[NativeAOT] Migrate runtime utility logging to printf

[simonrozsival]

Summary

Continue the printf-style native logging migration started by #12140.

This stacked PR converts formatted logging in NativeAOT-reachable shared runtime utilities to the log_*f() and Helpers::abort_applicationf() APIs introduced by #12140, avoiding additional std::format instantiations in those paths.

Base/dependency: #12155 must merge first. This PR targets dev/simonrozsival/nativeaot-config-printf-logging rather than main so its diff remains limited to this runtime utility migration.

Part of #12139.

Scope

The change is deliberately limited to four files that are compiled into the Android NativeAOT host:

• src/native/clr/include/runtime-base/util.hh
• src/native/clr/runtime-base/util.cc
• src/native/clr/runtime-base/android-system-shared.cc
• src/native/clr/host/host-shared.cc

These files do not overlap the currently open sibling work:

• [NativeAOT] Use POSIX primitives for GC bridge processing #12141 — POSIX GC bridge synchronization;
• [NativeAOT] Reduce owning C++ standard library state #12142 — owning logging/path state and source-location parsing;
• [NativeAOT] Use indexed temporary peers in GC bridge #12145 — indexed temporary-peer storage.

Changes

Runtime and environment utilities

• migrate file-stat, directory-creation, fopen, chmod, and fchmod diagnostics to printf-style logging;
• migrate environment-variable set/create diagnostics while preserving bounded std::string_view output through %.*s;
• preserve null-safe output for raw C-string inputs through optional_string().

Memory-mapped APK diagnostics

• replace the std::format allocation in the fatal mmap() error path with Helpers::abort_applicationf();
• migrate the detailed mmap range/length diagnostic to %p, %zu, %d, and %.*s formatting;
• migrate the debug-only non-ELF diagnostic without assuming that its std::string_view is NUL-terminated.

Android system properties

• migrate the property-buffer size warning using the correct size_t format;
• migrate invalid debug.mono.max_grefc values while preserving the compile-time property-name length;
• migrate the effective maximum-gref count using the correct long format.

Shared host diagnostics

• migrate Java-class-name lookup failures, including pointer output, to printf-style logging.

Formatting and behavior preservation

• raw pointers use %p, are explicitly passed as void*, and retain the existing %-8p minimum-width alignment;
• size_t uses %zu, long uses %ld, and descriptors use %d; existing mmap lengths retain their %-12zu alignment;
• non-owning strings use %.*s with an explicit length;
• debug/info category gating remains inside the [Native] Add printf-style native logging #12140 helpers;
• warning/error/fatal messages remain unconditional, matching the existing logging behavior;
• no logging category, error path, JNI behavior, or control flow is changed.

Non-goals

• This PR does not change the logging implementation introduced in [Native] Add printf-style native logging #12140.
• It does not touch GC bridge files or the files changed by [NativeAOT] Use POSIX primitives for GC bridge processing #12141, [NativeAOT] Reduce owning C++ standard library state #12142, or [NativeAOT] Use indexed temporary peers in GC bridge #12145.
• It does not migrate gref/lref line construction in os-bridge.cc; that path also writes the formatted text to files and needs a separate design.
• It does not attempt to remove all remaining std::format use in one change.

Validation

• git diff --check;
• no overlap with the file sets changed by [NativeAOT] Use POSIX primitives for GC bridge processing #12141, [NativeAOT] Reduce owning C++ standard library state #12142, or [NativeAOT] Use indexed temporary peers in GC bridge #12145;
• NDK Clang C++23 syntax compilation of all 36 Android arm64 Release NativeAOT compile variants;
• NDK Clang C++23 syntax compilation of all 38 Android arm64 Release CoreCLR compile variants;
• focused read-only review of printf format types, std::string_view lengths, pointer conversions, category semantics, and varargs use.

The higher-level native project builds were also attempted, but the local Gradle 9.4.1 distribution failed while starting the unrelated manifestmerger build, before native compilation. The direct checks above use the repository-generated production NDK compile commands and generated headers.

[Copilot]

Pull request overview

This PR continues the NativeAOT libc++ reduction work by migrating remaining formatted logging in NativeAOT-reachable shared runtime utilities away from std::format/{}-style logging and onto the printf-checked log_*f() and Helpers::abort_applicationf() APIs introduced in the stacked dependency PR #12140.

Changes:

• Convert runtime utility and environment diagnostics to log_*f() with bounded %.*s for std::string_view and null-safe optional_string() for const char*.
• Replace a fatal mmap() failure path’s std::format allocation with Helpers::abort_applicationf() and migrate detailed mmap diagnostics to printf formatting.
• Migrate Android system-property and shared host (JNI class-name lookup) diagnostics to log_*f() with correct format specifiers.

Show a summary per file

File	Description
src/native/clr/runtime-base/util.cc	Migrates directory creation, fopen, and chmod/fchmod error logging to log_*f().
src/native/clr/runtime-base/android-system-shared.cc	Migrates system property warnings and max-gref override diagnostics to log_warnf() with correct size_t/long formats.
src/native/clr/include/runtime-base/util.hh	Migrates env-var and mmap-related diagnostics to log_*f() / abort_applicationf(), using bounded %.*s formatting.
src/native/clr/host/host-shared.cc	Migrates Java class-name lookup failures to log_errorf() (including %p).

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 0

[jonathanpeppers]

/review

[github-actions]

✅ Android PR Reviewer completed successfully!

[github-actions]

🤖 Review Summary — ⚠️ Needs Changes (minor)

Verdict: ⚠️ Needs Changes (one minor observation) · Errors: 0 · Warnings: 0 · Suggestions: 1

This is a well-scoped, mechanical migration of formatted native logging from std::format/log_* to the printf-style log_*f() / Helpers::abort_applicationf() helpers introduced by #12140, limited to four NativeAOT-reachable runtime utility files. I reviewed the four in-scope files (the remaining files in the diff belong to the stacked base #12140).

What I verified

• Format-specifier correctness — %zu for size_t, %ld for the long gref count, %d for fd, %p with explicit void* casts, and %.*s with an explicit static_cast<int>(length()) + .data() for every std::string_view. All log_*f/abort_applicationf helpers carry __attribute__((format(printf, ...))), so type mismatches are compile-time errors — the PR's per-variant NDK syntax checks cover these.
• NUL-safety — non-owning string_views correctly use %.*s with a bounded length rather than %s on a possibly non-terminated .data(); raw C-strings are wrapped in optional_string(). The set_environment_variable warn path is now null-safe via optional_string(name) (an improvement over the previous {} on a raw pointer).
• Behavior preservation — category gating (debug/info) stays inside the helpers; warn/error/fatal remain unconditional; no control-flow, JNI, or error-path changes.

Observation

• 💡 The mmap log_infof diagnostic dropped the original field-width/alignment specifiers ({:<8p}, {:<12}) — see the inline comment. Cosmetic, but a real change to log column alignment versus the "formatting preserved" claim.

Notes

• mergeable_state is blocked and the PR depends on #12140 merging first (and targets the stacked branch), as documented in the description — not a code issue.

Nice, careful work — the varargs/string_view length handling is exactly right.

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