From 14b78f815fa02ffda48f8a6599d6af45868266ff Mon Sep 17 00:00:00 2001
From: Zack Rusin <zack@kde.org>
Date: Sat, 6 Aug 2011 19:26:46 -0400
Subject: [PATCH] Automatically detect whether trace is zlib or snappy
 compressed

---
 trace_file.cpp   | 15 +++++++++++++++
 trace_file.hpp   |  2 ++
 trace_parser.cpp | 12 ++++++++++--
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/trace_file.cpp b/trace_file.cpp
index 0272a5c..10e6565 100644
--- a/trace_file.cpp
+++ b/trace_file.cpp
@@ -89,6 +89,21 @@ int File::getc()
     return rawGetc();
 }
 
+bool File::isZLibCompressed(const std::string &filename)
+{
+    std::fstream stream(filename.c_str(),
+                        std::fstream::binary | std::fstream::in);
+    if (!stream.is_open())
+        return false;
+
+    unsigned char byte1, byte2;
+    stream >> byte1;
+    stream >> byte2;
+    stream.close();
+
+    return (byte1 == 0x1f && byte2 == 0x8b);
+}
+
 ZLibFile::ZLibFile(const std::string &filename,
                    File::Mode mode)
     : File(filename, mode),
diff --git a/trace_file.hpp b/trace_file.hpp
index 7e7f9bd..3afa709 100644
--- a/trace_file.hpp
+++ b/trace_file.hpp
@@ -12,6 +12,8 @@ public:
         Read,
         Write
     };
+public:
+    static bool isZLibCompressed(const std::string &filename);
 public:
     File(const std::string &filename = std::string(),
          File::Mode mode = File::Read);
diff --git a/trace_parser.cpp b/trace_parser.cpp
index d53d62c..b0b501a 100644
--- a/trace_parser.cpp
+++ b/trace_parser.cpp
@@ -39,7 +39,7 @@ namespace Trace {
 
 
 Parser::Parser() {
-    file = new Trace::SnappyFile;
+    file = NULL;
     next_call_no = 0;
     version = 0;
 }
@@ -47,11 +47,17 @@ Parser::Parser() {
 
 Parser::~Parser() {
     close();
-    delete file;
 }
 
 
 bool Parser::open(const char *filename) {
+    assert(!file);
+    if (File::isZLibCompressed(filename)) {
+        file = new ZLibFile;
+    } else {
+        file = new SnappyFile;
+    }
+
     if (!file->open(filename, File::Read)) {
         return false;
     }
@@ -84,6 +90,8 @@ deleteAll(const Container &c)
 
 void Parser::close(void) {
     file->close();
+    delete file;
+    file = NULL;
 
     deleteAll(calls);
     deleteAll(functions);
-- 
2.45.2