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Add more string edge case tests #632

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Merged
lukewagner merged 2 commits into from
Apr 6, 2026
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Merged

Add more string edge case tests #632

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adfc5bf
add some string test cases
friendlymatthew Apr 3, 2026
094f94c
refine trap msg
friendlymatthew Apr 6, 2026
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97 changes: 97 additions & 0 deletions test/values/strings.wast
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,37 @@
(assert_return (invoke "f1") (str.const "a"))
(assert_return (invoke "f2") (str.const "☃☺️öツ"))

;; empty string with ptr=0, len=0
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
(i32.store (i32.const 0) (i32.const 0))
(i32.store (i32.const 4) (i32.const 0))
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_return (invoke "f") (str.const ""))

;; empty string with non-zero in-bounds ptr, len=0
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
(i32.store (i32.const 0) (i32.const 100))
(i32.store (i32.const 4) (i32.const 0))
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_return (invoke "f") (str.const ""))

;; out-of-bounds pointer traps even with len=0
(component
(core module $M
(memory (export "mem") 1)
Expand All @@ -37,3 +68,69 @@
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_trap (invoke "f") "string pointer/length out of bounds of memory")

;; invalid UTF-8: 0xFF is never valid
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
(i32.store (i32.const 0) (i32.const 8))
(i32.store (i32.const 4) (i32.const 1))
(i32.store8 (i32.const 8) (i32.const 0xff))
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_trap (invoke "f") "invalid utf-8")

;; truncated multibyte UTF-8: leading byte 0xC3 expects a continuation byte
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
(i32.store (i32.const 0) (i32.const 8))
(i32.store (i32.const 4) (i32.const 1))
(i32.store8 (i32.const 8) (i32.const 0xc3))
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_trap (invoke "f") "incomplete utf-8 byte sequence")

;; string at end of memory page boundary
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
;; place "ok" at the very end of the first page (65536 - 2 = 65534)
(i32.store (i32.const 0) (i32.const 65534))
(i32.store (i32.const 4) (i32.const 2))
(i32.store8 (i32.const 65534) (i32.const 111)) ;; 'o'
(i32.store8 (i32.const 65535) (i32.const 107)) ;; 'k'
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_return (invoke "f") (str.const "ok"))

;; string one byte past end of memory traps
(component
(core module $M
(memory (export "mem") 1)
(func (export "f") (result i32)
(i32.store (i32.const 0) (i32.const 65535))
(i32.store (i32.const 4) (i32.const 2))
(i32.store8 (i32.const 65535) (i32.const 111))
(i32.const 0)
)
)
(core instance $m (instantiate $M))
(func (export "f") (result string) (canon lift (core func $m "f") (memory $m "mem")))
)
(assert_trap (invoke "f") "string pointer/length out of bounds of memory")
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