LD_PRELOAD for capping the revision number reported by the uname syscall

uname.c

/*
 * LD_PRELOAD that caps the revision reported by uname to 255.
 *
 * Compile:
 *     gcc -shared -fpic uname.c -ldl -o uname.so
 * Usage example:
 *     LD_PRELOAD='/path/to/uname.so' uname -r
 */
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdlib.h>
#include <sys/utsname.h>
static int (*orig_uname)(struct utsname *buf);
int uname(struct utsname *buf) {
    char *str;
    int ret;
    int vers;
    if (!orig_uname) {
        orig_uname = dlsym(RTLD_NEXT, "uname");
    }
    ret = orig_uname(buf);
    if (ret == 0 && buf && buf->release) {
        for (vers = 0, str = buf->release; *str && vers < 2; ++str) {
            if (*str == '.') {
                ++vers;
            }
        }
        if (vers == 2 && *str) {
            vers = atoi(str);
            if (vers > 255) {
                *str++ = '2';
                *str++ = '5';
                *str++ = '5';
                while (*str >= '0' && *str <= '9') {
                    *str++ = '-';
                }
            }
        }
    }
    return ret;
};