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fixed bug with memrchr(NULL, c, 0) #626

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Merged
merged 1 commit into from
Sep 1, 2025
Merged

fixed bug with memrchr(NULL, c, 0) #626

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16 changes: 8 additions & 8 deletions src/libc/memrchr.src
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Original file line number Diff line number Diff line change
Expand Up @@ -5,20 +5,20 @@
public _memrchr

_memrchr:
ld iy, 0
ld iy, -1
add iy, sp
ld hl, (iy + 3)
ld bc, (iy + 9)
dec bc
ld bc, (iy + 10)
sbc hl, hl
add hl, bc
jr c, .ret_zero
inc bc
ld a, (iy + 6)
jr nc, .ret_zero
ld de, (iy + 4)
add hl, de
ld a, (iy + 7)
cpdr
inc hl
ret z ; found match
; or a, a ; carry won't be set unless (ptr + size) wraps-around (which is UB)
.ret_zero:
; return NULL
or a, a
sbc hl, hl
ret
7 changes: 7 additions & 0 deletions test/standalone/asprintf_fprintf/src/main.c
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Expand Up @@ -24,6 +24,9 @@

#define SINK (char*)0xE40000

/* pass NULL into functions without triggering -Wnonnull */
extern void* NULL_ptr;

// prevents Clang from replacing function calls with builtins
#if 1

Expand Down Expand Up @@ -543,6 +546,9 @@ int strncmp_test(void) {
}

int memrchr_test(void) {
C(T_memrchr(NULL_ptr, 0x00, 0) == NULL_ptr);
C(T_memrchr(NULL_ptr, 0xFF, 0) == NULL_ptr);

C(T_memrchr(SINK, 0x00, 0) == NULL);
C(T_memrchr(SINK, 0x00, 1) == SINK);
C(T_memrchr(SINK, 0xFF, 1) == NULL);
Expand All @@ -565,6 +571,7 @@ int memrchr_test(void) {
C(T_memrchr(test, 'G', test_strlen) == NULL);
C(T_memrchr(test, 'G', test_size) == NULL);
C(T_memrchr(test0, 'G', sizeof(test0)) == test0);

return 0;
}

Expand Down
6 changes: 6 additions & 0 deletions test/standalone/asprintf_fprintf/src/rename.asm
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Expand Up @@ -20,6 +20,12 @@ _T_stpcpy := _stpcpy

_T_bzero := _bzero

section .rodata

public _NULL_ptr
_NULL_ptr:
db $00, $00, $00

extern _memset, _memcpy, _memcmp, _memccpy, _mempcpy, _memrchr
extern _strlen, _strcmp, _strncmp, _stpcpy
extern _bzero
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