I am trying to keep track of the last 10 commands in my shell, and have the ctrl + c signal handler output an array of them.
Obviously this array only contains 10 elements and always outputs 10; this is just temporary until I get the functionality correct.
At the moment when I have more than one command in the shell history, it outputs the array multiple times in a weird order with some things output more than others. I am guessing this is caused by child processes also calling the handler as well, but I don't know what to do at this point. .
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#define MAX_LINE 80 /* 80 chars per line, per command, should be enough. */
#define BUFFER_SIZE 10
char buffer[BUFFER_SIZE][MAX_LINE];
//char buffer[BUFFER_SIZE];
int pos = 0;
int handleEvent = 0;
void handle_SIGINT()
{
int i = 0;
while (i < BUFFER_SIZE)
{
//printf("%d\n", i);
write(STDOUT_FILENO, buffer[i], strlen(buffer[i]));
printf("\n");
i++;
}
}
void setup(char inputBuffer[], char *args[],int *background)
{
int length, /* # of characters in the command line */
i, /* loop index for accessing inputBuffer array */
start, /* index where beginning of next command parameter is */
ct; /* index of where to place the next parameter into args[] */
ct = 0;
/* read what the user enters on the command line */
length = read(STDIN_FILENO, inputBuffer, MAX_LINE);
start = -1;
if (length == 0)
exit(0); /* ^d was entered, end of user command stream */
if ((length < 0) && (errno !=EINTR)){
perror("error reading the command");
exit(-1); /* terminate with error code of -1 */
}
/* examine every character in the inputBuffer */
for (i = 0; i < length; i++) {
switch (inputBuffer[i]){
case ' ':
case '\t' : /* argument separators */
if(start != -1){
args[ct] = &inputBuffer[start]; /* set up pointer */
ct++;
}
inputBuffer[i] = '\0'; /* add a null char; make a C string */
start = -1;
break;
case '\n': /* should be the final char examined */
if (start != -1){
args[ct] = &inputBuffer[start];
ct++;
}
inputBuffer[i] = '\0';
args[ct] = NULL; /* no more arguments to this command */
break;
case '&':
*background = 1;
inputBuffer[i] = '\0';
break;
default : /* some other character */
if (start == -1)
start = i;
}
}
args[ct] = NULL; /* just in case the input line was > 80 */
}
int main(void)
{
char inputBuffer[MAX_LINE]; /* buffer to hold the command entered */
int background; /* equals 1 if a command is followed by '&' */
char *args[MAX_LINE/2+1];/* command line (of 80) has max of 40 arguments */
/* set up the signal handler */
struct sigaction handler;
handler.sa_handler = handle_SIGINT;
//handler.sa_flags = 0;
//sigemptyset(&handler.sa_mask);
sigaction(SIGINT, &handler, NULL);
while (1){ /* Program terminates normally inside setup */
background = 0;
printf("COMMAND->");
fflush(0);
setup(inputBuffer, args, &background); /* get next command */
strcpy(buffer[pos], inputBuffer);
pos++;
int pid;
int returnValue;
pid = fork(); /* for a child process */
if (pid < 0) { /* check if error occurred with child process */
fprintf(stderr, "Fork Failed");
return 1;
}
else if (pid == 0) { /* child process */
execvp(args[0], args);
}
//else {
if (background == 0){ /* check if the parent should wait */
//wait(&returnValue);
waitpid(pid, NULL, 0);
}
//}
/* the steps are:
(1) fork a child process using fork()
(2) the child process will invoke execvp()
(3) if background == 0, the parent will wait,
otherwise returns to the setup() function. */
}
}