Let's put some more safety to parse_arguments().

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2021-2023 Alexander "Arav" Andreev <me@arav.su>
+Copyright (c) 2021-2024 Alexander "Arav" Andreev <me@arav.su>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 

Makefile

@@ -5,13 +5,10 @@ PREFIX:=/usr/local
 
 CFLAGS=--std=c99 -O3 -Wall -Werror -Wextra -pedantic
 
-SRC_DIR=src
-
-DESTDIR=/
 
 .PHONY: clean install uninstall test
 
-${TARGET}: ${SRC_DIR}/main.c ${SRC_DIR}/main.h
+${TARGET}: main.c
 	${CC} ${CFLAGS} ${LDFLAGS} $< -o $@
 
 clean:

PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Alexander "Arav" Andreev <me@arav.su>
 pkgname=kwh-cost
-pkgver=1.1.1
+pkgver=1.1.2
 pkgrel=1
 pkgdesc="Calculates cost of electricity."
 arch=('i686' 'x86_64' 'arm' 'armv6h' 'armv7h' 'aarch64')
@@ -12,10 +12,10 @@ md5sums=('SKIP')
 
 build() {
     cd "$srcdir/$pkgname"
-    make DESTDIR="$pkgdir/"
+    make
 }
 
 package() {
     cd "$srcdir/$pkgname"
-    make DESTDIR="$pkgdir/" PREFIX="/usr" install
+    make DESTDIR="$pkgdir" PREFIX="/usr" install
 }

main.c

@@ -2,15 +2,27 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "main.h"
+#define VERSION "1.1.2"
+
+typedef long double   price_t;
+typedef long double   wattage_t;
+typedef unsigned long interval_t;
+
+int parse_arguments(const int argc, const char *const *const argv,
+                    price_t *const price, wattage_t *const wattage, interval_t *const interval);
+
+inline interval_t interval_to_seconds(const char *const interval);
+inline price_t    price_kwh_to_wattsecond(const price_t price);
+
+inline void print_version();
+inline void print_usage();
 
 int main(const int argc, const char *const *const argv) {
     price_t price;
     wattage_t wattage;
     interval_t interval = 0;
 
-    int res = parse_arguments(argc, argv, &price, &wattage, &interval);
-    switch (res) {
+    switch (parse_arguments(argc, argv, &price, &wattage, &interval)) {
         case 1: print_usage(); exit(0);
         case 2: print_version(); exit(0);
         case 99: fputs("Unknown flag provided.\n", stderr); print_usage(); exit(1);
@@ -27,16 +39,19 @@ int parse_arguments(const int argc, const char *const *const argv,
 
     for (int i = 1, pos = 0; i < argc; ++i)
         if (argv[i][0] == '-') {
-            if (argv[i][1] == 'h' || argv[i][2] == 'h')
+            size_t l = strlen(argv[i]);
+            if (l < 2)
+                return 99;
+            if (argv[i][1] == 'h' || (argv[i][1] == '-' && l > 2 && argv[i][2] == 'h'))
                 return 1;
-            else if (argv[i][1] == 'v' || argv[i][2] == 'v')
+            else if (argv[i][1] == 'v' || (argv[i][1] == '-' && l > 2 && argv[i][2] == 'v'))
                 return 2;
             else
                 return 99;
         } else if (argc < 4) {
             return 1;
         } else if (pos == 0) {
-            *price = price_kwh_to_wattspersecond((price_t)atof(argv[i]));
+            *price = price_kwh_to_wattsecond((price_t)atof(argv[i]));
             ++pos;
         } else if (pos == 1) {
             *wattage = (wattage_t)atof(argv[2]);
@@ -65,13 +80,14 @@ inline interval_t interval_to_seconds(const char *const interval) {
     }
 }
 
-inline price_t price_kwh_to_wattspersecond(const price_t price) {
+inline price_t price_kwh_to_wattsecond(const price_t price) {
     return price / 1000.f / 3600.f;
 }
 
 inline void print_version() {
     fputs("kwh-cost Ver. " VERSION "\n"
-         "Copyright (C) 2021-2023 Alexander \"Arav\" Andreev <me@arav.su>. All rights reserved.\n"
+         "Copyright (C) 2021-2024 Alexander \"Arav\" Andreev <me@arav.su>. All rights reserved.\n"
+         "This program is distributed under the terms of MIT+NIGGER licence.\n"
          "You can see a license for this program in /usr/share/licenses/kwh-cost/LICENSE.\n", stderr);
 }
 

src/main.h

@@ -1,19 +0,0 @@
-#ifndef _MAIN_H_
-#define _MAIN_H_
-
-#define VERSION "1.1.1"
-
-typedef long double   price_t;
-typedef long double   wattage_t;
-typedef unsigned long interval_t;
-
-int parse_arguments(const int argc, const char *const *const argv,
-                    price_t *const price, wattage_t *const wattage, interval_t *const interval);
-
-inline interval_t interval_to_seconds(const char *const interval);
-inline price_t    price_kwh_to_wattspersecond(const price_t price);
-
-inline void print_version();
-inline void print_usage();
-
-#endif