Can't add an array with data to shared memory - c

Question

I am trying to write a file with data into my shared memory segment. However everything I have tried seems just to give the error Segmentation fault. I have been searching the internet for help for more then one day.
int main(int argc, char *argv[]).
{
int sm;
char *data;
int pid=atoi(argv[1]);
int key=atoi(argv[2]);
char (*d)[1025];
data=(char*) malloc(1025);
//put the data in the shared memory segment
FILE *file=fopen(argv[3], "r"); //r for read
if (file==0)
{printf("Could not open file");}
else
{
while(fgets(data, 1025, file)!=NULL)
{
fputs(data, file);
// puts(d);
}
fclose(file);
}
//access shared memory
//S_IWUSR gives owner the write permession
sm = shmget(key, 1024, S_IWUSR);
//create a pointer to the shared memory segment
d = shmat(sm, (void *)0, 0); //shared memory id, shmaddr, shmflg
//for (int j=0; j<100; j++)
strcpy(d[0], data);
shmdt(d); //detach the shared memory segment
//remove the shared memory segment
shmctl(sm, IPC_RMID, NULL);
}
Any help would be greatly appreciated
Thanks in advance
EDIT: added malloc
EDIT2: maybe I should rephrase my question, my problem is to get the data into my shared memory

Answer 1

+1 about rjayavrp answer
And I can add that data is not allocated... This is just a pointer and not a array of chars..
Moreover what are you trying to do with
char (*d)[1025];
A quick and dirty example :
#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define SIZE_SHARED_MEMORY 1024
int main(int argc, char *argv[])
{
int sm = -1;
char *d = NULL;
FILE *file = NULL;
key_t key = 0;
int ret = 0;
if (argc != 4)
{
return 1;
}
key = atoi(argv[2]);
//access shared memory
sm = shmget(key, SIZE_SHARED_MEMORY, IPC_CREAT | 0600);
if (sm == -1)
{
perror("shmget : Failed");
return 2;
}
//create a pointer to the shared memory segment
d = shmat(sm, (char *)0, 0);
if (d == (void *)-1)
{
perror("shmat : Failed");
return 3;
}
// Open the file
file = fopen(argv[3], "r");
if (file == NULL)
{
perror("fopen : Failed");
ret = 4;
}
else
{
if(fgets(d, SIZE_SHARED_MEMORY, file) == NULL)
{
perror("fgets : Failed");
ret = 5;
}
fclose(file);
}
shmdt(d); //detach the shared memory segment
// remove the shared memory segment ???
// Don't understand why you are doing this
shmctl(sm, IPC_RMID, NULL);
return ret;
}

Answer 2

File is opened in read mode only.
change it to rw+ which will open a file in read/write mode. If the file is not available, it will be created.
fputs(data, file); here file is opened in read-only mode but write is happening.
But Im not sure, why you trying to write the read data to same file. You should consider your design first. 2. char (*d)[1025]; is a pointer to an char array of size 1025. You are using it in strcpy(). 3. memory should be allocated for data either statically or dynamically.