update buffer implementation

src/util/inc/tbuffer.h

@@ -24,45 +24,78 @@
 
 /*
 SBuffer can be used to read or write a buffer, but cannot be used for both
-read & write at a same time.
-Read example:
-   SBuffer rbuf;
-   if (tbufBeginOperation(&rbuf) != 0) {
-      // handling errors
-   }
-   tbufInitRead(&rbuf, data, 1024);
-   int32_t a = tbufReadInt32(&rbuf);
-   // other read functions
-
-Write example:
-   SBuffer wbuf;
-   if (tbufBeginOperation(&wbuf) != 0) {
-      // handling errors
-   }
-   tbufInitWrite(&wbuf, 1024);
-   tbufWriteInt32(&wbuf, 10);
-   // other write functions
-   size_t size = tbufGetSize(&wbuf);
-   char* data = tbufGetBuffer(&wbuf, true);
-   tbufUninitWrite(&wbuf);
+read & write at a same time. Below is an example:
+
+int main(int argc, char** argv) {
+  //--------------------- write ------------------------
+  SBuffer wbuf;
+  int32_t code = tbufBeginWrite(&wbuf);
+  if (code != 0) {
+    // handle errors
+    return 0;
+  }
+
+  // reserve 1024 bytes for the buffer to improve performance
+  tbufEnsureCapacity(&wbuf, 1024);
+
+  // write 5 integers to the buffer
+  for (int i = 0; i < 5; i++) {
+    tbufWriteInt32(&wbuf, i);
+  }
+
+  // write a string to the buffer
+  tbufWriteString(&wbuf, "this is a string.\n");
+
+  // acquire the result and close the write buffer
+  size_t size = tbufTell(&wbuf);
+  char*  data = tbufGetData(&wbuf, true);
+  tbufClose(&wbuf, true);
+
+
+  //------------------------ read -----------------------
+  SBuffer rbuf;
+  code = tbufBeginRead(&rbuf, data, size);
+  if (code != 0) {
+    printf("you will see this message after print out 5 integers and a string.\n");
+    tbufClose(&rbuf, false);
+    return 0;
+  }
+
+  // read & print out 5 integers
+  for (int i = 0; i < 5; i++) {
+    printf("%d\n", tbufReadInt32(&rbuf));
+  }
+
+  // read & print out a string
+  printf(tbufReadString(&rbuf, NULL));
+
+  // try read another integer, this result in an error as there no this integer
+  tbufReadInt32(&rbuf);
+
+  printf("you should not see this message.\n");
+  tbufClose(&rbuf, false);
+
+  return 0;
+}
 */
 typedef struct {
   jmp_buf jb;
-  char* buf;
+  char* data;
   size_t pos;
   size_t size;
 } SBuffer;
 
 
 // common functions can be used in both read & write
-#define tbufBeginOperation(buf) setjmp((buf)->jb)
+#define tbufThrowError(buf, code) longjmp((buf)->jb, (code))
 size_t tbufTell(SBuffer* buf);
 size_t tbufSeekTo(SBuffer* buf, size_t pos);
 size_t tbufSkip(SBuffer* buf, size_t size);
+void tbufClose(SBuffer* buf, bool keepData);
 
 
 // basic read functions
-void tbufInitRead(SBuffer* buf, void* data, size_t size);
+#define tbufBeginRead(buf, data, len) (((buf)->data = (char*)data), ((buf)->pos = 0), ((buf)->size = ((data) == NULL) ? 0 : (len)), setjmp((buf)->jb))
 char* tbufRead(SBuffer* buf, size_t size);
 void tbufReadToBuffer(SBuffer* buf, void* dst, size_t size);
 const char* tbufReadString(SBuffer* buf, size_t* len);
@@ -70,10 +103,9 @@ size_t tbufReadToString(SBuffer* buf, char* dst, size_t size);
 
