src/shared/specifier.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <errno.h>
   4 #include <stdbool.h>
   5 #include <stddef.h>
   6 #include <stdlib.h>
   7 #include <sys/utsname.h>
   8
   9 #include "sd-id128.h"
  10
  11 #include "alloc-util.h"
  12 #include "architecture.h"
  13 #include "chase.h"
  14 #include "fd-util.h"
  15 #include "format-util.h"
  16 #include "fs-util.h"
  17 #include "hostname-util.h"
  18 #include "id128-util.h"
  19 #include "macro.h"
  20 #include "os-util.h"
  21 #include "path-lookup.h"
  22 #include "path-util.h"
  23 #include "specifier.h"
  24 #include "string-util.h"
  25 #include "strv.h"
  26 #include "user-util.h"
  27
  28 /*
  29  * Generic infrastructure for replacing %x style specifiers in
  30  * strings. Will call a callback for each replacement.
  31  */
  32
  33 /* Any ASCII character or digit: our pool of potential specifiers,
  34  * and "%" used for escaping. */
  35 #define POSSIBLE_SPECIFIERS ALPHANUMERICAL "%"
  36
  37 int specifier_printf(const char *text, size_t max_length, const Specifier table[], const char *root, const void *userdata, char **ret) {
  38         _cleanup_free_ char *result = NULL;
  39         bool percent = false;
  40         size_t l;
  41         char *t;
  42         int r;
  43
  44         assert(ret);
  45         assert(text);
  46         assert(table);
  47
  48         l = strlen(text);
  49         if (!GREEDY_REALLOC(result, l + 1))
  50                 return -ENOMEM;
  51         t = result;
  52
  53         for (const char *f = text; *f != '\0'; f++, l--) {
  54                 if (percent) {
  55                         percent = false;
  56
  57                         if (*f == '%')
  58                                 *(t++) = '%';
  59                         else {
  60                                 const Specifier *i;
  61
  62                                 for (i = table; i->specifier; i++)
  63                                         if (i->specifier == *f)
  64                                                 break;
  65
  66                                 if (i->lookup) {
  67                                         _cleanup_free_ char *w = NULL;
  68                                         size_t k, j;
  69
  70                                         r = i->lookup(i->specifier, i->data, root, userdata, &w);
  71                                         if (r < 0)
  72                                                 return r;
  73                                         if (isempty(w))
  74                                                 continue;
  75
  76                                         j = t - result;
  77                                         k = strlen(w);
  78
  79                                         if (!GREEDY_REALLOC(result, j + k + l + 1))
  80                                                 return -ENOMEM;
  81                                         t = mempcpy(result + j, w, k);
  82                                 } else if (strchr(POSSIBLE_SPECIFIERS, *f))
  83                                         /* Oops, an unknown specifier. */
  84                                         return -EBADSLT;
  85                                 else {
  86                                         *(t++) = '%';
  87                                         *(t++) = *f;
  88                                 }
  89                         }
  90                 } else if (*f == '%')
  91                         percent = true;
  92                 else
  93                         *(t++) = *f;
  94
  95                 if ((size_t) (t - result) > max_length)
  96                         return -ENAMETOOLONG;
  97         }
  98
  99         /* If string ended with a stray %, also end with % */
 100         if (percent) {
 101                 *(t++) = '%';
 102                 if ((size_t) (t - result) > max_length)
 103                         return -ENAMETOOLONG;
 104         }
 105         *(t++) = 0;
 106
 107         *ret = TAKE_PTR(result);
 108         return 0;
 109 }
 110
 111 /* Generic handler for simple string replacements */
 112
 113 int specifier_string(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 114         return strdup_to(ASSERT_PTR(ret), empty_to_null(data));
 115 }
 116
 117 int specifier_real_path(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 118         const char *path = data;
 119
 120         assert(ret);
 121
 122         if (!path)
 123                 return -ENOENT;
 124
 125         return chase(path, root, 0, ret, NULL);
 126 }
 127
 128 int specifier_real_directory(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 129         _cleanup_free_ char *path = NULL;
 130         int r;
 131
 132         assert(ret);
 133
 134         r = specifier_real_path(specifier, data, root, userdata, &path);
 135         if (r < 0)
 136                 return r;
 137
 138         assert(path);
 139         return path_extract_directory(path, ret);
