I have been trying to build a device adapter for a open-source software called Micro-manager to control a microscope and there are some problems that I am facing, there are these two files (one header and the other CPP) that are already present in the open source package of Micro-Manager.
//MoudluleInterface.h
#ifndef _MODULE_INTERFACE_H_
#define _MODULE_INTERFACE_H_
#ifdef WIN32
#ifdef MODULE_EXPORTS
#define MODULE_API __declspec(dllexport)
#else
#define MODULE_API __declspec(dllimport)
#endif
#else
#define MODULE_API
#endif
#define MM_MODULE_ERR_OK 1000
#define MM_MODULE_ERR_WRONG_INDEX 1001
#define MM_MODULE_ERR_BUFFER_TOO_SMALL 1002
///////////////////////////////////////////////////////////////////////////////
// header version
// NOTE: If any of the exported module API calls changes, the interface version
// must be incremented
// new version 5 supports device discoverability
#define MODULE_INTERFACE_VERSION 7
#ifdef WIN32
const char* const LIB_NAME_PREFIX = "mmgr_dal_";
#else
const char* const LIB_NAME_PREFIX = "libmmgr_dal_";
#endif
#include "MMDevice.h"
///////////////////////////////////////////////////////////////////////////////
// Exported module interface
///////////////////////////////////////////////////////////////////////////////
extern "C" {
MODULE_API MM::Device* CreateDevice(const char* name);
MODULE_API void DeleteDevice(MM::Device* pDevice);
MODULE_API long GetModuleVersion();
MODULE_API long GetDeviceInterfaceVersion();
MODULE_API unsigned GetNumberOfDevices();
MODULE_API bool GetDeviceName(unsigned deviceIndex, char* name, unsigned bufferLength);
MODULE_API bool GetDeviceDescription(const char* deviceName, char* name, unsigned bufferLength);
And here is a part of the CPP file which defines these functions
//ModuleInterface.cpp
#define _CRT_SECURE_NO_DEPRECATE
#include "ModuleInterface.h"
#include <vector>
#include <string>
typedef std::pair<std::string, std::string> DeviceInfo;
std::vector<DeviceInfo> g_availableDevices;
int FindDeviceIndex(const char* deviceName)
{
for (unsigned i=0; i<g_availableDevices.size(); i++)
if (g_availableDevices[i].first.compare(deviceName) == 0)
return i;
return -1;
}
MODULE_API long GetModuleVersion()
{
return MODULE_INTERFACE_VERSION;
}
MODULE_API long GetDeviceInterfaceVersion()
{
return DEVICE_INTERFACE_VERSION;
}
MODULE_API unsigned GetNumberOfDevices()
{
return (unsigned) g_availableDevices.size();
}
MODULE_API bool GetDeviceName(unsigned deviceIndex, char* name, unsigned bufLen)
{
if (deviceIndex >= g_availableDevices.size())
return false;
Now the problem is it gives me an error C2491 (definition of dllimport function not allowed)
I did research about this and it usually is when a function is defined when it is supposed to be declared, I have already defined the function in ModuleInterface.h and then used it in ModuleInterface.cpp but it still shows the same error.
Can there be some other possibility for this error to occur? Or is there something wrong with the code?
You're not supposed to repeat your MODULE_API declaration in the definition, having it as part of the declaration is good enough. Remove the use of MODULE_API from the .cpp file and the code should compile.
Related
This is my main code:
#include "startup.h"
int main(int argc, char *argv[]) {
printBanner(); <-- Undefined symbol for x86_64
readParameters(argc, argv); <-- Undefined symbol for x86_64
}
Contents for startup.h:
#ifndef STARTUP_H
#define STARTUP_H
#if defined __cplusplus
extern "C" {
#endif
void printBanner(void);
void readParameters(const int argc, char *argv[]);
#if defined _cplusplus
}
#endif
#endif
The implementations of the above mentioned functions is in startup.c:
#include "startup.h"
void readParameters(const int argc, char *argv[]) {
// code
}
void printBanner() {
// code
}
All the 3 files are within the same folder. Is there anything that is missing in terms of settings? I'm using xcode for this project.
I'm calling a function that is defined in .h from my main and the header is included in the .c file where functions are implemented. Can't see anything wrong with it.
Here is my code:
helloworld.go:
package main
import "C"
import "unsafe"
//export HelloWorld
func HelloWorld() *C.char {
cs := C.CString("Hello World!")
