/* Copyright (C) 2003-2015 LiveCode Ltd.

This file is part of LiveCode.

LiveCode is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License v3 as published by the Free

Software Foundation.

LiveCode is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with LiveCode. If not see <http://www.gnu.org/licenses/>. */

#include "dbodbc.h"

#include <revolution/support.h>

#if defined(_LINUX) || defined(_MACOSX)

#define stricmp strcasecmp

#endif

#if not defined(min)

#define min(x, y) ((x) < (y) ? (x) : (y))

#endif

char DBConnection_ODBC::errmsg[512];

typedef unsigned short uint2;

int UTF8ToUnicode(const char * lpSrcStr, int cchSrc, uint2 * lpDestStr, int cchDest);

int UnicodeToUTF8(uint2 *lpSrcStr, int cchSrc, char *lpDestStr, int cchDest);

/*DBCONNECTION_ODBC - CONNECTION OBJECT FOR ODBC DATABASES CHILD OF DBCONNECTION*/

#define UTF8_TO_UNICODE_VAR(t_name) \

unsigned short *w_##t_name; \

unsigned int w_##t_name##_length; \

w_##t_name##_length = UTF8ToUnicode(t_name, strlen(t_name), NULL, 0); \

w_##t_name = (unsigned short *)_alloca((w_##t_name##_length + 1) * 2); \

UTF8ToUnicode(t_name, strlen(t_name), w_##t_name, w_##t_name##_length);

#define UTF8_TO_UNICODE_VAR_N(t_name) \

unsigned short *w_##t_name; \

unsigned int w_##t_name##_length; \

w_##t_name##_length = UTF8ToUnicode(t_name, t_name##_length, NULL, 0); \

w_##t_name = (unsigned short *)_alloca((w_##t_name##_length + 1) * 2); \

UTF8ToUnicode(t_name, t_name##_length, w_##t_name, w_##t_name##_length);

#ifndef UTF8MODE

#define SQL_NOUNICODEMAP

#endif

Bool DBConnection_ODBC::connect(char **args, int numargs)

{

if (isConnected)

return True;

// MW-2014-01-30: [[ Sqlite382 ]] Relaxed revdb_connect() so it only checks for at least

// one argument - we need at least 4 though.

if (numargs < 4)

return False;

char *t_user;

t_user = args[2];

char *t_password;

t_password = args[3];

char *t_host;

t_host = args[0];

char *t_dbname;

t_dbname = args[1];

// OK-2008-01-18 : Bug 5440. Used the fifth argument to allow users to specify which type

// of cursors should be used for ODBC. This is to solve the speed issues reported in this bug.

char *t_cursor_type;

if (numargs >= 5)

{

t_cursor_type = args[4];

// The default cursor type is emulated static, which means a static cursor is emulated if needed.

if (stricmp(t_cursor_type, "forward only") == 0)

m_cursor_type = kCursorTypeForward;

else if (stricmp(t_cursor_type, "static") == 0)

m_cursor_type = kCursorTypeStatic;

else if (stricmp(t_cursor_type, "emulated static") == 0)

m_cursor_type = kCursorTypeEmulated;

else

m_cursor_type = kCursorTypeForward;

}

else

m_cursor_type = kCursorTypeForward;

SQLRETURN t_result;

t_result = SQLAllocEnv(&henv);

if (t_result != SQL_SUCCESS)

return False;

t_result = SQLAllocConnect(henv, &hdbc);

if (t_result != SQL_SUCCESS)

return False;

// MW-2005-07-27: Because we are in no-prompt mode, this should be the same

// length as the input connection string.

unsigned char szConnStrOut[2048];

SWORD cb;

// OK-2008-01-18 : Bug 5440. Added ability to choose cursor type on ODBC.

// Only allow the ODBC cursor library to be used if we are using emulated static cursors,

// otherwise attempt to use the user-specified cursor type and throw an error if not supported.

if (m_cursor_type == kCursorTypeStatic || m_cursor_type == kCursorTypeForward)

t_result = SQLSetConnectAttr(hdbc, SQL_ATTR_ODBC_CURSORS, (SQLPOINTER)SQL_CUR_USE_DRIVER, 0);

else

t_result = SQLSetConnectAttr(hdbc, SQL_ATTR_ODBC_CURSORS, (SQLPOINTER)SQL_CUR_USE_IF_NEEDED, 0);

if (t_result != SQL_SUCCESS)

{

SetError(SQL_NULL_HSTMT);

return False;

