Preserve modification timestamp when zipping files.

third_party/zlib/google/zip.cc

Index: third_party/zlib/google/zip.cc
diff --git a/third_party/zlib/google/zip.cc b/third_party/zlib/google/zip.cc
index d1ba74fb147a328d6aabcca5fe697a1640291654..39f58ce596e075f423d32a5934f59a6b68f6f15d 100644
--- a/third_party/zlib/google/zip.cc
+++ b/third_party/zlib/google/zip.cc
@@ -4,6 +4,9 @@
 
 #include "third_party/zlib/google/zip.h"
 
+#include <string>
+#include <vector>
+
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/files/file_enumerator.h"
@@ -24,6 +27,38 @@
 
 namespace {
 
+// Returns a zip_fileinfo struct with the time represented by |file_time|.
+zip_fileinfo TimeToZipFileInfo(const base::Time& file_time) {
+  base::Time::Exploded file_time_parts;
+  file_time.LocalExplode(&file_time_parts);
+
+  zip_fileinfo zip_info = {};
+  if (file_time_parts.year >= 1980) {
+    // This if check works around the handling of the year value in
+    // contrib/minizip/zip.c in function zip64local_TmzDateToDosDate
+    // It assumes that dates below 1980 are in the double digit format.
+    // Hence the fail safe option is to leave the date unset. Some programs
+    // might show the unset date as 1980-0-0 which is invalid.
+    zip_info.tmz_date.tm_year = file_time_parts.year;
+    zip_info.tmz_date.tm_mon = file_time_parts.month - 1;
+    zip_info.tmz_date.tm_mday = file_time_parts.day_of_month;
+    zip_info.tmz_date.tm_hour = file_time_parts.hour;
+    zip_info.tmz_date.tm_min = file_time_parts.minute;
+    zip_info.tmz_date.tm_sec = file_time_parts.second;
+  }
+
+  return zip_info;
+}
+
+// Returns a zip_fileinfo with the last modification date of |path| set.
+zip_fileinfo GetFileInfoForZipping(const base::FilePath& path) {
+  base::Time file_time;
+  base::PlatformFileInfo file_info;
+  if (base::GetFileInfo(path, &file_info))
+    file_time = file_info.last_modified;
+  return TimeToZipFileInfo(file_time);
+}
+
 bool AddFileToZip(zipFile zip_file, const base::FilePath& src_dir) {
   net::FileStream stream(NULL);
   int flags = base::PLATFORM_FILE_OPEN | base::PLATFORM_FILE_READ;
@@ -65,12 +100,14 @@ bool AddEntryToZip(zipFile zip_file, const base::FilePath& path,
 
   // Section 4.4.4 http://www.pkware.com/documents/casestudies/APPNOTE.TXT
   // Setting the Language encoding flag so the file is told to be in utf-8.
-  const unsigned long LANGUAGE_ENCODING_FLAG = 0x1 << 11;
+  const uLong LANGUAGE_ENCODING_FLAG = 0x1 << 11;
+
+  zip_fileinfo file_info = GetFileInfoForZipping(path);
 
   if (ZIP_OK != zipOpenNewFileInZip4(
-                    zip_file,  //file
+                    zip_file,  // file
                     str_path.c_str(),  // filename
-                    NULL,  // zipfi (file_info)
+                    &file_info,  // zipfi
                     NULL,  // extrafield_local,
                     0u,  // size_extrafield_local
                     NULL,  // extrafield_global
@@ -82,7 +119,7 @@ bool AddEntryToZip(zipFile zip_file, const base::FilePath& path,
                     -MAX_WBITS,  // windowBits
                     DEF_MEM_LEVEL,  // memLevel
                     Z_DEFAULT_STRATEGY,  // strategy
-                    NULL,  //password
+                    NULL,  // password
                     0,  // crcForCrypting
                     0,  // versionMadeBy
                     LANGUAGE_ENCODING_FLAG)) {  // flagBase