%q format specifier not supported in sprintf funtion

[pkkhokhar]

Hi team,

We're hitting an issue where the %q format verb in Rego's sprintf function isn't being handled correctly by the WASM runtime. In standard OPA (non-WASM), %q wraps a string value in double quotes and escapes special characters, but when the same policy is evaluated via the WASM build, it fails.

Example:

package example

result := sprintf("requested %q is invalid", ["String"])

Expected output (standard OPA):
"requested "String" is invalid"

Actual output (WASM):
[throws exception]

for %s
result := sprintf("requested %s is invalid", ["String"])

output for both wasm and standard OPA:
"requested String is invalid"

We're currently working around this by switching %q to %s in our policies, but it would be great to have %q supported natively since it's part of the standard Rego sprintf spec. Could you let us know if support for %q is on the roadmap?

version: 1.0.2

Thanks!

[andreaTP]

Hi @pkkhokhar and thanks for your interest in the project.

I'm open to review a PR improving this aspect, it should be extending this function:

opa-java-wasm/core/src/main/java/com/styra/opa/wasm/builtins/String.java

Line 14 in 521a8e3

private static JsonNode sprintfImpl(OpaWasm instance, JsonNode operand0, JsonNode operand1) {

and adding tests covering the change here:
https://github.com/StyraOSS/opa-java-wasm/blob/main/core/src/test/java/com/styra/opa/wasm/OpaStringBuiltinsTest.java

Are you willing to give it a shot 🙂 ?

[pkkhokhar]

sure

[andreaTP]

@pkkhokhar I just released 1.0.4 containing the fixes to the issues you pointed out.

Thanks for taking the time to report those 🙏

Let me know how it goes!