The PostScript Language Reference (3rd ed., §3.7.3 "Save and Restore")
has `restore` reset composite objects in local VM to their values at the
`save`. The reader only restored the graphics state, so dictionary
entries changed between `save` and `restore` stayed changed: a program
that counts its open saves in a dictionary and refuses to go past a depth
stopped after that many saves in sequence, and the file fell back to its
preview. EPS files with many images, each drawn between `save` and
`restore`, are a likely case of #505; its reporter hasn't sent a file, so
this is part of it.
- While a `save` is open, `def`, `store`, `put`, `undef` and dictionary
`copy` keep each entry's old value in a journal (counted against the
memory budget); `restore` undoes it, newest change first, down to its
save. A save restored already, itself or through an outer one, is no
longer valid (`invalidrestore`, §3.7.3).
- `cachestatus` reports a device's cache sizes (chapter 8) instead of
zeros: its last value, the most bytes one cached glyph may take, is what
programs divide by.
- Tests (programs written from the reference): 100 saves counted in a
dictionary under a depth limit, each dictionary change undone, saves
restored twice, `cachestatus`'s glyph limit. Mutation-checked: without
the journal or with a zero `cachestatus` the test fails. The import fuzz
vocabulary has saves and restores around dictionary changes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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