OP-001: Read a byte range from a caller-supplied path

ReadFile is invoked over the FileService route on SAIF.Services.WCF.Services.FileService; this page documents the process end to end, from route dispatch to the message the caller receives.

Field	Value
Operation ID	OP-001
Trigger	Caller invokes ReadFile over the FileService route.
Entry operation	ReadFile
Owning component	SAIF.Services.WCF.Services.FileService.ReadFile
Inputs	Request message parts listed below
Outputs	The requested byte range from the file at path.
Failure behavior	Generic SOAP fault, per Faults and error pipeline

Request and response

Direction	Element	Type	Declared in	Notes
Request	path	string	BCL (System)	Absolute or relative filesystem path to read; not validated or constrained. (Yes)
Request	byteLength	int	BCL (System)	Number of bytes to allocate and read into the returned buffer. (Yes)
Response	byte[]	byte[]	BCL (System)	The requested byte range from the file at path.

Steps

1. Allocate new byte[byteLength] with no validation of byteLength against the real file length, so a byteLength larger than the file yields a trailing run of zero bytes and a byteLength of zero yields an empty array (BR-WCF-003).
2. Call File.OpenRead(path).Read(result, 0, byteLength) directly against the caller-supplied path with no canonicalization, containment check, or authorization; the stream is not disposed and the return value of Read is discarded (BR-WCF-004).
3. On failure: a filesystem exception (IOException, UnauthorizedAccessException, FileNotFoundException) is logged by the installed error handler and surfaced to the caller as a generic SOAP fault with exception detail included.
4. Return the buffer.

Process flow

The following diagram visualizes this process's control flow.

flowchart TD
    A["Allocate fixed-length buffer"]
    B["Read byte range from file into buffer"]
    C["Return the buffer."]
    A --> B
    B --> C

Transaction and side effects

Aspect	Finding
Unit of work	None
Commit point	Not applicable — no unit of work is opened
Records written	None
Downstream calls	None
Shared state touched	None
Repeat-call behavior	Re-reads the same bytes; no state is mutated

Logging

Surface	Written content
ErrorLogErrorHandler → LogService	Failure-path exception logging only, carrying method signature, calling user and exception detail; see Faults and error pipeline

Faults and error handling

Failure	Fault type the caller receives	Produced by	Source
Filesystem exception (IOException, UnauthorizedAccessException, FileNotFoundException)	Generic SOAP fault	The ErrorLogErrorHandler installed by [LogErrorBehavior]	src/WCF/SAIF.Services.WCF.Host/Services/FileService.cs

Authorization

Requirement	Enforced by	Source	Applies to
None in code	IIS authentication on the deployment (see Activation and hosting)	src/WCF/SAIF.Services.WCF.Host/Services/FileService.cs	This operation

Related documentation

• Index
• Overview
• Architecture
• Activation and hosting
• Operations
• Faults and error pipeline
• Authentication and authorization
• Dependencies
• Configuration
• Operations and processes
• Business rules
• Data model
• Operational runbook
• Tech debt

Note: Statements marked with * were inferred from code structure, naming conventions, or contextual evidence where direct confirmation was not available in source artifacts. Statements marked with ** could not be confirmed; treat as unknown until verified.

Sources

• src/WCF/SAIF.Services.WCF.Host/Services/FileService.cs