From ae5f98d6e18fe65eb4013e55663119855c556287 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Mon, 1 Sep 2003 07:43:14 +0000
Subject: [PATCH] Added a memory IO callback class. Not yet tested, though.

---
 src/mm_io.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/mm_io.h   | 20 +++++++++++++++--
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/src/mm_io.cpp b/src/mm_io.cpp
index 3dfd7de71..b46366f6a 100644
--- a/src/mm_io.cpp
+++ b/src/mm_io.cpp
@@ -393,6 +393,68 @@ size_t mm_null_io_c::write(const void *buffer, size_t size) {
 void mm_null_io_c::close() {
 }
 
+/*
+ * IO callback class working on memory
+ */
+mm_mem_io_c::mm_mem_io_c(unsigned char *nmem, uint64_t nsize) {
+  mem = nmem;
+  mem_size = nsize;
+  pos = 0;
+}
+
+uint64_t mm_mem_io_c::getFilePointer() {
+  return pos;
+}
+
+void mm_mem_io_c::setFilePointer(int64 offset, seek_mode mode) {
+  int64_t npos;
+
+  if ((mem == NULL) || (mem_size == 0))
+    throw exception();
+
+  if (mode == seek_beginning)
+    npos = offset;
+  else if (mode == seek_end)
+    npos = mem_size - offset;
+  else
+    npos = pos + offset;
+
+  if ((npos < 0) || (npos >= mem_size))
+    throw exception();
+
+  pos = npos;
+}
+
+uint32 mm_mem_io_c::read(void *buffer, size_t size) {
+  int64_t rbytes;
+
+  rbytes = (pos + size) >= mem_size ? mem_size - pos : size;
+  memcpy(buffer, &mem[pos], rbytes);
+  pos += rbytes;
+
+  return rbytes;
+}
+
+size_t mm_mem_io_c::write(const void *buffer, size_t size) {
+  int64_t wbytes;
+
+  wbytes = (pos + size) >= mem_size ? mem_size - pos : size;
+  memcpy(&mem[pos], buffer, wbytes);
+  pos += wbytes;
+
+  return wbytes;
+}
+
+void mm_mem_io_c::close() {
+  mem = NULL;
+  mem_size = 0;
+  pos = 0;
+}
+
+bool mm_mem_io_c::eof() {
+  return pos >= mem_size;
+}
+
 /*
  * Class for handling UTF-8/UTF-16/UTF-32 text files.
  */
diff --git a/src/mm_io.h b/src/mm_io.h
index c08126646..e4e81d6b7 100644
--- a/src/mm_io.h
+++ b/src/mm_io.h
@@ -48,7 +48,7 @@ public:
   virtual ~mm_io_c();
 
   virtual uint64 getFilePointer();
-  virtual void setFilePointer(int64 offset, seek_mode mode=seek_beginning);
+  virtual void setFilePointer(int64 offset, seek_mode mode = seek_beginning);
   virtual uint32 read(void *buffer, size_t size);
   virtual unsigned char read_uint8();
   virtual uint16_t read_uint16();
@@ -79,12 +79,28 @@ public:
   mm_null_io_c();
 
   virtual uint64 getFilePointer();
-  virtual void setFilePointer(int64 offset, seek_mode mode=seek_beginning);
+  virtual void setFilePointer(int64 offset, seek_mode mode = seek_beginning);
   virtual uint32 read(void *buffer, size_t size);
   virtual size_t write(const void *buffer, size_t size);
   virtual void close();
 };
 
+class mm_mem_io_c: public mm_io_c {
+protected:
+  int64_t pos, mem_size;
+  unsigned char *mem;
+
+public:
+  mm_mem_io_c(unsigned char *nmem, uint64_t nsize);
+
+  virtual uint64 getFilePointer();
+  virtual void setFilePointer(int64 offset, seek_mode mode = seek_beginning);
+  virtual uint32 read(void *buffer, size_t size);
+  virtual size_t write(const void *buffer, size_t size);
+  virtual void close();
+  virtual bool eof();
+};
+
 enum byte_order_e {BO_UTF8, BO_UTF16_LE, BO_UTF16_BE, BO_UTF32_LE, BO_UTF32_BE,
                    BO_NONE};