diff options
| author | Mike Pall <mike> | 2022-12-22 00:03:06 +0100 |
|---|---|---|
| committer | Mike Pall <mike> | 2022-12-22 00:03:06 +0100 |
| commit | 8a5e398c52c7f8ca3e1a0e574cc2ba38224b759b (patch) | |
| tree | dae089564f58db2963bae8e3530c1faae104cc61 /src/lj_strscan.c | |
| parent | b2791179ef96d652d00d78d2a8780af690537f6a (diff) | |
| download | luajit2-8a5e398c52c7f8ca3e1a0e574cc2ba38224b759b.tar.gz | |
Avoid negation of signed integers in C that may hold INT*_MIN.
Reported by minoki.
Recent C compilers 'take advantage' of the undefined behavior.
This completely changes the meaning of expressions like (k == -k).
Diffstat (limited to 'src/lj_strscan.c')
| -rw-r--r-- | src/lj_strscan.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/src/lj_strscan.c b/src/lj_strscan.c index 914cfb7a..9e8023b5 100644 --- a/src/lj_strscan.c +++ b/src/lj_strscan.c @@ -124,19 +124,19 @@ static StrScanFmt strscan_hex(const uint8_t *p, TValue *o, case STRSCAN_INT: if (!(opt & STRSCAN_OPT_TONUM) && x < 0x80000000u+neg && !(x == 0 && neg)) { - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~x+1u) : (int32_t)x; return STRSCAN_INT; /* Fast path for 32 bit integers. */ } if (!(opt & STRSCAN_OPT_C)) { fmt = STRSCAN_NUM; break; } /* fallthrough */ case STRSCAN_U32: if (dig > 8) return STRSCAN_ERROR; - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~x+1u) : (int32_t)x; return STRSCAN_U32; case STRSCAN_I64: case STRSCAN_U64: if (dig > 16) return STRSCAN_ERROR; - o->u64 = neg ? (uint64_t)-(int64_t)x : x; + o->u64 = neg ? ~x+1u : x; return fmt; default: break; @@ -168,12 +168,12 @@ static StrScanFmt strscan_oct(const uint8_t *p, TValue *o, /* fallthrough */ case STRSCAN_U32: if ((x >> 32)) return STRSCAN_ERROR; - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~(uint32_t)x+1u) : (int32_t)x; break; default: case STRSCAN_I64: case STRSCAN_U64: - o->u64 = neg ? (uint64_t)-(int64_t)x : x; + o->u64 = neg ? ~x+1u : x; break; } return fmt; @@ -229,18 +229,18 @@ static StrScanFmt strscan_dec(const uint8_t *p, TValue *o, switch (fmt) { case STRSCAN_INT: if (!(opt & STRSCAN_OPT_TONUM) && x < 0x80000000u+neg) { - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~x+1u) : (int32_t)x; return STRSCAN_INT; /* Fast path for 32 bit integers. */ } if (!(opt & STRSCAN_OPT_C)) { fmt = STRSCAN_NUM; goto plainnumber; } /* fallthrough */ case STRSCAN_U32: if ((x >> 32) != 0) return STRSCAN_ERROR; - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~x+1u) : (int32_t)x; return STRSCAN_U32; case STRSCAN_I64: case STRSCAN_U64: - o->u64 = neg ? (uint64_t)-(int64_t)x : x; + o->u64 = neg ? ~x+1u : x; return fmt; default: plainnumber: /* Fast path for plain numbers < 2^63. */ @@ -418,7 +418,7 @@ StrScanFmt lj_strscan_scan(const uint8_t *p, TValue *o, uint32_t opt) if (xx >= STRSCAN_MAXEXP) return STRSCAN_ERROR; p++; } - ex += negx ? -(int32_t)xx : (int32_t)xx; + ex += negx ? (int32_t)(~xx+1u) : (int32_t)xx; } /* Parse suffix. */ @@ -456,7 +456,7 @@ StrScanFmt lj_strscan_scan(const uint8_t *p, TValue *o, uint32_t opt) o->n = -0.0; return STRSCAN_NUM; } else { - o->i = neg ? -(int32_t)x : (int32_t)x; + o->i = neg ? (int32_t)(~x+1u) : (int32_t)x; return STRSCAN_INT; } } |