I'm working with a C function and want to persist data to disk. What's the fastest way to read and write this data. I was converting the char* and intptr_t to NSString and NSNumber, storing them in a dictionary and then storing each dictionary into an NSMutableArray. However, is there a faster way to store this data without the need to wrap the values in Objective-C objects?
static void _print_image(const struct mach_header *mh, bool added)
{
Dl_info image_info;
int result = dladdr(mh, &image_info);
if (result == 0) {
printf("Could not print info for mach_header: %p\n\n", mh);
return;
}
const char *image_name = image_info.dli_fname;
const intptr_t image_base_address = (intptr_t)image_info.dli_fbase;
const char *log = added ? "Added" : "Removed";
//printf("%s: 0x%02lx %s\n\n", log, image_base_address, image_name);
NSString *imageName = [NSString stringWithUTF8String:image_name];
NSNumber *baseAddress = [NSNumber numberWithInteger:image_base_address];
NSDictionary *info = #{#"imageName" : imageName, #"baseAddress" : baseAddress};
[arr addObject:info];
}
Related
Argh, I'm going nuts.
I've got the following function which I am trying to log with a custom logger
CFWriteStreamWrite(CFWriteStreamRef stream, const UInt8 *buffer,
CFIndex bufferLength) {
NSData *data = [[NSData alloc] initWithBytes:buffer length: bufferLength];
NSString *errorDesc = nil;
NSPropertyListFormat format;
NSString * str = (NSString*)[NSPropertyListSerialization
propertyListFromData:data
mutabilityOption:NSPropertyListMutableContainersAndLeaves
format:&format
errorDescription:&errorDesc];
custom_log(CF, "CFURLCreateWithString: %s", str);
}
When I use my custom logger I get rubbish output
CFURLCreateWithString: < °3€
But when using NSLog, everything works fine,
Feb 10 00:36:39: {
bundleID = "com.test.testapp";
pid = 2852;
}
Custom Logger
EXPORT void custom_log(unsigned int facility, const char *msg, ...) {
if (minLogLevel <= INFO) {
char *msgBuffer;
va_list args;
va_start(args, msg);
vasprintf(&msgBuffer, msg, args);
va_end(args);
dispatch_async(logQueue, ^{
write(facility, INFO, msgBuffer);
});
}
}
Please tell me where I'm going wrong, I have spent the past 3 hours trying to convert to different data types. No luck.
Also, is it possible to get the output from NSLog into a string and then I'll just pass it to my logger instead?
One of the problems that you might be experiencing here is that NSString is not the same as the c_str that your vasprintf method is likely expecting to substitute for %s.
To compound this issue, I'm pretty sure you can't directly convert NSPropertyListSerialization to NSString, though I didn't test it myself. You might be looking for such an alternative instead:
NSString * str = [NSString stringWithFormat:#"%#", [NSPropertyListSerialization
propertyListFromData:data
mutabilityOption:NSPropertyListMutableContainersAndLeaves
format:&format
errorDescription:&errorDesc]];
custom_log(CF, "CFURLCreateWithString: %s", [str UTF8String]);
Of course, since you're already compositing a string, why not just do it all in the same place?
NSString * str = [NSString stringWithFormat:#"CFURLCreateWithString: %#", [NSPropertyListSerialization
propertyListFromData:data
mutabilityOption:NSPropertyListMutableContainersAndLeaves
format:&format
errorDescription:&errorDesc]];
custom_log(CF, [str UTF8String]);
As a fun side project, you might consider doing something like this in your main.mm. Replace stderr with stdout if you want more than just error stuff:
#if COPY_NSLOG_TO_CUSTOM
typedef int (*MyStdWriter)(void *, const char *, int);
static MyStdWriter _oldStdWrite;
int __customStderrWrite(void *inFD, const char *buffer, int size) {
if (minLogLevel <= INFO) {
// write to your custom stream here.
}
return _oldStdWrite(inFD, buffer, size);
}
void __copyNSLogToCustom(void) {
_oldStdWrite = stderr->_write;
stderr->_write = __customStderrWrite;
}
#endif
int main(int argc, char *argv[]) {
#if COPY_NSLOG_TO_CUSTOM
__copyNSLogToCustom();
#endif
// ...
}
I have the following category method on NSData. I'm trying to extract the bit field at the given index and have it return as an NSNumber. I have it working perfectly for all positive but I need it to work with negative numbers as well.
