Verify memory safety of String functions (Challenge 10)#541
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jrey8343 wants to merge 1 commit intomodel-checking:mainfrom
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Verify memory safety of String functions (Challenge 10)#541jrey8343 wants to merge 1 commit intomodel-checking:mainfrom
jrey8343 wants to merge 1 commit intomodel-checking:mainfrom
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Add proof harnesses for all 15 public String functions that are safe abstractions over unsafe code: - UTF-16 decoding: from_utf16le, from_utf16le_lossy, from_utf16be, from_utf16be_lossy - Element operations: pop, remove, remove_matches, retain - Insertion: insert, insert_str - Splitting/draining: split_off, drain, replace_range - Conversion: into_boxed_str, leak All 15 harnesses verified with Kani 0.65.0.
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Summary
Adds 15 Kani verification harnesses proving the memory safety of all functions listed in Challenge 10, covering all unsafe operations in
library/alloc/src/string.rs.Functions verified
from_utf16lecheck_from_utf16lealign_to::<u16>()from_utf16le_lossycheck_from_utf16le_lossyalign_to::<u16>()from_utf16becheck_from_utf16bealign_to::<u16>()from_utf16be_lossycheck_from_utf16be_lossyalign_to::<u16>()popcheck_popset_len()removecheck_str_removeptr::copy+set_lenremove_matchescheck_remove_matchesptr::copy+set_lenin pattern search loopretaincheck_retainptr::copy_nonoverlapping+set_len+Dropguardinsertcheck_insertptr::copy+encode_utf8_raw_unchecked+set_leninsert_strcheck_insert_strptr::copy+ptr::copy_nonoverlapping+set_lensplit_offcheck_split_offfrom_utf8_unchecked+set_lendraincheck_drainget_unchecked+ raw pointer arithmeticreplace_rangecheck_replace_rangeas_mut_vec()+Vec::spliceinto_boxed_strcheck_into_boxed_strfrom_boxed_utf8_uncheckedleakcheck_leakfrom_utf8_unchecked_mutVerification approach
any_ascii_string<N>()generates symbolicStringvalues of 0..N bytes where each byte is constrained to be valid ASCII (<=127), ensuring UTF-8 validity. Used forpop,insert,insert_str,split_off,drain,replace_range,into_boxed_str, andleak.remove,remove_matches, andretainuse concrete strings (e.g.,String::from("abcd")) becauseCharsiterator raw pointer internals cause CBMC memory explosion with symbolic strings.align_to::<u16>()alignment cast anddecode_utf16iteration.#[kani::unwind(6)]for bounded loop unwinding.All 15 harnesses verified locally.
Test plan
kani verify-stdusing-Z loop-contracts --cbmc-args --object-bits 12rustfmt