[os2/process]: Force return on allocation errors and process not existing

core/os/os2/process_windows.odin

@@ -93,12 +93,33 @@ read_memory_as_slice :: proc(h: win32.HANDLE, addr: rawptr, dest: []$T) -> (byte
 @(private="package")
 _process_info_by_pid :: proc(pid: int, selection: Process_Info_Fields, allocator: runtime.Allocator) -> (info: Process_Info, err: Error) {
 	info.pid = pid
-	// Data obtained from process snapshots
+	// Note(flysand): Open the process handle right away to prevent some race
+	// conditions. Once the handle is open, the process will be kept alive by
+	// the OS.
+	ph := win32.INVALID_HANDLE_VALUE
+	if selection >= {.Command_Line, .Environment, .Working_Dir, .Username} {
+		ph = win32.OpenProcess(
+			win32.PROCESS_QUERY_LIMITED_INFORMATION | win32.PROCESS_VM_READ,
+			false,
+			u32(pid),
+		)
+		if ph == win32.INVALID_HANDLE_VALUE {
+			err = _get_platform_error()
+			return
+		}
+	}
+	defer if ph != win32.INVALID_HANDLE_VALUE {
+		win32.CloseHandle(ph)
+	}
 	snapshot_process: if selection >= {.PPid, .Priority} {
 		entry, entry_err := _process_entry_by_pid(info.pid)
 		if entry_err != nil {
-			err = General_Error.Not_Exist
-			return
+			err = entry_err
+			if entry_err == General_Error.Not_Exist {
+				return
+			} else {
+				break snapshot_process
+			}
 		}
 		if .PPid in selection {
 			info.fields += {.PPid}
@@ -110,23 +131,15 @@ _process_info_by_pid :: proc(pid: int, selection: Process_Info_Fields, allocator
 		}
 	}
 	snapshot_modules: if .Executable_Path in selection {
-		info.executable_path = _process_exe_by_pid(pid, allocator) or_break snapshot_modules
-		info.fields += {.Executable_Path}
-	}
-	ph := win32.INVALID_HANDLE_VALUE
-	if selection >= {.Command_Line, .Environment, .Working_Dir, .Username} {
-		ph = win32.OpenProcess(
-			win32.PROCESS_QUERY_LIMITED_INFORMATION | win32.PROCESS_VM_READ,
-			false,
-			u32(pid),
-		)
-		if ph == win32.INVALID_HANDLE_VALUE {
-			err = _get_platform_error()
+		exe_path: string
+		exe_path, err = _process_exe_by_pid(pid, allocator)
+		if _, ok := err.(runtime.Allocator_Error); ok {
 			return
+		} else if err != nil {
+			break snapshot_modules
 		}
-	}
-	defer if ph != win32.INVALID_HANDLE_VALUE {
-		win32.CloseHandle(ph)
+		info.executable_path = exe_path
+		info.fields += {.Executable_Path}
 	}
 	read_peb: if selection >= {.Command_Line, .Environment, .Working_Dir} {
 		process_info_size: u32
@@ -136,44 +149,66 @@ _process_info_by_pid :: proc(pid: int, selection: Process_Info_Fields, allocator
 			// TODO(flysand): There's probably a mismatch between NTSTATUS and
 			// windows userland error codes, I haven't checked.
