Add readOrThrow and seekOrThrow to BasicIo.

Author: kevinbackhouse

include/exiv2/basicio.hpp

@@ -27,6 +27,7 @@
 #include "exiv2lib_export.h"
 
 // included header files
+#include "error.hpp"
 #include "types.hpp"
 
 // + standard includes
@@ -142,6 +143,17 @@ namespace Exiv2 {
               0 if failure;
          */
         virtual long read(byte* buf, long rcount) = 0;
+        /*!
+          @brief Safe version of `read()` that checks for errors and throws
+              an exception if the read was unsuccessful.
+          @param buf Pointer to a block of memory into which the read data
+              is stored. The memory block must be at least \em rcount bytes
+              long.
+          @param rcount Maximum number of bytes to read. Fewer bytes may be
+              read if \em rcount bytes are not available.
+          @param err Error code to use if an exception is thrown.
+         */
+        void readOrThrow(byte* buf, long rcount, ErrorCode err);
         /*!
           @brief Read one byte from the IO source. Current IO position is
               advanced by one byte.
@@ -176,6 +188,19 @@ namespace Exiv2 {
 #else
         virtual int seek(long offset, Position pos) = 0;
 #endif
+        /*!
+          @brief Safe version of `seek()` that checks for errors and throws
+              an exception if the seek was unsuccessful.
+          @param offset Number of bytes to move the position relative
+              to the starting position specified by \em pos
+          @param pos Position from which the seek should start
+          @param err Error code to use if an exception is thrown.
+         */
+#if defined(_MSC_VER)
+        void seekOrThrow(int64_t offset, Position pos, ErrorCode err);
+#else
+        void seekOrThrow(long offset, Position pos, ErrorCode err);
+#endif
 
         /*!
           @brief Direct access to the IO data. For files, this is done by

src/basicio.cpp

@@ -28,6 +28,7 @@
 #include "futils.hpp"
 #include "types.hpp"
 #include "error.hpp"
+#include "enforce.hpp"
 #include "http.hpp"
 #include "properties.hpp"
 #include "image_int.hpp"
@@ -77,6 +78,21 @@ using nlink_t = short;
 // *****************************************************************************
 // class member definitions
 namespace Exiv2 {
+    void BasicIo::readOrThrow(byte* buf, long rcount, ErrorCode err) {
+        const long nread = read(buf, rcount);
+        enforce(nread == rcount, err);
+        enforce(!error(), err);
+    }
+
+#if defined(_MSC_VER)
+    void BasicIo::seekOrThrow(int64_t offset, Position pos, ErrorCode err) {
+#else
+    void BasicIo::seekOrThrow(long offset, Position pos, ErrorCode err) {
+#endif
+        const int r = seek(offset, pos);
+        enforce(r == 0, err);
+    }
+
     //! Internal Pimpl structure of class FileIo.
     class FileIo::Impl {
     public:

src/image.cpp

@@ -140,15 +140,12 @@ namespace {
 namespace Exiv2 {
     // BasicIo::read() with error checking
     static void readOrThrow(BasicIo& iIo, byte* buf, long rcount, ErrorCode err) {
-      const long nread = iIo.read(buf, rcount);
-      enforce(nread == rcount, err);
-      enforce(!iIo.error(), err);
+        iIo.readOrThrow(buf, rcount, err);
     }
 
     // BasicIo::seek() with error checking
     static void seekOrThrow(BasicIo& iIo, long offset, BasicIo::Position pos, ErrorCode err) {
-      const int r = iIo.seek(offset, pos);
-      enforce(r == 0, err);
+        iIo.seekOrThrow(offset, pos, err);
     }
 
     Image::Image(int imageType, uint16_t supportedMetadata, BasicIo::UniquePtr io)

src/jpgimage.cpp

@@ -96,15 +96,12 @@ namespace Exiv2 {
 
     // BasicIo::read() with error checking
     static void readOrThrow(BasicIo& iIo, byte* buf, long rcount, ErrorCode err) {
-      const long nread = iIo.read(buf, rcount);
-      enforce(nread == rcount, err);
-      enforce(!iIo.error(), err);
+        iIo.readOrThrow(buf, rcount, err);
     }
 
     // BasicIo::seek() with error checking
     static void seekOrThrow(BasicIo& iIo, long offset, BasicIo::Position pos, ErrorCode err) {
-      const int r = iIo.seek(offset, pos);
-      enforce(r == 0, err);
+        iIo.seekOrThrow(offset, pos, err);
     }
 
     static inline bool inRange(int lo,int value, int hi)

src/webpimage.cpp

@@ -58,9 +58,7 @@ namespace Exiv2 {
     // This static function is a temporary fix in v0.27. In the next version,
     // it will be added as a method of BasicIo.
     static void readOrThrow(BasicIo& iIo, byte* buf, long rcount, ErrorCode err) {
-      const long nread = iIo.read(buf, rcount);
-      enforce(nread == rcount, err);
-      enforce(!iIo.error(), err);
+        iIo.readOrThrow(buf, rcount, err);
     }
 
     WebPImage::WebPImage(BasicIo::UniquePtr io)