| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * System-dependent key filing operations |
| 4 | * |
| 5 | * (c) 1999 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | /*----- Header files ------------------------------------------------------*/ |
| 29 | |
| 30 | #include <errno.h> |
| 31 | #include <stdio.h> |
| 32 | #include <stdlib.h> |
| 33 | #include <string.h> |
| 34 | |
| 35 | #include <sys/types.h> |
| 36 | #include <sys/time.h> |
| 37 | #include <sys/stat.h> |
| 38 | #include <unistd.h> |
| 39 | #include <fcntl.h> |
| 40 | |
| 41 | #include <mLib/dstr.h> |
| 42 | #include <mLib/lock.h> |
| 43 | |
| 44 | #include "key.h" |
| 45 | |
| 46 | /*----- Main code ---------------------------------------------------------*/ |
| 47 | |
| 48 | /* --- @fdcopy@ --- * |
| 49 | * |
| 50 | * Arguments: @int source@ = source file descriptor |
| 51 | * @int dest@ = destination file descriptor |
| 52 | * |
| 53 | * Returns: Zero if OK, nonzero otherwise. |
| 54 | * |
| 55 | * Use: Copies data from one file descriptor to another. |
| 56 | */ |
| 57 | |
| 58 | static int fdcopy(int source, int dest) |
| 59 | { |
| 60 | char buf[4096]; |
| 61 | char *p; |
| 62 | |
| 63 | if (lseek(source, 0, SEEK_SET) < 0|| |
| 64 | lseek(dest, 0, SEEK_SET) < 0 || |
| 65 | ftruncate(dest, 0) < 0) |
| 66 | return (-1); |
| 67 | for (;;) { |
| 68 | int n = read(source, buf, sizeof(buf)); |
| 69 | if (n < 0) |
| 70 | return (-1); |
| 71 | else if (n == 0) |
| 72 | break; |
| 73 | p = buf; |
| 74 | while (n) { |
| 75 | int nn = write(dest, p, n); |
| 76 | if (nn < 0) |
| 77 | return (-1); |
| 78 | p += nn; |
| 79 | n -= nn; |
| 80 | } |
| 81 | } |
| 82 | return (0); |
| 83 | } |
| 84 | |
| 85 | /* --- @key_save@ --- * |
| 86 | * |
| 87 | * Arguments: @key_file *f@ = pointer to key file block |
| 88 | * |
| 89 | * Returns: A @KWRITE_@ code indicating how well it worked. |
| 90 | * |
| 91 | * Use: Writes a key file's data back to the actual file. This code |
| 92 | * is extremely careful about error handling. It should usually |
| 93 | * be able to back out somewhere sensible, but it can tell when |
| 94 | * it's got itself into a real pickle and starts leaving well |
| 95 | * alone. |
| 96 | * |
| 97 | * Callers, please make sure that you ring alarm bells when this |
| 98 | * function returns @KWRITE_BROKEN@. |
| 99 | */ |
| 100 | |
| 101 | int key_save(key_file *f) |
| 102 | { |
| 103 | dstr n_older = DSTR_INIT, n_old = DSTR_INIT, n_new = DSTR_INIT; |
| 104 | int rc = KWRITE_FAIL; |
| 105 | |
| 106 | if (!(f->f & KF_MODIFIED)) |
| 107 | return (KWRITE_OK); |
| 108 | if (!f->fp) |
| 109 | return (KWRITE_FAIL); |
| 110 | |
| 111 | /* --- Write a new key file out --- * |
| 112 | * |
| 113 | * Check for an error after each key line. This ought to be enough. |
| 114 | * Checking after each individual byte write and @fprintf@ isn't much fun. |
| 115 | */ |
| 116 | |
| 117 | dstr_putf(&n_new, "%s.new", f->name); |
| 118 | |
| 119 | { |
| 120 | key *k; |
| 121 | key_iter i; |
| 122 | FILE *fp; |
| 123 | |
| 124 | if ((fp = fopen(n_new.buf, "w")) == 0) |