 140 }
 141
 142 int specifier_id128(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 143         const sd_id128_t *id = ASSERT_PTR(data);
 144         char *n;
 145
 146         n = new(char, SD_ID128_STRING_MAX);
 147         if (!n)
 148                 return -ENOMEM;
 149
 150         *ret = sd_id128_to_string(*id, n);
 151         return 0;
 152 }
 153
 154 int specifier_uuid(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 155         const sd_id128_t *id = ASSERT_PTR(data);
 156         char *n;
 157
 158         n = new(char, SD_ID128_UUID_STRING_MAX);
 159         if (!n)
 160                 return -ENOMEM;
 161
 162         *ret = sd_id128_to_uuid_string(*id, n);
 163         return 0;
 164 }
 165
 166 int specifier_uint64(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 167         const uint64_t *n = ASSERT_PTR(data);
 168
 169         return asprintf(ret, "%" PRIu64, *n) < 0 ? -ENOMEM : 0;
 170 }
 171
 172 int specifier_machine_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 173         sd_id128_t id;
 174         int r;
 175
 176         assert(ret);
 177
 178         r = id128_get_machine(root, &id);
 179         if (r < 0) /* Translate error for missing /etc/machine-id file to EUNATCH. */
 180                 return r == -ENOENT ? -EUNATCH : r;
 181
 182         return specifier_id128(specifier, &id, root, userdata, ret);
 183 }
 184
 185 int specifier_boot_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 186         sd_id128_t id;
 187         int r;
 188
 189         assert(ret);
 190
 191         r = sd_id128_get_boot(&id);
 192         if (r < 0)
 193                 return r;
 194
 195         return specifier_id128(specifier, &id, root, userdata, ret);
 196 }
 197
 198 int specifier_hostname(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 199         char *n;
 200
 201         assert(ret);
 202
 203         n = gethostname_malloc();
 204         if (!n)
 205                 return -ENOMEM;
 206
 207         *ret = n;
 208         return 0;
 209 }
 210
 211 int specifier_short_hostname(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 212         char *n;
 213
 214         assert(ret);
 215
 216         n = gethostname_short_malloc();
 217         if (!n)
 218                 return -ENOMEM;
 219
 220         *ret = n;
 221         return 0;
 222 }
 223
 224 int specifier_pretty_hostname(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 225         char *n = NULL;
 226
 227         assert(ret);
 228
 229         if (get_pretty_hostname(&n) < 0) {
 230                 n = gethostname_short_malloc();
 231                 if (!n)
 232                         return -ENOMEM;
 233         }
 234
 235         *ret = n;
 236         return 0;
 237 }
 238
 239 int specifier_kernel_release(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 240         struct utsname uts;
 241
 242         assert(ret);
 243
 244         if (uname(&uts) < 0)
 245                 return -errno;
 246
 247         return strdup_to(ret, uts.release);
 248 }
 249
 250 int specifier_architecture(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 251         return strdup_to(ASSERT_PTR(ret),
 252                          architecture_to_string(uname_architecture()));
 253 }
 254
 255 /* Note: fields in /etc/os-release might quite possibly be missing, even if everything is entirely valid
 256  * otherwise. We'll return an empty value or NULL in that case from the functions below. But if the
 257  * os-release file is missing, we'll return -EUNATCH. This means that something is seriously wrong with the
 258  * installation. */
 259
 260 static int parse_os_release_specifier(const char *root, const char *id, char **ret) {
 261         _cleanup_free_ char *v = NULL;
 262         int r;
 263
 264         assert(ret);
 265
 266         r = parse_os_release(root, id, &v);
 267         if (r >= 0)
 268                 /* parse_os_release() calls parse_env_file() which only sets the return value for
 269                  * entries found. Let's make sure we set the return value in all cases. */
 270                 *ret = TAKE_PTR(v);
 271
 272         /* Translate error for missing os-release file to EUNATCH. */
 273         return r == -ENOENT ? -EUNATCH : r;
 274 }
 275
 276 int specifier_os_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 277         return parse_os_release_specifier(root, "ID", ret);
 278 }
 279
 280 int specifier_os_version_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 281         return parse_os_release_specifier(root, "VERSION_ID", ret);
 282 }
 283
 284 int specifier_os_build_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 285         return parse_os_release_specifier(root, "BUILD_ID", ret);
 286 }
 287
 288 int specifier_os_variant_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 289         return parse_os_release_specifier(root, "VARIANT_ID", ret);
 290 }
 291
