From 29054d42a01f1d897ce2c52c3b8f4cc523863f5b Mon Sep 17 00:00:00 2001
From: Scott Lamb <slamb@slamb.org>
Date: Sat, 9 Jan 2016 23:26:02 -0800
Subject: [PATCH] A few types of FileSlice useful for mp4 building.

---
 src/http.cc | 63 +++++++++++++++++++++++++++++++++++++----------------
 src/http.h  | 42 +++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 19 deletions(-)

diff --git a/src/http.cc b/src/http.cc
index c6aeb68..6afe1f4 100644
--- a/src/http.cc
+++ b/src/http.cc
@@ -58,41 +58,31 @@ class RealFile : public VirtualFile {
  public:
   RealFile(re2::StringPiece mime_type, re2::StringPiece filename,
            const struct stat &statbuf)
-      : mime_type_(mime_type.as_string()),
-        filename_(filename.as_string()),
-        stat_(statbuf) {}
+      : mime_type_(mime_type.as_string()), stat_(statbuf) {
+    slice_.Init(filename, ByteRange(0, statbuf.st_size));
+  }
+
   ~RealFile() final {}
 
   int64_t size() const final { return stat_.st_size; }
   time_t last_modified() const final { return stat_.st_mtime; }
+  std::string mime_type() const final { return mime_type_; }
+  std::string filename() const final { return slice_.filename(); }
+
   std::string etag() const final {
     return StrCat("\"", stat_.st_ino, ":", stat_.st_size, ":",
                   stat_.st_mtim.tv_sec, ":", stat_.st_mtim.tv_nsec, "\"");
   }
-  std::string mime_type() const final { return mime_type_; }
-  std::string filename() const final { return filename_; }
 
   // Add the given range of the file to the buffer.
   bool AddRange(ByteRange range, EvBuffer *buf,
                 std::string *error_message) const final {
-    int fd = open(filename_.c_str(), O_RDONLY);
-    if (fd < 0) {
-      int err = errno;
-      *error_message = StrCat("open: ", strerror(err));
-      return false;
-    }
-    if (!buf->AddFile(fd, range.begin, range.end - range.begin,
-                      error_message)) {
-      close(fd);
-      return false;
-    }
-    // |buf| now owns |fd|.
-    return true;
+    return slice_.AddRange(range, buf, error_message);
   }
 
  private:
+  RealFileSlice slice_;
   const std::string mime_type_;
-  const std::string filename_;
   const struct stat stat_;
 };
 
@@ -202,6 +192,28 @@ bool EvBuffer::AddFile(int fd, ev_off_t offset, ev_off_t length,
   return true;
 }
 
+void RealFileSlice::Init(re2::StringPiece filename, ByteRange range) {
+  filename_ = filename.as_string();
+  range_ = range;
+}
+
+bool RealFileSlice::AddRange(ByteRange range, EvBuffer *buf,
+                             std::string *error_message) const {
+  int fd = open(filename_.c_str(), O_RDONLY);
+  if (fd < 0) {
+    int err = errno;
+    *error_message = StrCat("open: ", strerror(err));
+    return false;
+  }
+  if (!buf->AddFile(fd, range_.begin + range.begin, range.size(),
+                    error_message)) {
+    close(fd);
+    return false;
+  }
+  // |buf| now owns |fd|.
+  return true;
+}
+
 bool FillerFileSlice::AddRange(ByteRange range, EvBuffer *buf,
                                std::string *error_message) const {
   std::unique_ptr<std::string> s(new std::string);
@@ -222,6 +234,19 @@ bool FillerFileSlice::AddRange(ByteRange range, EvBuffer *buf,
   return true;
 }
 
+bool StaticStringPieceSlice::AddRange(ByteRange range, EvBuffer *buf,
+                                      std::string *error_message) const {
+  buf->AddReference(piece_.data() + range.begin, range.size(), nullptr,
+                    nullptr);
+  return true;
+}
+
+bool CopyingStringPieceSlice::AddRange(ByteRange range, EvBuffer *buf,
+                                       std::string *error_message) const {
+  buf->Add(re2::StringPiece(piece_.data() + range.begin, range.size()));
+  return true;
+}
+
 bool FileSlices::AddRange(ByteRange range, EvBuffer *buf,
                           std::string *error_message) const {
   if (range.begin < 0 || range.begin > range.end || range.end > size_) {
diff --git a/src/http.h b/src/http.h
index 3088f7f..32bf0e6 100644
--- a/src/http.h
+++ b/src/http.h
@@ -134,6 +134,22 @@ class VirtualFile : public FileSlice {
   virtual std::string filename() const = 0;  // for logging.
 };
 
+class RealFileSlice : public FileSlice {
+ public:
+  void Init(re2::StringPiece filename, ByteRange range);
+
+  const std::string filename() const { return filename_; }
+
+  int64_t size() const final { return range_.size(); }
+
+  bool AddRange(ByteRange range, EvBuffer *buf,
+                std::string *error_message) const final;
+
+ private:
+  std::string filename_;
+  ByteRange range_;
+};
+
 // A FileSlice of a pre-defined length which calls a function which fills the
 // slice on demand. The FillerFileSlice is responsible for subsetting.
 class FillerFileSlice : public FileSlice {
@@ -156,6 +172,32 @@ class FillerFileSlice : public FileSlice {
   size_t size_;
 };
 
+// A FileSlice backed by in-memory data which lives forever (static data).
+class StaticStringPieceSlice : public FileSlice {
+ public:
+  explicit StaticStringPieceSlice(re2::StringPiece piece) : piece_(piece) {}
+
+  int64_t size() const final { return piece_.size(); }
+  bool AddRange(ByteRange range, EvBuffer *buf,
+                std::string *error_message) const final;
+
+ private:
+  re2::StringPiece piece_;
+};
+
+// A FileSlice backed by in-memory data which should be copied.
+class CopyingStringPieceSlice : public FileSlice {
+ public:
+  explicit CopyingStringPieceSlice(re2::StringPiece piece) : piece_(piece) {}
+
+  int64_t size() const final { return piece_.size(); }
+  bool AddRange(ByteRange range, EvBuffer *buf,
+                std::string *error_message) const final;
+
+ private:
+  re2::StringPiece piece_;
+};
+
 // A slice composed of other slices.
 class FileSlices : public FileSlice {
  public: