unix/windows inconsistency of uv_spawn errors

[oktal3700]

On unix, uv_spawn always returns an error code if it failed to spawn the child process.

On windows, whether or not uv_spawn returns an error code on failure depends upon the cause of the failure: some kinds of failures return an error code, other kinds return zero (e.g. file not found). Therefore user code can continue in the belief that there was no error, when in fact there was an error. In these cases, the error is saved in spawn_error, which is a private field of uv_process_t, so user code needs to special-case its error handling on windows.

[bnoordhuis]

/cc @piscisaureus

[piscisaureus]

@bnoordhuis Is it actually true that unix always returns the error immediately?
If I'm reading the code correctly, execve failure will set process->errno but uv_spawn will still return 0.

[bnoordhuis]

Is it actually true that unix always returns the error immediately?

Only sometimes, when the call to fork() fails, for example.