libsys/free: Differentiate between free and available memory

Author: byteduck

libraries/libsys/Memory.h

@@ -71,6 +71,14 @@ namespace Sys::Mem {
 		inline Amount free() const {
 			return {(size_t) usable - (size_t) used};
 		}
+
+		inline Amount available() const {
+			return {(size_t) usable - (size_t) used + (size_t) kernel_disk_cache};
+		}
+
+		inline double available_frac() const {
+			return (double)((long double) available() / (long double) usable);
+		}
 	};
 
 	Duck::ResultRet<Info> get_info(Duck::InputStream& file);

programs/coreutils/free.cpp

@@ -44,7 +44,8 @@ int main(int argc, char** argv, char** envp) {
 	if(human_readable) {
 		printf("Total: %s\n", info.usable.readable().c_str());
 		printf("Used: %s (%.2f%%)\n", info.used.readable().c_str(), info.used_frac() * 100.0);
-		printf("Available: %s (%.2f%%)\n", info.free().readable().c_str(), info.free_frac() * 100.0);
+		printf("Free: %s (%.2f%%)\n", info.free().readable().c_str(), info.free_frac() * 100.0);
+		printf("Available: %s (%.2f%%)\n", info.available().readable().c_str(), info.available_frac() * 100.0);
 		if(kernel_memory) {
 			printf("Kernel physical: %s\n", info.kernel_phys.readable().c_str());
 			printf("Kernel virtual: %s\n", info.kernel_virt.readable().c_str());
@@ -54,7 +55,8 @@ int main(int argc, char** argv, char** envp) {
 	} else {
 		printf("Total: %lu\n", info.usable.bytes);
 		printf("Used: %lu (%.2f%%)\n", info.used.bytes, info.used_frac() * 100.0);
-		printf("Available: %lu (%.2f%%)\n", info.free().bytes, info.free_frac() * 100.0);
+		printf("Free: %lu (%.2f%%)\n", info.free().bytes, info.free_frac() * 100.0);
+		printf("Available: %lu (%.2f%%)\n", info.available().bytes, info.available_frac() * 100.0);
 		if(kernel_memory) {
 			printf("Kernel physical: %lu\n", info.kernel_phys.bytes);
 			printf("Kernel virtual: %lu\n", info.kernel_virt.bytes);