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fix: make --ext-str-file lazy via importstr - #1035

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He-Pin:fix/cli-ext-str-file-missing
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He-Pin wants to merge 1 commit into
databricks:masterfrom
He-Pin:fix/cli-ext-str-file-missing

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@He-Pin

@He-Pin He-Pin commented Jun 24, 2026 •

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Motivation

--ext-str-file eagerly read the file during CLI argument parsing, causing a crash when the file was missing — even if the external variable was never used by the Jsonnet program. Reference implementations (C++ jsonnet, go-jsonnet, jrsonnet) defer the file read until std.extVar is evaluated.

Implementation --ext-str-file missing.json (unused)
C++ jsonnet 0.22.0 exit 0
go-jsonnet 0.22.0 exit 0
jrsonnet 0.5.0-pre99 exit 0
sjsonnet master crash: NoSuchFileException
this PR exit 0

Modification

  • Store file-backed string bindings as importstr @'path' code instead of eagerly reading via os.read.
  • File read is deferred until std.extVar is evaluated, using the normal Jsonnet import mechanism.
  • Quote escaping via v.replace("'", "''") matches go-jsonnet's verbatim string literal convention.
  • Stdin (- or /dev/stdin) remains eager since stdin cannot be lazily reopened.
  • Add @unused annotation to the wd parameter in parseBindings since it's no longer used after making file reads lazy.
  • Add golden tests for used-missing-file and unused-missing-file scenarios.

Result

  • Unused missing files succeed (exit 0), matching reference implementations.
  • Used missing files fail at evaluation time with a clear Couldn't import file error and proper stack trace.
  • Net performance improvement: unused file-backed bindings pay zero I/O cost.

@He-Pin
He-Pin force-pushed the fix/cli-ext-str-file-missing branch from 874ab83 to 4c353e4 Compare June 25, 2026 04:48
Motivation: --ext-str-file eagerly read files even when the binding was unused.

Modification: Model file-backed ext-str bindings through importstr while preserving existing CLI compatibility and tests.

Result: Missing ext-str files are evaluated lazily and fail only when referenced.
@He-Pin

He-Pin commented Jun 28, 2026

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Superseded by combined CLI PR #1032

@He-Pin He-Pin closed this Jun 28, 2026
stephenamar-db pushed a commit that referenced this pull request Jun 28, 2026
…y bindings (#1032)

## Motivation

Several CLI error paths leaked Java exception names
(`NoSuchFileException`, `InvalidPathException`, `upickle.core.Abort`) or
stack traces to end users. The `-V` short flag was ambiguously bound to
`--ext-str`, `--ext-code`, and `--tla-code`. The `--string` flag
produced internal errors for non-string results instead of a clean type
mismatch message. Binding file paths with invalid characters (e.g. null
bytes) were silently accepted. Reference implementations (C++ jsonnet,
go-jsonnet, jrsonnet) reserve `-V` exclusively for `--ext-str`.

This PR combines the following fixes into a single cohesive CLI
hardening change:

| Original PR | Fix |
| --- | --- |
| #1032 | Reserve `-V` exclusively for `--ext-str` |
| #1034 | Report undefined CLI binding env vars with clean error |
| #1035 | Make `--ext-str-file`/`--ext-code-file` lazy via
importstr/import |
| #1036 | Report missing input files without stack traces |
| #1038 | Report output file write failures cleanly |
| #1039 | Fix `--string` non-string error reporting |

## Modification

### Config / CLI parsing
- Remove `short = 'V'` from `--ext-code` and `--tla-code` `@arg`
annotations in `Config.scala`
- Keep `short = 'V'` on `--ext-str` only
- Update README help snapshot

### Error handling (`SjsonnetMainBase.scala`)
- Add `CliError` class with no stack trace for clean CLI error messages
- Add `handleRenderError` to wrap Jsonnet evaluation errors
- Add `handleWriteFile` to wrap file I/O errors with
C++/go-jsonnet-style messages
- Rewrite `parseBindings` to use `HashMap` with eager
`InvalidPathException` validation
- Make `--ext-str-file` and `--ext-code-file` lazy
(`importstr`/`import`) while still validating path syntax eagerly
- Add clean type error for `--string` with non-string results (matching
C++/go-jsonnet format)
- Wrap output file write and multi/yaml-stream render paths with error
handling

### Tests
- 18 new CLI integration tests covering all error paths
- `ConfigTests` verifies `-V` binds only to `--ext-str`
- 24 new test resource files (jsonnet inputs + golden outputs)

## Result

- All CLI errors produce clean messages matching C++/go-jsonnet
conventions
- `-V` binds only to `--ext-str`, matching reference implementations
- `--string` rejects non-string types with clear `expected string
result, got: <type>` error
- Malformed binding file paths fail eagerly with clean error
- Unused `--ext-str-file` bindings are lazy (file not read unless
referenced)
- 45/45 MainTests pass, 0 regressions in full test suite

## CLI Superset Status

sjsonnet is now a superset of go-jsonnet and C++ jsonnet CLI features,
with these extras:
- `--yaml-out`, `--yaml-debug`, `--debug-importer`, `--debug-stats`
- `--profile`, `--strict`, `--preserve-order`, `--indent`
- `--fatal-warnings`, `--throw-error-for-invalid-sets`
- `--max-stack`, `--max-parser-recursion-depth`
- `--reverse-jpaths-priority`, `--no-trailing-newline`
- `--broken-assertion-logic` (backwards compat)
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