dwmblocks.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <signal.h>
#include <errno.h>
#include <X11/Xlib.h>
#include <sys/signalfd.h>
#include <poll.h>
#define LENGTH(X) (sizeof(X) / sizeof(X[0]))
#define CMDLENGTH 500

typedef struct
{
    char *icon;
    char *command;
    unsigned int interval;
    unsigned int signal;
} Block;

void sighandler();
void buttonhandler(int ssi_int);
void replace(char *str, char old, char new);
void remove_all(char *str, char to_remove);
void getcmds(int time);
void getsigcmds(int signal);
void setupsignals();
int getstatus(char *str, char *last);
void setroot();
void statusloop();
void termhandler(int signum);

#include "config.h"

static Display *dpy;
static int screen;
static Window root;
static char statusbar[LENGTH(blocks)][CMDLENGTH] = {0};
static char statusstr[2][256];
static int statusContinue = 1;
static int signalFD;
static int timerInterval = -1;
static void (*writestatus)() = setroot;

void replace(char *str, char old, char new)
{
    for (char *c = str; *c; c++)
        if (*c == old)
            *c = new;
}

// the previous function looked nice but unfortunately it didnt work if to_remove was in any position other than the last character
// theres probably still a better way of doing this
void remove_all(char *str, char to_remove)
{
    char *read = str;
    char *write = str;
    while (*read)
    {
        if (*read != to_remove)
        {
            *write++ = *read;
        }
        ++read;
    }
    *write = '\0';
}

int gcd(int a, int b)
{
    int temp;
    while (b > 0)
    {
        temp = a % b;

        a = b;
        b = temp;
    }
    return a;
}

// opens process *cmd and stores output in *output
void getcmd(const Block *block, char *output)
{
    if (block->signal)
    {
        output[0] = block->signal;
        output++;
    }
    char *cmd = block->command;
    FILE *cmdf = popen(cmd, "r");
    if (!cmdf)
    {
        // printf("failed to run: %s, %d\n", block->command, errno);
        return;
    }
    char tmpstr[CMDLENGTH] = "";
    // TODO decide whether its better to use the last value till next time or just keep trying while the error was the interrupt
    // this keeps trying to read if it got nothing and the error was an interrupt
    //  could also just read to a separate buffer and not move the data over if interrupted
    //  this way will take longer trying to complete 1 thing but will get it done
    //  the other way will move on to keep going with everything and the part that failed to read will be wrong till its updated again
    // either way you have to save the data to a temp buffer because when it fails it writes nothing and then then it gets displayed before this finishes
    char *s;
    int e;
    do
    {
        errno = 0;
        s = fgets(tmpstr, CMDLENGTH - (strlen(delim) + 1), cmdf);
        e = errno;
    } while (!s && e == EINTR);
    pclose(cmdf);
    int i = strlen(block->icon);
    strcpy(output, block->icon);
    strcpy(output + i, tmpstr);
    remove_all(output, '\n');
    i = strlen(output);
    if ((i > 0 && block != &blocks[LENGTH(blocks) - 1]))
    {
        strcat(output, delim);
    }
    i += strlen(delim);
    output[i++] = '\0';
}

void getcmds(int time)
{
    const Block *current;
    for (int i = 0; i < LENGTH(blocks); i++)
    {
        current = blocks + i;
        if ((current->interval != 0 && time % current->interval == 0) || time == -1)
        {
            getcmd(current, statusbar[i]);
        }
    }
}

void getsigcmds(int signal)
{
    const Block *current;
    for (int i = 0; i < LENGTH(blocks); i++)
    {
        current = blocks + i;
        if (current->signal == signal)
        {
            getcmd(current, statusbar[i]);
        }
    }
}

