Find CBaseEntity_TakeDamageOld

Locate CBaseEntity::TakeDamageOld in CS2 server.dll / libserver.so using IDA Pro MCP tools.

Method

1. Find the Self-Identifying Warning String

mcp__ida-pro-mcp__find_regex pattern="TakeDamageOld: damagetype"

There are two closely related warning strings (one for GetDamagePosition() == VectorWS::vZero, one for GetDamageForce() == Vector::vZero); either works as an anchor since both are printed from inside the same function. Use "CBaseEntity::TakeDamageOld: damagetype %d with info.GetDamageForce() == Vector::vZero".

Linux 14168 reference: the string is at 0x982d40 (the GetDamagePosition variant is at 0x97a258).

2. Get the Referencing Function

mcp__ida-pro-mcp__xrefs_to addr="0x982d40"

The string has exactly one xref; its containing function is CBaseEntity::TakeDamageOld.

Linux 14168 reference: 0x982d40 is referenced from 0xd4c387, inside the function starting at 0xd4c280 (size 0xd15).

3. Sanity-Check the Candidate

mcp__ida-pro-mcp__decompile addr="0xd4c280"

Confirm the decompilation is consistent with TakeDamageOld's known role: takes this plus a CTakeDamageInfo-like structure/handle and additional damage-position/force parameters, validates the damage-force/position vectors are non-zero (emitting the anchor warning otherwise), and applies health reduction, armor absorption, and damage-event bookkeeping. The candidate's prologue also has a distinctive pxor xmm0, xmm0 (66 0F EF C0) immediately after the push rbp, used to zero-initialize a local vector/float before the standard mov rbp, rsp — a useful secondary fingerprint alongside the string anchor.

4. Generate Function Signature

ALWAYS Use SKILL /generate-signature-for-function with addr=0xd4c280 to generate a robust and unique func_sig.

Linux 14168 reference: generated signature is 55 66 0F EF C0 48 89 E5 41 57 41 56 41 55 49 89 FD 31 FF — already unique across the binary at this length.

5. Write IDA Analysis Output as YAML

ALWAYS Use SKILL /write-func-as-yaml to write the analysis results.

Required parameters:

• func_name: CBaseEntity_TakeDamageOld
• func_addr: 0xd4c280
• func_sig: The validated signature from step 4

Function Characteristics

• Purpose: Legacy/compat damage-application entry point on CBaseEntity. Validates the incoming damage info's force/position vectors (warning if either is exactly zero for a damage type that expects a nonzero value), then applies health/armor reduction and damage-event bookkeeping.
• Binary: server.dll / libserver.so
• Parameters: (this, damage info handle/pointer, double, float, ...) (observed decompiled shape: (_QWORD *a1, __int64 a2, void **a3, double a4, float a5)).
• Return value: __int64 (result/status, exact meaning not confirmed beyond "not a simple bool").

Discovery Strategy

1. TakeDamageOld prints a self-identifying warning message (embedding its own qualified name, "CBaseEntity::TakeDamageOld: ...") when it detects an invalid zero damage-force/position vector — this kind of self-naming assert string is an extremely reliable, low-ambiguity anchor since the function name is baked directly into the string.
2. The string has a single xref, so its containing function is unambiguous.
3. The candidate's parameter shape and the distinctive early pxor xmm0, xmm0 in its prologue corroborate the identification.

This is robust because the anchor string literally contains the fully-qualified function name, making misidentification essentially impossible as long as the string survives (which self-documenting assert/warning strings reliably do across recompiles).

Output YAML Format

The output YAML filename depends on the platform:

• server.dll -> CBaseEntity_TakeDamageOld.windows.yaml
• libserver.so -> CBaseEntity_TakeDamageOld.linux.yaml

Fields: func_name, func_va, func_rva, func_size, func_sig.