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Shared memory data using a header file

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0

I'm doing an assignment for class in which we need to create some shared memory that can be accessed from 2 different programs. There is a header file called shm.h that has the kinds of data we need to be able to share. So far my code looks like this.

shm.h

#ifndef SHM_H
#define SHM_H
//<Define an enum called StatusEnus with the enumerations "INVALID", "VALID" 
and "CONSUMED">
#define enum StatusEnusINVALID, VALID, CONSUMED StatusEnus

//<Define a typedef structure with the enum above and an "int" variable 
//called "data">

#define struct ShmDataStatusEnus status; int data;ShmData;
#define SIZE 8

#endif

server_template

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "shm.h"

int main(int argc, char* argv[])
 O_RDWR, 0666);
 if (file == -1) retVal =-1;

 /*<Use the "ftruncate" API to set the size to the size of your 
 structure shm.h>*/
 retVal = ftruncate(file,SIZE);

 //<Use the "mmap" API to memory map the file descriptor>
 void* data = mmap(0, SIZE,PROT_WRITE 

So my goal is to be able to access the fields like ShmData->StatusEnus from the server but also then be able to access these files from a separate program. However as it stands I keep getting to errors either related to the deceleration of ShmData. How do I make sure that the shared memory I am creating contains that enum and int field from my structure?

c linux structure header-files shared-memory

share|improve this question

edited Mar 9 at 4:35

Dan

asked Mar 9 at 4:27

DanDan

225

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  #define struct ShmDataStatusEnus status; int data;ShmData; is very confusing and invalid. It defines struct to be a macro. And it will substitute the word struct for ShmDataStatusEnus status; int data;ShmData; in the code anywhere you write it. Remove the #define.
  
  – Kamil Cuk
  Mar 9 at 6:46
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @KamilCuk Hi I made this change and now im recieving an error that reads "expected specifier-qualifier-list before 'StatusEnus' Can you also provide any insight as to how this code is added to the shared memory as i will need to be able to access ShmData's fields between two programs.
  
  – Dan
  Mar 9 at 18:34
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  After some tinkering I was able to figure it out. Thank you!
  
  – Dan
  Mar 9 at 18:48
  

  
  
  
  

add a comment | 

0

I'm doing an assignment for class in which we need to create some shared memory that can be accessed from 2 different programs. There is a header file called shm.h that has the kinds of data we need to be able to share. So far my code looks like this.

shm.h

#ifndef SHM_H
#define SHM_H
//<Define an enum called StatusEnus with the enumerations "INVALID", "VALID" 
and "CONSUMED">
#define enum StatusEnusINVALID, VALID, CONSUMED StatusEnus

//<Define a typedef structure with the enum above and an "int" variable 
//called "data">

#define struct ShmDataStatusEnus status; int data;ShmData;
#define SIZE 8

#endif

server_template

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "shm.h"

int main(int argc, char* argv[])
 O_RDWR, 0666);
 if (file == -1) retVal =-1;

 /*<Use the "ftruncate" API to set the size to the size of your 
 structure shm.h>*/
 retVal = ftruncate(file,SIZE);

 //<Use the "mmap" API to memory map the file descriptor>
 void* data = mmap(0, SIZE,PROT_WRITE 

So my goal is to be able to access the fields like ShmData->StatusEnus from the server but also then be able to access these files from a separate program. However as it stands I keep getting to errors either related to the deceleration of ShmData. How do I make sure that the shared memory I am creating contains that enum and int field from my structure?

c linux structure header-files shared-memory

share|improve this question

edited Mar 9 at 4:35

Dan

asked Mar 9 at 4:27

DanDan

225

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  #define struct ShmDataStatusEnus status; int data;ShmData; is very confusing and invalid. It defines struct to be a macro. And it will substitute the word struct for ShmDataStatusEnus status; int data;ShmData; in the code anywhere you write it. Remove the #define.
  
  – Kamil Cuk
  Mar 9 at 6:46
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @KamilCuk Hi I made this change and now im recieving an error that reads "expected specifier-qualifier-list before 'StatusEnus' Can you also provide any insight as to how this code is added to the shared memory as i will need to be able to access ShmData's fields between two programs.
  
  – Dan
  Mar 9 at 18:34
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  After some tinkering I was able to figure it out. Thank you!
  
  – Dan
  Mar 9 at 18:48
  

  
  
  
  

add a comment | 

I'm doing an assignment for class in which we need to create some shared memory that can be accessed from 2 different programs. There is a header file called shm.h that has the kinds of data we need to be able to share. So far my code looks like this.

shm.h

#ifndef SHM_H
#define SHM_H
//<Define an enum called StatusEnus with the enumerations "INVALID", "VALID" 
and "CONSUMED">
#define enum StatusEnusINVALID, VALID, CONSUMED StatusEnus

//<Define a typedef structure with the enum above and an "int" variable 
//called "data">

#define struct ShmDataStatusEnus status; int data;ShmData;
#define SIZE 8

#endif

server_template

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "shm.h"

int main(int argc, char* argv[])
 O_RDWR, 0666);
 if (file == -1) retVal =-1;

 /*<Use the "ftruncate" API to set the size to the size of your 
 structure shm.h>*/
 retVal = ftruncate(file,SIZE);

 //<Use the "mmap" API to memory map the file descriptor>
 void* data = mmap(0, SIZE,PROT_WRITE 

So my goal is to be able to access the fields like ShmData->StatusEnus from the server but also then be able to access these files from a separate program. However as it stands I keep getting to errors either related to the deceleration of ShmData. How do I make sure that the shared memory I am creating contains that enum and int field from my structure?

c linux structure header-files shared-memory

share|improve this question

edited Mar 9 at 4:35

Dan

asked Mar 9 at 4:27

DanDan

225

#ifndef SHM_H
#define SHM_H
//<Define an enum called StatusEnus with the enumerations "INVALID", "VALID" 
and "CONSUMED">
#define enum StatusEnusINVALID, VALID, CONSUMED StatusEnus

//<Define a typedef structure with the enum above and an "int" variable 
//called "data">

#define struct ShmDataStatusEnus status; int data;ShmData;
#define SIZE 8

#endif

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "shm.h"

int main(int argc, char* argv[])
 O_RDWR, 0666);
 if (file == -1) retVal =-1;

 /*<Use the "ftruncate" API to set the size to the size of your 
 structure shm.h>*/
 retVal = ftruncate(file,SIZE);

 //<Use the "mmap" API to memory map the file descriptor>
 void* data = mmap(0, SIZE,PROT_WRITE 

share|improve this question

edited Mar 9 at 4:35

Dan

asked Mar 9 at 4:27

DanDan

225

share|improve this question

edited Mar 9 at 4:35

Dan

asked Mar 9 at 4:27

DanDan

225

asked Mar 9 at 4:27

DanDan

225

asked Mar 9 at 4:27

DanDan

225