diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/rt/mod.rs | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/src/libstd/rt/mod.rs b/src/libstd/rt/mod.rs index 42cca73e5e2..fe32a51e81c 100644 --- a/src/libstd/rt/mod.rs +++ b/src/libstd/rt/mod.rs @@ -27,6 +27,7 @@ use marker::Send; use ops::FnOnce; use sys; use thunk::Thunk; +use usize; // Reexport some of our utilities which are expected by other crates. pub use self::util::{default_sched_threads, min_stack, running_on_valgrind}; @@ -78,7 +79,20 @@ fn lang_start(main: *const u8, argc: int, argv: *const *const u8) -> int { // FIXME #11359 we just assume that this thread has a stack of a // certain size, and estimate that there's at most 20KB of stack // frames above our current position. - let my_stack_bottom = my_stack_top + 20000 - OS_DEFAULT_STACK_ESTIMATE; + const TWENTY_KB: uint = 20000; + + // saturating-add to sidestep overflow + let top_plus_spill = if usize::MAX - TWENTY_KB < my_stack_top { + usize::MAX + } else { + my_stack_top + TWENTY_KB + }; + // saturating-sub to sidestep underflow + let my_stack_bottom = if top_plus_spill < OS_DEFAULT_STACK_ESTIMATE { + 0 + } else { + top_plus_spill - OS_DEFAULT_STACK_ESTIMATE + }; let failed = unsafe { // First, make sure we don't trigger any __morestack overflow checks, |