-    Path = ExitOnErr(getCachedOrDownloadDebuginfo(ID));
+    Path = fetchDebugInfo(ID);
   else
     llvm_unreachable("We have already checked that exactly one of the above "
                      "conditions is true.");
 
   if (DumpToStdout) {
     // Print the contents of the artifact.
     ErrorOr<std::unique_ptr<MemoryBuffer>> Buf = MemoryBuffer::getFile(
         Path, /*IsText=*/false, /*RequiresNullTerminator=*/false);
     ExitOnErr(errorCodeToError(Buf.getError()));
     outs() << Buf.get()->getBuffer();
   } else
     // Print the path to the cached artifact file.
     outs() << Path << "\n";
 }
+
+// Find a debug binary in local build ID directories and via debuginfod.
+std::string fetchDebugInfo(ArrayRef<uint8_t> BuildID) {
+  if (!DebugFileDirectory.empty()) {
+    symbolize::LocalDIFetcher Fetcher(DebugFileDirectory);
+    if (Optional<std::string> LocalPath = Fetcher.fetchBuildID(BuildID))
+      return *LocalPath;
+  }
+  return ExitOnErr(getCachedOrDownloadDebuginfo(BuildID));
+}