support large arguments

[RSulzmann]

There is a limit of the argument size in a command line (MAX_ARG_STRLEN = 131071 bytes) .
To support larger sizes, the input to the action code is passed via standard input.

To support also legacy action code (not reading input from stdin), but only if the input size is smaller than the limit, the input is also passed as a command line parameter.

[rabbah]

Closes apache/openwhisk#2542.

@jthomas can you review.

[rabbah]

I suggest that we always do this. That is we migrate all actions to use the stdin path instead of argv[1]. The code above will be a fail safe for all existing actions which will only work up to 128K.

[jthomas]

I agree with this. stdin should be the default. Input can be passed as an argument as well but not if it's larger than 128K.

[rabbah]

We will need to add a test. You can use this example, which I did for swift to test the change.
https://github.com/apache/incubator-openwhisk/compare/master...rabbah:arglist?expand=1#diff-cd4d7cf77b5a623c67fc14b0de34cc1aR165

[jthomas]

LGTM.

[rabbah]

See comments.

[csantanapr]

like @rabbah already said it needs a test

I added a test

[rabbah]

We could have made an addition to the standard tests all the runtimes run (bash, Perl, Swift, python) to check no regressions in the future for the large inputs.

[rabbah]

The if/else could be simpler.

[csantanapr]

I agree and can also read your mind 😉
Send the PR and I will merge

[csantanapr]

We could have made an addition to the standard tests all the runtimes run (bash, Perl, Swift, python) to check no regressions in the future for the large inputs.

Swift? There is no swift in this repo
Though about it but didn’t think there was a need since we are testing the proxy and not the programming language Perl or python, but easy to add you want to do the PR?

[csantanapr]

I think I will add the tests to the std ones don’t worry

[rabbah]

👍 Thanks. I was basically thinking adding a variant of the echo test would do (thestdCodeSamples) with reading/writing from stdin instead of argv[1], and then making the test you added run against that with the 1MB payload part of testEcho(stdCodeSamples).

[csantanapr]

Yep you read my mind 💯