battery.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include "common.h"

#define INTERVAL      3
#define FORMAT        "%s %i"
#define TOKSEP        "=\n"
#define BAT_PATH      "/sys/class/power_supply/BAT%i/uevent"
#define BAT_INDEX     0
#define KEY_PREFIX    "POWER_SUPPLY_"
#define STATUS_KEY    KEY_PREFIX "STATUS"
#define CAPACITY_KEY  KEY_PREFIX "CAPACITY"

int put_infos(char *path, char *format)
{
    FILE *bf = fopen(path, "r");
    if (bf == NULL) {
        fprintf(stderr, "Can't open '%s'.\n", path);
        return EXIT_FAILURE;
    }

    char line[MAXLEN] = {0};
    char status[MAXLEN] = {0};
    int capacity = -1;
    bool found_status = false, found_capacity = false;
    while (fgets(line, sizeof(line), bf) != NULL) {
        char *key = strtok(line, TOKSEP);
        if (key != NULL) { 
            if (!found_status && strcmp(key, STATUS_KEY) == 0) {
                strncpy(status, strtok(NULL, TOKSEP), sizeof(status)); 
                found_status = true;
            } else if (capacity == -1 && strcmp(key, CAPACITY_KEY) == 0) {
                capacity = atoi(strtok(NULL, TOKSEP));
                found_capacity = true;
            }
        }
    }
    fclose(bf);
    if (!found_capacity || !found_status) {
        fprintf(stderr, "The battery informations are missing.\n");
        return EXIT_FAILURE;
    } else {
        if (strstr(format, "%s") == NULL)
            printf(format, capacity);
        else if (strstr(format, "%i") == NULL)
            printf(format, status);
        else
            printf(format, status, capacity);
        printf("\n");
        fflush(stdout);
    }
    return EXIT_SUCCESS;
}

int main(int argc, char *argv[])
{
    char *path = BAT_PATH;
    char *format = FORMAT;
    int index = BAT_INDEX;
    int interval = INTERVAL;
    bool snoop = false;

    char opt;
    while ((opt = getopt(argc, argv, "hsf:i:p:n:")) != -1) {
        switch (opt) {
            case 'h':
                printf("battery [-h|-s|-f FORMAT|-i INTERVAL|-p PATH|-n INDEX]\n");
                exit(EXIT_SUCCESS);
                break;
            case 's':
                snoop = true;
                break;
            case 'f':
                format = optarg;
                break;
            case 'p':
                path = optarg;
                break;
            case 'i':
                interval = atoi(optarg);
                break;
            case 'n':
                index = atoi(optarg);
                break;
        }
    }

    char real_path[MAXLEN] = {0};
    snprintf(real_path, sizeof(real_path), path, index);

    int exit_code;

    if (snoop)
        while ((exit_code = put_infos(real_path, format)) != EXIT_FAILURE)
            sleep(interval);
    else
        exit_code = put_infos(real_path, format);

    return exit_code;
}