ALLOCA(3) BSD Library Functions Manual ALLOCA(3)NAMEalloca — memory allocator
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
void *
alloca(size_t size);
DESCRIPTION
The alloca() function allocates size bytes of space in the stack frame of
the caller. This temporary space is automatically freed on return.
RETURN VALUES
The alloca() function returns a pointer to the beginning of the allocated
space. If the allocation failed, a NULL pointer is returned.
SEE ALSObrk(2), calloc(3), getpagesize(3), malloc(3), realloc(3)CAVEATS
Few limitations can be mentioned:
· The alloca() function is machine dependent; its use is discouraged.
· The alloca() function is slightly unsafe because it cannot ensure
that the pointer returned points to a valid and usable block of mem‐
ory. The allocation made may exceed the bounds of the stack, or even
go further into other objects in memory, and alloca() cannot deter‐
mine such an error. Avoid alloca() with large unbounded allocations.
· Since alloca() modifies the stack at runtime, it causes problems to
certain security features. See security(7) for a discussion.
BSD March 21, 2011 BSD