Fix conversion of BIT fields (fixes #2254)

Frameworks/SPMySQLFramework/SPMySQL Unit Tests/DataConversion_Tests.m

@@ -0,0 +1,71 @@
//
//  DataConversion_Tests.m
//  SPMySQLFramework
//
//  Created by Max Lohrmann on 01.10.15.
//  Copyright (c) 2015 Max Lohrmann. All rights reserved.
//
//  Permission is hereby granted, free of charge, to any person
//  obtaining a copy of this software and associated documentation
//  files (the "Software"), to deal in the Software without
//  restriction, including without limitation the rights to use,
//  copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following
//  conditions:
//
//  The above copyright notice and this permission notice shall be
//  included in all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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//
//  More info at <https://github.com/sequelpro/sequelpro>

@interface DataConversion_Tests : XCTestCase

- (void)test_bitStringWithBytes;

@end

@implementation DataConversion_Tests

- (void)test_bitStringWithBytes
{
	// BIT(1)
	{
		unsigned char y = 1;
		unsigned char n = 0;
		XCTAssertEqualObjects(_bitStringWithBytes(&y,sizeof(y),1), @"1");
		XCTAssertEqualObjects(_bitStringWithBytes(&n,sizeof(n),0), @"0");
	}
	// BIT(3)
	{
		const char input[] = {5};
		NSUInteger bitSize = 3;
		NSString *res = _bitStringWithBytes(input,sizeof(input),bitSize);
		XCTAssertEqualObjects(res, @"101");
	}
	// BIT(16)
	{
		const char input[] = {0xcc,0xf0};
		NSUInteger bitSize = 16;
		NSString *res = _bitStringWithBytes(input,sizeof(input),bitSize);
		XCTAssertEqualObjects(res, @"1100110011110000");
	}
	// BIT(20)
	{
		const char input[] = {0x0f,0xcc,0xf0};
		NSUInteger bitSize = 20;
		NSString *res = _bitStringWithBytes(input,sizeof(input),bitSize);
		XCTAssertEqualObjects(res, @"11111100110011110000");
	}
}

@end

Frameworks/SPMySQLFramework/Source/SPMySQLResult Categories/Data Conversion.m

@@ -209,27 +209,26 @@ static inline SPMySQLResultFieldProcessor _processorForField(MYSQL_FIELD aField)
		return nil;
	}

	// Ensure padLength is never lower than the length
	if (padLength < bitLength) {
		padLength = bitLength;
	}

	// use whatever is smaller. padLength comes from BIT(x), bitLength from the actual bytes transmitted.
	// if bitLength < padLength it means the value is smaller than what the field can accomodate.
	// if bitLength > padLength it means BIT(x) is not a full n bytes long and was extended by mysqls storage.
	//   In that case the additional bits should still be 0 as mysql does not allow to set bits over the size of x.
	bitLength = MIN(bitLength,padLength);
	// Generate a nul-terminated C string representation of the binary data
	char *cStringBuffer = malloc(padLength + 1);
	cStringBuffer[padLength] = '\0';
	memset(cStringBuffer, '0', padLength);

	while (i < bitLength)
	{
		// start with the least significant bit (the rightmost bit in the last byte) and move left
		unsigned char bitInByteMask =  i % 8; // 0-7, the cycle is 0,1,...,7,0,...
		unsigned long bytesOffset = (length - 1) - (i >> 3); // i>>3 == floor(i/8)
		++i;

		cStringBuffer[padLength - i] = ((bytes[length - 1 - (i >> 3)] >> (i & 0x7)) & 1 ) ? '1' : '0';
		cStringBuffer[padLength - i] = ((bytes[bytesOffset] & (1 << bitInByteMask)) != 0) ? '1' : '0';
	}

	while (i++ < padLength)
	{
		cStringBuffer[padLength - i] = '0';
	}

	
	cStringBuffer[padLength] = '\0';
	
	// Convert to a string
	NSString *returnString = [NSString stringWithUTF8String:cStringBuffer];