Logging

The Interposer can write a detailed access log showing every file and registry operation it intercepts. This log is useful for diagnosing redirect problems, discovering what paths a game uses, and verifying that virtual registry entries are being served correctly.

Enabling the Log

Configure logging in the Logging section of .interposer\Config.yml:

Logging:
  Files: true
  Registry: true
  Downloads: true

Key	Type	Default	Description
`Files`	bool	`false`	Log file open and attribute operations.
`Registry`	bool	`false`	Log registry open, read, write, and delete operations.
`Downloads`	bool	`true`	Log file downloads from FastDL

Logs are written automatically to .interposer\Logs\<timestamp>.log — one file per session, no path configuration required. Each session log begins with a header:

# === Session started 2025-03-14 12:00:00 ===

Log Format

Each line follows this structure:

YYYY-MM-DD HH:MM:SS  [VERB]  <path>  [->  <redirected-path>]

The -> portion only appears when a path was changed — for example, when a file redirect matches or a FastDL file is served from the overlay cache.

Log Verbs

File Operations

Verb	Meaning
`[FILE READ]`	A file was opened for reading via `CreateFileW/A`.
`[FILE WRITE]`	A file was opened for writing via `CreateFileW/A`.
`[FILE R/W]`	A file was opened for both reading and writing.
`[FILE ATTR]`	`GetFileAttributesW/A` was called on a path.
`[FILE REDIRECT]`	A file open or attribute query was redirected by a rule. The line shows the original path and the destination path separated by `->`.
`[FILE FIND]`	`FindFirstFileW/A` was called on a path.
`[DLL LOAD]`	A DLL was loaded via `LoadLibraryW/A` or `LoadLibraryExW/A`.
`[FILE OVERLAY]`	A file open was served from the FastDL overlay cache instead of the game directory.

FastDL Operations

Verb	Meaning
`[FASTDL]`	A file was checked against or downloaded from the FastDL server. The path shows the URL and the local destination separated by `->`.

Registry Operations

Verb	Meaning
`[REG OPEN]`	A registry key was opened via `RegOpenKeyExW/A`.
`[REG CREATE]`	A registry key was opened or created via `RegCreateKeyExW/A`.
`[REG READ]`	A registry value was queried via `RegQueryValueExW/A`.
`[REG WRITE]`	A registry value was written via `RegSetValueExW/A`.
`[REG DELETE]`	A registry key or value was deleted.
`[REG ENUM]`	Registry subkeys or values were enumerated.
`[REG QUERY]`	Key metadata was queried via `RegQueryInfoKeyW/A`.

Example Log Output

# === Session started 2025-03-14 12:00:00 ===
2025-03-14 12:00:01  [FILE READ]    C:\Games\MyGame\config.cfg
2025-03-14 12:00:01  [FILE REDIRECT]  C:\Games\MyGame\Saves\profile.dat  ->  C:\Users\Pat\AppData\Roaming\MyGame\Saves\profile.dat
2025-03-14 12:00:01  [FILE READ]    C:\Users\Pat\AppData\Roaming\MyGame\Saves\profile.dat
2025-03-14 12:00:02  [REG OPEN]     HKEY_LOCAL_MACHINE\SOFTWARE\MyGame\1.0
2025-03-14 12:00:02  [REG READ]     HKEY_LOCAL_MACHINE\SOFTWARE\MyGame\1.0\PlayerName
2025-03-14 12:00:02  [FASTDL]       http://fastdl.lan/baseq3/maps/q3dm1.bsp  ->  C:\Games\Quake3\.interposer\Downloads\baseq3\maps\q3dm1.bsp

Using Logs to Diagnose Problems

Finding what paths a game uses: Enable Files: true, run the game briefly, then search the log for paths that look like save directories, config files, or hard-coded installation paths.

Checking if a redirect fired: Look for [FILE REDIRECT] entries. If you expect a redirect but don't see one, the path did not match your regex pattern — copy the exact path from a [FILE READ] or [FILE ATTR] entry and test your pattern against it.

Verifying virtual registry: Enable Registry: true. Registry operations on keys that exist in .interposer\Registry.reg are served from memory and will still appear in the log — a [REG READ] line confirms the hook is active.

Registry key paths are uppercased in the log to normalize comparisons. This is expected behavior.

Enabling the Log​

Log Format​

Log Verbs​

File Operations​

FastDL Operations​

Registry Operations​

Example Log Output​

Using Logs to Diagnose Problems​