Add --nocache option to disable caching

Bug: #7

lib/data_node.cc

@@ -256,7 +256,8 @@ DataNode DataNode::Make(zip_t* const zip,
 
 Reader::Ptr DataNode::GetReader(zip_t* zip) const {
   if (cached_reader) {
-    Log(LOG_DEBUG, *cached_reader, ": Reused for File [", id, "]");
+    Log(LOG_DEBUG, *cached_reader, ": Cached ", *cached_reader,
+        " reused for File [", id, "]");
     return cached_reader->AddRef();
   }
 

lib/reader.cc

@@ -24,12 +24,15 @@
 
 #include <fcntl.h>
 #include <sys/stat.h>
+#include <sys/syslog.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 #include "error.h"
 #include "scoped_file.h"
 
+bool Reader::may_cache_ = true;
+std::string Reader::cache_dir_ = "/tmp";
 zip_int64_t Reader::reader_count_ = 0;
 
 static void LimitSize(ssize_t* const a, off_t b) {
@@ -102,11 +105,15 @@ class CacheFileReader : public UnbufferedReader {
   // Creates a new, empty and hidden cache file.
   // Throws std::system_error in case of error.
   static ScopedFile CreateCacheFile() {
-    ScopedFile file(open("/tmp", O_TMPFILE | O_RDWR | O_EXCL, 0));
+    if (!may_cache_)
+      throw std::runtime_error("Option --nocache is in use");
+
+    ScopedFile file(open(cache_dir_.c_str(), O_TMPFILE | O_RDWR | O_EXCL, 0));
 
     if (!file.IsValid())
-      ThrowSystemError("Cannot create cache file");
+      ThrowSystemError("Cannot create cache file in ", cache_dir_);
 
+    Log(LOG_DEBUG, "Created cache file in ", cache_dir_);
     return file;
   }
 
@@ -227,7 +234,7 @@ class CacheFileReader : public UnbufferedReader {
 };
 
 // Exception thrown by BufferedReader::Advance() when the decompression engine
-// has to jump too far and a cached reader is reader to be used instead.
+// has to jump too far and a cached reader is to be used instead.
 class TooFar : public std::exception {
  public:
   const char* what() const noexcept override { return "Too far"; }
@@ -253,7 +260,7 @@ bool BufferedReader::CreateCachedReader() const noexcept {
     Log(LOG_DEBUG, *this, ": Created Cached ", *cached_reader_);
     return true;
   } catch (const std::exception& e) {
-    Log(LOG_ERR, *this, ": Cannot create cached reader: ", e.what());
+    Log(LOG_ERR, *this, ": Cannot create Cached Reader: ", e.what());
     return false;
   }
 }

lib/reader.h

@@ -69,6 +69,12 @@ class Reader {
     return out << "Reader " << reader.reader_id_;
   }
 
+  // Whether a cache file may be created if needed.
+  static bool may_cache_;
+
+  // Directory in which the cache file is created if needed.
+  static std::string cache_dir_;
+
  protected:
   virtual ~Reader() = default;
 

main.cc

@@ -40,6 +40,7 @@
 #include "error.h"
 #include "log.h"
 #include "path.h"
+#include "reader.h"
 #include "tree.h"
 
 #if (LIBZIP_VERSION_MAJOR < 1)
@@ -52,26 +53,25 @@
 
 // Prints usage information.
 void print_usage() {
-  fprintf(
-      stderr,
-      "Mounts a ZIP archive as a FUSE filesystem\n"
-      "\n"
-      "Usage: %s [options] <ZIP-file> [mount-point]\n"
-      "\n"
-      "General options:\n"
-      "    --help    -h           print help\n"
-      "    --version              print version\n"
-      "    --quiet   -q           print fewer log messages\n"
-      "    --verbose              print more log messages\n"
-      "    --redact               redact file names from log messages\n"
-      "    --force                mount ZIP even if password is wrong\n"
-      "    --encoding=CHARSET     original encoding of file names\n"
-      "\n"
-      "    -o nospecials          no special files (FIFOs, sockets, devices)\n"
-      "    -o nosymlinks          no symbolic links\n"
-      "    -o nohardlinks         no hard links\n"
-      "\n",
-      PROGRAM);
+  fprintf(stderr,
+          R"(Mounts a ZIP archive as a FUSE filesystem
+
+Usage: %s [options] <ZIP-file> [mount-point]
+
+General options:
+    --help    -h           print help
+    --version              print version
+    --quiet   -q           print fewer log messages
+    --verbose              print more log messages
+    --redact               redact file names from log messages
+    --force                mount ZIP even if password is wrong
+    --encoding=CHARSET     original encoding of file names
+    --nocache              no caching of uncompressed data
+    -o nospecials          no special files (FIFOs, sockets, devices)
+    -o nosymlinks          no symbolic links
+    -o nohardlinks         no hard links
+)",
+          PROGRAM);
 }
 
