Processing Input file in c - c

Question

So Im just wondering about a few tips on doing a scheduler simulation.
So far, I just want to input a file at the command line i.e. /.scheduler in.file
The in.file holds the following information:
./Job1.txt
./Job2.txt
./Job3.txt
./Job4.txt
Each Job .txt file has random lines of code. With only the first line being significant. The first line is starting 'tick' time.
Job A:
10
1fi
3sdkfj
4ksdkk
5kdkfk
6kdkjf
7dkjkfd
9dkkf
10dku
At the moment I just want to take the in.file and order the 'Job' files in order of their arrival tick time i.e. first line.
My code thus far:
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "projscheduler.h"
/* I/O Files */
//static char *inputFile;
char * in;
static FILE *input;
/*Scheduled jobs indexed by PID*/
struct job list[20];
/* the next job to schedule */
//static struct job *job_next = NULL;
/* Time */
time clock;
/*Initialises job list*/
static void initialise_list(void) {
for(int i = 0; i < sizeof(list)/sizeof(list[0]); i++) {
list[i].parameters.pid = -1;
}
}
/** Read and parse input from input file */
static void parse_input(void)
{
char buffer[BUFSIZ];
//int jobs;
initialise_list();
while( fgets(buffer, sizeof(buffer), input) )
{
pid j_pid;
sscanf(buffer, "./%d.txt", &j_pid);
}
}
int main(int argc, char **argv)
{
if ( (input = fopen(in, "r")) == NULL ) {
fprintf(stderr, "cannot open %s\n", argv[1]);
}
parse_input();
return EXIT_SUCCESS;
}
HEADER FILE:
/**
* Simulation of a process scheduler
*/
//#ifndef SCHEDULER_H_
#define SCHEDULER_H_
#include <stddef.h>
/* types */
/** units of time */
typedef long time;
/** process identifier */
typedef int pid;
/** Information about a job of interest to the task scheduler */
struct job_data {
/* pid of this process */
pid pid;
/* time process starts */
time start;
/* time needed to finish */
time finish;
/* time spent processing so far */
time scheduled;
/* size of the process */
size_t size;
};
struct job {
/* Various parameters used by the scheduler */
char job_name[BUFSIZ];
struct job_data parameters;
/* next job to be scheduled */
//struct job *next;
};

Answer 1

I am unsure what problems you are having exactly but I can see the following errors in the code:
In the initialise_list() function the for loop will be iterating too many times and going beyond the bounds the of array:
for(int i = 0; i < sizeof(list); i++) {
as sizeof(list) will return the number of bytes occupied by the array which is 20 * sizeof(struct job). Change to:
for(int i = 0; i < sizeof(list) / sizeof(list[0]); i++) {
this is a missing left parenthesis from fopen() attempt (meaning the posted code does not compile):
if( (input = fopen(inputfile, "r") == NULL )
should be:
if( (input = fopen(inputfile, "r")) == NULL )
proj is an initialised char* and this will mostly likely cause a segmentation fault:
char *proj;
sscanf(buffer, "./%s.txt", proj);

Answer 2

#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include "projscheduler.h"
/* I/O Files */
//static char *inputFile;
char * in;
static FILE *input;
static FILE *cur;
/*Scheduled jobs indexed by PID*/
struct job list[20];
/* the next job to schedule */
//static struct job *job_next = NULL;
/* Time */
time clock;
/*Initialises job list*/
static void initialise_list(void) {
for(int i = 0; i < sizeof(list)/sizeof(list[0]); i++) {
list[i].parameters.pid = -1;
}
}
/*Order Jobs*/
/*=static void order_jobs(void)
{
for(int i=0; i < sizeof(list)/sizeof(list[0]); i++)
{
}
*/
/** Read and parse input from input file */
static void parse_input(void)
{
char buffer[BUFSIZ];
char lines[BUFSIZ];
int jobs = 0;
struct job *current;
initialise_list();
while( fgets(buffer, sizeof(buffer), input) )
{
time start;
char buf[20];
sscanf(buffer,"./%s/", buf);
cur = fopen(buf, "r" );
fgets(lines, sizeof(lines), cur);
sscanf(lines,"%ld", &start);
current = &list[jobs];
current->job_id = buf;
current->parameters.start = start;
jobs++;
}
for (int i = 0; i < jobs; i++)
{
printf("%s starts at %ld\n", list[i].job_id, list[i].parameters.start);
}
}
int main(int argc, char **argv)
{
in = argv[1];
if ( (input = fopen(in, "r")) == NULL ) {
fprintf(stderr, "cannot open %s\n", argv[1]);
}
parse_input();
return EXIT_SUCCESS;
}
Above, I successfully read the in.file and extracted the first line from each address representing a text file.
Code above associated with following header:
/**
* Simulation of a process scheduler
*/
//#ifndef SCHEDULER_H_
#define SCHEDULER_H_
#include <stddef.h>
/* types */
/** units of time */
typedef long time;
/** process identifier */
typedef int pid;
/** Information about a job of interest to the task scheduler */
struct job_data {
/* pid of this process */
pid pid;
/* time process starts */
time start;
/* time needed to finish */
time finish;
/* time spent processing so far */
time scheduled;
/* size of the process */
size_t size;
};
struct job {
/* Various parameters used by the scheduler */
char * job_id;
struct job_data parameters;
/* next job to be scheduled */
//struct job *next;
};