| 125 | goto fail_open; |
| 126 | |
| 127 | for (key_mkiter(&i, f); (k = key_next(&i)) != 0; ) { |
| 128 | if (key_extract(f, k, fp, 0)) { |
| 129 | fclose(fp); |
| 130 | goto fail_write; |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | if (fclose(fp)) |
| 135 | goto fail_write; |
| 136 | } |
| 137 | |
| 138 | /* --- Set up the other filenames --- */ |
| 139 | |
| 140 | dstr_putf(&n_older, "%s.older", f->name); |
| 141 | dstr_putf(&n_old, "%s.old", f->name); |
| 142 | |
| 143 | /* --- Move the current backup on one --- * |
| 144 | * |
| 145 | * If the `older' file exists, then we're in need of attention. |
| 146 | */ |
| 147 | |
| 148 | { |
| 149 | struct stat st; |
| 150 | if (stat(n_older.buf, &st) == 0 || errno != ENOENT) { |
| 151 | errno = EEXIST; |
| 152 | rc = KWRITE_BROKEN; |
| 153 | goto fail_shift; |
| 154 | } |
| 155 | if (rename(n_old.buf, n_older.buf) && errno != ENOENT) |
| 156 | goto fail_shift; |
| 157 | } |
| 158 | |
| 159 | /* --- Copy the current file to the backup --- */ |
| 160 | |
| 161 | { |
| 162 | int fd; |
| 163 | if ((fd = open(n_old.buf, O_WRONLY | O_CREAT | O_EXCL, 0600)) < 0) |
| 164 | goto fail_backup; |
| 165 | if (fdcopy(fileno(f->fp), fd)) { |
| 166 | close(fd); |
| 167 | goto fail_backup; |
| 168 | } |
| 169 | if (close(fd)) |
| 170 | goto fail_backup; |
| 171 | } |
| 172 | |
| 173 | /* --- Copy the newly created file to the current one --- * |
| 174 | * |
| 175 | * This is the dangerous bit. |
| 176 | */ |
| 177 | |
| 178 | { |
| 179 | int fd; |
| 180 | if ((fd = open(n_new.buf, O_RDONLY)) < 0) |
| 181 | goto fail_update; |
| 182 | if (fdcopy(fd, fileno(f->fp))) { |
| 183 | close(fd); |
| 184 | goto fail_update; |
| 185 | } |
| 186 | close(fd); |
| 187 | if (fsync(fileno(f->fp))) |
| 188 | goto fail_update; |
| 189 | } |
| 190 | |
| 191 | /* --- Clean up --- * |
| 192 | * |
| 193 | * Remove the `new' file and the `older' backup. Then we're done. |
| 194 | */ |
| 195 | |
| 196 | unlink(n_new.buf); |
| 197 | unlink(n_older.buf); |
| 198 | dstr_destroy(&n_new); |
| 199 | dstr_destroy(&n_old); |
| 200 | dstr_destroy(&n_older); |
| 201 | return (KWRITE_OK); |
| 202 | |
| 203 | /* --- Failure while writing the new key file --- * |
| 204 | * |
| 205 | * I need to copy the backup back. If that fails then I'm really stuffed. |
| 206 | * If not, then I might as well try to get the backups sorted back out |
| 207 | * again. |
| 208 | */ |
| 209 | |
| 210 | fail_update: |
| 211 | { |
| 212 | int fd; |
| 213 | int e = errno; |
| 214 | |
| 215 | if ((fd = open(n_old.buf, O_RDONLY)) < 0) |
| 216 | rc = KWRITE_BROKEN; |
| 217 | else if (fdcopy(fd, fileno(f->fp))) { |
| 218 | close(fd); |
| 219 | rc = KWRITE_BROKEN; |
| 220 | } else { |
| 221 | close(fd); |
| 222 | if (fsync(fileno(f->fp))) |
| 223 | rc = KWRITE_BROKEN; |
| 224 | } |
| 225 | |
| 226 | errno = e; |
| 227 | if (rc == KWRITE_BROKEN) |
| 228 | goto fail_shift; |
| 229 | } |
| 230 | /* Now drop through */ |
| 231 | |
| 232 | /* --- Failure while writing the new backup --- * |
| 233 | * |
| 234 | * The new backup isn't any use. Try to recover the old one. |
