Fix illegal memory access while moving gap#19
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jserv merged 2 commits intoOct 10, 2025
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When operations are: open new file -> insert one character -> arrow left -> insert one character -> arrow right -> insert one character -> insert one character. Above cause segmentation fault for undo_clear_redo function executes undo_node_t *node = stack->current->next; the source of problem: gap_ptr return gb->egap+(pos-front_size) when pos is located at [text after gap]. As the result, dest in gap_move also points to [text after gap]. If computes len = dest - gap, will easily cause unecessay move for byte after ebuffer. For example, if dest points to first byte of text after gap, and memory layout is [text before gap][gap][text after gap] -> [1 byte][64Kib-2][1 byte] then len = 64Kib-1. Causing illegal memory access after egap. test: this commit pass the test.
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Improve the test suite accordingly.
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When operations are: open new file -> insert one character -> arrow left -> insert one character ->
arrow right -> insert one character -> insert one character. Above cause segmentation fault for undo_clear_redo function executes undo_node_t *node = stack->current->next;
the source of problem:
gap_ptr return gb->egap+(pos-front_size) when pos is located at [text after gap]. As the result, dest in gap_move also points to [text after gap]. If computes len = dest - gap, will easily cause unecessay move for byte after ebuffer.
For example, if dest points to first byte of text after gap, and memory layout is [text before gap][gap][text after gap] -> [1 byte][64Kib-2][1 byte] then len = 64Kib-1. Causing illegal memory access after egap.
test:
this commit pass the test.