fix: Windows large file support and binary-safe downloads

[jiuker]

fix #208

Fixes two Windows (LLP64) issues reported via the VCPKG port: binary file corruption on download and 32-bit 'long' overflow for files larger than 2 GiB.

Binary-safe downloads:

• DownloadObject: open the temp output stream with std::ios::binary. On Windows the default text mode translates newlines and treats 0x1A as EOF, corrupting downloaded binary content (e.g. zip archives).

Large file support (LLP64: 'long' is strictly 32-bit on Windows):

• SelectResult (types.h) and the parser in select.cc: bytes_scanned / bytes_processed / bytes_returned switch from 'long int' to 'long long', and std::stol to std::stoll
• StatObject (baseclient.cc): parse the content-length header with std::stoll so resp.size (size_t) is not truncated above 2 GiB
• ComposeSource (args.h/args.cc): object_size_ member and its assignment switch from 'long' to 'long long' so composing sources larger than 2 GiB does not overflow

No behavioral change on LP64 platforms (Linux/macOS), where 'long' is already 64-bit.

Files changed: include/miniocpp/args.h, include/miniocpp/types.h, src/args.cc, src/baseclient.cc, src/client.cc, src/select.cc

Summary by CodeRabbit

• Bug Fixes
  • Improved support for large object sizes and Select-operation metrics with expanded numeric range handling.
  • Enhanced parsing of large content-length and event metric values.
  • Empty metric values are now represented as unavailable instead of misleading placeholder values.
  • Fixed object downloads to reliably write data in binary format across platforms.

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Review details

⚙️ Run configuration

Configuration used: Organization UI

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Run ID: c7e07a33-6fab-46e1-88d1-820a704cd4af

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Reviewing files that changed from the base of the PR and between a788fe3 and 1d9fe92.

📒 Files selected for processing (1)

• tests/tests.cc

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: f141675d-d0b1-4411-a608-9b78a6740b81

📥 Commits

Reviewing files that changed from the base of the PR and between 9e2ce43 and a788fe3.

📒 Files selected for processing (4)

• include/miniocpp/args.h
• include/miniocpp/types.h
• src/args.cc
• src/select.cc

---

📝 Walkthrough

Walkthrough

The change replaces sentinel-based size values with optional types, uses 64-bit parsing for object and Select metrics, and opens temporary download files in binary mode.

Changes

Large-file and binary compatibility

Layer / File(s)	Summary
Optional object-size handling include/miniocpp/args.h, src/args.cc, src/baseclient.cc	ComposeSource::object_size_ uses std::optional<size_t>. Header construction and initialization checks use optional-value presence. StatObject parses content-length with std::stoll.
Optional Select metrics include/miniocpp/types.h, src/select.cc	SelectResult metrics and Select event counters use std::optional<long long>. Empty XML values remain unset, and present values use std::stoll.
Binary temporary downloads src/client.cc	Temporary download files open with std::ios::binary.

Estimated code review effort: 2 (Simple) | ~10 minutes

Mergeability Score: ⚪ Minimal · up to a788f

The PR fixes Windows binary downloads and large-file handling; the SelectResult API/ABI representation change should be documented for consumers, but no actionable merge-blocking risk remains.

Suggested reviewers: harshavardhana

Poem

A rabbit counts each byte with care,
Wide values travel everywhere.
Empty fields stay clearly bare,
Binary files keep their form,
Hop safely through the Windows storm.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the Windows large-file and binary-download fixes in the changeset.
Linked Issues check	✅ Passed	The changes implement the linked issue requirements for binary-safe downloads and 64-bit file-size parsing and storage [#208].
Out of Scope Changes check	✅ Passed	All changes directly support the linked issue objectives and no unrelated code changes are evident.

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Actionable comments posted: 3

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@include/miniocpp/args.h`:
- Line 385: Replace ComposeSource::object_size_’s -1 sentinel with
std::optional<size_t>, initialize it empty, and set it when BuildHeaders
succeeds. Update ComposeSource::ObjectSize() to check has_value() and return the
stored size through the existing size_t API without signed-to-unsigned
conversion.

In `@include/miniocpp/types.h`:
- Around line 296-298: Update include/miniocpp/types.h at lines 296-298 and
305-309 to include <optional> and change the three public Select metric fields
and corresponding constructor parameters to std::optional<long long>. Update
src/select.cc lines 198-212 to leave each metric unset when its XML text is
empty and assign the parsed long long value otherwise.

In `@src/select.cc`:
- Around line 198-212: Add focused test coverage for SelectHandler::DataFunction
by supplying a synthetic Stats event whose BytesScanned, BytesProcessed, and
BytesReturned values all exceed INT32_MAX, then assert the callback receives the
exact long long values. Keep the test independent of large objects and ensure it
would detect any regression from std::stoll to std::stol, particularly on
Windows.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: ced86126-1a6c-4cd9-9d7c-2a8a831768b9

📥 Commits

Reviewing files that changed from the base of the PR and between e764b82 and 9e2ce43.

📒 Files selected for processing (6)

• include/miniocpp/args.h
• include/miniocpp/types.h
• src/args.cc
• src/baseclient.cc
• src/client.cc
• src/select.cc