My Implementation looks as follows:
#import <Foundation/Foundation.h>
#interface NSData (ExternalDevices)
#end
#implementation NSData (ExternalDevices)
- (NSNumber *)extractLittleEndianBitFieldAtIndex:(int)index forLength:(int)length
{
//This function has limitations on the "length" parameter that are not yet know/defined
//These limitations are due to the max size of "NSInteger intData" defined below
int first_byte = index/8; //Index of the first byte containing this bit field
int last_byte = (length+index-1)/8; //Index of the last byte containing this bit field
int byte_length = last_byte - first_byte + 1; //number of bytes containing this bit field
Byte *byteArray = (Byte*)malloc(byte_length);
memcpy(byteArray, [[self subdataWithRange:NSMakeRange(first_byte, byte_length)] bytes], byte_length);
NSInteger intData = *((NSInteger *)byteArray);
free(byteArray);
return [NSNumber numberWithInt:intData];
}
+ (NSData *)dataFromHexString:(NSString *)string
{
string = [string lowercaseString];
NSMutableData *data= [NSMutableData new];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i = 0;
NSUInteger length = string.length;
while (i < length-1) {
char c = [string characterAtIndex:i++];
if (c < '0' || (c > '9' && c < 'a') || c > 'f')
continue;
byte_chars[0] = c;
byte_chars[1] = [string characterAtIndex:i++];
whole_byte = strtol(byte_chars, NULL, 16);
[data appendBytes:&whole_byte length:1];
}
return data;
}
#end
#interface Testing:NSObject
#end
#implementation Testing
- (instancetype)init
{
self = [super init];
if (self)
{
{
NSData *data = [NSData dataFromHexString:#"e30b"];
NSLog(#"%# should be 3043", [data extractLittleEndianBitFieldAtIndex:0 forLength:16]);
}
{
NSData *data = [NSData dataFromHexString:#"46e0"];
NSLog(#"%# should be -8122", [data extractLittleEndianBitFieldAtIndex:0 forLength:16]);
}
{
NSData *data = [NSData dataFromHexString:#"f208"];
NSLog(#"%# should be 2290", [data extractLittleEndianBitFieldAtIndex:0 forLength:16]);
}
{
NSData *data = [NSData dataFromHexString:#"10e6"];
NSLog(#"%# should be -6640", [data extractLittleEndianBitFieldAtIndex:0 forLength:16]);
}
{
NSData *data = [NSData dataFromHexString:#"018900"];
NSLog(#"%# should be 137", [data extractLittleEndianBitFieldAtIndex:8 forLength:16]);
}
}
return self;
}
#end
int main(int argc, char *argv[]) {
#autoreleasepool {
[[Testing alloc] init];
}
}
The following website seems to always yield the results I want under INT16 - Little Endian (BA)
http://www.scadacore.com/field-applications/miscellaneous/online-hex-converter.html
Although it is important to note that not every number I work with will be an INT16
Your line:
NSInteger intData = *((NSInteger *)byteArray);
is your key problem for two reasons:
byteArray may be shorter (or less likely, longer) than an NSInteger and you'll end up reading garbage. E.g. if byteArray is 2 bytes as in your examples and NSInteger is 4 bytes - which it will be in 64-bit - you'll read two bytes of garbage.
If you are converting signed values you need to sign-extend the value - that is replicate the sign bit into the higher unused bits. E.g. if you are converting a signed 16-bit field into a 32-bit signed value then the upper 16-bits need to be a replication of the most significant bit of the 16-bit value, so 0x7000 -> 0x00007000 and 0x8000 -> 0xFFFF8000.
You need to come up with an algorithm that handles these issues. You may find it easier to do the conversion a byte at a time using masking (and'ing), or'ing and shifting.
HTH
I'm trying to encrypt data with an RSA public key using openssl.
I have the Java implementation of what I need to do in Objective-C.
