Assignment 1 - Hello World ! - Simple thread Creation

Requirement

1. Print the output of uname -a in the first line of the syslog file.
2. Each syslog statement should have [COURSE:X][ASSIGNMENT:Y] where X corresponds to Course Number i.e. 1 in this case and Y corresponds to Assignment No.

Example - Aug 30 22:10:54 raspberrypi pthread:
[COURSE:1][ASSIGNMENT:1] YOUR DATA HERE

This is what your output should look like. Also, please note that the uname output is generated from the program and not copied from the terminal and pasted into the program as a string.
All syslog prints in this assignment and upcoming assignments shall follow this format. (The time, name of the machine, and the program name are generated by syslog, you do not need to add them in manually).
3. This assignment expects two log statements as below from the main and the thread in execution

Hello World from Main!
Hello World from Thread!

Solution

1. how to log uname -a info into syslog?

a. use system function

• using man system to get how to use this interface. please note that we need to #include <stdlib.h>
• system("logger [COURSE:1][ASSIGNMENT:1]: `uname -a`");`

b. print uname struct elements (this makes things a little bit complicated)

• uname struct

struct utsname {
    
    char sysname[];    /* Operating system name (e.g., "Linux") */
    char nodename[];   /* Name within "some implementation-defined network" */
    char release[];    /* Operating system release (e.g., "2.6.28") */
    char version[];    /* Operating system version */
    char machine[];    /* Hardware identifier */
#ifdef _GNU_SOURCE
    char domainname[]; /* NIS or YP domain name */
#endif
     };

reference: https://www.man7.org/linux/man-pages/man2/uname.2.html

• corresponding code

struct utsname *buf = malloc(sizeof(struct utsname));
    uname(buf);
    syslog(LOG_INFO, "%s %s %s %s %s GNU/Linux\n", buf->sysname, buf->nodename, buf->release, buf->version, buf->machine);

it has disadvantages since there is no operation system info in the struct.

2. how to use syslog

• openlog() and closelog()

3. the whole code

#include <pthread.h>
#include <sys/utsname.h>
#include <stdlib.h>
#include <stdio.h>
#include <sched.h>
#include <syslog.h>

#define NUM_THREADS 1
#define COURSE_INFO "[COURSE:1][ASSIGNMENT:1]"

typedef struct
{
    
    int threadIdx;
} threadParams_t;

// POSIX thread declarations and scheduling attributes
//
pthread_t threads[NUM_THREADS];
threadParams_t threadParams[NUM_THREADS];

void *counterThread(void *threadp)
{
    
    openlog(COURSE_INFO, LOG_CONS, LOG_USER);
	syslog(LOG_INFO, "Hello World from Thread!");
	closelog();
    return 0;
}

int main (int argc, char *argv[])
{
    
    int i;
    struct utsname *buf = malloc(sizeof(struct utsname));
    uname(buf);
  
    openlog(COURSE_INFO, LOG_CONS, LOG_USER);
    syslog(LOG_INFO, "%s %s %s %s %s GNU/Linux\n", buf->sysname, buf->nodename, buf->release, buf->version, buf->machine);
// I know we could use system call cmd to print uname, but here I keep my original code which print the uname struct elements one by one 
#if (0)
	system("logger [COURSE:1][ASSIGNMENT:1]: `uname -a`");
#endif
    
	syslog(LOG_INFO, "Hello World from Main!");
   
    for(i=0; i < NUM_THREADS; i++)
    {
    
        threadParams[i].threadIdx=i;

        pthread_create(&threads[i],   // pointer to thread descriptor
                       (void *)0,     // use default attributes
                       counterThread, // thread function entry point
                       (void *)&(threadParams[i]) // parameters to pass in
                      );
    }

    for(i=0;i<NUM_THREADS;i++)
        pthread_join(threads[i], NULL);

    closelog();
}