Input Limits

Overview

Implementations MUST enforce limits on input size to prevent resource exhaustion attacks.

Requirements

File Size

Limit	Minimum	Recommended	Maximum
Single file	10 MB	100 MB	1 GB
Total (with includes)	50 MB	500 MB	5 GB

Implementations MUST:

• Check file size before reading into memory
• Reject files exceeding the configured limit
• Report clear error messages with the limit value

Line Length

Limit	Minimum	Recommended
Line length	4 KB	64 KB

Implementations MUST:

• Handle lines up to the limit without truncation
• Reject or truncate lines exceeding the limit
• Not allocate unbounded memory for a single line

Line Count

Limit	Minimum	Recommended
Lines per file	100,000	10,000,000

Include Count

Limit	Minimum	Recommended
Total includes	100	10,000

Implementations MUST:

• Track number of included files
• Reject when limit exceeded
• Count each unique file only once

Configuration

Implementations SHOULD allow configuration of limits:

option "max_file_size" "100MB"
option "max_include_count" "1000"

Or via command-line:

beancount --max-file-size=100MB ledger.beancount

Error Messages

When limits are exceeded, report:

error: File size limit exceeded
  --> large-file.beancount
  |
  = file size: 150 MB
  = limit: 100 MB
  = hint: increase limit with --max-file-size or split into multiple files

Rationale

• 10 MB minimum: Handles typical personal ledgers (10+ years)
• 100 MB recommended: Handles large business ledgers
• 1 GB maximum: Prevents accidental DoS, still allows enterprise use

Test Vectors

Implementations SHOULD pass these tests:

1. Accept file at exactly the limit
2. Reject file 1 byte over the limit
3. Accept total includes at exactly the limit
4. Reject when include count exceeds limit