Here's what I have so far:
- (RSA *)rsaFromExponent:(NSString *)exponent modulus:(NSString *)modulus
{
RSA *rsa_pub = RSA_new();
const char *N = [modulus UTF8String];
const char *E = [exponent UTF8String];
if (!BN_hex2bn(&rsa_pub->n, N))
{
// TODO
}
printf("N: %s\n", N);
printf("n: %s\n", BN_bn2dec(rsa_pub->n));
if (!BN_hex2bn(&rsa_pub->e, E))
{
// TODO
}
printf("E: %s\n", E);
printf("e: %s\n", BN_bn2dec(rsa_pub->e));
return rsa_pub;
}
- (NSString *)cleanString:(NSString *)input
{
NSString *output = input;
output = [output stringByReplacingOccurrencesOfString:#"<" withString:#""];
output = [output stringByReplacingOccurrencesOfString:#">" withString:#""];
output = [output stringByReplacingOccurrencesOfString:#" " withString:#""];
return output;
}
// main code
NSString *exponentB64 = #"AQAB";
NSString *modulusB64 = #"AKDbnFpblq7LHfWDfGTR48B34MKaHQosMwVu8cCc6fH2pZ8Ypx/OgzG6VJlKHXeELtlo5tddBSJpwnkEQdvkkmwuOpCkacTTLon6EHqX4WwFW+waqHxmj419SxiDDlo9tsbg7vfFIMpKyGzq1zvTAN3TroW+MxogZfZD3/N6dNTzvBoXe/Ca1e/zVwYXKbiegLMjNwsruz/WvuMiNKTK4U3GEmb0gIODd1shAH10ube8Nrz/e1u9kr25VQ+7kZAFjnkPTp2AvNGYHQt35m1TRMQhTylVwTZqFkHC/jMt7WxuS8q7ftjM828wa1fEWTgWYrdkzmqZSK5CHBYSys/N1Ws=";
// 1. decode base64 (http://projectswithlove.com/projects/NSData_Base64.zip)
NSData *exponent = [NSData dataFromBase64String:exponentB64];
NSData *modulus = [NSData dataFromBase64String:modulusB64];
NSString *exponentHex = [self cleanString:[exponent description]];
NSString *modulusHex = [self cleanString:[modulus description]];
// 2. create RSA public key
RSA *rsa_pub = [self rsaFromExponent:exponentHex modulus:modulusHex];
NSString *user = #"TEST";
// 3. encode base 64
NSData *userData = [user dataUsingEncoding:NSASCIIStringEncoding];
NSString *userB64String = [userData base64EncodedString];
// 4. encrypt
const unsigned char *from = (const unsigned char *)[userB64String cStringUsingEncoding:NSASCIIStringEncoding];
int flen = strlen((const char *)from);
unsigned char *to = (unsigned char *) malloc(RSA_size(rsa_pub));
int padding = RSA_PKCS1_PADDING;
int result = RSA_public_encrypt(flen, from, to, rsa_pub, padding);
if (-1 == result)
{
NSLog(#"WAT?");
}
else
{
NSLog(#"from: %s", from); // echo VEVTVA==
NSLog(#"to: %s", to); // echo something strange with characters like: ~™Ÿû—...
}
// 5. encode base 64
NSString *cipherString = [NSString stringWithCString:(const char *)to
encoding:NSASCIIStringEncoding];
NSData *cipherData = [cipherString dataUsingEncoding:NSASCIIStringEncoding];
NSString *cipherDataB64 = [cipherData base64EncodedString];
NSLog(#"user encrypted b64: %#", cipherDataB64); // echo null :-(
In Java, I have no problem to base64 encode the encrypted data.
I'm sure I'm doing something wrong but I don't know where because it's not something I do everyday.
Or if you know another way to do this with iOS frameworks like Security.framework.
Thanks in advance.
Someone else helped me figure it out. I don't know why but I was assuming that the output buffer from RSA_public_encrypt function would be an ascii string. Though it's just bytes as the documentation says too. The char * type often leads me to think it's gonna store a string (it's so wrong I think it's the last time I make this kind of error).
So from step 5:
// 5. encode base 64
NSData *cipherData = [NSData dataWithBytes:(const void *)to length:result];
NSString *cipherDataB64 = [cipherData base64EncodedString];
NSLog(#"user encrypted b64: %#", cipherDataB64); // now echo the expected value
I have a requirement to integrate with a web service that serves as a login. The hash needs to be generated on the client. I am able to produce the correct hash as NSMutableData, but then I need to convert it to a string, without the spaces or brackets produced when the NSMutableData object is rendered as a string in the output console. I have read several posts, all seeming to say the same thing:
NSString *newstring = [[NSString alloc] initWithDSata:dataToConvert encoding:NSUTF8StringEncoding];
Unfortunately, this doesnt work for me. Using NSUTF8StringEncoding returns null. NSASCIIStringEncoding is even worse.
Here is my code:
NSString *password = [NSString stringWithFormat:#"%#%#", kPrefix, [self.txtPassword text]];
NSLog(#"PLAIN: %#", password);
NSData *data = [password dataUsingEncoding:NSASCIIStringEncoding];
NSMutableData *sha256Out = [NSMutableData dataWithLength:CC_SHA256_DIGEST_LENGTH];
CC_SHA256(data.bytes, data.length, sha256Out.mutableBytes);
NSString *preppedPassword = [[NSString alloc] initWithData:sha256Out encoding:NSASCIIStringEncoding];
NSLog(#"HASH: %#\n", preppedPassword);
How can I convert the NSMutableData to string?