}

#ifdef UTF8MODE

UTF8_TO_UNICODE_VAR(host);

rc = SQLDriverConnectW(hdbc, 0, w_host, SQL_NTS, (SQLWCHAR *)szConnStrOut, sizeof(szConnStrOut), &cb, SQL_DRIVER_NOPROMPT);

#else

t_result = SQLDriverConnectA(hdbc, 0, (SQLCHAR *)t_host, SQL_NTS, szConnStrOut, sizeof(szConnStrOut), &cb, SQL_DRIVER_NOPROMPT);

#endif

if (t_result != SQL_SUCCESS && t_result != SQL_SUCCESS_WITH_INFO)

{

#ifdef UTF8MODE

UTF8_TO_UNICODE_VAR(user);

UTF8_TO_UNICODE_VAR(password);

rc = SQLConnectW(hdbc, w_host, SQL_NTS, (*user ? w_user : NULL), SQL_NTS, (*password ? w_password : NULL), SQL_NTS);

#else

t_result = SQLConnectA(hdbc, (SQLCHAR *)t_host, SQL_NTS, (SQLCHAR *)(*t_user ? t_user : NULL), SQL_NTS, (SQLCHAR *)(*t_password ? t_password : NULL), SQL_NTS);

#endif

}

if (t_result != SQL_SUCCESS && t_result != SQL_SUCCESS_WITH_INFO)

{

SetError(SQL_NULL_HSTMT);

return False;

}

connectionType = CT_ODBC,

isConnected = True;

return True;

}

/*Method to disconnect from ODBC server*/

void DBConnection_ODBC::disconnect()

{

if (!isConnected)

return;

//close all open cursors from this connection

closeCursors();

//close odbc connection

SQLDisconnect(hdbc);

//free data associated with connection

SQLFreeConnect(hdbc);

SQLFreeEnv(henv);

isConnected = False;

}

bool queryCallback(void *p_context, int p_placeholder, DBBuffer &p_output)

{

p_output . append("?", 1);

PlaceholderMap *t_placeholder_map;

t_placeholder_map = (PlaceholderMap *)p_context;

t_placeholder_map -> elements = (int *)realloc(t_placeholder_map -> elements, sizeof(int) * (t_placeholder_map -> length + 1));

t_placeholder_map -> elements[t_placeholder_map -> length] = p_placeholder;

t_placeholder_map -> length += 1;

return true;

}

const char *DBConnection_ODBC::getconnectionstring()

{

if (!isConnected)

return DB_ODBC_STRING;

char tmp[] = DB_ODBC_STRING;

strcpy(connstring, tmp);

char tbuffer[300] = "";

SQLSMALLINT outlen;

SQLGetInfoA(hdbc, SQL_DBMS_NAME, tbuffer, 255, &outlen);

if (*tbuffer)

{

strcat(connstring,",");

strcat(connstring,tbuffer);

}

return connstring;

}

/*Method to execute quick and fast sql statements like UPDATE and INSERT

Inputs:

query- string containing sql query

qlength - length of query (for binary data). if 0 then assume null terminated.

affectedrows - will recieve number of rows updated or inserted

Output: False on error

*/

Bool DBConnection_ODBC::sqlExecute(char *p_query, DBString *p_arguments, int p_argument_count, unsigned int &p_affected_rows)

{

bool t_success;

t_success = true;

Bool t_result;

t_result = True;

SQLHSTMT t_statement;

SQLRETURN t_query_result;

t_success = ExecuteQuery(p_query, p_arguments, p_argument_count, t_statement, t_query_result);

DBCursor_ODBC *t_cursor;

t_cursor = NULL;

SQLLEN t_affected_rows;

t_affected_rows = 0;

if (t_success && (t_query_result == SQL_SUCCESS || t_query_result == SQL_SUCCESS_WITH_INFO))

t_result = True;

else

t_result = False;

if (t_success)

{

SQLSMALLINT t_column_count;

SQLNumResultCols(t_statement, &t_column_count);

if (t_column_count == 0)

{

SQLRowCount(t_statement, &t_affected_rows);

if (t_affected_rows < 0)

t_affected_rows = 0;

}

}

// OK-2007-09-10 : Bug 5360

if (!t_result)

SetError(t_statement);

else

SetError(NULL);

SQLFreeStmt(t_statement, SQL_DROP);

p_affected_rows = t_affected_rows;

return t_result;

}

/*Method to execute sql statements like SELECT and return Cursor

Inputs:

query- string containing sql query

qlength - length of query (for binary data). if 0 then assume null terminated.

