Initial commit. Works.

Makefile copied from pokemath project

Reads two files from sysfs: charge_now and charge_full under BAT0,
then divides them using float math.

Output is guaranteed to be stable across major versions.

Supported options:
	-v gives verbose output for debugging purposes
	-h shows help text and exits
	-t gives terse output

Known issues:
	The path to charge_now and charge_full is hard-coded. This utility will not work with batteries that do not happen to be named BAT0.
	The float value given by this program is not actually a percentage.

TODO:
	Move help text #defines into a header file
	Add support to traverse /sys/class/power_supply and locate
	batteries
	Possibly add support to store default battery paths in /etc/battery_percent.conf

DISCLAIMER:
	This program is already too overcomplicated and shows no signs of slowing down.

Makefile

@@ -0,0 +1,58 @@
+#NEWPROJECT requires refactor.sh main.c
+# Taken from https://stackoverflow.com/questions/30573481/how-to-write-a-makefile-with-separate-source-and-header-directories
+
+SRCDIR    := sources
+MAINDIR   := $(SRCDIR)/main
+INCDIR    := include
+OBJDIR    := objects
+MAINOD    := $(OBJDIR)/main
+BINDIR    := build
+
+REFACTOR  := refactor.h
+
+HEADERS   := $(wildcard $(INCDIR)/*.h)
+
+MAINS     := $(wildcard $(MAINDIR)/*.c)
+MAINOBJS  := $(patsubst $(MAINDIR)/%.c, $(MAINOD)/%.o, $(MAINS))
+
+TARGETS   := $(patsubst $(MAINDIR)/%.c, $(BINDIR)/%, $(MAINS))
+
+SOURCES   := $(wildcard $(SRCDIR)/*.c)
+
+OBJECTS   := $(patsubst $(SRCDIR)/%.c, $(OBJDIR)/%.o, $(SOURCES))
+
+CPPFLAGS  := -Iinclude -MMD -MP
+CFLAGS    := -Wall -Werror -Wpedantic
+LDFLAGS   := #-Lmath or whatever
+LDLIBS    := #-lm or whatever
+
+.PHONY: all clean
+
+all: $(TARGETS)
+	@echo $(TARGETS)
+
+refactor:
+	./refactor.sh
+
+$(TARGETS): $(OBJECTS) $(MAINOBJS) | $(BINDIR) $(OBJDIR) $(MAINOD)
+	$(CC) $(LDFLAGS) $(OBJECTS) $(patsubst $(BINDIR)/%, $(MAINOD)/%.o, $@)       $(LDLIBS) -o $@
+
+$(BINDIR) $(OBJDIR) $(MAINOD):
+	mkdir --parents $@
+
+$(OBJDIR)/%.o: $(SRCDIR)/%.c $(HEADERS) | $(OBJDIR)
+	$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@
+
+$(MAINOD)/%.o: $(MAINDIR)/%.c $(HEADERS) | $(MAINOD)
+	$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@
+
+clean:
+	$(RM) -rv $(BINDIR) $(OBJDIR)
+
+# Honestly still not sure what this directive does.
+# It's an include directive, which processes all .d files that correspond to members of $(OBJ),
+# with the hyphen in front meaning that it suppresses/ignores errors (from nonexistent .d files)
+# Seems to be included under the stipulation that GNU make will auto-generate .d files based on
+# a given file's #include directives?
+# https://stackoverflow.com/questions/19114410/what-is-d-file-after-building-with-make
+-include $(OBJ:.o=.d)

sources/main/battery.c

@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+
+#define CHARGE_NOW_PATH "/sys/class/power_supply/BAT0/charge_now"
+#define CHARGE_FULL_PATH "/sys/class/power_supply/BAT0/charge_full"
+#define VERSION "v0.0"
+#define TITLE "Battery Percentage, by Catluck Kettlemerry"
+#define PROGNAME "battery_percentage"
+#define USAGE0 "Usage: "
+#define USAGE1 "[option]"
+#define OPTIONS0 "Options:"
+#define OPTIONS1 "\t-v run verbosely"
+#define OPTIONS2 "\t-h show help and exit"
+#define OPTIONS3 "\t-t provide terse output"
+
+int run_verbose = 0;
+int run_terse = 0;
+
+void print_help(void){
+	printf("%s %s\n", TITLE, VERSION);
+	printf("%s %s %s\n", USAGE0, PROGNAME, USAGE1);
+	printf("%s\n%s\n%s\n%s\n", OPTIONS0, OPTIONS1, OPTIONS2, OPTIONS3);
+}
+
+int main(int argc, char *const argv[]){
+
+	int opt;
+	while((opt = getopt(argc, argv, "vht")) != -1) {
+		switch(opt){
+		case 'v':
+			run_verbose = 1;
+			break;
+		case 'h':
+			print_help();
+			return 0;
+		case 't':
+			run_terse = 1;
+			break;
+		default:
+			printf("Literally how could you pass an unspecified argument to this program");
+		}
+	}
+	
+	FILE * fd_now = fopen(CHARGE_NOW_PATH, "r");
+	FILE * fd_full = fopen(CHARGE_FULL_PATH, "r");
+
+	int c_now;
+	int c_full;
+
+	int vals_read = fscanf(fd_now, "%d", &c_now);
+	if(vals_read != 1){
+		if(errno != 0){
+			perror("Error reading full battery charge: ");
+		} else if(vals_read == EOF){
+			printf("End-of-file reached while reading current battery charge(?)");
+		} else {
+			printf("Invalid number of arguments (%d) returned while reading full battery charge", vals_read);
+		}
+		return 1;
+	}
+	vals_read = fscanf(fd_full, "%d", &c_full);
+	if(vals_read != 1){
+		if(errno != 0){
+			perror("Error reading full battery charge: ");
+		} else if(vals_read == EOF){
+			printf("End-of-file reached while reading full battery charge(?)");
+		} else {
+			printf("Invalid number of arguments (%d) returned while reading full battery charge", vals_read);
+		}
+		return 1;
+	}
+
+	if(run_verbose){
+		printf("Current charge: %d\n", c_now);
+		printf("Full charge: %d\n", c_full);
+	}
+
+	if(!run_terse) {
+		printf("Battery percentage: ");
+	}
+	float pct = ((float)c_now) / ((float)c_full);
+	printf("%f\n", pct);
+	
+	return 0;
+}