Refactor createdump

[eduardo-vp]

Summary

Refactor createdump so the process-inspection and dump-writing code that can be shared with a linked NativeAOT createdump lives under src/coreclr/debug/createdump/shared.

This PR is preparatory refactoring only. It does not enable linked createdump for NativeAOT.

Changes

• Split process initialization, thread snapshots, memory-map enumeration, dump-region selection, option parsing, and dump naming into shared implementations.
• Keep external createdump's DAC integration and std::set-based region storage in CrashInfo while exposing only the operations required by the shared algorithms.
• Add lightweight shared DynamicArray and owned-string utilities that do not require standard-library containers.
• Make the ELF writer generic over the module-mapping and dump-region containers, allowing external createdump to use std::set and a future linked implementation to use DynamicArray without copying regions.
• Separate opening a dump from writing it and retain the existing ELF and Mach-O writer paths.
• Preserve existing external createdump behavior, including dump naming, diagnostics, crash metadata, thread contexts, and partial-file cleanup.

The runtime-diagnostics pipeline was run for this commit and the dump tests pass.

Note

This PR description was generated with GitHub Copilot.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Failed dump writes now leave truncated files behind instead of deleting them.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Remove partially written core files after write failures · New
• Correct malformed field comment · New

What changed in this PR

Refactors createdump by separating process/thread snapshots, shared dump-writing logic, and platform-specific orchestration.

Changes:

• Introduces shared process, thread, memory-region, and utility abstractions.
• Reworks ELF/Mach-O writers around captured snapshots.
• Moves common parsing, naming, and lifecycle logic into shared sources.

File	Description
threadinfounix.cpp	Uses captured thread snapshots.
threadinfomac.cpp	Moves Mach thread capture into snapshots.
threadinfo.h	Delegates thread state to snapshots.
threadinfo.cpp	Updates snapshot-backed access.
shared/​threadsnapshot.h	Defines portable thread snapshots.
shared/​threadsnapshot.cpp	Captures Unix registers.
shared/​specialdiaginfo.h	Shares diagnostic dump metadata.
shared/​processinfo.h	Defines captured process state.
shared/​memoryregion.h	Adds movable region storage.
shared/​dumpwritermacho.h	Shares Mach-O writer declarations.
shared/​dumpwritermacho.cpp	Updates Mach-O thread serialization.
shared/​dumpwriterelf.inl	Generalizes ELF dump writing.
shared/​dumpwriterelf.h	Defines snapshot-based ELF writer.
shared/​dumpwriterelf.cpp	Writes ELF process and thread notes.
shared/​dumpwriter.h	Selects the platform writer.
shared/​dumpwriter.cpp	Shares writer lifecycle and metadata.
shared/​dumpname.cpp	Adds bounded dump-name formatting.
shared/​createdumpunixcore.cpp	Implements Unix process initialization.
shared/​createdumpcore.h	Defines shared createdump contracts.
shared/​createdumpcore.cpp	Shares parsing and diagnostics.
shared/​crashinfounixcore.cpp	Captures Linux process mappings.
shared/​crashinfocore.cpp	Shares dump-region selection.
shared/​coreutils.h	Adds no-STL strings and arrays.
dumpwritermacho.h	Removes relocated declarations.
createdumpwindows.cpp	Uses bounded name formatting.
createdumpunix.cpp	Orchestrates the new snapshot flow.
createdumpmain.cpp	Uses shared parsing and defaults.
createdump.h	Includes shared core definitions.
crashinfounix.cpp	Delegates process capture.
crashinfomac.cpp	Integrates macOS snapshots.
crashinfo.h	References shared process state.
crashinfo.cpp	Populates from process snapshots.
CMakeLists.txt	Builds the relocated shared sources.

[eduardo-vp]

/azp run runtime-diagnostics

[azure-pipelines]

Azure Pipelines:
1 pipeline(s) were filtered out due to trigger conditions.

[Copilot]

🔵 Needs a closer look

Allocation failures can silently produce incomplete module mappings and apparently successful dumps.

0 open findings

2 resolved since last review

• Remove partially written core files after write failures
• Correct malformed field comment

Previously missed (2)

In code that hasn't changed since last review

Propagate module mapping allocation failure

src/​coreclr/​debug/​createdump/​crashinfo.cpp:435

AddOrReplaceModuleMapping now returns false when allocating the owned filename fails, but this caller only traces the failure and continues. That allows dump generation to succeed with a missing or stale module mapping. Propagate the failure so the existing GatherCrashInfo error path aborts the dump.

Propagate segment filename allocation failure

src/​coreclr/​debug/​createdump/​crashinfomac.cpp:341

SetFileName can fail on OOM, but returning from this void visitor merely skips the segment and lets dump creation report success with an incomplete module map. Propagate the failure through segment enumeration or fail fast instead of silently continuing.

This issue also appears on line 368 of the same file.

🧠 Review effort: Balanced

[Copilot]

🔵 Needs a closer look

Value-taking command-line options can dereference a missing argument and crash createdump.

0 open findings

Previously missed (1)

In code that hasn't changed since last review

Validate arguments before parsing value-taking options

src/​coreclr/​debug/​createdump/​shared/​createdumpcore.cpp:116

Validate that each value-taking option has a following argument before incrementing argv. For example, invoking createdump --signal currently calls atoi(nullptr) and can crash instead of reporting invalid usage. The same check is needed for -f/--name, --crashthread, --code, --errno, --address, --exception-record, and -l/--logtofile.

🧠 Review effort: Balanced