Improve Zip File Scanning on Mac

This CL fixes two aspects of broken ZIP processing on Mac. First, it ensures
that .app files are treated as directories and as such do not break binary
feature extraction, causing analysis to fail. Second, it performs
type-sniffing to identify the existence of executable MachO files that do not
have any file extension, as is the usual case on Mac.

BUG=600392

Review-Url: https://codereview.chromium.org/2961373002
Cr-Original-Commit-Position: refs/heads/master@{#492032}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 034ecb569929e1202f39cf744a32e8deeade06c8

1 files changed, 19 insertions, 16 deletions

diff --git a/google/zip_reader.h b/google/zip_reader.h
index c1b6fb3..0464acd 100644
--- a/google/zip_reader.h
+++ b/google/zip_reader.h
@@ -159,8 +159,11 @@ class ZipReader {
   // success. On failure, current_entry_info() becomes NULL.
   bool LocateAndOpenEntry(const base::FilePath& path_in_zip);
 
-  // Extracts the current entry in chunks to |delegate|.
-  bool ExtractCurrentEntry(WriterDelegate* delegate) const;
+  // Extracts |num_bytes_to_extract| bytes of the current entry to |delegate|,
+  // starting from the beginning of the entry. Return value specifies whether
+  // the entire file was extracted.
+  bool ExtractCurrentEntry(WriterDelegate* delegate,
+                           uint64_t num_bytes_to_extract) const;
 
   // Extracts the current entry to the given output file path. If the
   // current file is a directory, just creates a directory
@@ -202,20 +205,20 @@ class ZipReader {
   // Does not close the file. Returns true on success.
   bool ExtractCurrentEntryToFile(base::File* file) const;
 
-  // Extracts the current entry into memory. If the current entry is a directory
-  // the |output| parameter is set to the empty string. If the current entry is
-  // a file, the |output| parameter is filled with its contents. Returns true on
-  // success. OpenCurrentEntryInZip() must be called beforehand.
-  // Note: the |output| parameter can be filled with a big amount of data, avoid
-  // passing it around by value, but by reference or pointer.
-  // Note: the value returned by EntryInfo::original_size() cannot be
-  // trusted, so the real size of the uncompressed contents can be different.
-  // Use max_read_bytes to limit the ammount of memory used to carry the entry.
-  // If the real size of the uncompressed data is bigger than max_read_bytes
-  // then false is returned. |max_read_bytes| must be non-zero.
-  bool ExtractCurrentEntryToString(
-      size_t max_read_bytes,
-      std::string* output) const;
+  // Extracts the current entry into memory. If the current entry is a
+  // directory, the |output| parameter is set to the empty string. If the
+  // current entry is a file, the |output| parameter is filled with its
+  // contents. OpenCurrentEntryInZip() must be called beforehand. Note: the
+  // |output| parameter can be filled with a big amount of data, avoid passing
+  // it around by value, but by reference or pointer. Note: the value returned
+  // by EntryInfo::original_size() cannot be trusted, so the real size of the
+  // uncompressed contents can be different. |max_read_bytes| limits the ammount
+  // of memory used to carry the entry. Returns true if the entire content is
+  // read. If the entry is bigger than |max_read_bytes|, returns false and
+  // |output| is filled with |max_read_bytes| of data. If an error occurs,
+  // returns false, and |output| is set to the empty string.
+  bool ExtractCurrentEntryToString(uint64_t max_read_bytes,
+                                   std::string* output) const;
 
   // Returns the current entry info. Returns NULL if the current entry is
   // not yet opened. OpenCurrentEntryInZip() must be called beforehand.