a simple notification service demo

notifyd.c

// a simple notification daemon that sits on a fifo and calls a popup commend when new lines appear
// to use:
// cc -o notifyd notifyd.c
// ./notifyd
// <in a different terminal>
// echo 'a wild notification appears!' > /etc/notidsock
// <bask in the glory of a simple notification service that's less than 100 lines of code>

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#define MAX_MSG 48

#define FIFOPATH "/tmp/notidsock"

int main(int argc, char **argv) {
    char buf[MAX_MSG];

    mkfifo(FIFOPATH, 0600);

    int fifofd = open(FIFOPATH, O_RDONLY);

    while(1) {
        size_t bytes = read(fifofd, buf, MAX_MSG);
        if(bytes > 0) {
            buf[bytes] = '\0'; // set the end of the str (in case it's not filled with zeros)

            char *start, *end; // start of line, end of line (so we can do a notification for each line)
            start = buf;

            while(1) { // popup for each line in the fifo
                end = strchr(start, '\n'); // find next newline

                if(!end || !*start) // check if we're at the end of the queue
                    break; // if so, break

                end[0] = '\0'; // set the end of the string to the next newline

                // NOTE: this is insecure and can be pwned.
                // use fork + execve for something real.
                char cmd[MAX_MSG + 24]; // 24 more bytes for the command
                sprintf(cmd, "popup '%s'", start);
                system(cmd);

                start = end + 1; // step over \0 to next line
            }
        }
    }
    close(fifofd); // heh - maybe cleanup? probably should through this in a signal trap instead
}

popup.sh

#!/bin/sh
#
# z3bra - (c) wtfpl 2014
# Create a small popup with the given text
#
# depends: lemonbar, wattr and common sense

# bar options
#font="-f terminus"
bg="#000000"
fg="#FFFFFF"
hl="#FFFFFF"
strlen=30

default_geometry() {
    # get screen size
    x=$(wattr w `lsw -r`)
    y=$(wattr h `lsw -r`)

    width=250
    height=20

    offy=${2:-$OFF}
    offx=$(( x - width ))

    echo "${width}x${height}+${offx}+${offy}"
}

while getopts "c:d:g:h" opt; do
    case $opt in
        d) SLEEP=$OPTARG   ;;
        g) GEOM=$OPTARG    ;;
        h) usage; exit 0   ;;
        c) COMMAND=$OPTARG ;;
    esac
done

GEOM=${GEOM:-$(default_geometry)}
SLEEP=${SLEEP:-5}

if [ -t 0 ]; then
    CONTENT=$@
else
    CONTENT=$(cat)
fi

str="$CONTENT"

if [ ! -z "$COMMAND" ]; then
    str="%{A:$COMMAND:}$str%{A}"
fi

(echo "%{c}" $str; sleep $SLEEP) | lemonbar -d -g $GEOM -B $bg -F $fg $font | sh