Upstream was changed:
long cmdlen = get_arg_max() * sizeof(char);
where get_arg_max is defined as:
/*
* SC_ARG_MAX used to return the maximum size a command line can be
* however changes to the kernel mean this can be bigger than we can
* alloc. Clamp it to 128kB like xargs and friends do
* Should also not be smaller than POSIX_ARG_MAX which is 4096
*/
static size_t get_arg_max(void)
{
#define MIN_ARG_SIZE 4096u
#define MAX_ARG_SIZE (128u * 1024u)
size_t val = sysconf(_SC_ARG_MAX);
if (val < MIN_ARG_SIZE)
val = MIN_ARG_SIZE;
if (val > MAX_ARG_SIZE)
val = MAX_ARG_SIZE;
return val;
}