 
 // basic write functions
-void tbufInitWrite(SBuffer* buf, size_t size);
+#define tbufBeginWrite(buf) ((buf)->data = NULL, ((buf)->pos = 0), ((buf)->size = 0), setjmp((buf)->jb))
 void tbufEnsureCapacity(SBuffer* buf, size_t size);
-char* tbufGetResult(SBuffer* buf, bool takeOver);
-void tbufUninitWrite(SBuffer* buf);
+char* tbufGetData(SBuffer* buf, bool takeOver);
 void tbufWrite(SBuffer* buf, const void* data, size_t size);
 void tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size);
 void tbufWriteStringLen(SBuffer* buf, const char* str, size_t len);
@@ -81,24 +113,24 @@ void tbufWriteString(SBuffer* buf, const char* str);
 
 
 // read & write function for primitive types
-#ifndef TBUFFER_DEFINE_OPERATION
-#define TBUFFER_DEFINE_OPERATION(type, name) \
+#ifndef TBUFFER_DEFINE_FUNCTION
+#define TBUFFER_DEFINE_FUNCTION(type, name) \
   type tbufRead##name(SBuffer* buf); \
   void tbufWrite##name(SBuffer* buf, type data); \
   void tbufWrite##name##At(SBuffer* buf, size_t pos, type data);
 #endif
 
-TBUFFER_DEFINE_OPERATION( bool, Bool )
-TBUFFER_DEFINE_OPERATION( char, Char )
-TBUFFER_DEFINE_OPERATION( int8_t, Int8 )
-TBUFFER_DEFINE_OPERATION( uint8_t, Unt8 )
-TBUFFER_DEFINE_OPERATION( int16_t, Int16 )
-TBUFFER_DEFINE_OPERATION( uint16_t, Uint16 )
-TBUFFER_DEFINE_OPERATION( int32_t, Int32 )
-TBUFFER_DEFINE_OPERATION( uint32_t, Uint32 )
-TBUFFER_DEFINE_OPERATION( int64_t, Int64 )
-TBUFFER_DEFINE_OPERATION( uint64_t, Uint64 )
-TBUFFER_DEFINE_OPERATION( float, Float )
-TBUFFER_DEFINE_OPERATION( double, Double )
+TBUFFER_DEFINE_FUNCTION( bool, Bool )
+TBUFFER_DEFINE_FUNCTION( char, Char )
+TBUFFER_DEFINE_FUNCTION( int8_t, Int8 )
+TBUFFER_DEFINE_FUNCTION( uint8_t, Unt8 )
+TBUFFER_DEFINE_FUNCTION( int16_t, Int16 )
+TBUFFER_DEFINE_FUNCTION( uint16_t, Uint16 )
+TBUFFER_DEFINE_FUNCTION( int32_t, Int32 )
+TBUFFER_DEFINE_FUNCTION( uint32_t, Uint32 )
+TBUFFER_DEFINE_FUNCTION( int64_t, Int64 )
+TBUFFER_DEFINE_FUNCTION( uint64_t, Uint64 )
+TBUFFER_DEFINE_FUNCTION( float, Float )
+TBUFFER_DEFINE_FUNCTION( double, Double )
 
 #endif
\ No newline at end of file

src/util/src/tbuffer.c

@@ -13,7 +13,11 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#define TBUFFER_DEFINE_OPERATION(type, name) \
+#include <stdlib.h>
+#include <memory.h>
+#include <assert.h>
+
+#define TBUFFER_DEFINE_FUNCTION(type, name) \
   type tbufRead##name(SBuffer* buf) {            \
     type ret;                                    \
     tbufReadToBuffer(buf, &ret, sizeof(type));   \
@@ -38,7 +42,8 @@ size_t tbufTell(SBuffer* buf) {
 
 size_t tbufSeekTo(SBuffer* buf, size_t pos) {
   if (pos > buf->size) {
-    longjmp(buf->jb, 1);
+    // TODO: update error code, other tbufThrowError need to be changed too
+    tbufThrowError(buf, 1);
   }
   size_t old = buf->pos;
   buf->pos = pos;
@@ -49,18 +54,20 @@ size_t tbufSkip(SBuffer* buf, size_t size) {
   return tbufSeekTo(buf, buf->pos + size);
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// read functions
-
-void tbufInitRead(SBuffer* buf, void* data, size_t size) {
-  buf->buf = (char*)data;
+void tbufClose(SBuffer* buf, bool keepData) {
+  if (!keepData) {
+    free(buf->data);
+  }
+  buf->data = NULL;
   buf->pos = 0;
-  // empty buffer is not an error, but read an empty buffer is
-  buf->size = (data == NULL) ? 0 : size;
+  buf->size = 0;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// read functions
+
 char* tbufRead(SBuffer* buf, size_t size) {
-  char* ret = buf->buf + buf->pos;
+  char* ret = buf->data + buf->pos;
   tbufSkip(buf, size);
   return ret;
 }
@@ -72,8 +79,8 @@ void tbufReadToBuffer(SBuffer* buf, void* dst, size_t size) {
 }
 