C.free(unsafe.Pointer(cs))
return cs
}
func main() {}
One of the errors I got:
src/helloworld.go:9:2: could not determine kind of name for C.free
Based on this article: https://blog.golang.org/c-go-cgo
I also found out that I need to add #include <stdlib.h> at top of my C file.
helloworld.h:
#include <stdlib.h>
/* Created by "go tool cgo" - DO NOT EDIT. */
/* package command-line-arguments */
/* Start of preamble from import "C" comments. */
/* End of preamble from import "C" comments. */
/* Start of boilerplate cgo prologue. */
#line 1 "cgo-gcc-export-header-prolog"
#ifndef GO_CGO_PROLOGUE_H
#define GO_CGO_PROLOGUE_H
typedef signed char GoInt8;
typedef unsigned char GoUint8;
typedef short GoInt16;
typedef unsigned short GoUint16;
typedef int GoInt32;
typedef unsigned int GoUint32;
typedef long long GoInt64;
typedef unsigned long long GoUint64;
typedef GoInt64 GoInt;
typedef GoUint64 GoUint;
typedef __SIZE_TYPE__ GoUintptr;
typedef float GoFloat32;
typedef double GoFloat64;
typedef float _Complex GoComplex64;
typedef double _Complex GoComplex128;
/*
static assertion to make sure the file is being used on architecture
at least with matching size of GoInt.
*/
typedef char _check_for_64_bit_pointer_matching_GoInt[sizeof(void*)==64/8 ? 1:-1];
typedef struct { const char *p; GoInt n; } GoString;
typedef void *GoMap;
typedef void *GoChan;
typedef struct { void *t; void *v; } GoInterface;
typedef struct { void *data; GoInt len; GoInt cap; } GoSlice;
#endif
/* End of boilerplate cgo prologue. */
#ifdef __cplusplus
extern "C" {
#endif
extern char* HelloWorld();
#ifdef __cplusplus
}
#endif
I tried it to no success.
I need to free the memory.
How do I do this? Because in there example it prints out the string. I want to return it. Without C.free. I am able to do it. I am just worried of causing a memory leak or some other issue.
Command cgo
// Go string to C string
// The C string is allocated in the C heap using malloc.
// It is the caller's responsibility to arrange for it to be
// freed, such as by calling C.free (be sure to include stdlib.h
// if C.free is needed).
func C.CString(string) *C.char
If the import of "C" is immediately preceded by a comment, that
comment, called the preamble, is used as a header when compiling the C
parts of the package.
For example,
package main
/*
#include <stdlib.h>
*/
import "C"
import "unsafe"
//export HelloWorld
func HelloWorld() *C.char {
cs := C.CString("Hello World!")
C.free(unsafe.Pointer(cs))
return cs
}
func main() {}
I was testing the network hook code given in https://en.wikipedia.org/wiki/Hooking . My kernel version is 3.11.
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <net/ip.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/in.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
/* Port we want to drop packets on */
static const uint16_t port = 25;
/* This is the hook function itself */
static unsigned int hook_func(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *)){
struct iphdr *iph = ip_hdr(*pskb);
struct tcphdr *tcph, tcpbuf;
if (iph->protocol != IPPROTO_TCP)
return NF_ACCEPT;
tcph = skb_header_pointer(*pskb, ip_hdrlen(*pskb), sizeof(*tcph), &tcpbuf);
if (tcph == NULL)
return NF_ACCEPT;
return (tcph->dest == port) ? NF_DROP : NF_ACCEPT;
}
/* Used to register our hook function */
static struct nf_hook_ops nfho = {
.hook = hook_func,
.hooknum = NF_INET_PRE_ROUTING,
.pf = NFPROTO_IPV4,
.priority = NF_IP_PRI_FIRST,
};
static __init int my_init(void)
{
return nf_register_hook(&nfho);
}
static __exit void my_exit(void)
{
nf_unregister_hook(&nfho);
}
module_init(my_init);
module_exit(my_exit);
But after loading , the above code is freezing the system. Can anybody please tell, what is the reason for that?. I think that the above code might have already tested in some lower versions of kernel. So I doubt, some kernel parameters or features have been changed.
I'm trying to implement a custom event in my wxWidgets application but I can't write the event table macros in a proper way.
the files that I use to implement the event is like the following:
the .h file
#ifndef __APP_FRAME_H__
#define __APP_FRAME_H__
#include "wx/wxprec.h"
#ifndef WX_PRECOMP
#include "wx/wx.h"
#endif
#include <wx/evtloop.h>
#include "wxApp.h"
#include "sampleCefApp.h"
class appFrame: public wxFrame
{
public:
appFrame(const wxString &title, const wxPoint &pos, const wxSize &size);
private:
int OnExit();
void OnCefStartEvent(wxCommandEvent &e);
DECLARE_EVENT_TABLE()
};
#endif
the .cpp file
// File : appFrame.cpp
#include "appFrame.h"
wxDEFINE_EVENT(CEF_START_EVT, wxCommandEvent)
void appFrame::OnCefStartEvent(wxCommandEvent &e)
{
CefRunMessageLoop();
}
int appFrame::OnExit(){
CefShutdown();
Destroy();
return 0;
}
appFrame::appFrame(const wxString &title, const wxPoint &pos, const wxSize &size)
: wxFrame(NULL, wxID_ANY, title, pos, size)
{
}
wxBEGIN_EVENT_TABLE(appFrame, wxFrame)
EVT_COMMAND(wxID_ANY, CEF_START_EVT, appFrame::OnCefStartEvent)
wxEND_EVENT_TABLE()
And when I build my make file I get the following errors:
../src/appFrame.cpp:4:15: error: expected constructor, destructor, or type conversion before ‘(’ token
../src/appFrame.cpp:24:2: error: expected constructor, destructor, or type conversion before ‘wxEventTableEntry
I think the problem is related to mis-placing event table macros.
