runtime: fix spurious "[string too long]" error
Maxstring is not updated in the new string routines,
this makes runtime think that long strings are bogus.
Fixes #8339.
LGTM=crawshaw, iant
R=golang-codereviews, crawshaw, iant
CC=golang-codereviews, khr, rsc
https://golang.org/cl/110930043
diff --git a/src/pkg/runtime/string_test.go b/src/pkg/runtime/string_test.go
index b05e0c7..73ac95e 100644
--- a/src/pkg/runtime/string_test.go
+++ b/src/pkg/runtime/string_test.go
@@ -6,6 +6,7 @@
import (
"runtime"
+ "strings"
"testing"
)
@@ -122,3 +123,25 @@
}
}
}
+
+func TestLargeStringConcat(t *testing.T) {
+ output := executeTest(t, largeStringConcatSource, nil)
+ want := "panic: " + strings.Repeat("0", 1<<10) + strings.Repeat("1", 1<<10) +
+ strings.Repeat("2", 1<<10) + strings.Repeat("3", 1<<10)
+ if !strings.HasPrefix(output, want) {
+ t.Fatalf("output does not start with %q:\n%s", want, output)
+ }
+}
+
+var largeStringConcatSource = `
+package main
+import "strings"
+func main() {
+ s0 := strings.Repeat("0", 1<<10)
+ s1 := strings.Repeat("1", 1<<10)
+ s2 := strings.Repeat("2", 1<<10)
+ s3 := strings.Repeat("3", 1<<10)
+ s := s0 + s1 + s2 + s3
+ panic(s)
+}
+`
diff --git a/src/pkg/runtime/stubs.goc b/src/pkg/runtime/stubs.goc
index 901efa4..137c10e 100644
--- a/src/pkg/runtime/stubs.goc
+++ b/src/pkg/runtime/stubs.goc
@@ -24,6 +24,7 @@
#pragma textflag NOSPLIT
func rawstring(size intgo) (s String, b Slice) {
+ uintptr ms;
byte *p;
p = runtime·mallocgc(size, 0, FlagNoScan|FlagNoZero);
@@ -32,6 +33,11 @@
b.array = p;
b.len = size;
b.cap = size;
+ for(;;) {
+ ms = runtime·maxstring;
+ if((uintptr)size <= ms || runtime·casp((void**)&runtime·maxstring, (void*)ms, (void*)size))
+ break;
+ }
}
#pragma textflag NOSPLIT
