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A category on NSData for coding and encoding Base64
//
// NSData+Base64.h
// base64
//
// Created by Matt Gallagher on 2009/06/03.
// Copyright 2009 Matt Gallagher. All rights reserved.
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software. Permission is granted to anyone to
// use this software for any purpose, including commercial applications, and to
// alter it and redistribute it freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source
// distribution.
//
#import <Foundation/Foundation.h>
void *NewBase64Decode(
const char *inputBuffer,
size_t length,
size_t *outputLength);
char *NewBase64Encode(
const void *inputBuffer,
size_t length,
bool separateLines,
size_t *outputLength);
@interface NSData (Base64)
+ (NSData *)dataFromBase64String:(NSString *)aString;
- (NSString *)base64EncodedString;
@end
//
// NSData+Base64.m
// base64
//
// Created by Matt Gallagher on 2009/06/03.
// Copyright 2009 Matt Gallagher. All rights reserved.
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software. Permission is granted to anyone to
// use this software for any purpose, including commercial applications, and to
// alter it and redistribute it freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source
// distribution.
//
// Comments converted to be ARC compatible
#import "NSData+Base64.h"
//
// Mapping from 6 bit pattern to ASCII character.
//
static unsigned char base64EncodeLookup[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
//
// Definition for "masked-out" areas of the base64DecodeLookup mapping
//
#define xx 65
//
// Mapping from ASCII character to 6 bit pattern.
//
static unsigned char base64DecodeLookup[256] =
{
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, 62, xx, xx, xx, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, xx, xx, xx, xx, xx, xx,
xx, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, xx, xx, xx, xx, xx,
xx, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx, xx,
};
//
// Fundamental sizes of the binary and base64 encode/decode units in bytes
//
#define BINARY_UNIT_SIZE 3
#define BASE64_UNIT_SIZE 4
//
// NewBase64Decode
//
// Decodes the base64 ASCII string in the inputBuffer to a newly malloced
// output buffer.
//
// inputBuffer - the source ASCII string for the decode
// length - the length of the string or -1 (to specify strlen should be used)
// outputLength - if not-NULL, on output will contain the decoded length
//
// returns the decoded buffer. Must be free'd by caller. Length is given by
// outputLength.
//
void *NewBase64Decode(
const char *inputBuffer,
size_t length,
size_t *outputLength)
{
if (length == -1)
{
length = strlen(inputBuffer);
}
size_t outputBufferSize =
((length+BASE64_UNIT_SIZE-1) / BASE64_UNIT_SIZE) * BINARY_UNIT_SIZE;
unsigned char *outputBuffer = (unsigned char *)malloc(outputBufferSize);
size_t i = 0;
size_t j = 0;
while (i < length)
{
//
// Accumulate 4 valid characters (ignore everything else)
//
unsigned char accumulated[BASE64_UNIT_SIZE];
size_t accumulateIndex = 0;
while (i < length)
{
unsigned char decode = base64DecodeLookup[inputBuffer[i++]];
if (decode != xx)
{
accumulated[accumulateIndex] = decode;
accumulateIndex++;
if (accumulateIndex == BASE64_UNIT_SIZE)
{
break;
}
}
}
//
// Store the 6 bits from each of the 4 characters as 3 bytes
//
// (Uses improved bounds checking suggested by Alexandre Colucci)
//
if(accumulateIndex >= 2)
outputBuffer[j] = (accumulated[0] << 2) | (accumulated[1] >> 4);
if(accumulateIndex >= 3)
outputBuffer[j + 1] = (accumulated[1] << 4) | (accumulated[2] >> 2);
if(accumulateIndex >= 4)
outputBuffer[j + 2] = (accumulated[2] << 6) | accumulated[3];
j += accumulateIndex - 1;
}
if (outputLength)
{
*outputLength = j;
}
return outputBuffer;
}
//
// NewBase64Encode
//
// Encodes the arbitrary data in the inputBuffer as base64 into a newly malloced
// output buffer.
//
// inputBuffer - the source data for the encode
// length - the length of the input in bytes
// separateLines - if zero, no CR/LF characters will be added. Otherwise
// a CR/LF pair will be added every 64 encoded chars.
// outputLength - if not-NULL, on output will contain the encoded length
// (not including terminating 0 char)
//
// returns the encoded buffer. Must be free'd by caller. Length is given by
// outputLength.
