[llvm-strip] Add support for -p/--preserve-dates

Summary: [llvm-strip] Preserve access/modification timestamps when -p is used.

Reviewers: jakehehrlich, jhenderson, alexshap

Reviewed By: jhenderson

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50744

llvm-svn: 339921

llvm/test/tools/llvm-objcopy/strip-preserve-time.test

@@ -0,0 +1,70 @@
+# Note: ls -lu prints the accessed timestamp, ls -l prints the modified timestamp
+
+# Preserve dates when stripping to an output file.
+# RUN: yaml2obj %s > %t.1.o
+# RUN: touch -a -t 199505050555.55 %t.1.o
+# RUN: touch -m -t 199705050555.55 %t.1.o
+# RUN: llvm-strip -p %t.1.o -o %t-preserved.1.o
+# RUN: ls -lu %t-preserved.1.o | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t-preserved.1.o | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+
+# Preserve dates available via objcopy interface as well.
+# RUN: yaml2obj %s > %t.2.o
+# RUN: touch -a -t 199505050555.55 %t.2.o
+# RUN: touch -m -t 199705050555.55 %t.2.o
+# RUN: llvm-objcopy -p %t.2.o %t-preserved.2.o
+# RUN: ls -lu %t-preserved.2.o | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t-preserved.2.o | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+
+# Preserve dates when stripping in place.
+# RUN: yaml2obj %s > %t.3.o
+# RUN: touch -a -t 199505050555.55 %t.3.o
+# RUN: touch -m -t 199705050555.55 %t.3.o
+# RUN: llvm-strip -p %t.3.o
+# RUN: ls -lu %t.3.o | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t.3.o | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+
+# Without -p set, don't preserve dates.
+# RUN: yaml2obj %s > %t.4.o
+# RUN: touch -a -t 199505050555.55 %t.4.o
+# RUN: touch -m -t 199705050555.55 %t.4.o
+# RUN: llvm-strip %t.4.o
+# RUN: ls -lu %t.4.o | FileCheck %s --check-prefix=CHECK-NO-PRESERVE-ATIME
+# RUN: ls -l %t.4.o | FileCheck %s --check-prefix=CHECK-NO-PRESERVE-MTIME
+
+# Preserve dates in archives.
+# RUN: yaml2obj %s > %t.5.o
+# RUN: rm -f %t.a
+# RUN: llvm-ar cr %t.a %t.5.o
+# RUN: touch -a -t 199505050555.55 %t.a
+# RUN: touch -m -t 199705050555.55 %t.a
+# RUN: llvm-strip -p %t.a
+# RUN: ls -lu %t.a | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t.a | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+
+# Preserve dates in split DWO files.
+# RUN: cp %p/Inputs/dwarf.dwo %t-input.dwo
+# RUN: touch -a -t 199505050555.55 %t-input.dwo
+# RUN: touch -m -t 199705050555.55 %t-input.dwo
+# RUN: llvm-objcopy -p -split-dwo=%t-dwo %t-input.dwo %t-nondwo
+# RUN: ls -lu %t-dwo | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t-dwo | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+# RUN: ls -lu %t-nondwo | FileCheck %s --check-prefix=CHECK-PRESERVE-ATIME
+# RUN: ls -l %t-nondwo | FileCheck %s --check-prefix=CHECK-PRESERVE-MTIME
+
+# CHECK-PRESERVE-ATIME:        1995
+# CHECK-PRESERVE-MTIME:        1997
+
+# CHECK-NO-PRESERVE-ATIME-NOT: 1995
+# CHECK-NO-PRESERVE-MTIME-NOT: 1997
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]

llvm/tools/llvm-objcopy/ObjcopyOpts.td

@@ -22,6 +22,12 @@ def O : JoinedOrSeparate<["-"], "O">,
 defm split_dwo : Eq<"split-dwo">,
                  MetaVarName<"dwo-file">,
                  HelpText<"Equivalent to extract-dwo on the input file to <dwo-file>, then strip-dwo on the input file">;
+
+def preserve_dates : Flag<[ "-", "--" ], "preserve-dates">,
+                     HelpText<"Preserve access and modification timestamps">;
+
+def p : Flag<[ "-" ], "p">, Alias<preserve_dates>;
+
 defm add_gnu_debuglink : Eq<"add-gnu-debuglink">,
                          MetaVarName<"debug-file">,
                          HelpText<"Add a .gnu_debuglink for <debug-file>">;

llvm/tools/llvm-objcopy/StripOpts.td

@@ -11,6 +11,11 @@ defm output : Eq<"o">,
               MetaVarName<"output">,
               HelpText<"Write output to <file>">;
 