Output: NULL cursor on error

*/

DBCursor *DBConnection_ODBC::sqlQuery(char *p_query, DBString *p_arguments, int p_argument_count, int p_rows)

{

bool t_success;

t_success = true;

SQLHSTMT t_statement;

SQLRETURN t_result;

t_success = ExecuteQuery(p_query, p_arguments, p_argument_count, t_statement, t_result);

DBCursor_ODBC *t_cursor;

t_cursor = NULL;

if (t_success && (t_result == SQL_SUCCESS || t_result == SQL_SUCCESS_WITH_INFO))

{

SQLSMALLINT t_column_count;

SQLNumResultCols(t_statement, &t_column_count);

if (t_column_count != 0)

{

t_cursor = new DBCursor_ODBC();

if (!t_cursor -> open((DBConnection *)this, t_statement, p_rows))

{

delete t_cursor;

t_cursor = NULL;

SetError(t_statement);

SQLFreeStmt(t_statement, SQL_DROP);

t_statement = NULL;

}

else

{

addCursor(t_cursor);

SetError(NULL);

}

}

}

else

SetError(t_statement);

return (DBCursor *)t_cursor;

}

char * getDiagnosticRecord(SQLHSTMT p_statement)

{

SQLCHAR t_message_buffer[300];

SQLRETURN t_result;

SQLCHAR t_state[6];

SQLINTEGER t_native_error;

SQLSMALLINT t_text_length;

t_result = SQLGetDiagRecA(SQL_HANDLE_STMT, p_statement, 1, t_state, &t_native_error, t_message_buffer, 300, &t_text_length);

if (t_result != SQL_SUCCESS)

{

return NULL;

}

return NULL;

}

// @brief Executes an SQL query and returns the statement handle and ODBC return value.

// @param p_query : The query to execute.

// @param p_arguments : Array containing arguments to bind with the query.

// @param p_argument_count : The number of elements in p_arguments.

// @param p_statement : (Out) Reference to a statement handle, this will be set to the statement handle resulting from the execution.

// @param p_result : (Out) Reference to a result handle, this will be set the to the result handle resulting from the execution.

//

// @return True if successful, false otherwise.

bool DBConnection_ODBC::ExecuteQuery(char *p_query, DBString *p_arguments, int p_argument_count, SQLHSTMT &p_statement, SQLRETURN &p_result)

{

if (!isConnected)

return NULL;

unsigned int t_query_length;

t_query_length = strlen(p_query);

bool t_success;

t_success = true;

SQLHSTMT t_statement;

SQLAllocStmt(hdbc,&t_statement);

DBCursor_ODBC *t_cursor = NULL;

SQLRETURN t_result;

if (t_success)

{

SQLUINTEGER t_cursor_type;

// OK-2008-01-18 : Bug 5440. Set the required cursor type here.

if (m_cursor_type == kCursorTypeStatic || m_cursor_type == kCursorTypeEmulated)

t_cursor_type = SQL_CURSOR_STATIC;

else

t_cursor_type = SQL_CURSOR_FORWARD_ONLY;

t_result = SQLSetStmtAttr(t_statement, SQL_ATTR_CURSOR_TYPE, (SQLPOINTER)t_cursor_type, 0);

if (t_result != SQL_SUCCESS && t_result != SQL_SUCCESS_WITH_INFO)

{

SQLFreeStmt(t_statement, SQL_CLOSE);

return false;

}

}

char *t_parsed_query;

t_parsed_query = p_query;

int *t_param_sizes = NULL;

// The placeholder map contains a mapping from bind to argument.

PlaceholderMap t_placeholder_map;

t_placeholder_map . length = 0;

t_placeholder_map . elements = NULL;

if (t_success)

{

if (p_argument_count != 0)

{

DBBuffer t_query_buffer(t_query_length + 1);

t_success = processQuery(p_query, t_query_buffer, queryCallback, &t_placeholder_map);

t_query_length = t_query_buffer . getSize();

t_parsed_query = t_query_buffer . grab();

}

}

if (t_success)

{

#ifdef UTF8MODE

UTF8_TO_UNICODE_VAR(t_parsed_query);

err = SQLPrepareW(t_statement, (SQLWCHAR *)w_newquery , w_newquery_length);

#else

t_result = SQLPrepareA(t_statement, (SQLCHAR *)t_parsed_query , t_query_length);

#endif

if (t_result == SQL_SUCCESS || t_result == SQL_SUCCESS_WITH_INFO)

