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/* sh - the standard command language interpreter
* Copyright (C) 2022 Ferass EL HAFIDI
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/* Define feature test macro. It doesn't compile with gcc without that for
* some reason.
*/
#define _POSIX_C_SOURCE 1
/* POSIX Header files */
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <stdint.h>
#include <sys/wait.h>
#include <spawn.h>
#include <libgen.h>
#include <signal.h>
/* Our own header files */
#include "parser.h"
#include "version.h"
#ifndef COMPILETIME
#define COMPILETIME
#endif
#warning "This shell implementation is really buggy and incomplete. \
Please don't use this as a /bin/sh replacement."
void commandLoop();
int getopt(int argc, char *const argv[], const char *optstring);
char *pathSearch(const char *path, const char *name);
void printUsage();
int main(int argc, char *const argv[]) {
int argument, i = 1;
char param[256];
struct sigaction signal_action;
signal_action.sa_handler = SIG_IGN;
sigemptyset(&signal_action.sa_mask);
for (; i <= 256; i++) param[i] = 0;
while ((argument = getopt(argc, argv, "c")) != -1) {
if (argument == '?') {
printUsage();
return 1;
}
param[(uint8_t)argument] = argument;
}
sigaction(SIGINT, &signal_action, NULL);
if (errno) return errno;
commandLoop(1);
return 0;
}
/* USAGE
* -----
* commandLoop()
*
* DESCRIPTION
* -----------
* This function is the actual command prompt.
*/
void commandLoop(int isinteractive) {
struct sigaction signal_action;
char *prompt = getenv("PS1");
char *path = getenv("PATH");
char *command[4096];
pid_t isparent;
char name[4096];
int return_code;
int command_argc;
if (prompt == NULL) prompt = "$ ";
for (;;) {
for (int i = 0; i <= 4096; i++) {
name[i] = 0; /* (Re)Initialise name and command,
* very important. */
command[i] = 0;
}
setvbuf(stdout, NULL, _IONBF, 0);
if (isinteractive) { printf(prompt); }
read(STDIN_FILENO, name, 4096);
if (!strcmp(name, "\n")) {
continue;
}
name[strlen(name) - 1] = 0;
command_argc = splitCommand(name, command); /* See parser.c */
if (parseCommand(command_argc, command) == 127 /* See parser.c */ ) {
isparent = fork();
wait(NULL);
if (!isparent) {
/* Do not ignore SIGINT when in a child process. */
signal_action.sa_handler = SIG_DFL;
sigemptyset(&signal_action.sa_mask);
sigaction(SIGINT, &signal_action, NULL);
/* Some sh implementations manually search for the command in PATH.
* This is not needed here because execvp is going to search for
* that command in PATH anyway.
*/
return_code = execvp(command[0], command);
/* If the child process is still alive, we know execvp(3) failed. */
printf("sh: %s: %s\n", command[0], strerror(errno));
exit(0);
}
}
}
}
void printUsage() {
printf("Ferass' Base System. (%s)\n\n"
"Usage: sh [-c command_string]\n\n"
"The standard command language interpreter.\n\n"
"\t-c command_string\tExecute command_string and exit.\n", COMPILETIME);
}
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