readrec.c revision 169857
1/*- 2 * Copyright (c) 2007 Diomidis Spinellis 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD: head/usr.bin/lastcomm/readrec.c 169857 2007-05-22 06:51:38Z dds $"); 30 31#include <sys/param.h> 32#include <sys/stat.h> 33#include <sys/types.h> 34#include <sys/acct.h> 35 36#include <ctype.h> 37#include <err.h> 38#include <errno.h> 39#include <fcntl.h> 40#include <stddef.h> 41#include <stdio.h> 42#include <stdlib.h> 43#include <string.h> 44 45int readrec_forward(FILE *f, struct acctv2 *av2); 46int readrec_backward(FILE *f, struct acctv2 *av2); 47 48/* 49 * Reverse offsetof: return the offset of field f 50 * from the end of the structure s. 51 */ 52#define roffsetof(s, f) (sizeof(s) - offsetof(s, f)) 53 54/* 55 * Read exactly one record of size size from stream f into ptr. 56 * Failure to read the complete record is considered a file format error, 57 * and will set errno to EFTYPE. 58 * Return 0 on success, EOF on end of file or error. 59 */ 60static int 61fread_record(void *ptr, size_t size, FILE *f) 62{ 63 size_t rv; 64 65 if ((rv = fread(ptr, 1, size, f)) == size) 66 return (0); 67 else if (ferror(f) || rv == 0) 68 return (EOF); 69 else { 70 /* Short read. */ 71 errno = EFTYPE; 72 return (EOF); 73 } 74} 75 76/* 77 * Return the value of a comp_t field. 78 */ 79static float 80decode_comp(comp_t v) 81{ 82 int result, exp; 83 84 result = v & 017777; 85 for (exp = v >> 13; exp; exp--) 86 result <<= 3; 87 return ((double)result / AHZV1); 88} 89 90/* 91 * Read a v1 accounting record stored at the current 92 * position of stream f. 93 * Convert the data to the current record format. 94 * Return EOF on error or end-of-file. 95 */ 96static int 97readrec_v1(FILE *f, struct acctv2 *av2) 98{ 99 struct acctv1 av1; 100 int rv; 101 102 if ((rv = fread_record(&av1, sizeof(av1), f)) == EOF) 103 return (EOF); 104 av2->ac_zero = 0; 105 av2->ac_version = 2; 106 av2->ac_len = av2->ac_len2 = sizeof(*av2); 107 memcpy(av2->ac_comm, av1.ac_comm, AC_COMM_LEN); 108 av2->ac_utime = decode_comp(av1.ac_utime) * 1000000; 109 av2->ac_stime = decode_comp(av1.ac_stime) * 1000000; 110 av2->ac_etime = decode_comp(av1.ac_etime) * 1000000; 111 av2->ac_btime = av1.ac_btime; 112 av2->ac_uid = av1.ac_uid; 113 av2->ac_gid = av1.ac_gid; 114 av2->ac_mem = av1.ac_mem; 115 av2->ac_io = decode_comp(av1.ac_io); 116 av2->ac_tty = av1.ac_tty; 117 av2->ac_flagx = av1.ac_flag | ANVER; 118 return (0); 119} 120 121/* 122 * Read an v2 accounting record stored at the current 123 * position of stream f. 124 * Return EOF on error or end-of-file. 125 */ 126static int 127readrec_v2(FILE *f, struct acctv2 *av2) 128{ 129 return (fread_record(av2, sizeof(*av2), f)); 130} 131 132/* 133 * Read a new-style (post-v1) accounting record stored at 134 * the current position of stream f. 135 * Convert the data to the current record format. 136 * Return EOF on error or end-of-file. 137 */ 138static int 139readrec_vx(FILE *f, struct acctv2 *av2) 140{ 141 uint8_t magic, version; 142 143 if (fread_record(&magic, sizeof(magic), f) == EOF || 144 fread_record(&version, sizeof(version), f) == EOF || 145 ungetc(version, f) == EOF || 146 ungetc(magic, f) == EOF) 147 return (EOF); 148 switch (version) { 149 case 2: 150 return (readrec_v2(f, av2)); 151 152 /* Add handling for more versions here. */ 153 154 default: 155 errno = EFTYPE; 156 return (EOF); 157 } 158} 159 160/* 161 * Read an accounting record stored at the current 162 * position of stream f. 163 * Old-format records are converted to the current record 164 * format. 165 * Return the number of records read (1 or 0 at the end-of-file), 166 * or EOF on error. 167 */ 168int 169readrec_forward(FILE *f, struct acctv2 *av2) 170{ 171 int magic, rv; 172 173 if ((magic = getc(f)) == EOF) 174 return (ferror(f) ? EOF : 0); 175 if (ungetc(magic, f) == EOF) 176 return (EOF); 177 if (magic != 0) 178 /* Old record format. */ 179 rv = readrec_v1(f, av2); 180 else 181 /* New record formats. */ 182 rv = readrec_vx(f, av2); 183 return (rv == EOF ? EOF : 1); 184} 185 186/* 187 * Read an accounting record ending at the current 188 * position of stream f. 189 * Old-format records are converted to the current record 190 * format. 191 * The file pointer is positioned at the beginning of the 192 * record read. 193 * Return the number of records read (1 or 0 at the end-of-file), 194 * or EOF on error. 195 */ 196int 197readrec_backward(FILE *f, struct acctv2 *av2) 198{ 199 off_t pos; 200 int c; 201 uint16_t len; 202 203 if ((pos = ftell(f)) == -1) 204 return (EOF); 205 if (pos == 0) 206 return (0); 207 if (fseek(f, -roffsetof(struct acctv2, ac_trailer), 208 SEEK_CUR) == EOF || 209 (c = getc(f)) == EOF) 210 return (EOF); 211 if (c & ANVER) { 212 /* New record formats. */ 213 if (fseeko(f, pos - roffsetof(struct acctv2, ac_len2), 214 SEEK_SET) == EOF || 215 fread_record(&len, sizeof(len), f) == EOF || 216 fseeko(f, pos - len, SEEK_SET) == EOF || 217 readrec_vx(f, av2) == EOF || 218 fseeko(f, pos - len, SEEK_SET) == EOF) 219 return (EOF); 220 else 221 return (1); 222 } else { 223 /* Old record format. */ 224 if (fseeko(f, pos - sizeof(struct acctv1), SEEK_SET) == EOF || 225 readrec_v1(f, av2) == EOF || 226 fseeko(f, pos - sizeof(struct acctv1), SEEK_SET) == EOF) 227 return (EOF); 228 else 229 return (1); 230 } 231} 232