How do i check whether a file exists with resource fork or not?
Note : With out using the API's of CarbonCore->Resources.h, Since they
are deprecated.
I will be able to open the file where there exist resource fork or not. But i need to check whether the resource fork exists or not. This is what exactly i'm looking for.
Use getattrlist or fgetattrlist passing ATTR_FILE_RSRCLENGTH in the attrList parameter. see the man page for getattrlist.
Alternatively
BOOL hasResourceFork = getxattr("/path/To/file", "com.apple.ResourceFork", NULL, 0, 0, 0) != -1;
That requires
#include <sys/xattr.h>
For those who want to get the actual resource fork length, here's the code:
#include <sys/attr.h>
struct attrlist attrlist = {0};
attrlist.bitmapcount = ATTR_BIT_MAP_COUNT;
attrlist.fileattr = ATTR_FILE_RSRCLENGTH;
typedef struct __attribute__((__packed__)) {
uint32_t size;
off_t forkSize;
} result_t;
result_t result = {0};
if (getattrlist (filepath, &attrlist, &result, sizeof(result), 0) == 0) {
assert(sizeof(result)==result.size); // makes sure we got the struct right
// now we find the rsrc fork size in result.forkSize
}
Related
I want to read analyze a plane (IODeviceTree IOUSB IOService IOACPIPlane)
without using ioreg, by creating a pointer (segment offset) in memory, my question is how to get the address of a plane, that in C or Objective C. Thank you for your answers.
First of all, I'm not sure what you mean by "segment offset" in this context, but the rest of the question makes sense, so I'll just ignore that part for my answer.
Second, the source code for ioreg is available here so you can see exactly how that does it.
A quick summary of how I would do it:
The main function you need to call is IORegistryCreateIterator().
Do not set the options argument to kIORegistryIterateRecursively - otherwise it will be difficult to find the graph structure.
For the plane argument, specify e.g. kIOServicePlane.
Keep calling IOIteratorNext(), and every time you get a registry entry back, try to recurse using IORegistryIteratorEnterEntry() and every time you get IO_OBJECT_NULL back, step one level back out using IORegistryIteratorExitEntry().
Working example code:
#include <stdio.h>
#include <IOKit/IOKitLib.h>
int main(int argc, const char * argv[])
{
io_iterator_t iter = IO_OBJECT_NULL;
unsigned recursion_level = 0;
kern_return_t result = IORegistryCreateIterator(kIOMasterPortDefault, kIOServicePlane, 0, &iter);
if (result == 0 && iter != IO_OBJECT_NULL)
{
while (true)
{
io_object_t entry = IOIteratorNext(iter);
if (entry != IO_OBJECT_NULL)
{
io_name_t name = "";
IORegistryEntryGetName(entry, name);
printf("%*s+ %s\n", recursion_level * 2, "", name);
++recursion_level;
result = IORegistryIteratorEnterEntry(iter);
assert(result == KERN_SUCCESS);
}
else
{
if (recursion_level == 0)
break;
result = IORegistryIteratorExitEntry(iter);
assert(result == KERN_SUCCESS);
--recursion_level;
}
}
}
return 0;
}
(Make sure to link against the IOKit.framework)
Of course, you can do much more interesting things than call IORegistryEntryGetName() on each registry entry.
I am starting with Vulkan and I follow the Niko Kauppi's tutorial on Youtube.
I have an error when creating a device with vkCreateDevice, it returns VK_ERROR_EXTENSION_NOT_PRESENT
Here some part of my code:
The call to vkCreateDevice
_gpu_count = 0;
vkEnumeratePhysicalDevices(instance, &_gpu_count, nullptr);
std::vector<VkPhysicalDevice> gpu_list(_gpu_count);
vkEnumeratePhysicalDevices(instance, &_gpu_count, gpu_list.data());
_gpu = gpu_list[0];
vkGetPhysicalDeviceProperties(_gpu, &_gpu_properties);
VkDeviceCreateInfo device_create_info = _CreateDeviceInfo();
vulkanCheckError(vkCreateDevice(_gpu, &device_create_info, nullptr, &_device));
_gpu_count = 1 and _gpu_properties seems to recognize well my nvidia gpu (which is not up to date)
device_create_info
VkDeviceCreateInfo _createDeviceInfo;
_createDeviceInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
_createDeviceInfo.queueCreateInfoCount = 1;
VkDeviceQueueCreateInfo _queueInfo = _CreateDeviceQueueInfo();
_createDeviceInfo.pQueueCreateInfos = &_queueInfo;
I don't understand the meaning of the error: "A requested extension is not supported" according to Khronos' doc.
Thanks for your help
VK_ERROR_EXTENSION_NOT_PRESENT is returned when one of the extensions in [enabledExtensionCount, ppEnabledExtensionNames] vector you provided is not supported by the driver (as queried by vkEnumerateDeviceExtensionProperties()).
Extensions can also have dependencies, so VK_ERROR_EXTENSION_NOT_PRESENT is also returned when an extension dependency of extension in the list is missing there too.