+def preserve_dates : Flag<[ "-", "--" ], "preserve-dates">,
+                     HelpText<"Preserve access and modification timestamps">;
+
+def p : Flag<[ "-" ], "p">, Alias<preserve_dates>;
+
 def strip_all : Flag<["-", "--"], "strip-all">,
                 HelpText<"Remove non-allocated sections other than .gnu.warning* sections">;
 

llvm/tools/llvm-objcopy/llvm-objcopy.cpp

@@ -35,6 +35,7 @@
 #include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -161,6 +162,7 @@ struct CopyConfig {
   bool DiscardAll = false;
   bool OnlyKeepDebug = false;
   bool KeepFileSymbols = false;
+  bool PreserveDates = false;
 };
 
 using SectionPred = std::function<bool(const SectionBase &Sec)>;
@@ -675,17 +677,44 @@ static void executeElfObjcopyOnArchive(const CopyConfig &Config,
     reportError(Config.OutputFilename, std::move(E));
 }
 
+static void restoreDateOnFile(StringRef Filename,
+                              const sys::fs::file_status &Stat) {
+  int FD;
+
+  if (auto EC = sys::fs::openFileForWrite(Filename, FD))
+    reportError(Filename, EC);
+
+  if (auto EC = sys::fs::setLastAccessAndModificationTime(
+          FD, Stat.getLastAccessedTime(), Stat.getLastModificationTime()))
+    reportError(Filename, EC);
+
+  if (auto EC = sys::Process::SafelyCloseFileDescriptor(FD))
+    reportError(Filename, EC);
+}
+
 static void executeElfObjcopy(const CopyConfig &Config) {
+  sys::fs::file_status Stat;
+  if (Config.PreserveDates)
+    if (auto EC = sys::fs::status(Config.InputFilename, Stat))
+      reportError(Config.InputFilename, EC);
+
   Expected<OwningBinary<llvm::object::Binary>> BinaryOrErr =
       createBinary(Config.InputFilename);
   if (!BinaryOrErr)
     reportError(Config.InputFilename, BinaryOrErr.takeError());
 
-  if (Archive *Ar = dyn_cast<Archive>(BinaryOrErr.get().getBinary()))
-    return executeElfObjcopyOnArchive(Config, *Ar);
+  if (Archive *Ar = dyn_cast<Archive>(BinaryOrErr.get().getBinary())) {
+    executeElfObjcopyOnArchive(Config, *Ar);
+  } else {
+    FileBuffer FB(Config.OutputFilename);
+    executeElfObjcopyOnBinary(Config, *BinaryOrErr.get().getBinary(), FB);
+  }
 
-  FileBuffer FB(Config.OutputFilename);
-  executeElfObjcopyOnBinary(Config, *BinaryOrErr.get().getBinary(), FB);
+  if (Config.PreserveDates) {
+    restoreDateOnFile(Config.OutputFilename, Stat);
+    if (!Config.SplitDWO.empty())
+      restoreDateOnFile(Config.SplitDWO, Stat);
+  }
 }
 
 // ParseObjcopyOptions returns the config and sets the input arguments. If a
@@ -780,6 +809,8 @@ static CopyConfig parseObjcopyOptions(ArrayRef<const char *> ArgsArr) {
   for (auto Arg : InputArgs.filtered(OBJCOPY_keep_symbol))
     Config.SymbolsToKeep.push_back(Arg->getValue());
 
+  Config.PreserveDates = InputArgs.hasArg(OBJCOPY_preserve_dates);
+
   return Config;
 }
 
@@ -834,6 +865,8 @@ static CopyConfig parseStripOptions(ArrayRef<const char *> ArgsArr) {
   for (auto Arg : InputArgs.filtered(STRIP_keep_symbol))
     Config.SymbolsToKeep.push_back(Arg->getValue());
 
+  Config.PreserveDates = InputArgs.hasArg(STRIP_preserve_dates);
+
   return Config;
 }