#5071: GHCi crashes on large alloca/allocaBytes requests
---------------------------------+------------------------------------------
Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.0.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Comment(by guest):
I don't know if Haskell's `alloca` was intended to behave like C's
`alloca`, but this is from the man page for `alloca` on my linux machine:
{{{
RETURN VALUE
The alloca() function returns a pointer to the beginning of the
allocated space.
If the allocation causes stack overflow, program behavior is undefined.
}}}
The following program segfaults for me:
{{{
$ cat alloc.c
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <alloca.h>
int main() {
int *p = alloca(INT_MAX);
printf("p = %p\n", p);
return 0;
}
}}}
What initially attracted me to using `alloca` is that I thought it was
equivalent to the pseudo-code: `bracket malloc free`. Perhaps I had the
wrong expectation and the FFI should be amended to say that `alloca`
requests for too many bytes are undefined like the C variant?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5071#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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