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| author | Peter Stephenson <pws@users.sourceforge.net> | 2012-09-06 18:22:30 +0000 |
|---|---|---|
| committer | Peter Stephenson <pws@users.sourceforge.net> | 2012-09-06 18:22:30 +0000 |
| commit | 361e1716729a34d19aa8bace4e6be44c295c3e1d (patch) | |
| tree | c9a6d68e2f0028a10f8d6088592d9f6073be8d0b /Src/math.c | |
| parent | 1f5ef83f0f3aea0597ef3db7a05970420646bfdc (diff) | |
| download | zsh-361e1716729a34d19aa8bace4e6be44c295c3e1d.tar.gz zsh-361e1716729a34d19aa8bace4e6be44c295c3e1d.tar.xz zsh-361e1716729a34d19aa8bace4e6be44c295c3e1d.zip | |
30656: prevent SIGFPE in division by -1 by multiplying instead
Diffstat (limited to 'Src/math.c')
| -rw-r--r-- | Src/math.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/Src/math.c b/Src/math.c index cca521098..c7d384019 100644 --- a/Src/math.c +++ b/Src/math.c @@ -1053,14 +1053,34 @@ op(int what) return; if (c.type == MN_FLOAT) c.u.d = a.u.d / b.u.d; - else - c.u.l = a.u.l / b.u.l; + else { + /* + * Avoid exception when dividing the smallest + * negative integer by -1. Always treat it the + * same as multiplication. This still doesn't give + * numerically the right answer in two's complement, + * but treating both these in the same way seems + * reasonable. + */ + if (b.u.l == -1) + c.u.l = - a.u.l; + else + c.u.l = a.u.l / b.u.l; + } break; case MOD: case MODEQ: if (!notzero(b)) return; - c.u.l = a.u.l % b.u.l; + /* + * Avoid exception as above. + * Any integer mod -1 is the same as any integer mod 1 + * i.e. zero. + */ + if (b.u.l == -1) + c.u.l = 0; + else + c.u.l = a.u.l % b.u.l; break; case PLUS: case PLUSEQ: |