Very Computer

1. size of argument list can be larger than ARG_MAX?

As I understand
The size of environment variable and the size of argument list, i.e.
strlen(envp[0]) + strlen(envp[1]) + .. + strlen(argv[0]) + strlen(argv[1]) + ..
can not be larger than ARG_MAX, which is 1048320 on Solaris.

By using env -i, none of environment variables are used, so
the size of argument list can not be larger than ARG_MAX,
which is 1048320 on Solaris.

However the following example can be compiled and run with
env -i ./a.out
And this shows that the size of argument list can be
1048355+6=1048461. What is the matter?

I run different tests, and all show that the size of argument list can be
larger than ARG_MAX, but how much larger is different.

Please help me to understand this issue, thanks.

#include <stdlib.h>
#include <string.h>

#ifndef _ARG_MAX
#define _ARG_MAX 1048355
#endif

int
main(int argc, char **argv, char **envp)
{
    char *arg = malloc((size_t) _ARG_MAX);
    memset(arg, ' ', _ARG_MAX);

    execlp("/bin/ls", arg, '\0');
    perror("exec");

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