1 /* 2 * 3 * Copyright (c) Linux Test Project, 2016 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See 13 * the GNU General Public License for more details. 14 */ 15 16 /* 17 * Test Description: 18 * Verify writev() behaviour with partially valid iovec list. 19 * Kernel <4.8 used to shorten write up to first bad invalid 20 * iovec. Starting with 4.8, a writev with short data (under 21 * page size) is likely to get shorten to 0 bytes and return 22 * EFAULT. 23 * 24 * This test doesn't make assumptions how much will write get 25 * shortened. It only tests that file content/offset after 26 * syscall corresponds to return value of writev(). 27 * 28 * See: [RFC] writev() semantics with invalid iovec in the middle 29 * https://marc.info/?l=linux-kernel&m=147388891614289&w=2 30 */ 31 32 #include <errno.h> 33 #include <fcntl.h> 34 #include <stdio.h> 35 #include <sys/mman.h> 36 #include <sys/stat.h> 37 #include <sys/types.h> 38 #include <sys/uio.h> 39 #include "tst_test.h" 40 41 #define TESTFILE "testfile" 42 #define CHUNK 64 43 #define BUFSIZE (CHUNK * 4) 44 45 static void *bad_addr; 46 47 static void test_partially_valid_iovec(int initial_file_offset) 48 { 49 int i, fd; 50 unsigned char buffer[BUFSIZE], fpattern[BUFSIZE], tmp[BUFSIZE]; 51 long off_after; 52 struct iovec wr_iovec[] = { 53 { buffer, CHUNK }, 54 { bad_addr, CHUNK }, 55 { buffer + CHUNK, CHUNK }, 56 { buffer + CHUNK * 2, CHUNK }, 57 }; 58 59 tst_res(TINFO, "starting test with initial file offset: %d ", 60 initial_file_offset); 61 62 for (i = 0; i < BUFSIZE; i++) 63 buffer[i] = i % (CHUNK - 1); 64 65 memset(fpattern, 0xff, BUFSIZE); 66 tst_fill_file(TESTFILE, 0xff, CHUNK, BUFSIZE / CHUNK); 67 68 fd = SAFE_OPEN(TESTFILE, O_RDWR, 0644); 69 SAFE_LSEEK(fd, initial_file_offset, SEEK_SET); 70 TEST(writev(fd, wr_iovec, ARRAY_SIZE(wr_iovec))); 71 off_after = (long) SAFE_LSEEK(fd, 0, SEEK_CUR); 72 73 /* bad errno */ 74 if (TEST_RETURN == -1 && TEST_ERRNO != EFAULT) { 75 tst_res(TFAIL | TTERRNO, "unexpected errno"); 76 SAFE_CLOSE(fd); 77 return; 78 } 79 80 /* nothing has been written */ 81 if (TEST_RETURN == -1 && TEST_ERRNO == EFAULT) { 82 tst_res(TINFO, "got EFAULT"); 83 /* initial file content remains untouched */ 84 SAFE_LSEEK(fd, 0, SEEK_SET); 85 SAFE_READ(1, fd, tmp, BUFSIZE); 86 if (memcmp(tmp, fpattern, BUFSIZE)) 87 tst_res(TFAIL, "file was written to"); 88 else 89 tst_res(TPASS, "file stayed untouched"); 90 91 /* offset hasn't changed */ 92 if (off_after == initial_file_offset) 93 tst_res(TPASS, "offset stayed unchanged"); 94 else 95 tst_res(TFAIL, "offset changed to %ld", 96 off_after); 97 98 SAFE_CLOSE(fd); 99 return; 100 } 101 102 /* writev() wrote more bytes than bytes preceding invalid iovec */ 103 tst_res(TINFO, "writev() has written %ld bytes", TEST_RETURN); 104 if (TEST_RETURN > (long) wr_iovec[0].iov_len) { 105 tst_res(TFAIL, "writev wrote more than expected"); 106 SAFE_CLOSE(fd); 107 return; 108 } 109 110 /* file content matches written bytes */ 111 SAFE_LSEEK(fd, initial_file_offset, SEEK_SET); 112 SAFE_READ(1, fd, tmp, TEST_RETURN); 113 if (memcmp(tmp, wr_iovec[0].iov_base, TEST_RETURN) == 0) { 114 tst_res(TPASS, "file has expected content"); 115 } else { 116 tst_res(TFAIL, "file has unexpected content"); 117 tst_res_hexd(TFAIL, wr_iovec[0].iov_base, TEST_RETURN, 118 "expected:"); 119 tst_res_hexd(TFAIL, tmp, TEST_RETURN, 120 "actual file content:"); 121 } 122 123 /* file offset has been updated according to written bytes */ 124 if (off_after == initial_file_offset + TEST_RETURN) 125 tst_res(TPASS, "offset at %ld as expected", off_after); 126 else 127 tst_res(TFAIL, "offset unexpected %ld", off_after); 128 129 SAFE_CLOSE(fd); 130 } 131 132 static void test_writev(void) 133 { 134 test_partially_valid_iovec(0); 135 test_partially_valid_iovec(CHUNK + 1); 136 test_partially_valid_iovec(getpagesize()); 137 test_partially_valid_iovec(getpagesize() + 1); 138 } 139 140 static void setup(void) 141 { 142 bad_addr = SAFE_MMAP(0, 1, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, 143 0, 0); 144 } 145 146 static struct tst_test test = { 147 .needs_tmpdir = 1, 148 .setup = setup, 149 .test_all = test_writev, 150 }; 151
