RAM usage reading from /proc/meminfo

code/linux_platform.cpp

@@ -221,9 +221,12 @@ void   p_free(void *ptr)
 bool p_file_init(p_file *file, const char *filename, b32 flags)
 {
 	bool create_flag_set = flags & P_FILE_CREATE_IF_NOT_EXISTS;
+	bool readonly = flags & P_FILE_READONLY;
 
-
-	file->handle = fopen(filename, "rb+");
+	const char *mode = "rb+";
+	if(readonly)
+		mode = "rb";
+	file->handle = fopen(filename, mode);
 	if(create_flag_set && file->handle == NULL) // @Robustness: check errno
 	{
 		file->handle = fopen(filename, "wb+");

code/main.cpp

@@ -683,6 +683,64 @@ void collect_static_data()
 	snprintf(system_info.kernel, 128, "%s %s", host_info.sysname, host_info.release);
 }
 
+// key and value are views into buffer. Copy them if you need them for a longer lifetime
+size_t meminfo_extract_next_entry(String *buffer, size_t start, String *key, String *value)
+{
+	size_t separator = 0;
+	size_t end = 0;
+	for(int i = start; i < buffer->size; i++)
+	{
+		if(buffer->text[i] == ':')
+		{
+			separator = i;
+		}
+		else if(buffer->text[i] == '\n')
+		{
+			end = i;
+			break;
+		}
+	}
+
+	if(end == 0) // no newline found
+		end = buffer->size;
+
+	if(key)
+	{
+		key->text = buffer->text + start;
+		key->size = separator - start;
+	}
+	if(value)
+	{
+		// TODO: Check if seaparator is actually found. This will return the wrong data if separator is 0
+		value->text = buffer->text + separator + 1;
+		value->size = end - (separator + 1);
+	}
+
+	return end + 1 - start;
+}
+
+String String_trim(String s)
+{
+	String result;
+
+	result.text = s.text;
+	result.size = s.size;
+
+	// Trim front
+	while(result.size > 0 && result.text[0] == ' ')
+	{
+		result.text++;
+		result.size--;
+	}
+	// Trim back
+	while(result.size > 0 && result.text[result.size-1] == ' ')
+	{
+		result.size--;
+	}
+
+	return result;
+}
+
 void collect_new_data_if_needed()
 {
 	if(engine.time - app_data.glib_iteration_t >= app_data.glib_iteration_delta)
@@ -715,9 +773,56 @@ void collect_new_data_if_needed()
 			system_info.load[i] = round((f32)sys_info.loads[i] / (1 << SI_LOAD_SHIFT) * 100) / 100;
 
 		// Memory
-		system_info.ram_total = sys_info.totalram * sys_info.mem_unit;
-		system_info.ram_available = (sys_info.freeram + sys_info.bufferram) * sys_info.mem_unit;
-		system_info.ram_used = sys_info.totalram * sys_info.mem_unit - system_info.ram_available;
+		{
+			p_file file;
+			if(p_file_init(&file, "/proc/meminfo", P_FILE_READONLY))
+			{
+				u64 size = p_file_size(&file);
+				if(size == 0)
+					size = 1024;
+				u8 backing_buff[size + 1];
+				Buffer buffer = { .size = size + 1, .data = backing_buff };
+				if(p_file_read(&file, &buffer, size + 1))
+				{
+					String s = { .size = buffer.size, .text = buffer.data };
+					// Parse meminfo data
+					size_t parsed = 0;
+					while(1)
+					{
+						String key, value;
+						size_t read = meminfo_extract_next_entry(&s, parsed, &key, &value);
+						parsed += read;
+						if(read == 0)
+							break;
+
+						key = String_trim(key);
+						value = String_trim(value);
+
+						if(strncmp((const char *)key.text, "MemTotal", key.size) == 0)
+						{
+							// LOG(LOG_INFO, "MemTotal: %.*s\n", value.size, value.text);
+							u64 converted = 0;
+							sscanf((const char *)value.text, "%lu", &converted);
+							system_info.ram_total = converted * 1024;
+						}
+						else if(strncmp((const char *)key.text, "MemAvailable", key.size) == 0)
+						{
+							// LOG(LOG_INFO, "MemAvailable: %.*s\n", value.size, value.text);
+							u64 converted = 0;
+							sscanf((const char *)value.text, "%lu", &converted);
+							system_info.ram_available = converted * 1024;
+						}
+					}
+				}
+
+				p_file_deinit(&file);
+			}
+		}
+
+		// system_info.ram_total = sys_info.totalram * sys_info.mem_unit;
+		// system_info.ram_available = (sys_info.freeram + sys_info.bufferram) * sys_info.mem_unit;
+		// system_info.ram_used = sys_info.totalram * sys_info.mem_unit - system_info.ram_available;
+		system_info.ram_used = system_info.ram_total - system_info.ram_available;
 
 
 		// Status

code/platform.h

@@ -23,6 +23,7 @@ void   p_free(void *ptr);
 
 // File IO
 #define P_FILE_CREATE_IF_NOT_EXISTS 1
+#define P_FILE_READONLY 2
 
 struct p_file; // Defined by specific platform implementation