Fix binary scan for too-few bytes.

According to the Tcl manual, in this case "binary scan returns immediately
with the number of variables that were set".

(Tests added by Steve Bennett)

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

2 files changed, 17 insertions, 2 deletions

diff --git a/binary.tcl b/binary.tcl
index 5e9ae3f..cc9c9ea 100644
--- a/binary.tcl
+++ b/binary.tcl
@@ -125,7 +125,7 @@ proc "binary scan" {value formatString {args varName}} {
 				set n 1
 			}
 			if {$n > $rembytes} {
-				continue
+				break
 			}
 
 			set var [binary.nextarg varName]
@@ -148,7 +148,7 @@ proc "binary scan" {value formatString {args varName}} {
 				}
 			}
 			if {$n * $size > $rembytes * 8} {
-				continue
+				break
 			}
 
 			if {$type ne "int"} {
diff --git a/tests/binary-scan.test b/tests/binary-scan.test
index c758f05..ec6c95c 100644
--- a/tests/binary-scan.test
+++ b/tests/binary-scan.test
@@ -74,6 +74,13 @@ test binary-20.9 {Tcl_BinaryObjCmd: scan} -setup {
     list [binary scan abc a arg1(a)] $arg1(a)
 } -result {1 a}
 
+# As soon as a conversion runs out of bytes, scan should stop
+test binary-20.10 {Tcl_BinaryObjCmd: scan, too few bytes} -setup {
+    unset -nocomplain arg1 arg2
+} -body {
+    list [binary scan abc a5a2 arg1 arg2] [info exists arg1] [info exists arg2]
+} -result {0 0 0}
+
 test binary-21.1 {Tcl_BinaryObjCmd: scan} -returnCodes error -body {
     binary scan abc A
 } -result {not enough arguments for all format specifiers}
@@ -185,6 +192,14 @@ test binary-22.11 {Tcl_BinaryObjCmd: scan} -setup {
     list [binary scan \x07\x87\x05 b5b* arg1 arg2] $arg1 $arg2
 } -result {2 11100 1110000110100000}
 
+# As soon as a conversion runs out of bytes, scan should stop
+test binary-20.12 {Tcl_BinaryObjCmd: scan, too few bytes} {
+    unset -nocomplain arg1 arg2
+    set arg1 foo
+    set arg2 bar
+    list [binary scan \x52 b14b8 arg1 arg2] $arg1 $arg2
+} {0 foo bar}
+
 test binary-23.1 {Tcl_BinaryObjCmd: scan} -returnCodes error -body {
     binary scan abc B
 } -result {not enough arguments for all format specifiers}