better code

bmon.c

@@ -1,8 +1,10 @@
 #define _POSIX_C_SOURCE 200809L
-#include <stdio.h>
-#include <stdlib.h>
+
 #include <sys/types.h>
 #include <sys/stat.h>
+
+#include <stdio.h>
+#include <stdlib.h>
 #include <fcntl.h>
 #include <dirent.h>
 #include <errno.h>
@@ -10,8 +12,12 @@
 #include <unistd.h>
 #include <signal.h>
 #include <time.h>
+#include <limits.h>
 
-const char *bat_base_path = "/sys/class/power_supply/";
+		// TODO: handle multiple batteries
+const char *CAPACITY_PATH = "/sys/class/power_supply/BAT1/capacity";
+const char *STATUS_PATH = "/sys/class/power_supply/BAT1/status";
+const char *POWER_PATH = "/sys/class/power_supply/BAT1/power_now";
 int dead = 0;
 
 void usage (void)
@@ -26,17 +32,26 @@ void usage (void)
 
 void int_handler (int signum)
 {
+	(void)signum;
         dead = 1;
 }
 
+int read_int (FILE *fp)
+{
+	int x;
+	freopen(NULL, "r", fp);
+	fscanf(fp, "%d", &x); 
+	return x;
+}
+
 int main (int argc, char *argv[])
 {
 	/* Handle SIGINT */
-        dead = 0;
-        struct sigaction action;
-        memset(&action, 0, sizeof(action));
-        action.sa_handler = int_handler;
-        sigaction(SIGINT, &action, NULL);
+	dead = 0;
+	struct sigaction action;
+	memset(&action, 0, sizeof(action));
+	action.sa_handler = int_handler;
+	sigaction(SIGINT, &action, NULL);
 
 	int wflag = 0;
 	int wait_time = 10;
@@ -73,100 +88,87 @@ int main (int argc, char *argv[])
 
 	}
 
-	DIR *bdir = NULL;
-	if (!(bdir = opendir(bat_base_path))) {
-		perror("error opening base directory");
+	FILE *capacity_fp = NULL, *status_fp = NULL, *power_fp = NULL;
+	capacity_fp = fopen(CAPACITY_PATH, "r");
+	if (capacity_fp == NULL) {
+		fprintf(stderr, "Error opening %s: %s\n", CAPACITY_PATH, strerror(errno));
 		exit(1);
 	}
 
-	struct dirent *ent = NULL;
-	FILE **fp_list = NULL;
-	int fp_num = 0;
-	for (;;) {
-		errno = 0;
-		if (!(ent = readdir(bdir))) {
-			if (errno) {
-				perror("error reading base directory");
-				exit(1);
-			}
-			else break;
+	if (wflag) {
+		power_fp = fopen(POWER_PATH, "r");
+		if (power_fp == NULL) {
+			fprintf(stderr, "Error opening %s: %s\n", POWER_PATH, strerror(errno));
+			exit(1);
+		}
+		status_fp = fopen(STATUS_PATH, "r");
+		if (status_fp == NULL) {
+			fprintf(stderr, "Error opening %s: %s\n", STATUS_PATH, strerror(errno));
+			exit(1);
 		}
-
-		if (!strstr(ent->d_name, "BAT1"))
-			continue;
-
-		FILE *fp;
-		char path[sizeof(bat_base_path) + 256 + 64];
-		strcpy(path, bat_base_path);
-		strcat(path, ent->d_name);
-		if (wflag) {
-			char *tmp = malloc(1024);
-			strcpy(tmp, path);
-			strcat(tmp, "/status");
-			FILE *tmf = fopen(tmp, "r");
-			fgets(tmp, 1024, tmf);
-			if (!strstr(tmp, "Dis")) {
-				fprintf(stderr, "currently not discharging, cannot read power draw\n");
-				dead = 1;
-			}
-			fclose(tmf);
-			free(tmp);
-			strcat(path, "/power_now");
-		} else strcat(path, "/capacity");
-
-		if ((fp = fopen(path, "r"))) {
-			FILE **tmp = NULL;
-			tmp = realloc(fp_list, sizeof(FILE *) * (fp_num + 1));
-			if (!tmp)
-				perror("failed realloc");
-			fp_list = tmp;
-			fp_list[fp_num++] = fp;
-		} else printf("err: %s\n", strerror(errno));
-
-	}
-	closedir(bdir);
-	if (!fp_num) {
-		printf("no files were opened\n");
-		dead = 1;
 	}
 
-	FILE * ofile_ptr = stdout;
+
+	FILE *output_fp = stdout;
 	if (fflag) {
-		if (!(ofile_ptr = fopen(ofile_path, "w"))) {
-			char *tmp = malloc(1024);
-			snprintf(tmp, 1024, "could not open %s", ofile_path);
-			perror(tmp);
-			free(tmp);
+		if ((output_fp = fopen(ofile_path, "w")) == NULL) {
+			fprintf(stderr, "Error opening %s: %s\n", ofile_path, strerror(errno));
 			exit(1);
 		}
 	}
 
 	long int elapsed_time = 0;
-	long val;
-	char buf[64];
-	for (; !dead ; sleep(wait_time)) {
-		for (int i = 0; i < fp_num; i++) {
-			if (!freopen(NULL, "r", fp_list[i])) {
-				perror("error reading the file");
-				dead = 1;
-			}
-			if (!fgets(buf, 64, fp_list[i]))
-				dead = 1;
-			val = atol(buf);
-			fprintf(ofile_ptr, "%ld\t", wflag ? (long)(val / 1E3) : val);
+	fprintf(output_fp, "TIME\t");
+	fprintf(output_fp, "CAP\t");
+	if (wflag) fprintf(output_fp, "WATTS");
+	fprintf(output_fp, "\n");
+	while (!dead) {
+		int capacity = read_int(capacity_fp);
+		float power = 0;
+		if (capacity < 0) {
+			fprintf(stderr, "Error reading capacity: %s\n", strerror(errno));
+			break;
 		}
-		fprintf(ofile_ptr, "%ld\n", uflag ? time(NULL) : elapsed_time);
-		if (fflush(ofile_ptr)) {
-			perror("error writing to file");
-			dead = 1;
+		if (wflag) {
+			power = read_int(power_fp);
+			if (power < 0) {
+				fprintf(stderr, "Error reading power: %s\n", strerror(errno));
+				break;
+			}
+			static char b[128] = {0};
+			freopen(NULL, "r", status_fp);
+			if (fgets(b, sizeof(b), status_fp) == NULL) {
+				fprintf(stderr, "Error reading status: %s\n", strerror(errno));
+			}
+			if (strncmp(b, "Discharging\n", sizeof(b)) == 0) {
+				power *= -1;
+			}
+
+			// power is in microwatts
+			power /= 1e6;
 		}
+
+		fprintf(output_fp, "%ld\t", uflag ? time(NULL) : elapsed_time);
+		fprintf(output_fp, "%d\t", capacity);
+		if (wflag) fprintf(output_fp, "%.2f", power);
+		fprintf(output_fp, "\n");
+
+		sleep(wait_time);
 		elapsed_time += wait_time;
 	}
 
-	if (fflag)
-		fclose(ofile_ptr);
-	for (int i = 0; i < fp_num; i++)
-		fclose(fp_list[i]);
-	free(fp_list);
+	if (fflag) {
+		fclose(output_fp);
+	}
+	if (capacity_fp) {
+		fclose(capacity_fp);
+	}
+	if (status_fp) {
+		fclose(status_fp);
+	}
+	if (power_fp) {
+		fclose(power_fp);
+	}
+	
 	return 0;
 }