filemax: Fix crash when undoing a page deletion - #88
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Deleting pages from a stack and then pressing Ctrl-Z to undo crashes with a segfault in fseek() with a NULL stream. restorePages() calls restore_page(), which reads each deleted page's chunk data back from disc through max_read_data(), but unlike removePages() it never opens the file first. The stream _fin is left NULL between operations, so the read dereferences a NULL FILE *. Open the file around restore_page(), mirroring how removePages() opens it around free_page(), and close it again afterwards. As a safety net, make max_read_data() and max_write_data() return an error instead of calling fseek() on a NULL stream, so a similar mistake can no longer crash the program. Also drop a stray debug printf() that fired on every restored page. Add a Filemax test that removes a page and then restores it, checking the page count round-trips and the restored page still decodes. Co-developed-by: Claude <noreply@anthropic.com>
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Fix segfault when undoing a page deletion
Deleting pages from a stack (untick the green "keep" arrows) and then
pressing Ctrl-Z to undo crashes with a segfault:
Root cause
restorePages()callsrestore_page(), which reads each deleted page'schunk data back from disc via
max_read_data(). Unlike the matchingremovePages()— which wrapsfree_page()inensure_open()/ensure_closed()—restorePages()never opens the file first._finis NULL between operations, so
fseek(NULL, …)crashes.Fix
restore_page()and close it afterwards,mirroring
removePages().max_read_data()/max_write_data()return anerror instead of calling
fseek()on a NULL stream, so a similaromission can't crash again.
printf()that fired on every restored page.Test
Adds
TestFile::testRemoveRestorePages: removes a page then restoresit, checking the page count round-trips and the restored page still
decodes (this is the path that used to crash).