fmt: check newline in the end of input

Sscanf doc says:
Newlines in the input must match newlines in the format.

However Sscanf didn't check newline in the end of input (EOF).
A test for the case is broken.

* check newline in EOF
* fix the test
* slightly simplify ss.doScanf

Fixes #12788

Change-Id: Iaf6b7d81324a72e557543ac22ecea5cecb72e0d6
Reviewed-on: https://go-review.googlesource.com/16165
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

diff --git a/src/fmt/scan.go b/src/fmt/scan.go
index 4618ed4a827f4ee41e10f7f53fb3796bf161b984..553deb4327c12a0478a2b3cb37ab0528e10f8d0e 100644 (file)
--- a/src/fmt/scan.go
+++ b/src/fmt/scan.go
@@ -1108,6 +1108,10 @@ func (s *ss) advance(format string) (i int) {
                        // in the input.
                        inputc := s.getRune()
                        if inputc == eof {
+                               if wasNewline {
+                                       // Newlines are mandatory.
+                                       return -1
+                               }
                                return
                        }
                        if !isSpace(inputc) {
@@ -1148,17 +1152,18 @@ func (s *ss) doScanf(format string, a []interface{}) (numProcessed int, err erro
        end := len(format) - 1
        // We process one item per non-trivial format
        for i := 0; i <= end; {
-               w := s.advance(format[i:])
-               if w > 0 {
+               switch w := s.advance(format[i:]); {
+               case w > 0:
                        i += w
                        continue
+               case w < 0:
+                       // Can't advance format. Why not?
+                       s.errorString("input does not match format")
                }
-               // Either we failed to advance, we have a percent character, or we ran out of input.
+
+               // Either we have a percent character, or we ran out of input.
+
                if format[i] != '%' {
-                       // Can't advance format.  Why not?
-                       if w < 0 {
-                               s.errorString("input does not match format")
-                       }
                        // Otherwise at EOF; "too many operands" error handled below
                        break
                }

diff --git a/src/fmt/scan_test.go b/src/fmt/scan_test.go
index 7ac74dcb4bd7ce1b22ce050e6ea8609b8b9fbb93..bcc2844ef08f867cc5f3ff68249478b28b8d9747 100644 (file)
--- a/src/fmt/scan_test.go
+++ b/src/fmt/scan_test.go
@@ -1114,14 +1114,22 @@ func TestScanfNewlineMatchFormat(t *testing.T) {
                count  int
                ok     bool
        }{
-               {"newline in both", "1\n2", "%d\n%d\n", 2, true},
+               {"newline in both", "1\n2", "%d\n%d", 2, true},
                {"newline in input", "1\n2", "%d %d", 1, false},
+               {"extra newline in format", "1\n2", "%d\n%d\n", 2, false},
+               {"newline-newline in both", "1\n\n2", "%d\n\n%d", 2, true},
+               {"newline-newline in format", "1\n2", "%d\n\n%d", 1, false},
+               {"newline-newline in input", "1\n\n2", "%d\n%d", 1, false},
                {"space-newline in input", "1 \n2", "%d %d", 1, false},
                {"newline in format", "1 2", "%d\n%d", 1, false},
                {"space-newline in format", "1 2", "%d \n%d", 1, false},
                {"space-newline in both", "1 \n2", "%d \n%d", 2, true},
                {"extra space in format", "1\n2", "%d\n %d", 2, true},
                {"two extra spaces in format", "1\n2", "%d \n %d", 2, true},
+               {"newline start in both", "\n1 2", "\n%d %d", 2, true},
+               {"newline start in format", "1 2", "\n%d %d", 0, false},
+               {"newline start in input", "\n1 2", "%d %d", 0, false},
+               {"space-newline start in input", " \n1 2", "\n%d %d", 2, true},
        }
        for _, test := range tests {
                n, err := Sscanf(test.text, test.format, &a, &b)