{

int *t_argument_sizes;

t_argument_sizes = new int[t_placeholder_map . length];

BindVariables(t_statement, p_arguments, p_argument_count, t_argument_sizes, &t_placeholder_map);

t_result = SQLExecute(t_statement);

delete[] t_argument_sizes;

}

if (t_result == SQL_NEED_DATA && useDataAtExecution())

{

// This happens if one or more of the parameters bound in BindVariables required data-at-execution. What we need to do here

// is pass the data to ODBC so it can populate these columns.

t_success = handleDataAtExecutionParameters(t_statement);

t_result = SQL_SUCCESS;

}

else if (t_result != SQL_SUCCESS && t_result != SQL_SUCCESS_WITH_INFO)

{

// OK-2008-01-16 : Bug 5725. Multi-line SQL statements would previously have appeared to fail

t_success = false;

}

}

if (p_argument_count != 0)

{

free(t_parsed_query);

free(t_placeholder_map . elements);

}

p_statement = t_statement;

p_result = t_result;

return t_success;

}

// OK-2009-02-18: Added to allow data at execution to be turned off.

bool DBConnection_ODBC::useDataAtExecution(void)

{

return false;

}

// OK-2009-02-18: Added to support data-at-execution. This function should be called if execution of p_statement resulted in

// SQL_NEED_DATA. It sends the required data for all parameters.

bool DBConnection_ODBC::handleDataAtExecutionParameters(SQLHSTMT p_statement)

{

SQLRETURN t_result;

t_result = SQL_NEED_DATA;

DBString t_default("", 0, False);

DBString *t_value;

t_value = NULL;

while (t_result == SQL_NEED_DATA)

{

t_result = SQLParamData(p_statement, (SQLPOINTER *)&t_value);

if (t_result != SQL_NEED_DATA)

continue;

if (t_value -> length > 8000)

{

int t_test;

t_test = 1;

}

char *t_current_position;

const char *t_end;

t_current_position = (char *)t_value -> sptr;

t_end = t_value -> sptr + t_value -> length;

// TODO: adjust this for putting data-at-execution into action.

unsigned int t_block_size;

t_block_size = 4096;

SQLRETURN t_put_result;

do

{

int t_length;

t_length = min(t_block_size, t_end - t_current_position);

t_put_result = SQLPutData(p_statement, (SQLPOINTER)t_current_position, t_length);

t_current_position = t_current_position + t_block_size;

} while (t_current_position < t_end);

if (t_put_result != SQL_SUCCESS)

{

char *t_error;

t_error = getDiagnosticRecord(p_statement);

return false;

}

}

return (t_result == SQL_SUCCESS);

}

/*IsError-True on error*/

Bool DBConnection_ODBC::IsError()

{

return errmsg[0] != '\0';

}

void DBConnection_ODBC::SetError(SQLHSTMT p_statement)

{

SQLINTEGER t_error;

SWORD t_errormsgsize;

SQLCHAR t_state[6];

SQLRETURN err = SQLErrorA(henv, hdbc, p_statement, t_state, &t_error, (SQLCHAR *)errmsg, SQL_MAX_MESSAGE_LENGTH-1, &t_errormsgsize);

if (err != SQL_SUCCESS)

errmsg[0] = '\0';

}

/*getErrorMessage- return error string*/

char *DBConnection_ODBC::getErrorMessage(Bool p_last)

{

if (IsError() == True) return errmsg;

else return (char *)DBNullValue;

}

/*BindVariables-parses querystring and binds variables*/

Bool DBConnection_ODBC::BindVariables(SQLHSTMT p_cursor, DBString *p_arguments, int p_argument_count, int *p_argument_sizes, PlaceholderMap *p_placeholder_map)

{

if (p_argument_count == 0)

return True;

DBString t_default("", 0, False);

for(int i = 0; i < p_placeholder_map -> length; ++i)

{

DBString *t_value;

if (p_placeholder_map -> elements[i] > p_argument_count)

t_value = &t_default;

else

t_value = &p_arguments[p_placeholder_map -> elements[i] - 1];

// OK-2009-02-18: [[Bug 7722]] - If non-binary data is being passed that is over 8000 bytes, we use the SQL_LONGVARCHAR type

// as otherwise we get a data-truncation error.