I want to know what is the problem exactly and how to fix it ?
You need a semicolon after wxDEFINE_EVENT() macro (as for almost all macros with wx prefix, they consistently require a semicolon, unlike the legacy macros without the prefix).
As usual, see the sample for the example of use of this macro.
I want to create a file under a /proc/driver directory. I would like to use a macro like proc_root_driver (or something else provided) rather than use "driver/MODULE_NAME" explicitly. I use create_proc_entry :
struct proc_dir_entry *simpleproc_fops_entry;
simpleproc_fops_entry = create_proc_entry(MODULE_NAME, 0400, NULL /* proc_root_dir */);
After googling, I found suggestion to use proc_root_driver, but when I use it, I get the error
proc_root_driver undeclared in this function
And also, proc_root_driver is not available in linux/proc_fs.h.
I have tried to declare structure like this:
struct proc_dir_entry proc_root;
struct proc_dir_entry *proc_root_driver = &proc_root;
The compilation errors gone, but the file didn't appear under /proc/driver or /proc. How can I make create an entry in /proc?
Looking at proc_fs.h, proc_root_driver is defined as :
extern struct proc_dir_entry *proc_root_driver;
so long as CONFIG_PROC_FS is enabled. If you have CONFIG_PROC_FS selected when you configure your kernel, you should be able to use it as you suggested yourself i.e. :
#include <linux/proc_fs.h>
struct proc_dir_entry * procfile
procfile = create_proc_entry("myprocfile", 0400, proc_root_driver);
If this does not work, check that you have CONFIG_PROC_FS set. To make sure, you can compile your source file with the -E option and check that the create_proc_entry call includes a non NULL parameter as the last parameter. If it is NULL, or the call is not there at all, then CONFIG_PROC_FS is not enabled.
/* proc entries for ayyaz */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#ifdef CONFIG_PROC_FS
/*====================================================================*/
/* Support for /proc/ayyaz */
static struct proc_dir_entry *proc_ayyaz;
DEFINE_MUTEX(ayyaz_table_mutex);
/*====================================================================*/
/* Init code */
static int ayyaz_read_proc (char *page, char **start, off_t off, int count,
int *eof, void *data_unused)
{
int len, l, i;
off_t begin = 0;
mutex_lock(&ayyaz_table_mutex);
len = sprintf(page, "hello ayyaz here\n");
mutex_unlock(&ayyaz_table_mutex);
if (off >= len+begin)
return 0;
*start = page + (off-begin);
return ((count < begin+len-off) ? count : begin+len-off);
}
static int __init init_ayyaz(void)
{
if ((proc_ayyaz = create_proc_entry( "ayyaz_maps", 0, NULL )))
proc_ayyaz->read_proc = ayyaz_read_proc;
return 0;
}
static void __exit cleanup_ayyaz(void)
{
if (proc_ayyaz)
remove_proc_entry( "ayyaz", NULL);
}
module_init(init_ayyaz);
module_exit(cleanup_ayyaz);
#else
#error "Please add CONFIG_PROC_FS=y in your .config "
#endif /* CONFIG_PROC_FS */
MODULE_LICENSE("proprietary");
MODULE_AUTHOR("Md.Ayyaz A Mulla <md.ayyaz#gmail.com>");
MODULE_DESCRIPTION("proc files for ayyaz");
Compile this driver. If it compiles sucessfully, then you will see /proc/ayyaz.
#define PROC_ENTRY_NAME "driver/XX"
static struct proc_dir_entry *proc_XX;
static int XX_read_proc (char *page, char **start, off_t off, int count,
int *eof, void *data_unused)
{
return 0;
}
static int XX_write_proc (struct file *file, const char __user *buffer,
unsigned long count, void *data)
{
return 0;
}
static int __init XX_add_driver(void)
{
if ((proc_flash = XX_entry(PROC_ENTRY_NAME, 0, NULL))) {
proc_XX->read_proc = XX_read_proc;
proc_XX->write_proc = XX_write_proc;
}
...
}
static void __exit XX_remove(void)
{
if (proc_flash)
remove_proc_entry(PROC_ENTRY_NAME, NULL);
return;
}
Then you can find the /proc/driver/XX entry.