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// clang -no-pie -static chat.c -lpthread -ochat -Wl,-z,now -Wl,-z,relro
// strip -g chat
#include <poll.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define MAXCHANNELS 5
static int cpipe[2];
static pthread_t channels[MAXCHANNELS];
static int active[MAXCHANNELS] = {0};
static int pipes[MAXCHANNELS][2];
static bool quit = false;
#define QUIT_CHANNEL(x) do { \
active[x] = 2; \
return NULL; \
} while (0);
static char command[32] = {0};
static int wait_loop(bool is_command_channel, int channel) {
struct pollfd pfd;
if (is_command_channel) {
pfd.fd = cpipe[0];
} else {
pfd.fd = pipes[channel][0];
}
pfd.events = POLLIN;
if (is_command_channel && channel != -1) {
write(pipes[channel][1], "c", 1);
} else if (!is_command_channel) {
write(cpipe[1], "c", 1);
}
while (1) {
int ret;
if ((ret = poll(&pfd, 1, 1000)) == -1) {
// error
return 1;
} else if (ret == 0) {
// timeout
if (quit == true) {
return 1;
}
continue;
}
char c;
if (is_command_channel) {
read(cpipe[0], &c, 1);
} else {
read(pipes[channel][0], &c, 1);
}
break;
}
return 0;
}
static void chat_channel_help() {
printf("Chat Commands:\n"
"\t/e\t- Echo - The first line following this command specifies the number of characters to echo.\n"
"\t/pc\t- Pause Chat Channel - Return to Command Channel. The Chat Channel stays open.\n"
"\t/qc\t- Quit Chat Channel - Return to Command Channel. The Chat Channel is terminated.\n"
"\t/h\t- Help - Print this help message.\n"
"That's all for now :/\n");
}
static void *chat_channel_handler(void * arg) {
int channel = (int) arg;
if (pipe(pipes[channel]) == -1) {
printf("Chat Channel Creation Failed: Pipes\n");
QUIT_CHANNEL(channel);
}
printf("Chat Channel %d:\n", channel+1);
while (1) {
printf("> ");
if(!fgets(command, 32, stdin)) {
QUIT_CHANNEL(channel);
}
if (strlen(command) == 3 && command[0] == '/' && command[1] == 'e') {
if(!fgets(command, 32, stdin)) {
printf("Chat Command Error: Reading Echo Size\n");
}
int length = atoi(command) + 1;
char *line = (char *)alloca(length);
if (!fgets(line, length, stdin)) {
QUIT_CHANNEL(channel);
}
write(1, line, strlen(line));
write(1, "\n", 1);
} else if (strlen(command) == 4 && command[0] == '/' && command[1] == 'p' && command[2] == 'c') {
if (wait_loop(false, channel)) {
QUIT_CHANNEL(channel);
}
printf("Chat Channel %d:\n", channel+1);
} else if (strlen(command) == 4 && command[0] == '/' && command[1] == 'q' && command[2] == 'c') {
write(cpipe[1], "c", 1);
QUIT_CHANNEL(channel);
} else if (strlen(command) == 3 && command[0] == '/' && command[1] == 'h') {
chat_channel_help();
}
}
}
static void command_channel_help() {
printf("Command Commands:\n"
"\t/nc\t- New Chat Channel - Create and join a new Chat Channel.\n"
"\t/jc x\t- Join Chat Channel - Join the Chat Channel number x.\n"
"\t/lc\t- List Chat Channels - Lists the Chat Channels.\n"
"\t/q\t- Quit - Quit this awesome chat program.\n"
"\t/h\t- Help - Print this help message.\n");
}
int main() {
if (pipe(cpipe) == -1) {
return 1;
}
printf("Command Channel:\n");
while (1) {
printf("> ");
if(!fgets(command, 32, stdin)) {
return 1;
}
if (strlen(command) == 4 && command[0] == '/' && command[1] == 'n' && command[2] == 'c') {
int channel = -1;
for (int i = 0; i < MAXCHANNELS; i++) {
if (active[i] == 0) {
channel = i;
break;
}
}
if (channel == -1) {
printf("Chat Channel Creation Failed: No channel slots left\n");
} else {
pthread_attr_t attr;
pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, 0x3C000);
pthread_create(&channels[channel], &attr, chat_channel_handler, (void *)channel);
active[channel] = 1;
wait_loop(true, -1);
printf("Command Channel:\n");
}
} else if (command[0] == '/' && command[1] == 'j' && command[2] == 'c' && command[3] == ' ') {
printf("Joining Chat Channel.\n");
int channel = atoi(command + 4) - 1;
if (0 <= channel && channel < MAXCHANNELS && active[channel] == 1) {
wait_loop(true, channel);
printf("Command Channel:\n");
} else {
printf("Invalid Chat Channel number.\n");
}
} else if (strlen(command) == 4 && command[0] == '/' && command[1] == 'l' && command[2] == 'c') {
printf("Chat Channels:\n");
for (int i = 0; i < MAXCHANNELS; i++) {
if (active[i] == 1) {
printf("\tChat Channel %d\n", i+1);
}
}
} else if (strlen(command) == 3 && command[0] == '/' && command[1] == 'q') {
printf("Quitting.\n");
quit = true;
break;
} else if (strlen(command) == 3 && command[0] == '/' && command[1] == 'h') {
command_channel_help();
} else {
printf("Invalid command.\n");
}
for (int i = 0; i < MAXCHANNELS; i++) {
if (active[i] == 2) {
pthread_join(channels[i], NULL);
close(pipes[i][0]);
close(pipes[i][1]);
active[i] = 0;
}
}
}
for (int i = 0; i < MAXCHANNELS; i++) {
if (active[i] == 1 || active[i] == 2) {
pthread_join(channels[i], NULL);
}
}
close(cpipe[0]);
close(cpipe[1]);
return 0;
}
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