aio: gets: Improve behaviour for non-blocking streams

Previously calling gets on a non-blocking stream could easily
result in a partial line. Now if a partial line is read, return zero/empty
to indicate that nothing is available while storing the partial line.
The next call to gets (typically within a readable script) will continue
appending to the previous partial line until a complete line can be returned.

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 38 insertions, 0 deletions

diff --git a/examples/nonblocking-gets.tcl b/examples/nonblocking-gets.tcl
new file mode 100644
index 0000000..a9ac4bd
--- /dev/null
+++ b/examples/nonblocking-gets.tcl
@@ -0,0 +1,38 @@
+#!/usr/bin/env jimsh
+
+# Tests that 'gets' on a non-blocking socket
+# does not return partial lines
+
+lassign [socket pipe] r w
+
+if {[os.fork] == 0} {
+	# The child will be our client
+	$r close
+	# Output increasingly long lines
+	loop i 10000 {
+		$w puts [string repeat a $i]
+	}
+} else {
+	# The server reads lines with gets.
+	# Each one should be one longer than the last
+	$w close
+
+	set exp 0
+	$r ndelay 1
+	$r readable {
+		while {[$r gets buf] >= 0} {
+			set len [string length $buf]
+			if {$len != $exp} {
+				puts "Read line of length $len but expected $exp"
+				incr done
+				break
+			}
+			incr exp
+		}
+		if {[$r eof]} {
+			incr done
+		}
+	}
+
+	vwait done
+}