void setupsignals()
{
    sigset_t signals;
    sigemptyset(&signals);
    sigaddset(&signals, SIGALRM); // Timer events
    sigaddset(&signals, SIGUSR1); // Button events
    // All signals assigned to blocks
    for (size_t i = 0; i < LENGTH(blocks); i++)
        if (blocks[i].signal > 0)
            sigaddset(&signals, SIGRTMIN + blocks[i].signal);
    // Create signal file descriptor for pooling
    signalFD = signalfd(-1, &signals, 0);
    // Block all real-time signals
    for (int i = SIGRTMIN; i <= SIGRTMAX; i++)
        sigaddset(&signals, i);
    sigprocmask(SIG_BLOCK, &signals, NULL);
    // Do not transform children into zombies
    struct sigaction sigchld_action = {
        .sa_handler = SIG_DFL,
        .sa_flags = SA_NOCLDWAIT};
    sigaction(SIGCHLD, &sigchld_action, NULL);
}

int getstatus(char *str, char *last)
{
    strcpy(last, str);
    str[0] = '\0';
    for (int i = 0; i < LENGTH(blocks); i++)
    {
        strcat(str, statusbar[i]);
        if (i == LENGTH(blocks) - 1)
            strcat(str, " ");
    }
    str[strlen(str) - 1] = '\0';
    return strcmp(str, last); // 0 if they are the same
}

void setroot()
{
    if (!getstatus(statusstr[0], statusstr[1])) // Only set root if text has changed.
        return;
    Display *d = XOpenDisplay(NULL);
    if (d)
    {
        dpy = d;
    }
    screen = DefaultScreen(dpy);
    root = RootWindow(dpy, screen);
    XStoreName(dpy, root, statusstr[0]);
    XCloseDisplay(dpy);
}

void pstdout()
{
    if (!getstatus(statusstr[0], statusstr[1])) // Only write out if text has changed.
        return;
    printf("%s\n", statusstr[0]);
    fflush(stdout);
}

void statusloop()
{
    setupsignals();
    // first figure out the default wait interval by finding the
    // greatest common denominator of the intervals
    for (int i = 0; i < LENGTH(blocks); i++)
    {
        if (blocks[i].interval)
        {
            timerInterval = gcd(blocks[i].interval, timerInterval);
        }
    }
    getcmds(-1);    // Fist time run all commands
    raise(SIGALRM); // Schedule first timer event
    int ret;
    struct pollfd pfd[] = {{.fd = signalFD, .events = POLLIN}};
    while (statusContinue)
    {
        // Wait for new signal
        ret = poll(pfd, sizeof(pfd) / sizeof(pfd[0]), -1);
        if (ret < 0 || !(pfd[0].revents & POLLIN))
            break;
        sighandler(); // Handle signal
    }
}

void sighandler()
{
    static int time = 0;
    struct signalfd_siginfo si;
    int ret = read(signalFD, &si, sizeof(si));
    if (ret < 0)
        return;
    int signal = si.ssi_signo;
    switch (signal)
    {
    case SIGALRM:
        // Execute blocks and schedule the next timer event
        getcmds(time);
        alarm(timerInterval);
        time += timerInterval;
        break;
    case SIGUSR1:
        // Handle buttons
        buttonhandler(si.ssi_int);
        return;
    default:
        // Execute the block that has the given signal
        getsigcmds(signal - SIGRTMIN);
        break;
    }
    writestatus();
}

void buttonhandler(int ssi_int)
{
    char button[2] = {'0' + ssi_int & 0xff, '\0'};
    pid_t process_id = getpid();
    int sig = ssi_int >> 8;
    if (fork() == 0)
    {
        const Block *current;
        for (int i = 0; i < LENGTH(blocks); i++)
        {
            current = blocks + i;
            if (current->signal == sig)
                break;
        }
        char shcmd[1024];
        sprintf(shcmd, "%s && kill -%d %d", current->command, current->signal + 34, process_id);
        char *command[] = {"/bin/sh", "-c", shcmd, NULL};
        setenv("BLOCK_BUTTON", button, 1);
        setsid();
        execvp(command[0], command);
        exit(EXIT_SUCCESS);
    }
}

void termhandler(int signum)
{
    statusContinue = 0;
}

int main(int argc, char **argv)
{
    for (int i = 0; i < argc; i++)
    {
        if (!strcmp("-d", argv[i]))
            delim = argv[++i];
        else if (!strcmp("-p", argv[i]))
            writestatus = pstdout;
    }
    signal(SIGTERM, termhandler);
    signal(SIGINT, termhandler);
    statusloop();
    close(signalFD);
}