os: ReadFile: don't check for re-allocation in the first iteration

At the beginning of the for-loop iteration cap(data) > len(data) always. Therefore, in the first iteration, this check becomes unnecessary. we can move this check to after the read operation. Change-Id: I205e4a842ced74f31124b45a39b70523b56ad840 GitHub-Last-Rev: 2fdf25dff2e9984d3a8f8e5e612ea802c88e88a1 GitHub-Pull-Request: golang/go#60473 Reviewed-on: https://go-review.googlesource.com/c/go/+/498915 Reviewed-by: Rob Pike <[email protected]> Reviewed-by: Bryan Mills <[email protected]> Run-TryBot: Rob Pike <[email protected]> TryBot-Result: Gopher Robot <[email protected]> Run-TryBot: Ian Lance Taylor <[email protected]> Reviewed-by: Ian Lance Taylor <[email protected]> Auto-Submit: Ian Lance Taylor <[email protected]>
cloudflare · Jul 25, 2023 · a3a9b10 · a3a9b10
1 parent df0a129
commit a3a9b10
Showing 1 changed file with 5 additions and 4 deletions.
diff --git a/src/os/file.go b/src/os/file.go
@@ -725,10 +725,6 @@ func ReadFile(name string) ([]byte, error) {
 
  data := make([]byte, 0, size)
  for {
- if len(data) >= cap(data) {
- d := append(data[:cap(data)], 0)
- data = d[:len(data)]
- }
  n, err := f.Read(data[len(data):cap(data)])
  data = data[:len(data)+n]
  if err != nil {
@@ -737,6 +733,11 @@ func ReadFile(name string) ([]byte, error) {
  }
  return data, err
  }
+
+ if len(data) >= cap(data) {
+ d := append(data[:cap(data)], 0)
+ data = d[:len(data)]
+ }
  }
 }