Why does DriverManager.loadDriver() swallow ClassNotFoundException?

[LSantha]

I was looking at core/src/driver/... and found that DriverManager.loadDriver() catches ClassNotFoundException and just returns null without logging anything. This is making it really hard to debug why a driver fails to load — the symptom is just "driver not registered" with no clue as to why.

Looking at the call sites, the catch block at DriverManager.java:142 (or thereabouts) silently swallows it. This seems like a bug — the exception should at least be logged so the user has a chance to figure out what's wrong.

Can you take a look?

[LSantha]

/oc investigate

[LSantha]

/oc investigate

[opencode-agent]

🤖 Investigation Report

Question: Does DriverManager.loadDriver() (or equivalent) silently swallow ClassNotFoundException, and where?

Findings:

• There is no class named DriverManager in the JNode source tree. The only *DriverManager* file is NativeDriverManager.java (a JDBC helper).
• The closest match to the described pattern is AbstractPCIDeviceToDriverMapper.newDriver() (core/src/driver/org/jnode/driver/bus/pci/AbstractPCIDeviceToDriverMapper.java:71-95). It loads a driver class by name, catches ClassNotFoundException at line 86, and returns null at line 94. It does log log.error("Cannot find driver class " + driverClass) but without the exception object (ex), so the stack trace is lost.
• DefaultDeviceManager.configureFinder() (core/src/driver/org/jnode/driver/DefaultDeviceManager.java:177-178) has the same issue — logs a message string but not the exception object.
• DefaultDeviceManager.configureMapper() (line 211-212) is the one correct example — it does include ex in BootLogInstance.get().error("Cannot find mapper class " + className, ex).
• Other files with the same pattern of logging without the exception: FileSystemTypeManager.java:128-129, PartitionTableTypeManager.java:110-111, MouseProtocolHandlerManager.java:157-158.

Root cause: ClassNotFoundException is caught and a message is logged, but the exception object (ex) is omitted from the log.error(...) call in several places. This loses the stack trace, making root-cause debugging difficult.

Suggested fix: Add , ex to the following log.error / BootLogInstance.get().error calls:

File	Line	Current	Fix
AbstractPCIDeviceToDriverMapper.java	87	log.error("Cannot find driver class " + driverClass)	log.error("Cannot find driver class " + driverClass, ex)
DefaultDeviceManager.java	178	BootLogInstance.get().error("Cannot find finder class " + className)	BootLogInstance.get().error("Cannot find finder class " + className, ex)
DefaultDeviceManager.java	180	BootLogInstance.get().error("Cannot access finder class " + className)	BootLogInstance.get().error("Cannot access finder class " + className, ex)
FileSystemTypeManager.java	129	log.error("Cannot load FileSystemType " + className)	log.error("Cannot load FileSystemType " + className, ex)
PartitionTableTypeManager.java	111	log.error("Cannot load PartitionTableType " + className)	log.error("Cannot load PartitionTableType " + className, ex)
MouseProtocolHandlerManager.java	158	log.error("Mouse protocol handler class not found: " + className)	log.error("Mouse protocol handler class not found: " + className, ex)

(Note: AbstractPCIDeviceToDriverMapper.java:91 also omits ex for IllegalAccessException.)

Confidence: medium — the method name is inexact (newDriver vs loadDriver), but the location (core/src/driver/), behavior (ClassNotFoundException → return null), and debugging difficulty all match the report.

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[LSantha]

/oc investigate

[opencode-agent]

🤖 Investigation Report

Question: Does DriverManager.loadDriver() silently swallow ClassNotFoundException, and where?

Findings:

• There is no DriverManager.java or loadDriver() method in JNode — the reported class name is incorrect. The closest behavioral match is AbstractPCIDeviceToDriverMapper.newDriver() in core/src/driver/.
• AbstractPCIDeviceToDriverMapper.newDriver() (core/src/driver/org/jnode/driver/bus/pci/AbstractPCIDeviceToDriverMapper.java:86-87) catches ClassNotFoundException and logs the message string without the exception object ex, losing the stack trace.
• The same file also omits ex for IllegalAccessException at line 90-91.
• DefaultDeviceManager.configureFinder() (core/src/driver/org/jnode/driver/DefaultDeviceManager.java:177-182) omits ex for ClassNotFoundException, IllegalAccessException, and InstantiationException — but configureMapper() (line 211-219) correctly includes ex for all three exceptions, revealing an inconsistency.
• FileSystemTypeManager.createType() (fs/src/fs/org/jnode/fs/service/def/FileSystemTypeManager.java:128-129) omits ex for ClassNotFoundException.
• PartitionTableTypeManager.createType() (fs/src/partitions/org/jnode/partitions/service/def/PartitionTableTypeManager.java:110-111) omits ex for ClassNotFoundException.
• MouseProtocolHandlerManager.add() (core/src/driver/org/jnode/driver/input/MouseProtocolHandlerManager.java:157-158) omits ex for ClassNotFoundException.

Root cause: The ClassNotFoundException catch blocks at 6 locations across 5 files log the message string but omit the exception parameter ex. This discards the stack trace, making root-cause debugging difficult for driver/plugin class-loading failures.

Suggested fix: Add , ex to the following log.error calls (Java 1.6 compatible, no API change):

File	Line	Change
AbstractPCIDeviceToDriverMapper.java	87	log.error("Cannot find driver class " + driverClass, ex)
AbstractPCIDeviceToDriverMapper.java	91	log.error("Cannot access driver class " + driverClass, ex)
DefaultDeviceManager.java	178	BootLogInstance.get().error("Cannot find finder class " + className, ex)
DefaultDeviceManager.java	180	BootLogInstance.get().error("Cannot access finder class " + className, ex)
DefaultDeviceManager.java	182	BootLogInstance.get().error("Cannot instantiate finder class " + className, ex)
FileSystemTypeManager.java	129	log.error("Cannot load FileSystemType " + className, ex)
PartitionTableTypeManager.java	111	log.error("Cannot load PartitionTableType " + className, ex)
MouseProtocolHandlerManager.java	158	log.error("Mouse protocol handler class not found: " + className, ex)

Confidence: high

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