If you want no device extensions, make sure enabledExtensionCount of VkDeviceCreateInfo is 0 (and not e.g. some uninitialized value).
I assume 2. is the whole body of _CreateDeviceInfo(), which would confirm the "uninitialized value" suspicion.
Usually though you would want a swapchain extension there to be able to render to screen directly.
First of all, make sure your VkDeviceCreateInfo is zero filled, otherwise it may carry garbage to your VkCreateDevice() call.
Add following line just after declaring your VkDeviceCreateInfo:
memset ( &_createDeviceInfo, 0, sizeof(VkDeviceCreateInfo) );
Some extensions are absolutely necessary, as swapchain one.
To retrieve available extensions do this:
// Available extensions and layers names
const char* const* _ppExtensionNames = NULL;
// get extension names
uint32 _extensionCount = 0;
vkEnumerateDeviceExtensionProperties( _gpu, NULL, &_extensionCount, NULL);
std::vector<const char *> extNames;
std::vector<VkExtensionProperties> extProps(_extensionCount);
vkEnumerateDeviceExtensionProperties(_gpu, NULL, &_extensionCount, extProps.data());
for (uint32_t i = 0; i < _extensionCount; i++) {
extNames.push_back(extProps[i].extensionName);
}
_ppExtensionNames = extNames.data();
Once you have all extension names in _ppExtensionNames, pass it to your deviceCreateInfo struct:
VkDeviceCreateInfo device_create_info ...
[...]
device_create_info.enabledExtensionCount = _extensionCount;
device_create_info.ppEnabledExtensionNames = _ppExtensionNames;
[...]
vulkanCheckError(vkCreateDevice(_gpu, &device_create_info, nullptr, &_device));
I hope it helps.
Please double check above code, as I'm writing it by heart.
i am new to spider monkey and want to use it for transform java script file to sequence of byte code.
i get spider monkey and build it in debug mode.
i want to use JS_CompileScript function in jsapi.h to compile javascript code and analysis this to get bytecode , but when in compile below code and run it , i get run time error.
the error is "Unhandled exception at 0x0f55c020 (mozjs185-1.0.dll) in spiderMonkeyTest.exe: 0xC0000005: Access violation reading location 0x00000d4c." and i do not resolve it.
any body can help me to resolve this or introducing other solutions to get byte code from javascript code by using spider monkey ?
// spiderMonkeyTest.cpp : Defines the entry point for the console application.
//
#define XP_WIN
#include <iostream>
#include <fstream>
#include "stdafx.h"
#include "jsapi.h"
#include "jsanalyze.h"
using namespace std;
using namespace js;
static JSClass global_class = { "global",
JSCLASS_NEW_RESOLVE | JSCLASS_GLOBAL_FLAGS,
JS_PropertyStub,
NULL,
JS_PropertyStub,
JS_StrictPropertyStub,
JS_EnumerateStub,
JS_ResolveStub,
JS_ConvertStub,
NULL,
JSCLASS_NO_OPTIONAL_MEMBERS
};
int _tmain(int argc, _TCHAR* argv[]) {
/* Create a JS runtime. */
JSRuntime *rt = JS_NewRuntime(16L * 1024L * 1024L);
if (rt == NULL)
return 1;
/* Create a context. */
JSContext *cx = JS_NewContext(rt, 8192);
if (cx == NULL)
return 1;
JS_SetOptions(cx, JSOPTION_VAROBJFIX);
JSScript *script;
JSObject *obj;
const char *js = "function a() { var tmp; tmp = 1 + 2; temp = temp * 2; alert(tmp); return 1; }";
obj = JS_CompileScript(cx,JS_GetGlobalObject(cx),js,strlen(js),"code.js",NULL);
script = obj->getScript();
if (script == NULL)
return JS_FALSE; /* compilation error */
js::analyze::Script *sc = new js::analyze::Script();
sc->analyze(cx,script);
JS_DestroyContext(cx);
JS_DestroyRuntime(rt);
/* Shut down the JS engine. */
JS_ShutDown();
return 1;
}
Which version of Spidermonkey are you using? I am using the one that comes with FireFox 10 so the API may be different.
You should create a new global object and initialize it by calling JS_NewCompartmentAndGlobalObject() and JS_InitStandardClasses() before compiling your script :
.....
/*
* Create the global object in a new compartment.
* You always need a global object per context.
*/
global = JS_NewCompartmentAndGlobalObject(cx, &global_class, NULL);
if (global == NULL)
return 1;
/*
* Populate the global object with the standard JavaScript
* function and object classes, such as Object, Array, Date.
*/
if (!JS_InitStandardClasses(cx, global))
return 1;
......
Note, the function JS_NewCompartmentAndGlobalObject() is obsolete now, check the latest JSAPI documentation for the version your are using. Your JS_CompileScript() call just try to retrieve a global object which has not been created and probably this causes the exception.
how about using function "SaveCompiled" ? it will save object/op-code (compiled javascript) to file
I need to implement a Linux Kernel Driver, that (in the first step) only forwards all file operations to another file (in later steps, this should be managed and manipulated, but I don't want to discuss this here).