 const char* tbufReadString(SBuffer* buf, size_t* len) {
-  uint16_t l = tbufReadUint16();
-  char*    ret = buf->buf + buf->pos;
+  uint16_t l = tbufReadUint16(buf);
+  char*    ret = buf->data + buf->pos;
   tbufSkip(buf, l + 1);
   ret[l] = 0;  // ensure the string end with '\0'
   if (len != NULL) {
@@ -83,9 +90,12 @@ const char* tbufReadString(SBuffer* buf, size_t* len) {
 }
 
 size_t tbufReadToString(SBuffer* buf, char* dst, size_t size) {
+  assert(dst != NULL);
   size_t      len;
   const char* str = tbufReadString(buf, &len);
-  if (len >= size) len = size - 1;
+  if (len >= size) {
+    len = size - 1;
+  }
   memcpy(dst, str, len);
   dst[len] = 0;
   return len;
@@ -98,57 +108,53 @@ size_t tbufReadToString(SBuffer* buf, char* dst, size_t size) {
 void tbufEnsureCapacity(SBuffer* buf, size_t size) {
   size += buf->pos;
   if (size > buf->size) {
-    char*  nbuf = NULL;
     size_t nsize = size + buf->size;
-    nbuf = realloc(buf->buf, nsize);
-    if (nbuf == NULL) {
-      longjmp(buf->jb, 2);
+    char* data = realloc(buf->data, nsize);
+    if (data == NULL) {
+      tbufThrowError(buf, 2);
     }
-    buf->buf = nbuf;
+    buf->data = data;
     buf->size = nsize;
   }
 }
 
-void tbufInitWrite(SBuffer* buf, size_t size) {
-    buf->buf = NULL;
-    buf->pos = 0;
-    buf->size = 0;
-    tbufEnsureCapacity(buf, size);
-}
-
-char* tbufGetResult(SBuffer* buf, bool takeOver) {
-		char* ret = buf->buf;
+char* tbufGetData(SBuffer* buf, bool takeOver) {
+		char* ret = buf->data;
 		if (takeOver) {
       buf->pos = 0;
       buf->size = 0;
-			buf->buf = NULL;
+			buf->data = NULL;
     }
 		return ret;
 }
 
-void tbufUninitWrite(SBuffer* buf) {
-    free(buf->buf);
+void tbufEndWrite(SBuffer* buf) {
+    free(buf->data);
+    buf->data = NULL;
+    buf->pos = 0;
+    buf->size = 0;
 }
 
 void tbufWrite(SBuffer* buf, const void* data, size_t size) {
-  tbufEnsureCapacity(size);
-  memcpy(buf->buf + buf->pos, data, size);
+  assert(data != NULL);
+  tbufEnsureCapacity(buf, size);
+  memcpy(buf->data + buf->pos, data, size);
   buf->pos += size;
 }
 
 void tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size) {
+  assert(data != NULL);
   // this function can only be called to fill the gap on previous writes,
   // so 'pos + size <= buf->pos' must be true
-  if (pos + size > buf->pos) {
-    longjmp(buf->jb, 3);
-  }
-  memcpy(buf->buf + pos, data, size);
+  assert(pos + size <= buf->pos);
+  memcpy(buf->data + pos, data, size);
 }
 
 void tbufWriteStringLen(SBuffer* buf, const char* str, size_t len) {
-  if (len > 0xffff) {
-    longjmp(buf->jb , 4);
-  }
+  // maximum string length is 65535, if longer string is required
+  // this function and the corresponding read function need to be
+  // revised.
+  assert(len <= 0xffff);
   tbufWriteUint16(buf, (uint16_t)len);
   tbufWrite(buf, str, len + 1);
 }