| 235 | */ |
| 236 | |
| 237 | fail_backup: |
| 238 | { |
| 239 | int e = errno; |
| 240 | unlink(n_old.buf); |
| 241 | if (rename(n_older.buf, n_old.buf) && errno != ENOENT) |
| 242 | rc = KWRITE_BROKEN; |
| 243 | errno = e; |
| 244 | } |
| 245 | /* Now drop through */ |
| 246 | |
| 247 | /* --- Failure while demoting the current backup --- * |
| 248 | * |
| 249 | * Leave the completed output file there for the operator in case he wants |
| 250 | * to clean up. |
| 251 | */ |
| 252 | |
| 253 | fail_shift: |
| 254 | dstr_destroy(&n_new); |
| 255 | dstr_destroy(&n_old); |
| 256 | dstr_destroy(&n_older); |
| 257 | return (rc); |
| 258 | |
| 259 | /* --- Failure during write of new data --- * |
| 260 | * |
| 261 | * Clean up the new file and return. These errors can never cause |
| 262 | * breakage. |
| 263 | */ |
| 264 | |
| 265 | fail_write: |
| 266 | unlink(n_new.buf); |
| 267 | fail_open: |
| 268 | dstr_destroy(&n_new); |
| 269 | return (rc); |
| 270 | } |
| 271 | |
| 272 | /* --- @key_lockfile@ --- * |
| 273 | * |
| 274 | * Arguments: @key_file *f@ = pointer to file structure to initialize |
| 275 | * @const char *file@ = pointer to the file name |
| 276 | * @unsigned how@ = opening options (@KOPEN_*@). |
| 277 | * |
| 278 | * Returns: Zero if it worked, nonzero otherwise. |
| 279 | * |
| 280 | * Use: Opens a keyfile and stores the information needed for |
| 281 | * continued access in the structure. |
| 282 | * |
| 283 | * If the file is opened with @KOPEN_WRITE@, it's created if |
| 284 | * necessary with read and write permissions for owner only, and |
| 285 | * locked for update while it's open. |
| 286 | * |
| 287 | * This is a system-dependent routine, and only really intended |
| 288 | * for the private use of @key_open@. |
| 289 | */ |
| 290 | |
| 291 | int key_lockfile(key_file *f, const char *file, unsigned how) |
| 292 | { |
| 293 | int of, lf; |
| 294 | const char *ff; |
| 295 | int fd; |
| 296 | |
| 297 | /* --- Handle the magic no-file option --- */ |
| 298 | |
| 299 | if (how & KOPEN_NOFILE) { |
| 300 | f->fp = 0; |
| 301 | return (0); |
| 302 | } |
| 303 | |
| 304 | /* --- Lots of things depend on whether we're writing --- */ |
| 305 | |
| 306 | switch (how & KOPEN_MASK) { |
| 307 | case KOPEN_READ: |
| 308 | of = O_RDONLY; |
| 309 | lf = LOCK_NONEXCL; |
| 310 | ff = "r"; |
| 311 | break; |
| 312 | case KOPEN_WRITE: |
| 313 | of = O_RDWR | O_CREAT; |
| 314 | lf = LOCK_EXCL; |
| 315 | ff = "r+"; |
| 316 | break; |
| 317 | default: |
| 318 | errno = EINVAL; |
| 319 | return (-1); |
| 320 | } |
| 321 | |
| 322 | /* --- Open and lock the file --- */ |
| 323 | |
| 324 | if ((fd = open(file, of, 0600)) < 0) |
| 325 | return (-1); |
| 326 | if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0 || |
| 327 | lock_file(fd, lf) < 0 || |
| 328 | (f->fp = fdopen(fd, ff)) == 0) { |
| 329 | close(fd); |
| 330 | return (-1); |
| 331 | } |
| 332 | |
| 333 | return (0); |
| 334 | } |
| 335 | |
| 336 | /*----- That's all, folks -------------------------------------------------*/ |