Seeds above 32bit max int. #6898

Blauw67 · 2018-09-11T14:14:01Z

When trying to create a new game with the same seed as an older game (even when it's from the same version), and the seed created with the older game is higher than the 32-bit integer, the one that will be created, will use the 32-bit (2^31 -1) as the seed.

(For example "C:\Program Files\OpenTTD\openttd.exe" -g -G 3584050622 will result in a game with seed 2147483647)

LordAro · 2018-09-11T15:42:28Z

Found the issue:

OpenTTD/src/openttd.cpp

Line 669 in 9496173

case 'G': scanner->generation_seed = atoi(mgo.opt); break;

Specifically, generation_seed is a uint (32 bits), atoi is an int (32 bits).

Apparently it's undefined behaviour when atoi is given a number outside int bounds. Should probably be a strtoul or similar function

Normalize usage of generation_seed across all files Add static_assert() to ensure correct type

Normalize type and parsing of generation_seed across all files Add assert_compile() to ensure correct type

LordAro added good first issue Good for newcomers bug Something isn't working labels Sep 11, 2018

MiguelHorta pushed a commit to MiguelHorta/OpenTTD that referenced this issue Oct 10, 2018

Fix OpenTTD#6898: Replace atoi() with strtoul()

f6e51ef

Normalize usage of generation_seed across all files Add static_assert() to ensure correct type

MiguelHorta pushed a commit to MiguelHorta/OpenTTD that referenced this issue Oct 10, 2018

Fix OpenTTD#6898: Replace atoi() with strtoul()

0a4a426

Normalize type and parsing of generation_seed across all files Add assert_compile() to ensure correct type

MiguelHorta added a commit to MiguelHorta/OpenTTD that referenced this issue Oct 10, 2018

Fix OpenTTD#6898: Replace atoi() with strtoul()

a0f1629

Normalize type and parsing of generation_seed across all files Add assert_compile() to ensure correct type

orudge closed this as completed in e00908f Oct 11, 2018

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Seeds above 32bit max int. #6898

Seeds above 32bit max int. #6898

Blauw67 commented Sep 11, 2018

LordAro commented Sep 11, 2018 •

edited

Seeds above 32bit max int. #6898

Seeds above 32bit max int. #6898

Comments

Blauw67 commented Sep 11, 2018

LordAro commented Sep 11, 2018 • edited

LordAro commented Sep 11, 2018 •

edited