SQLSMALLINT t_data_type;

if (!t_value -> isbinary)

t_data_type = (t_value -> length > 8000 ? SQL_LONGVARCHAR : SQL_CHAR);

else

t_data_type = SQL_LONGVARBINARY;

// OK-2009-02-18: The ability to use data-at-execution was added to fix bug 7722

bool t_use_data_at_execution;

t_use_data_at_execution = useDataAtExecution();

if (!t_use_data_at_execution)

{

p_argument_sizes[i] = t_value -> length;

// MW-2008-07-30: [[ Bug 6415 ]] Inserting data into SQL Server doesn't work.

// This is because the bind parameter call was only being issued for binary columns!

SQLBindParameter(p_cursor, i + 1, SQL_PARAM_INPUT,

t_value -> isbinary ? SQL_C_BINARY : SQL_C_CHAR, t_data_type,

t_value -> length, 0, (void *)t_value -> sptr, t_value -> length, (long int *)&p_argument_sizes[i]);

}

else

{

// To use data_at_execution, it seems that the only thing required is to put the result of this macro

// into the strlen_or_indptr parameter (the last one). As p_argument_sizes is not used

// by anything else, and is deleted after this method returns, it should be safe to change it.

p_argument_sizes[i] = SQL_LEN_DATA_AT_EXEC(t_value -> length);

// The parameters are binded slightly differently here. Notice that we pass the actual DBString pointer instead

// of the value buffer. This pointer will be returned by ODBC for us later, meaning that we don't need to look up

// which parameter is needed again.

SQLBindParameter(p_cursor, i + 1, SQL_PARAM_INPUT,

t_value -> isbinary ? SQL_C_BINARY : SQL_C_CHAR, t_data_type,

t_value -> length, 0, (void *)t_value, t_value -> length, (long int *)&p_argument_sizes[i]);

}

}

return True;

}

/*ODBC doesn't support transactions so leave blank for now*/

void DBConnection_ODBC::transBegin() {}

void DBConnection_ODBC::transCommit()

{

SQLEndTran(SQL_HANDLE_DBC, hdbc, SQL_COMMIT);

}

void DBConnection_ODBC::transRollback()

{

SQLEndTran(SQL_HANDLE_DBC, hdbc, SQL_ROLLBACK);

}

void DBConnection_ODBC::getTables(char *buffer, int *bufsize)

{

int rowseplen = 1;

char rowsep[] = "\n";

if (!buffer)

*bufsize = 0;

SQLHSTMT querycursor;

SQLAllocStmt(hdbc,&querycursor);

DBCursor_ODBC *newcursor = NULL;

SQLRETURN err;

err = SQLTablesA(querycursor, NULL ,0, NULL ,0, (SQLCHAR *)"%" , SQL_NTS, (SQLCHAR *)"TABLE" ,SQL_NTS);

if (err == SQL_SUCCESS || err == SQL_SUCCESS_WITH_INFO)

{

SQLSMALLINT ncolumns;

SQLNumResultCols(querycursor,&ncolumns);

char *result = buffer;

char *resultptr = result;

if (ncolumns)

{

newcursor = new DBCursor_ODBC();

if (newcursor->open((DBConnection *)this, querycursor, 1))

{

if (!newcursor->getEOF())

{

while (True)

{

unsigned int colsize;

char *coldata = newcursor -> getFieldDataBinary(3, colsize);

if (newcursor -> getFieldType(3) == FT_WSTRING)

{

coldata = string_from_utf16((unsigned short *)coldata, colsize);

colsize = colsize / 2;

}

else

coldata = strdup(coldata);

if (buffer != NULL && ((resultptr - result) + (int)colsize + rowseplen ) > *bufsize)

{

free(coldata);

break;

}

if (buffer != NULL)

memcpy(resultptr, coldata, colsize);

resultptr += colsize;

newcursor -> next();

if (newcursor -> getEOF())

{

free(coldata);

break;

}

free(coldata);

if (buffer != NULL)

memcpy(resultptr, rowsep, rowseplen);

resultptr += rowseplen;

}

}

}

if (buffer != NULL)

*resultptr++ = '\0';

else

resultptr += 1;

*bufsize = resultptr-result;

delete newcursor;

newcursor = NULL;

querycursor = NULL;

}

}

}

#define ASCII 0x007f

#define SHIFT_IN '+' // beginning of a shift sequence

#define SHIFT_OUT '-' // end of a shift sequence

#define UTF8_2_MAX 0x07ff // max UTF8 2-byte sequence (32 * 64 = 2048)

