From 8a80f41b779f8da4f9ad937151d0e25f9058023f Mon Sep 17 00:00:00 2001 From: John Kaniarz Date: Wed, 19 Jun 2024 16:51:21 -0400 Subject: [PATCH] Added check for n<0 in SDL_rand_n() --- src/stdlib/SDL_random.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/stdlib/SDL_random.c b/src/stdlib/SDL_random.c index 642f3a72fe..2007431733 100644 --- a/src/stdlib/SDL_random.c +++ b/src/stdlib/SDL_random.c @@ -67,6 +67,14 @@ Sint32 SDL_rand_n(Sint32 n) // fixed point number. Multiply by the 31.0 bit n to get a 31.32 bit // result. Shift right by 32 to get the 31 bit integer that we want. + if (n < 0) { + // The algorithm looks like it works for numbers < 0 but it has an + // infintesimal chance of returning a value out of range. + // Returning -SDL_rand_n(abs(n)) blows up at INT_MIN instead. + // It's easier to just say no. + return 0; + } + // On 32-bit arch, the compiler will optimize to a single 32-bit multiply Uint64 val = (Uint64)SDL_rand_bits() * n; return (Sint32)(val >> 32);