 // Prints version information.
@@ -244,6 +244,7 @@ enum {
   KEY_NO_SPECIALS,
   KEY_NO_SYMLINKS,
   KEY_NO_HARDLINKS,
+  KEY_NO_CACHE,
 };
 
 // Processes command line arguments.
@@ -315,6 +316,10 @@ static int ProcessArg(void* data,
       param.opts.check_password = false;
       return DISCARD;
 
+    case KEY_NO_CACHE:
+      Reader::may_cache_ = false;
+      return DISCARD;
+
     case KEY_NO_SPECIALS:
       param.opts.include_special_files = false;
       return DISCARD;
@@ -384,6 +389,7 @@ int main(int argc, char* argv[]) try {
                            FUSE_OPT_KEY("-v", KEY_VERBOSE),
                            FUSE_OPT_KEY("--redact", KEY_REDACT),
                            FUSE_OPT_KEY("--force", KEY_FORCE),
+                           FUSE_OPT_KEY("--nocache", KEY_NO_CACHE),
                            FUSE_OPT_KEY("nospecials", KEY_NO_SPECIALS),
                            FUSE_OPT_KEY("nosymlinks", KEY_NO_SYMLINKS),
                            FUSE_OPT_KEY("nohardlinks", KEY_NO_HARDLINKS),

tests/blackbox/test.py

@@ -1466,7 +1466,7 @@ def TestZipWithDefaultOptions():
 
 
 # Tests the ZIP with lots of files.
-def TestBigZip():
+def TestZipWithManyFiles():
     # Only check a few files: the first one, the last one, and one in the middle.
     want_tree = {
         '1': {
@@ -1548,7 +1548,7 @@ def TestBigZip():
 
 
 # Tests that a big file can be accessed in random order.
-def TestBigZip2():
+def TestBigZip():
     zip_name = 'big.zip'
     logging.info(f'Checking {zip_name!r}...')
     with tempfile.TemporaryDirectory() as mount_point:
@@ -1589,6 +1589,41 @@ def TestBigZip2():
             subprocess.run(['fusermount', '-u', '-z', mount_point], check=True)
             logging.debug(f'Unmounted {zip_path!r} from {mount_point!r}')
 
+# Tests that a big file can be accessed in somewhat random order even with no
+# cache file.
+def TestBigZipNoCache():
+    zip_name = 'big.zip'
+    logging.info(f'Checking {zip_name!r}...')
+    with tempfile.TemporaryDirectory() as mount_point:
+        zip_path = os.path.join(script_dir, 'data', zip_name)
+        logging.debug(f'Mounting {zip_path!r} on {mount_point!r}...')
+        subprocess.run([mount_program, '--nocache', zip_path, mount_point],
+                       check=True,
+                       capture_output=True,
+                       input='',
+                       encoding='UTF-8')
+        try:
+            logging.debug(f'Mounted ZIP {zip_path!r} on {mount_point!r}')
+            tree = GetTree(mount_point, use_md5=False)
+            fd = os.open(os.path.join(mount_point, 'big.txt'), os.O_RDONLY)
+            try:
+                random.seed()
+                n = 100000000
+                for j in sorted([random.randrange(n) for i in range(50)]) + [n - 1, 0] + sorted([random.randrange(n) for i in range(50)]) + [n - 1, 0]:
+                    logging.debug(f'Getting line {j}...')
+                    want_line = b'%08d The quick brown fox jumps over the lazy dog.\n' % j
+                    got_line = os.pread(fd, len(want_line), j * len(want_line))
+                    if (got_line != want_line):
+                        LogError(
+                            f'Want line: {want_line!r}, Got line: {got_line!r}'
+                        )
+            finally:
+                os.close(fd)
+        finally:
+            logging.debug(f'Unmounting {zip_path!r} from {mount_point!r}...')
+            subprocess.run(['fusermount', '-u', '-z', mount_point], check=True)
+            logging.debug(f'Unmounted {zip_path!r} from {mount_point!r}')
+
 
 # Tests encrypted ZIP.
 def TestEncryptedZip():
@@ -2310,8 +2345,9 @@ def TestInvalidZip():
 TestZipWithSpecialFiles()
 TestEncryptedZip()
 TestInvalidZip()
+TestZipWithManyFiles()
 TestBigZip()
-TestBigZip2()
+TestBigZipNoCache()
 
 if error_count:
     LogError(f'There were {error_count} errors')