#define UTF8_1ST_OF_2 0xc0 // 110x xxxx

#define UTF8_1ST_OF_3 0xe0 // 1110 xxxx

#define UTF8_TRAIL 0x80 // 10xx xxxx

#define HIGER_6_BIT(u) ((u) >> 12)

#define MIDDLE_6_BIT(u) (((u) & 0x0fc0) >> 6)

#define LOWER_6_BIT(u) ((u) & 0x003f)

#define BIT7(a) ((a) & 0x80)

#define BIT6(a) ((a) & 0x40)

int UTF8ToUnicode(const char * lpSrcStr, int cchSrc, uint2 * lpDestStr, int cchDest)

{

int nTB = 0; // # trail bytes to follow

int cchWC = 0; // # of Unicode code points generated

char * pUTF8 = (char *)lpSrcStr;

char UTF8;

while ((cchSrc--) && ((cchDest == 0) || ((cchWC << 1) < cchDest)))

{

// See if there are any trail bytes.

if (BIT7(*pUTF8) == 0)

{

// Found ASCII.

if (cchDest)

{

lpDestStr[cchWC] = (uint2)*pUTF8;

}

cchWC++;

}

else

if (BIT6(*pUTF8) == 0)

{

// Found a trail byte.

// Note : Ignore the trail byte if there was no lead byte.

if (nTB != 0)

{

// Decrement the trail byte counter.

nTB--;

// Make room for the trail byte and add the trail byte value.

if (cchDest)

{

lpDestStr[cchWC] <<= 6;

lpDestStr[cchWC] |= LOWER_6_BIT(*pUTF8);

}

if (nTB == 0)

{

// End of sequence. Advance the output counter.

cchWC++;

}

}

}

else

{

// Found a lead byte.

if (nTB > 0)

{

// Error - previous sequence not finished.

nTB = 0;

cchWC++;

}

else

{

// Calculate the number of bytes to follow.

// Look for the first 0 from left to right.

UTF8 = *pUTF8;

while (BIT7(UTF8) != 0)

{

UTF8 <<= 1;

nTB++;

}

// Store the value from the first byte and decrement

// the number of bytes to follow.

if (cchDest)

{

lpDestStr[cchWC] = UTF8 >> nTB;

}

nTB--;

}

}

pUTF8++;

}

// Make sure the destination buffer was large enough.

if (cchDest && (cchSrc >= 0))

return 0;

// Return the number of Unicode characters written.

if (lpDestStr)

lpDestStr[cchWC] = 0;

return cchWC << 1;

}

int UnicodeToUTF8(uint2 *lpSrcStr, int cchSrc, char *lpDestStr, int cchDest)

{

uint2 * lpWC = lpSrcStr;

int cchU8 = 0; // # of UTF8 chars generated

while ((cchSrc--) && (cchSrc--) && ((cchDest == 0) || (cchU8 < cchDest)))

{

if (*lpWC <= ASCII)

{

// Found ASCII.

if (cchDest)

{

lpDestStr[cchU8] = (char)*lpWC;

}

cchU8++;

}

else

if (*lpWC <= UTF8_2_MAX)

{

// Found 2 byte sequence if < 0x07ff (11 bits).

if (cchDest)

{

if ((cchU8 + 1) < cchDest)

{

// Use upper 5 bits in first byte.

// Use lower 6 bits in second byte.

lpDestStr[cchU8++] = UTF8_1ST_OF_2 | (*lpWC >> 6);

lpDestStr[cchU8++] = UTF8_TRAIL | LOWER_6_BIT(*lpWC);

}

else

{

// Error - buffer too small.

cchSrc++;

break;

}

}

else

cchU8 += 2;

}

else

{

// Found 3 byte sequence.

if (cchDest)

{

if ((cchU8 + 2) < cchDest)

{

// Use upper 4 bits in first byte.

// Use middle 6 bits in second byte.

// Use lower 6 bits in third byte.

lpDestStr[cchU8++] = UTF8_1ST_OF_3 | (*lpWC >> 12);

lpDestStr[cchU8++] = UTF8_TRAIL | MIDDLE_6_BIT(*lpWC);

lpDestStr[cchU8++] = UTF8_TRAIL | LOWER_6_BIT(*lpWC);

}

else

{

// Error - buffer too small.

cchSrc++;

break;

}

}

else

cchU8 += 3;

}

lpWC++;

}

// Make sure the destination buffer was large enough.

if (cchDest && (cchSrc >= 0))

return 0;

if (lpDestStr)

lpDestStr[cchU8] = 0;

// Return the number of UTF-8 characters written.

return cchU8;

}