From 906a25cb3106a16f9dec77045367e0f78a39aef6 Mon Sep 17 00:00:00 2001
From: KAMADA Ken'ichi <kamada@nanohz.org>
Date: Thu, 12 Jan 2017 21:51:11 +0900
Subject: [PATCH] Add parse_image(), which accepts a JPEG or TIFF image.

---
 src/image.rs | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/jpeg.rs  |  7 +++++++
 src/lib.rs   |  8 ++++---
 src/tiff.rs  |  6 ++++++
 4 files changed, 77 insertions(+), 3 deletions(-)
 create mode 100644 src/image.rs

diff --git a/src/image.rs b/src/image.rs
new file mode 100644
index 0000000..cdb21af
--- /dev/null
+++ b/src/image.rs
@@ -0,0 +1,59 @@
+//
+// Copyright (c) 2016 KAMADA Ken'ichi.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+//
+
+use std::io;
+use std::io::Read;
+use std::mem;
+
+use error::Error;
+use jpeg;
+use tiff;
+use tiff::Field;
+
+/// Parse the Exif attributes in a JPEG or TIFF image data.
+///
+/// Returns a Vec of Exif fields and a bool.
+/// The boolean value is true if the data is little endian.
+/// If an error occurred, `exif::Error` is returned.
+///
+/// The `buf` must be an empty `Vec<u8>` when this function is called.
+/// The raw Exif data is read into it.
+pub fn parse_image<'a, R>(mut reader: &mut R, mut buf: &'a mut Vec<u8>)
+                          -> Result<(Vec<Field<'a>>, bool), Error>
+    where R: io::BufRead
+{
+    try!(reader.by_ref().take(4).read_to_end(buf));
+    if jpeg::is_jpeg(buf) {
+        let exif_buf = try!(jpeg::get_exif_attr(
+            &mut buf.as_mut_slice().chain(reader)));
+        mem::replace(buf, exif_buf);
+    } else if tiff::is_tiff(buf) {
+        try!(reader.read_to_end(&mut buf));
+    } else {
+        return Err(Error::InvalidFormat("Unknown image format"));
+    }
+    tiff::parse_exif(buf)
+}
diff --git a/src/jpeg.rs b/src/jpeg.rs
index 679fc63..409adcf 100644
--- a/src/jpeg.rs
+++ b/src/jpeg.rs
@@ -45,6 +45,9 @@ mod marker {
     pub const APP1: u8 = 0xe1;
 }
 
+// SOI marker as the JPEG header.
+const JPEG_SIG: [u8; 2] = [marker::P, marker::SOI];
+
 // Exif identifier code "Exif\0\0". [EXIF23 4.7.2]
 const EXIF_ID: [u8; 6] = [0x45, 0x78, 0x69, 0x66, 0x00, 0x00];
 
@@ -99,6 +102,10 @@ fn get_exif_attr_sub<R>(reader: &mut R)
     }
 }
 
+pub fn is_jpeg(buf: &[u8]) -> bool {
+    buf.starts_with(&JPEG_SIG)
+}
+
 #[cfg(test)]
 mod tests {
     use std::io::Cursor;
diff --git a/src/lib.rs b/src/lib.rs
index a1a079f..2516fef 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -28,19 +28,20 @@
 //!
 //! # Examples
 //!
-//! An example to parse a JPEG file:
+//! An example to parse a JPEG/TIFF file:
 //!
 //! ```
 //! let file = std::fs::File::open("tests/exif.jpg").unwrap();
 //! let mut reader = std::io::BufReader::new(&file);
-//! let buf = exif::get_exif_attr_from_jpeg(&mut reader).unwrap();
-//! let (fields, _) = exif::parse_exif(&buf).unwrap();
+//! let mut buf = Vec::new();
+//! let (fields, _) = exif::parse_image(&mut reader, &mut buf).unwrap();
 //! for f in fields {
 //!     println!("{} {} {:?}", f.tag, f.thumbnail, f.value);
 //! }
 //! ```
 
 pub use error::Error;
+pub use image::parse_image;
 pub use jpeg::get_exif_attr as get_exif_attr_from_jpeg;
 pub use tag::{Context, Tag};
 pub use tiff::Field;
@@ -54,6 +55,7 @@ mod tmacro;
 
 mod endian;
 mod error;
+mod image;
 mod jpeg;
 pub mod tag;
 mod tiff;
diff --git a/src/tiff.rs b/src/tiff.rs
index c297ea0..32ffa2d 100644
--- a/src/tiff.rs
+++ b/src/tiff.rs
@@ -35,6 +35,8 @@ use value::get_type_info;
 const TIFF_BE: u16 = 0x4d4d;
 const TIFF_LE: u16 = 0x4949;
 const TIFF_FORTY_TWO: u16 = 0x002a;
+const TIFF_BE_SIG: [u8; 4] = [0x4d, 0x4d, 0x00, 0x2a];
+const TIFF_LE_SIG: [u8; 4] = [0x49, 0x49, 0x2a, 0x00];
 
 /// A TIFF field.
 #[derive(Debug)]
@@ -149,6 +151,10 @@ fn parse_ifd<E>(data: &[u8], offset: usize, ctx: Context, thumbnail: bool)
     Ok(fields)
 }
 
+pub fn is_tiff(buf: &[u8]) -> bool {
+    buf.starts_with(&TIFF_BE_SIG) || buf.starts_with(&TIFF_LE_SIG)
+}
+
 #[cfg(test)]
 mod tests {
     use error::Error;