filer: shrink zip spool threshold in tests to fix 32-bit OOM (#11796)

TestSpoolZipReaderTempFile and TestSpoolZipReaderLimit each allocate
~33-70 MiB to cross the 32 MiB in-memory spool threshold. On linux/386 the
weed/filer test binary already runs near the 4 GiB address-space limit, so
these allocations reliably crash it with "out of memory" mid-suite.

Make zipSpoolMemoryLimit a var and drop it to 1 KiB in those tests, which
exercises the same memory-vs-temp-file spool paths with KiB-sized buffers.

weed/filer/zip_extract.go

@@ -22,9 +22,15 @@ const (
 	// the TUS default max upload size.
 	ZipExtractMaxArchiveBytes = int64(5) << 30 // 5 GiB
 
-	zipSpoolMemoryLimit = 32 << 20 // 32 MiB; larger archives spool to a temp file
 )
 
+// zipSpoolMemoryLimit caps how much of one archive is buffered in memory
+// before the spool falls through to a temp file. It is a var rather than a
+// const so tests can shrink it: exercising the temp-file path with the real
+// 32 MiB threshold allocates hundreds of MiB, which tips the 32-bit test
+// binary over its 4 GiB address space.
+var zipSpoolMemoryLimit int64 = 32 << 20 // 32 MiB
+
 // ErrZipTooLarge marks a spool failure caused by the archive exceeding the
 // caller's size limit, so handlers can answer 4xx instead of 5xx.
 var ErrZipTooLarge = errors.New("zip archive too large")

weed/filer/zip_extract_test.go

@@ -46,6 +46,16 @@ func TestSanitizeZipMemberName(t *testing.T) {
 	}
 }
 
+// smallZipSpoolLimit drops the in-memory spool threshold to 1 KiB for the
+// duration of a test. Crossing the real 32 MiB threshold needs buffers that
+// are too large for the 32-bit test binary's address space.
+func smallZipSpoolLimit(t *testing.T) {
+	t.Helper()
+	old := zipSpoolMemoryLimit
+	zipSpoolMemoryLimit = 1024
+	t.Cleanup(func() { zipSpoolMemoryLimit = old })
+}
+
 func TestSpoolZipReaderMemory(t *testing.T) {
 	data := []byte(strings.Repeat("x", 1024))
 	ra, n, cleanup, err := SpoolZipReader(bytes.NewReader(data), 0)
@@ -66,7 +76,8 @@ func TestSpoolZipReaderMemory(t *testing.T) {
 }
 
 func TestSpoolZipReaderTempFile(t *testing.T) {
-	data := bytes.Repeat([]byte("y"), zipSpoolMemoryLimit+1)
+	smallZipSpoolLimit(t)
+	data := bytes.Repeat([]byte("y"), int(zipSpoolMemoryLimit)+1)
 	ra, n, cleanup, err := SpoolZipReader(bytes.NewReader(data), 0)
 	if err != nil {
 		t.Fatalf("spool: %v", err)
@@ -87,11 +98,12 @@ func TestSpoolZipReaderTempFile(t *testing.T) {
 }
 
 func TestSpoolZipReaderLimit(t *testing.T) {
+	smallZipSpoolLimit(t)
 	data := []byte(strings.Repeat("x", 2048))
 	if _, _, _, err := SpoolZipReader(bytes.NewReader(data), 1024); err == nil {
 		t.Fatal("expected limit error for in-memory archive")
 	}
-	if _, _, cleanup, err := SpoolZipReader(bytes.NewReader(bytes.Repeat([]byte("y"), zipSpoolMemoryLimit+1024)), zipSpoolMemoryLimit+512); err == nil {
+	if _, _, cleanup, err := SpoolZipReader(bytes.NewReader(bytes.Repeat([]byte("y"), int(zipSpoolMemoryLimit)+1024)), zipSpoolMemoryLimit+512); err == nil {
 		t.Fatal("expected limit error for spooled archive")
 	} else {
 		cleanup()