fix: Return an error on writing partial bytes instead of crashing

Author: richard-viney

gleam.toml

@@ -7,7 +7,7 @@ links = [
 ]
 
 [dependencies]
-gleam_stdlib = ">= 0.41.0 and < 2.0.0"
+gleam_stdlib = ">= 0.42.0 and < 2.0.0"
 
 [dev-dependencies]
 gleeunit = ">= 1.2.0 and < 2.0.0"

manifest.toml

@@ -2,13 +2,13 @@
 # You typically do not need to edit this file
 
 packages = [
-  { name = "filepath", version = "1.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "EFB6FF65C98B2A16378ABC3EE2B14124168C0CE5201553DE652E2644DCFDB594" },
-  { name = "gleam_stdlib", version = "0.41.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "1B2F80CB1B66B027E3198A2FF71EF3F2F31DF89ED97AD606F25FD387A4C3C1EF" },
+  { name = "filepath", version = "1.1.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "67A6D15FB39EEB69DD31F8C145BB5A421790581BD6AA14B33D64D5A55DBD6587" },
+  { name = "gleam_stdlib", version = "0.47.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "3B22D46743C46498C8355365243327AC731ECD3959216344FA9CF9AD348620AC" },
   { name = "gleeunit", version = "1.2.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "F7A7228925D3EE7D0813C922E062BFD6D7E9310F0BEE585D3A42F3307E3CFD13" },
   { name = "simplifile", version = "2.2.0", build_tools = ["gleam"], requirements = ["filepath", "gleam_stdlib"], otp_app = "simplifile", source = "hex", outer_checksum = "0DFABEF7DC7A9E2FF4BB27B108034E60C81BEBFCB7AB816B9E7E18ED4503ACD8" },
 ]
 
 [requirements]
-gleam_stdlib = { version = ">= 0.41.0 and < 2.0.0" }
+gleam_stdlib = { version = ">= 0.42.0 and < 2.0.0" }
 gleeunit = { version = ">= 1.2.0 and < 2.0.0" }
 simplifile = { version = ">= 2.0.1 and < 3.0.0" }

src/file_streams/file_stream.gleam

@@ -274,6 +274,12 @@ pub fn write_bytes(
     Error(file_stream_error.Enotsup),
   )
 
+  // Check that the bit array contains a whole number of bytes
+  use <- bool.guard(
+    bit_array.bit_size(bytes) % 8 != 0,
+    Error(file_stream_error.Einval),
+  )
+
   case file_write(stream.io_device, bytes) {
     raw_result.Ok -> Ok(Nil)
     raw_result.Error(e) -> Error(e)

test/file_streams_test.gleam

@@ -547,3 +547,17 @@ pub fn set_encoding_test() {
   simplifile.delete(tmp_file_name)
   |> should.equal(Ok(Nil))
 }
+
+@target(erlang)
+pub fn write_partial_bytes_test() {
+  let assert Ok(stream) = file_stream.open_write(tmp_file_name)
+
+  file_stream.write_bytes(stream, <<"A", 0:7>>)
+  |> should.equal(Error(file_stream_error.Einval))
+
+  file_stream.close(stream)
+  |> should.equal(Ok(Nil))
+
+  simplifile.delete(tmp_file_name)
+  |> should.equal(Ok(Nil))
+}