internal/testpty: fix error handling

When calling a c library function, you discover that an error has
occurred, typically by looking at the return value of the function. Only
after that can you use errno to figure out the cause of the error.

Nothing about cgo changes that story -- you still have to look at the
result before checking the error that represents errno. If not you can
get false errors if the function happens to leak a non-zero errno.

Fix testpty to check errors correctly.

Change-Id: Idb95f8dd6a8ed63f653190c2e722e742cf50542b
Reviewed-on: https://go-review.googlesource.com/c/go/+/463397
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
1 file changed
tree: dda1e394caa751b3513bbc2b40bbd08b7caca914
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg
  11. CONTRIBUTING.md
  12. go.env
  13. LICENSE
  14. PATENTS
  15. README.md
  16. SECURITY.md
README.md

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image Gopher image by Renee French, licensed under Creative Commons 4.0 Attributions license.

Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.

Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.

Download and Install

Binary Distributions

Official binary distributions are available at https://go.dev/dl/.

After downloading a binary release, visit https://go.dev/doc/install for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.

Contributing

Go is the work of thousands of contributors. We appreciate your help!

To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.

Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.