操作系统设计.zip

#include "kernel/param.h" #include "kernel/types.h" #include "kernel/stat.h" #include "user/user.h" #include "kernel/fs.h" #include "kernel/fcntl.h" #include "kernel/syscall.h" #include "kernel/memlayout.h" #include "kernel/riscv.h" // // Tests xv6 system calls. usertests without arguments runs them all // and usertests <name> runs <name> test. The test runner creates for // each test a process and based on the exit status of the process, // the test runner reports "OK" or "FAILED". Some tests result in // kernel printing usertrap messages, which can be ignored if test // prints "OK". // #define BUFSZ (MAXOPBLOCKS+2)*BSIZE char buf[BUFSZ]; char name[3]; // what if you pass ridiculous pointers to system calls // that read user memory with copyin? void copyin(char *s) { uint64 addrs[] = { 0x80000000LL, 0xffffffffffffffff }; for(int ai = 0; ai < 2; ai++){ uint64 addr = addrs[ai]; int fd = open("copyin1", O_CREATE|O_WRONLY); if(fd < 0){ printf("open(copyin1) failed\n"); exit(1); } int n = write(fd, (void*)addr, 8192); if(n >= 0){ printf("write(fd, %p, 8192) returned %d, not -1\n", addr, n); exit(1); } close(fd); unlink("copyin1"); n = write(1, (char*)addr, 8192); if(n > 0){ printf("write(1, %p, 8192) returned %d, not -1 or 0\n", addr, n); exit(1); } int fds[2]; if(pipe(fds) < 0){ printf("pipe() failed\n"); exit(1); } n = write(fds[1], (char*)addr, 8192); if(n > 0){ printf("write(pipe, %p, 8192) returned %d, not -1 or 0\n", addr, n); exit(1); } close(fds[0]); close(fds[1]); } } // what if you pass ridiculous pointers to system calls // that write user memory with copyout? void copyout(char *s) { uint64 addrs[] = { 0x80000000LL, 0xffffffffffffffff }; for(int ai = 0; ai < 2; ai++){ uint64 addr = addrs[ai]; int fd = open("README", 0); if(fd < 0){ printf("open(README) failed\n"); exit(1); } int n = read(fd, (void*)addr, 8192); if(n > 0){ printf("read(fd, %p, 8192) returned %d, not -1 or 0\n", addr, n); exit(1); } close(fd); int fds[2]; if(pipe(fds) < 0){ printf("pipe() failed\n"); exit(1); } n = write(fds[1], "x", 1); if(n != 1){ printf("pipe write failed\n"); exit(1); } n = read(fds[0], (void*)addr, 8192); if(n > 0){ printf("read(pipe, %p, 8192) returned %d, not -1 or 0\n", addr, n); exit(1); } close(fds[0]); close(fds[1]); } } // what if you pass ridiculous string pointers to system calls? void copyinstr1(char *s) { uint64 addrs[] = { 0x80000000LL, 0xffffffffffffffff }; for(int ai = 0; ai < 2; ai++){ uint64 addr = addrs[ai]; int fd = open((char *)addr, O_CREATE|O_WRONLY); if(fd >= 0){ printf("open(%p) returned %d, not -1\n", addr, fd); exit(1); } } } // what if a string system call argument is exactly the size // of the kernel buffer it is copied into, so that the null // would fall just beyond the end of the kernel buffer? void copyinstr2(char *s) { char b[MAXPATH+1]; for(int i = 0; i < MAXPATH; i++) b[i] = 'x'; b[MAXPATH] = '\0'; int ret = unlink(b); if(ret != -1){ printf("unlink(%s) returned %d, not -1\n", b, ret); exit(1); } int fd = open(b, O_CREATE | O_WRONLY); if(fd != -1){ printf("open(%s) returned %d, not -1\n", b, fd); exit(1); } ret = link(b, b); if(ret != -1){ printf("link(%s, %s) returned %d, not -1\n", b, b, ret); exit(1); } char *args[] = { "xx", 0 }; ret = exec(b, args); if(ret != -1){ printf("exec(%s) returned %d, not -1\n", b, fd); exit(1); } int pid = fork(); if(pid < 0){ printf("fork failed\n"); exit(1); } if(pid == 0){ static char big[PGSIZE+1]; for(int i = 0; i < PGSIZE; i++) big[i] = 'x'; big[PGSIZE] = '\0'; char *args2[] = { big, big, big, 0 }; ret = exec("echo", args2); if(ret != -1){ printf("exec(echo, BIG) returned %d, not -1\n", fd); exit(1); } exit(747); // OK } int st = 0; wait(&st); if(st != 747){ printf("exec(echo, BIG) succeeded, should have failed\n"); exit(1); } } // what if a string argument crosses over the end of last user page? void copyinstr3(char *s) { sbrk(8192); uint64 top = (uint64) sbrk(0); if((top % PGSIZE) != 0){ sbrk(PGSIZE - (top % PGSIZE)); } top = (uint64) sbrk(0); if(top % PGSIZE){ printf("oops\n"); exit(1); } char *b = (char *) (top - 1); *b = 'x'; int ret = unlink(b); if(ret != -1){ printf("unlink(%s) returned %d, not -1\n", b, ret); exit(1); } int fd = open(b, O_CREATE | O_WRONLY); if(fd != -1){ printf("open(%s) returned %d, not -1\n", b, fd); exit(1); } ret = link(b, b); if(ret != -1){ printf("link(%s, %s) returned %d, not -1\n", b, b, ret); exit(1); } char *args[] = { "xx", 0 }; ret = exec(b, args); if(ret != -1){ printf("exec(%s) returned %d, not -1\n", b, fd); exit(1); } } // test O_TRUNC. void truncate1(char *s) { char buf[32]; unlink("truncfile"); int fd1 = open("truncfile", O_CREATE|O_WRONLY|O_TRUNC); write(fd1, "abcd", 4); close(fd1); int fd2 = open("truncfile", O_RDONLY); int n = read(fd2, buf, sizeof(buf)); if(n != 4){ printf("%s: read %d bytes, wanted 4\n", s, n); exit(1); } fd1 = open("truncfile", O_WRONLY|O_TRUNC); int fd3 = open("truncfile", O_RDONLY); n = read(fd3, buf, sizeof(buf)); if(n != 0){ printf("aaa fd3=%d\n", fd3); printf("%s: read %d bytes, wanted 0\n", s, n); exit(1); } n = read(fd2, buf, sizeof(buf)); if(n != 0){ printf("bbb fd2=%d\n", fd2); printf("%s: read %d bytes, wanted 0\n", s, n); exit(1); } write(fd1, "abcdef", 6); n = read(fd3, buf, sizeof(buf)); if(n != 6){ printf("%s: read %d bytes, wanted 6\n", s, n); exit(1); } n = read(fd2, buf, sizeof(buf)); if(n != 2){ printf("%s: read %d bytes, wanted 2\n", s, n); exit(1); } unlink("truncfile"); close(fd1); close(fd2); close(fd3); } // write to an open FD whose file has just been truncated. // this causes a write at an offset beyond the end of the file. // such writes fail on xv6 (unlike POSIX) but at least // they don't crash. void truncate2(char *s) { unlink("truncfile"); int fd1 = open("truncfile", O_CREATE|O_TRUNC|O_WRONLY); write(fd1, "abcd", 4); int fd2 = open("truncfile", O_TRUNC|O_WRONLY); int n = write(fd1, "x", 1); if(n != -1){ printf("%s: write returned %d, expected -1\n", s, n); exit(1); } unlink("truncfile"); close(fd1); close(fd2); } void truncate3(char *s) { int pid, xstatus; close(open("truncfile", O_CREATE|O_TRUNC|O_WRONLY)); pid = fork(); if(pid < 0){ printf("%s: fork failed\n", s); exit(1); } if(pid == 0){ for(int i = 0; i < 100; i++){ char buf[32]; int fd = open("truncfile", O_WRONLY); if(fd < 0){ printf("%s: open failed\n", s); exit(1); } int n = write(fd, "1234567890", 10); if(n != 10){ printf("%s: write got %d, expected 10\n", s, n); exit(1); } close(fd); fd = open("truncfile", O_RDONLY); read(fd, buf, sizeof(buf)); close(fd); } exit(0); } for(int i = 0; i < 150; i++){ int fd = open("truncfile", O_CREATE|O_WRONLY|O_TRUNC); if(fd < 0){ printf("%s: open failed\n", s); exit(1); } int n = write(fd, "xxx", 3); if(n != 3){ printf("%s: write got %d, expected 3\n", s, n); exit(1); } close(fd); } wait(&xstatus); unlink("truncfile"); exit(xstatus); } // does chdir() call iput(p->cwd) in a transaction? void iputtest(char *s) { if(mkdir("iputdir") < 0){ printf("%s: mkdir failed\n", s); exit(1); } if(chdir("iputdir") < 0){ printf("%s: chdir iputdir fa