fread(): Unable to read file for /proc/$pid/status

Question

I am trying to read the file /proc/$pid/status in a function. I am able to open the file using fopen and when I read it using fread() I get Segmentation fault (core dumped) .

Function:

void getContextSwitches() {
    FILE* fp;

    int pid = getpid();
    char spid[10];
    snprintf(spid, 10, "%d", pid);

    char buffer[3000];
    size_t bytesRead;

    printf("\nPid of the process is: %s", spid);

    char path[50];
    path[0] = '\0';
    strcat(path, "/proc/");
    strcat(path, spid);
    strcat(path, "/status");

    printf("\nPath: %s\n", path);

    fp = getFile(fp, path);

    if(NULL == fp) {
        printf("File status is not read\n");
        exit(1);
    }
    printf("File pointer not null");
    printf("size of buffer: %ld", sizeof(buffer));
    bytesRead = fread(buffer, 1, sizeof(buffer), fp);
    printf("\nIt's not coming here");
    fclose(fp);
}

And here is the output which I obtain:

Pid of the process is: 85244
Path: /proc/85244/status

File pointer not null
Size of buffer: 3000
Segmentation fault (core dumped)

The buffer size has been allocated properly and also the fp is not null. I have similar functionalities in other areas of my code and they work fine. I have checked the signature of fread() and that looks fine too.

Can someone help me understand the issue behind this?

Answer 1

The issue is in your getFile() function. The rest of the code is OK.

I suspect you're returning an invalid FILE* from getFile() .