projet-systeme-exploitation.../Q5.c

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2021-04-24 15:32:54 +00:00
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <setjmp.h>
#include "readcmd.h"
extern int errno;
struct cmdline *cmd;
int pid_fils;
int prompting = 0;
jmp_buf goto_prompt;
char initcd[256], currentcd[256];
void handler_sigchld(int sig_num)
{
if (prompting)
{
printf("\n");
siglongjmp(goto_prompt, sig_num);
}
}
int main(int argc, char *argv[])
{
getcwd(initcd, sizeof(initcd));
// gestion des signaux
struct sigaction action;
sigemptyset(&action.sa_mask);
action.sa_flags = SA_SIGINFO | SA_RESTART;
action.sa_handler = handler_sigchld;
sigaction(SIGCHLD, &action, NULL);
// loop principal
while (1)
{
sigsetjmp(goto_prompt, 1);
prompting = 1;
getcwd(currentcd, sizeof(currentcd));
printf("%s >>> ", currentcd);
cmd = readcmd();
prompting = 0;
if (cmd == NULL)
{ // EOF
break;
}
else if (cmd->seq[0] == NULL)
{ // empty
continue;
}
else if (!strcmp(cmd->seq[0][0], "exit"))
{ // "exit"
break;
}
else if (!strcmp(cmd->seq[0][0], "cd"))
{ // "cd"
int ret = 0;
if (cmd->seq[0][1] == NULL)
{ // no path
ret = chdir(initcd);
}
else
{ // with path
ret = chdir(cmd->seq[0][1]);
}
if (ret)
{ // wrong path
fprintf(stderr, "ERROR: cd failed, (%d) %s\n", errno, strerror(errno));
}
continue;
}
pid_fils = fork();
if (pid_fils == -1)
{ // fork fail ?
fprintf(stderr, "ERROR: forking failed, (%d) %s\n", errno, strerror(errno));
exit(errno);
}
if (pid_fils == 0)
{ // instructions du fils
execvp(cmd->seq[0][0], cmd->seq[0]);
exit(errno); // si execlp échoue on exit avec une erreur
}
else
{ // instructions du père
if (!cmd->backgrounded)
{ // background
int wait_code;
pid_t id = waitpid(pid_fils, &wait_code, 0); // on attend la fin de l'exec du fils
if (id == -1)
{ // wait fail ?
fprintf(stderr, "ERROR: waiting for %d failed, (%d) %s\n", wait_code, errno, strerror(errno));
exit(errno);
}
if (wait_code)
{ // execvp fail ?
fprintf(stderr, "ERROR: %d's execution failed, (%d) %s\n", pid_fils, wait_code, strerror(wait_code));
}
}
}
}
return EXIT_SUCCESS;
}