My idea is the following, but when reading, the kernel crashes:
static struct {
struct file *file;
char *file_name;
int open;
} file_out_data = {
.file_name = "/any_file",
.open = 0,
};
int memory_open(struct inode *inode, struct file *filp) {
PRINTK("<1>open memory module\n");
/*
* We don't want to talk to two processes at the same time
*/
if (file_out_data.open)
return -EBUSY;
/*
* Initialize the message
*/
Message_Ptr = Message;
try_module_get(THIS_MODULE);
file_out_data.file = filp_open(file_out_data.file_name, filp->f_flags, filp->f_mode); //here should be another return handling in case of fail
file_out_data.open++;
/* Success */
return 0;
}
int memory_release(struct inode *inode, struct file *filp) {
PRINTK("<1>release memory module\n");
/*
* We're now ready for our next caller
*/
file_out_data.open--;
filp_close(file_out_data.file,NULL);
module_put(THIS_MODULE);
/* Success */
return 0;
}
ssize_t memory_read(struct file *filp, char *buf,
size_t count, loff_t *f_pos) {
PRINTK("<1>read memory module \n");
ret=file_out_data.file->f_op->read(file_out_data.file,buf,count,f_pos); //corrected one, false one is to find in the history
return ret;
}
So, can anyone please tell me why?
Don't use set_fs() as there is no reason to do it.
Use file->f_fop->read() instead of the vfs_read. Take a look at the file and file_operations structures.
Why are you incrementing file_out_data.open twice and decrementing it once? This could cause you to use file_out_data.file after it has been closed.
You want to write memory in your file ou read?
Because you are reading and not writing...
possible i'm wrong
I'm working on getting audio into the iPhone in a form where I can pass it to a (C++) analysis algorithm. There are, of course, many options: the AudioQueue tutorial at trailsinthesand gets things started.
The audio callback, though, gives an AudioQueueRef, and I'm finding Apple's documentation thin on this side of things. Built-in methods to write to a file, but nothing where you actually peer inside the packets to see the data.
I need data. I don't want to write anything to a file, which is what all the tutorials — and even Apple's convenience I/O objects — seem to be aiming at. Apple's AVAudioRecorder (infuriatingly) will give you levels and write the data, but not actually give you access to it. Unless I'm missing something...
How to do this? In the code below there is inBuffer->mAudioData which is tantalizingly close but I can find no information about what format this 'data' is in or how to access it.
AudioQueue Callback:
void AudioInputCallback(void *inUserData,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer,
const AudioTimeStamp *inStartTime,
UInt32 inNumberPacketDescriptions,
const AudioStreamPacketDescription *inPacketDescs)
{
static int count = 0;
RecordState* recordState = (RecordState*)inUserData;
AudioQueueEnqueueBuffer(recordState->queue, inBuffer, 0, NULL);
++count;
printf("Got buffer %d\n", count);
}
And the code to write the audio to a file:
OSStatus status = AudioFileWritePackets(recordState->audioFile,
false,
inBuffer->mAudioDataByteSize,
inPacketDescs,
recordState->currentPacket,
&inNumberPacketDescriptions,
inBuffer->mAudioData); // THIS! This is what I want to look inside of.
if(status == 0)
{
recordState->currentPacket += inNumberPacketDescriptions;
}
// so you don't have to hunt them all down when you decide to switch to float:
#define AUDIO_DATA_TYPE_FORMAT SInt16
// the actual sample-grabbing code:
int sampleCount = inBuffer->mAudioDataBytesCapacity / sizeof(AUDIO_DATA_TYPE_FORMAT);
AUDIO_DATA_TYPE_FORMAT *samples = (AUDIO_DATA_TYPE_FORMAT*)inBuffer->mAudioData;
Then you have your (in this case SInt16) array samples which you can access from samples[0] to samples[sampleCount-1].
The above solution did not work for me, I was getting the wrong sample data itself.(an endian issue) If incase someone is getting wrong sample data in future, I hope this helps you :
-(void)feedSamplesToEngine:(UInt32)audioDataBytesCapacity audioData:(void *)audioData {
int sampleCount = audioDataBytesCapacity / sizeof(SAMPLE_TYPE);
SAMPLE_TYPE *samples = (SAMPLE_TYPE*)audioData;
//SAMPLE_TYPE *sample_le = (SAMPLE_TYPE *)malloc(sizeof(SAMPLE_TYPE)*sampleCount );//for swapping endians
std::string shorts;
double power = pow(2,10);
for(int i = 0; i < sampleCount; i++)
{
SAMPLE_TYPE sample_le = (0xff00 & (samples[i] << 8)) | (0x00ff & (samples[i] >> 8)) ; //Endianess issue
char dataInterim[30];
sprintf(dataInterim,"%f ", sample_le/power); // normalize it.
shorts.append(dataInterim);
}