Support gzip-based compression of raw_outstreams

Provide initial zlib-based compression support for
raw_outstreams. Replacing llvm::raw_fd_outstreams
with compressed_fd_outstreams automatically compresses
data in gzip format before writing to file.

Options added:
* --compress-log to compress all query log files (e.g. *.pc, *.smt2) on
  the fly. Every query log file gets extended with .gz.
* --debug-compress-instructions to compress logfile for instruction
  stream on the fly.

1 files changed, 119 insertions, 0 deletions

diff --git a/lib/Support/CompressionStream.cpp b/lib/Support/CompressionStream.cpp
new file mode 100644
index 00000000..eb208edf
--- /dev/null
+++ b/lib/Support/CompressionStream.cpp
@@ -0,0 +1,119 @@
+//===-- CompressionStream.cpp --------------------------------------------===//
+//
+//                     The KLEE Symbolic Virtual Machine
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "klee/Config/config.h"
+#include "klee/Config/Version.h"
+#ifdef HAVE_ZLIB_H
+#include "klee/Internal/Support/CompressionStream.h"
+#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 3)
+#include "llvm/Support/system_error.h"
+#else
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#endif
+
+namespace klee {
+
+compressed_fd_ostream::compressed_fd_ostream(const char *Filename,
+                                             std::string &ErrorInfo)
+    : llvm::raw_ostream(), pos(0) {
+  ErrorInfo = "";
+#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 3)
+  // Open file in binary mode
+  llvm::error_code EC =
+      llvm::sys::fs::openFileForWrite(Filename, FD, llvm::sys::fs::F_Binary);
+
+  if (EC) {
+    ErrorInfo = EC.message();
+    FD = -1;
+  }
+#else
+  FD = ::open(Filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
+  if (FD < 0) {
+    ErrorInfo = "Could not open file.";
+    FD = -1;
+  }
+#endif
+  // Initialize the compression library
+  strm.zalloc = 0;
+  strm.zfree = 0;
+  strm.next_out = buffer;
+  strm.avail_out = BUFSIZE;
+
+  deflateInit2(&strm, Z_BEST_COMPRESSION, Z_DEFLATED, 15 | 16,
+               8 /* memory usage default, 0 smalles, 9 highest*/,
+               Z_DEFAULT_STRATEGY);
+}
+
+void compressed_fd_ostream::writeFullCompressedData() {
+  // Check if no space available and write the buffer
+  if (strm.avail_out == 0) {
+    write_file(reinterpret_cast<const char *>(buffer), BUFSIZE);
+    strm.next_out = buffer;
+    strm.avail_out = BUFSIZE;
+  }
+}
+
+void compressed_fd_ostream::flush_compressed_data() {
+  // flush data from the raw buffer
+  flush();
+
+  // write the remaining data
+  int deflate_res = Z_OK;
+  while (deflate_res == Z_OK) {
+    // Check if no space available and write the buffer
+    writeFullCompressedData();
+    deflate_res = deflate(&strm, Z_FINISH);
+  }
+  assert(deflate_res == Z_STREAM_END);
+  write_file(reinterpret_cast<const char *>(buffer), BUFSIZE - strm.avail_out);
+}
+
+compressed_fd_ostream::~compressed_fd_ostream() {
+  if (FD >= 0) {
+    // write the remaining data
+    flush_compressed_data();
+    close(FD);
+  }
+  deflateEnd(&strm);
+}
+
+void compressed_fd_ostream::write_impl(const char *Ptr, size_t Size) {
+  strm.next_in =
+      const_cast<unsigned char *>(reinterpret_cast<const unsigned char *>(Ptr));
+  strm.avail_in = Size;
+
+  // Check if there is still data to compress
+  while (strm.avail_in != 0) {
+    // compress data
+    int res = deflate(&strm, Z_NO_FLUSH);
+    assert(res == Z_OK);
+    writeFullCompressedData();
+  }
+}
+
+void compressed_fd_ostream::write_file(const char *Ptr, size_t Size) {
+  pos += Size;
+  assert(FD >= 0 && "File already closed");
+  do {
+    ssize_t ret = ::write(FD, Ptr, Size);
+    if (ret < 0) {
+      if (errno == EINTR || errno == EAGAIN)
+        continue;
+      assert(0 && "Could not write to file");
+      break;
+    }
+
+    Ptr += ret;
+    Size -= ret;
+  } while (Size > 0);
+}
+}
+#endif