 			err = Platform_Error(status)
-			return
+			break read_peb
 		}
 		assert(process_info.PebBaseAddress != nil)
 		process_peb: win32.PEB
-		_ = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb) or_break read_peb
+		_, err = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb)
+		if err != nil {
+			break read_peb
+		}
 		process_params: win32.RTL_USER_PROCESS_PARAMETERS
-		_ = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params) or_break read_peb
+		_, err = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params)
+		if err != nil {
+			break read_peb
+		}
 		if selection >= {.Command_Line, .Command_Args} {
 			TEMP_ALLOCATOR_GUARD()
-			cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w) or_break read_peb
+			cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w)
+			if err != nil {
+				break read_peb
+			}
 			if .Command_Line in selection {
-				info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_break read_peb
+				info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_return
 				info.fields += {.Command_Line}
 			}
 			if .Command_Args in selection {
-				info.command_args = _parse_command_line(raw_data(cmdline_w), allocator) or_break read_peb
+				info.command_args = _parse_command_line(raw_data(cmdline_w), allocator) or_return
 				info.fields += {.Command_Args}
 			}
 		}
 		if .Environment in selection {
 			TEMP_ALLOCATOR_GUARD()
 			env_len := process_params.EnvironmentSize / 2
-			envs_w := make([]u16, env_len, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.Environment, envs_w) or_break read_peb
-			info.environment = _parse_environment_block(raw_data(envs_w), allocator) or_break read_peb
+			envs_w := make([]u16, env_len, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.Environment, envs_w)
+			if err != nil {
+				break read_peb
+			}
+			info.environment = _parse_environment_block(raw_data(envs_w), allocator) or_return
 			info.fields += {.Environment}
 		}
 		if .Working_Dir in selection {
 			TEMP_ALLOCATOR_GUARD()
-			cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w) or_break read_peb
-			info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_break read_peb
+			cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w)
+			if err != nil {
+				break read_peb
+			}
+			info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_return
 			info.fields += {.Working_Dir}
 		}
 	}
 	read_username: if .Username in selection {
-		info.username = _get_process_user(ph, allocator) or_break read_username
+		username: string
+		username, err = _get_process_user(ph, allocator)
+		if _, ok := err.(runtime.Allocator_Error); ok {
+			return
+		} else if err != nil {
+			break read_username
+		}
+		info.username = username
 		info.fields += {.Username}
 	}
 	err = nil
@@ -188,8 +223,12 @@ _process_info_by_handle :: proc(process: Process, selection: Process_Info_Fields
 	snapshot_process: if selection >= {.PPid, .Priority} {
 		entry, entry_err := _process_entry_by_pid(info.pid)
 		if entry_err != nil {
-			err = General_Error.Not_Exist
-			return
+			err = entry_err
+			if entry_err == General_Error.Not_Exist {
+				return
+			} else {
+				break snapshot_process
+			}
 		}
 		if .PPid in selection {
 			info.fields += {.PPid}
@@ -201,7 +240,14 @@ _process_info_by_handle :: proc(process: Process, selection: Process_Info_Fields
 		}
 	}
 	snapshot_module: if .Executable_Path in selection {
-		info.executable_path = _process_exe_by_pid(pid, allocator) or_break snapshot_module
+		exe_path: string
+		exe_path, err = _process_exe_by_pid(pid, allocator)
+		if _, ok := err.(runtime.Allocator_Error); ok {
+			return
+		} else if err != nil {
+			break snapshot_module
+		}
+		info.executable_path = exe_path
 		info.fields += {.Executable_Path}
 	}
 	ph := win32.HANDLE(process.handle)
@@ -217,40 +263,62 @@ _process_info_by_handle :: proc(process: Process, selection: Process_Info_Fields
 		}
 		assert(process_info.PebBaseAddress != nil)
 		process_peb: win32.PEB
-		_ = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb) or_break read_peb
+		_, err = read_memory_as_struct(ph, process_info.PebBaseAddress, &process_peb)
+		if err != nil {
+			break read_peb
+		}
 		process_params: win32.RTL_USER_PROCESS_PARAMETERS
-		_ = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params) or_break read_peb
+		_, err = read_memory_as_struct(ph, process_peb.ProcessParameters, &process_params)
+		if err != nil {
+			break read_peb
+		}
 		if selection >= {.Command_Line, .Command_Args} {
 			TEMP_ALLOCATOR_GUARD()
-			cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w) or_break read_peb
+			cmdline_w := make([]u16, process_params.CommandLine.Length, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.CommandLine.Buffer, cmdline_w)