 292 int specifier_os_image_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 293         return parse_os_release_specifier(root, "IMAGE_ID", ret);
 294 }
 295
 296 int specifier_os_image_version(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 297         return parse_os_release_specifier(root, "IMAGE_VERSION", ret);
 298 }
 299
 300 int specifier_group_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 301         RuntimeScope scope = PTR_TO_INT(data);
 302         char *t;
 303
 304         assert(ret);
 305
 306         if (scope == RUNTIME_SCOPE_GLOBAL)
 307                 return -EINVAL;
 308
 309         t = gid_to_name(scope == RUNTIME_SCOPE_USER ? getgid() : 0);
 310         if (!t)
 311                 return -ENOMEM;
 312
 313         *ret = t;
 314         return 0;
 315 }
 316
 317 int specifier_group_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 318         RuntimeScope scope = PTR_TO_INT(data);
 319         gid_t gid;
 320
 321         assert(ret);
 322
 323         if (scope == RUNTIME_SCOPE_GLOBAL)
 324                 return -EINVAL;
 325
 326         gid = scope == RUNTIME_SCOPE_USER ? getgid() : 0;
 327
 328         if (asprintf(ret, UID_FMT, gid) < 0)
 329                 return -ENOMEM;
 330
 331         return 0;
 332 }
 333
 334 int specifier_user_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 335         RuntimeScope scope = PTR_TO_INT(data);
 336         uid_t uid;
 337         char *t;
 338
 339         assert(ret);
 340
 341         if (scope == RUNTIME_SCOPE_GLOBAL)
 342                 return -EINVAL;
 343
 344         uid = scope == RUNTIME_SCOPE_USER ? getuid() : 0;
 345
 346         /* If we are UID 0 (root), this will not result in NSS, otherwise it might. This is good, as we want
 347          * to be able to run this in PID 1, where our user ID is 0, but where NSS lookups are not allowed.
 348
 349          * We don't use getusername_malloc() here, because we don't want to look at $USER, to remain
 350          * consistent with specifer_user_id() below.
 351          */
 352
 353         t = uid_to_name(uid);
 354         if (!t)
 355                 return -ENOMEM;
 356
 357         *ret = t;
 358         return 0;
 359 }
 360
 361 int specifier_user_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 362         RuntimeScope scope = PTR_TO_INT(data);
 363         uid_t uid;
 364
 365         assert(ret);
 366
 367         if (scope == RUNTIME_SCOPE_GLOBAL)
 368                 return -EINVAL;
 369
 370         uid = scope == RUNTIME_SCOPE_USER ? getuid() : 0;
 371
 372         if (asprintf(ret, UID_FMT, uid) < 0)
 373                 return -ENOMEM;
 374
 375         return 0;
 376 }
 377
 378 int specifier_user_home(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 379         assert(ret);
 380
 381         /* On PID 1 (which runs as root) this will not result in NSS,
 382          * which is good. See above */
 383
 384         return get_home_dir(ret);
 385 }
 386
 387 int specifier_user_shell(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 388         assert(ret);
 389
 390         /* On PID 1 (which runs as root) this will not result in NSS,
 391          * which is good. See above */
 392
 393         return get_shell(ret);
 394 }
 395
 396 int specifier_tmp_dir(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 397         const char *p;
 398         int r;
 399
 400         assert(ret);
 401
 402         if (root) /* If root dir is set, don't honour $TMP or similar */
 403                 p = "/tmp";
 404         else {
 405                 r = tmp_dir(&p);
 406                 if (r < 0)
 407                         return r;
 408         }
 409
 410         return strdup_to(ret, p);
 411 }
 412
 413 int specifier_var_tmp_dir(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 414         const char *p;
 415         int r;
 416
 417         assert(ret);
 418
 419         if (root)
 420                 p = "/var/tmp";
 421         else {
 422                 r = var_tmp_dir(&p);
 423                 if (r < 0)
 424                         return r;
 425         }
 426
 427         return strdup_to(ret, p);
 428 }
 429
 430 int specifier_escape_strv(char **l, char ***ret) {
 431         _cleanup_strv_free_ char **z = NULL;
 432         char **p, **q;
 433
 434         assert(ret);
 435
 436         if (strv_isempty(l)) {
 437                 *ret = NULL;
 438                 return 0;
 439         }
 440
 441         z = new(char*, strv_length(l)+1);
 442         if (!z)
 443                 return -ENOMEM;
 444
 445         for (p = l, q = z; *p; p++, q++) {
 446
 447                 *q = specifier_escape(*p);
 448                 if (!*q)
 449                         return -ENOMEM;
 450         }
 451
 452         *q = NULL;
 453         *ret = TAKE_PTR(z);
 454
 455         return 0;
 456 }
 457
 458 const Specifier system_and_tmp_specifier_table[] = {
 459         COMMON_SYSTEM_SPECIFIERS,
 460         COMMON_TMP_SPECIFIERS,
 461         {}
 462 };