//
char *NewBase64Encode(
const void *buffer,
size_t length,
bool separateLines,
size_t *outputLength)
{
const unsigned char *inputBuffer = (const unsigned char *)buffer;
#define MAX_NUM_PADDING_CHARS 2
#define OUTPUT_LINE_LENGTH 64
#define INPUT_LINE_LENGTH ((OUTPUT_LINE_LENGTH / BASE64_UNIT_SIZE) * BINARY_UNIT_SIZE)
#define CR_LF_SIZE 2
//
// Byte accurate calculation of final buffer size
//
size_t outputBufferSize =
((length / BINARY_UNIT_SIZE)
+ ((length % BINARY_UNIT_SIZE) ? 1 : 0))
* BASE64_UNIT_SIZE;
if (separateLines)
{
outputBufferSize +=
(outputBufferSize / OUTPUT_LINE_LENGTH) * CR_LF_SIZE;
}
//
// Include space for a terminating zero
//
outputBufferSize += 1;
//
// Allocate the output buffer
//
char *outputBuffer = (char *)malloc(outputBufferSize);
if (!outputBuffer)
{
return NULL;
}
size_t i = 0;
size_t j = 0;
const size_t lineLength = separateLines ? INPUT_LINE_LENGTH : length;
size_t lineEnd = lineLength;
while (true)
{
if (lineEnd > length)
{
lineEnd = length;
}
for (; i + BINARY_UNIT_SIZE - 1 < lineEnd; i += BINARY_UNIT_SIZE)
{
//
// Inner loop: turn 48 bytes into 64 base64 characters
//
outputBuffer[j++] = base64EncodeLookup[(inputBuffer[i] & 0xFC) >> 2];
outputBuffer[j++] = base64EncodeLookup[((inputBuffer[i] & 0x03) << 4)
| ((inputBuffer[i + 1] & 0xF0) >> 4)];
outputBuffer[j++] = base64EncodeLookup[((inputBuffer[i + 1] & 0x0F) << 2)
| ((inputBuffer[i + 2] & 0xC0) >> 6)];
outputBuffer[j++] = base64EncodeLookup[inputBuffer[i + 2] & 0x3F];
}
if (lineEnd == length)
{
break;
}
//
// Add the newline
//
outputBuffer[j++] = '\r';
outputBuffer[j++] = '\n';
lineEnd += lineLength;
}
if (i + 1 < length)
{
//
// Handle the single '=' case
//
outputBuffer[j++] = base64EncodeLookup[(inputBuffer[i] & 0xFC) >> 2];
outputBuffer[j++] = base64EncodeLookup[((inputBuffer[i] & 0x03) << 4)
| ((inputBuffer[i + 1] & 0xF0) >> 4)];
outputBuffer[j++] = base64EncodeLookup[(inputBuffer[i + 1] & 0x0F) << 2];
outputBuffer[j++] = '=';
}
else if (i < length)
{
//
// Handle the double '=' case
//
outputBuffer[j++] = base64EncodeLookup[(inputBuffer[i] & 0xFC) >> 2];
outputBuffer[j++] = base64EncodeLookup[(inputBuffer[i] & 0x03) << 4];
outputBuffer[j++] = '=';
outputBuffer[j++] = '=';
}
outputBuffer[j] = 0;
//
// Set the output length and return the buffer
//
if (outputLength)
{
*outputLength = j;
}
return outputBuffer;
}
@implementation NSData (Base64)
//
// dataFromBase64String:
//
// Creates an NSData object containing the base64 decoded representation of
// the base64 string 'aString'
//
// Parameters:
// aString - the base64 string to decode
//
// returns the NSData representation of the base64 string
//
+ (NSData *)dataFromBase64String:(NSString *)aString
{
NSData *data = [aString dataUsingEncoding:NSASCIIStringEncoding];
size_t outputLength;
void *outputBuffer = NewBase64Decode([data bytes], [data length], &outputLength);
NSData *result = [NSData dataWithBytes:outputBuffer length:outputLength];
free(outputBuffer);
return result;
}
//
// base64EncodedString
//
// Creates an NSString object that contains the base 64 encoding of the
// receiver's data. Lines are broken at 64 characters long.
//
// returns an NSString being the base 64 representation of the
// receiver.
//
- (NSString *)base64EncodedString
{
size_t outputLength;
char *outputBuffer =
NewBase64Encode([self bytes], [self length], true, &outputLength);
NSString *result =
[[NSString alloc] initWithBytes:outputBuffer length:outputLength encoding:NSASCIIStringEncoding];
free(outputBuffer);
return result;
}
@end
@nfs3250

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commented Apr 30, 2013

Thanks for this category. Just one doubt, when I analyze this code in Xcode , it shows me below issue

        NSData+Base64.m:304:4: Argument in message expression is an uninitialized value

I think this is due to size_t outputLength; is not initialized. Can you tell me appropriate way to initialize this ?
Thanks .

@ghost

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commented May 11, 2013

size_t outputLength = 0;

@douglaslondrina

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commented Jan 13, 2014

Why add a new line at the end of the decoded string (at line 226)? Its a not desirable behavior, at least for me. Could this be optional?
Thanks!

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