+			if err != nil {
+				break read_peb
+			}
 			if .Command_Line in selection {
-				info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_break read_peb
+				info.command_line = win32_utf16_to_utf8(cmdline_w, allocator) or_return
 				info.fields += {.Command_Line}
 			}
 			if .Command_Args in selection {
-				info.command_args = _parse_command_line(raw_data(cmdline_w), allocator) or_break read_peb
+				info.command_args = _parse_command_line(raw_data(cmdline_w), allocator) or_return
 				info.fields += {.Command_Args}
 			}
 		}
 		if .Environment in selection {
 			TEMP_ALLOCATOR_GUARD()
 			env_len := process_params.EnvironmentSize / 2
-			envs_w := make([]u16, env_len, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.Environment, envs_w) or_break read_peb
-			info.environment =  _parse_environment_block(raw_data(envs_w), allocator) or_break read_peb
+			envs_w := make([]u16, env_len, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.Environment, envs_w)
+			if err != nil {
+				break read_peb
+			}
+			info.environment =  _parse_environment_block(raw_data(envs_w), allocator) or_return
 			info.fields += {.Environment}
 		}
 		if .Working_Dir in selection {
 			TEMP_ALLOCATOR_GUARD()
-			cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator()) or_break read_peb
-			_ = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w) or_break read_peb
-			info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_break read_peb
+			cwd_w := make([]u16, process_params.CurrentDirectoryPath.Length, temp_allocator()) or_return
+			_, err = read_memory_as_slice(ph, process_params.CurrentDirectoryPath.Buffer, cwd_w)
+			if err != nil {
+				break read_peb
+			}
+			info.working_dir = win32_utf16_to_utf8(cwd_w, allocator) or_return
 			info.fields += {.Working_Dir}
 		}
 	}
 	read_username: if .Username in selection {
-		info.username = _get_process_user(ph, allocator) or_break read_username
+		username: string
+		username, err = _get_process_user(ph, allocator)
+		if _, ok := err.(runtime.Allocator_Error); ok {
+			return
+		} else if err != nil {
+			break read_username
+		}
+		info.username = username
 		info.fields += {.Username}
 	}
 	err = nil
@@ -263,8 +331,12 @@ _current_process_info :: proc(selection: Process_Info_Fields, allocator: runtime
 	snapshot_process: if selection >= {.PPid, .Priority} {
 		entry, entry_err := _process_entry_by_pid(info.pid)
 		if entry_err != nil {
-			err = General_Error.Not_Exist
-			return
+			err = entry_err
+			if entry_err == General_Error.Not_Exist {
+				return
+			} else {
+				break snapshot_process
+			}
 		}
 		if .PPid in selection {
 			info.fields += {.PPid}
@@ -278,28 +350,38 @@ _current_process_info :: proc(selection: Process_Info_Fields, allocator: runtime
 	module_filename: if .Executable_Path in selection {
 		exe_filename_w: [256]u16
 		path_len := win32.GetModuleFileNameW(nil, raw_data(exe_filename_w[:]), len(exe_filename_w))
-		info.executable_path = win32_utf16_to_utf8(exe_filename_w[:path_len], allocator) or_break module_filename
+		assert(path_len > 0)
+		info.executable_path = win32_utf16_to_utf8(exe_filename_w[:path_len], allocator) or_return
 		info.fields += {.Executable_Path}
 	}
 	command_line: if selection >= {.Command_Line,  .Command_Args} {
 		command_line_w := win32.GetCommandLineW()
+		assert(command_line_w != nil)
 		if .Command_Line in selection {
-			info.command_line = win32_wstring_to_utf8(command_line_w, allocator) or_break command_line
+			info.command_line = win32_wstring_to_utf8(command_line_w, allocator) or_return
 			info.fields += {.Command_Line}
 		}
 		if .Command_Args in selection {
-			info.command_args = _parse_command_line(command_line_w, allocator) or_break command_line
+			info.command_args = _parse_command_line(command_line_w, allocator) or_return
 			info.fields += {.Command_Args}
 		}
 	}
-	environment: if .Environment in selection {
+	read_environment: if .Environment in selection {
 		env_block := win32.GetEnvironmentStringsW()
-		info.environment = _parse_environment_block(env_block, allocator) or_break environment
+		assert(env_block != nil)
+		info.environment = _parse_environment_block(env_block, allocator) or_return
 		info.fields += {.Environment}
 	}
-	username: if .Username in selection {
+	read_username: if .Username in selection {
 		process_handle := win32.GetCurrentProcess()
-		info.username = _get_process_user(process_handle, allocator) or_break username
+		username: string
+		username, err := _get_process_user(process_handle, allocator)
+		if _, ok := err.(runtime.Allocator_Error); ok {
+			return
+		} else if err != nil {
+			break read_username
+		}
+		info.username = username
 		info.fields += {.Username}
 	}
 	if .Working_Dir in selection {