My problem is that I need to from this
<7e8df5b3 17c99263 e4fe6220 bb75b798 4a41de45 44464ba8 06266397 f165742e>
to this
7e8df5b317c99263e4fe6220bb75b7984a41de4544464ba806266397f165742e
See How to convert an NSData into an NSString Hex string?
I use a slightly modified version myself:
#implementation NSData (Hex)
- (NSString *)hexRepresentationWithSpaces:(BOOL)spaces uppercase:(BOOL)uppercase {
const unsigned char *bytes = (const unsigned char *)[self bytes];
NSUInteger nbBytes = [self length];
// If spaces is true, insert a space every this many input bytes (twice this many output characters).
static const NSUInteger spaceEveryThisManyBytes = 4UL;
// If spaces is true, insert a line-break instead of a space every this many spaces.
static const NSUInteger lineBreakEveryThisManySpaces = 4UL;
const NSUInteger lineBreakEveryThisManyBytes = spaceEveryThisManyBytes * lineBreakEveryThisManySpaces;
NSUInteger strLen = 2 * nbBytes + (spaces ? nbBytes / spaceEveryThisManyBytes : 0);
NSMutableString *hex = [[NSMutableString alloc] initWithCapacity:strLen];
for (NSUInteger i = 0; i < nbBytes; ) {
if (uppercase) {
[hex appendFormat:#"%02X", bytes[i]];
} else {
[hex appendFormat:#"%02x", bytes[i]];
}
// We need to increment here so that the every-n-bytes computations are right.
++i;
if (spaces) {
if (i % lineBreakEveryThisManyBytes == 0) {
[hex appendString:#"\n"];
} else if (i % spaceEveryThisManyBytes == 0) {
[hex appendString:#" "];
}
}
}
return hex;
}
#end
In my iPhone app I am getting the device token from Apple which I am assigning a public property inside the Delegate file as shown below:
- (void)application:(UIApplication*)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData*)deviceToken
{
self.dToken = [[NSString alloc] initWithData:deviceToken encoding:NSUTF8StringEncoding];
}
The dToken property is declared as shown below:
NSString *dToken;
#property (nonatomic,retain) NSString *dToken;
But when I try to retrieve the device token from another file I get the null value.
+(NSString *) getDeviceToken
{
NSString *deviceToken = [(MyAppDelegate *)[[UIApplication sharedApplication] delegate] dToken];
NSLog(#" getDeviceToken = %#",deviceToken); // This prints NULL
return deviceToken;
}
What am I doing wrong?
I suggest you to convert token to string in this way:
self.dToken = [[[deviceToken description]
stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:#"<>"]]
stringByReplacingOccurrencesOfString:#" "
withString:#""];
UPDATED:
As many people mentioned it is better to use next approach to convert NSData * to NSString *:
#implementation NSData (Conversion)
- (NSString *)hexadecimalString
{
const unsigned char *dataBuffer = (const unsigned char *)[self bytes];
if (!dataBuffer) {
return [NSString string];
}
NSUInteger dataLength = [self length];
NSMutableString *hexString = [NSMutableString stringWithCapacity:(dataLength * 2)];
for (int i = 0; i < dataLength; ++i) {
[hexString appendFormat:#"%02lx", (unsigned long)dataBuffer[i]];
}
return hexString;
}
#end
From the discussion at Best way to serialize an NSData into a hexadeximal string, here is a better way to do it. Is longer, but your code will be future-proof if Apple changes the way NSData emit debugger descriptions.
Extend NSData as follows:
#implementation NSData (Hex)
- (NSString*)hexString {
unichar* hexChars = (unichar*)malloc(sizeof(unichar) * (self.length*2));
unsigned char* bytes = (unsigned char*)self.bytes;
for (NSUInteger i = 0; i < self.length; i++) {
unichar c = bytes[i] / 16;
if (c < 10) c += '0';
else c += 'A' - 10;
hexChars[i*2] = c;
c = bytes[i] % 16;
if (c < 10) c += '0';
else c += 'A' - 10;
hexChars[i*2+1] = c;
}
NSString* retVal = [[NSString alloc] initWithCharactersNoCopy:hexChars
length:self.length*2
freeWhenDone:YES];
return [retVal autorelease];
}
#end
I know that this is an old question and that this may be new information that has come up since then, but I'd just like to point something out to all of the people who are claiming that using the description method is a really bad idea. In most cases, you'd be exactly right. The description property is generally just used for debugging, but for the NSData class, it's specifically defined as returning a hexadecimal representation of the receivers contents which is exactly what is needed here. Since Apple has put it in their documentation, I think you're pretty safe as far as them changing it.
This can be found in the NSData Class Reference here: https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSData_Class/Reference/Reference.html