/* * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #define _GNU_SOURCE #include <unistd.h> #include <sys/syscall.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <errno.h> #include <unistd.h> #include <string.h> #include <stdio.h> static inline ssize_t sys_read(int fd, void *buf, size_t len) { return syscall(SYS_read, fd, buf, len); } int main(void) { char buf1[64]; char buf2[64]; int fd; ssize_t rv; fd = open("/proc/self/syscall", O_RDONLY); if (fd == -1) { if (errno == ENOENT) return 2; return 1; } /* Do direct system call as libc can wrap anything. */ snprintf(buf1, sizeof(buf1), "%ld 0x%lx 0x%lx 0x%lx", (long)SYS_read, (long)fd, (long)buf2, (long)sizeof(buf2)); memset(buf2, 0, sizeof(buf2)); rv = sys_read(fd, buf2, sizeof(buf2)); if (rv < 0) return 1; if (rv < strlen(buf1)) return 1; if (strncmp(buf1, buf2, strlen(buf1)) != 0) return 1; return 0; }