hare

commit 0cf6503998baa3f68b9d680f2f4d448bf291f7f9
parent 4ef0cf5bba13a1437a7f9b959a09822ead7adf8c
Author: Armin Preiml <apreiml@strohwolke.at>
Date:   Wed, 18 Jan 2023 15:24:23 +0100

io::writeall: abort on error after partial write

Errors after partial writes may lead to subtle bugs. Which may cause
invalid data e.g. on non-blocking writes. Therefore abort on partial
writes and dissuade from using writeall, if the underlying write can
fail.

Signed-off-by: Armin Preiml <apreiml@strohwolke.at>

Diffstat:
M
io/util.ha
 | 
13
++++++++++++-

1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/io/util.ha b/io/util.ha
@@ -23,10 +23,21 @@ export fn readall(in: handle, buf: []u8) (size | EOF | error) = {
 };
 
 // Writes an entire buffer, perhaps issuing several [[write]] calls to do so.
+// Aborts on errors after partial writes. Hence it should only be used if it is
+// certain that the underlying writes will not fail after an initial write.
 export fn writeall(out: handle, buf: []u8) (size | error) = {
 	let z: size = 0;
 	for (z < len(buf)) {
-		z += write(out, buf[z..])?;
+		z += match (write(out, buf[z..])) {
+		case let s: size =>
+			yield s;
+		case let e: error =>
+			if (z == 0) {
+				return e;
+			};
+
+			abort("error after partial write");
+		};
 	};
 	return z;
 };