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-symlinks.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-util.h"
  22 #include "specifier.h"
  23 #include "string-util.h"
  24 #include "strv.h"
  25 #include "user-util.h"
  26
  27 /*
  28  * Generic infrastructure for replacing %x style specifiers in
  29  * strings. Will call a callback for each replacement.
  30  */
  31
  32 /* Any ASCII character or digit: our pool of potential specifiers,
  33  * and "%" used for escaping. */
  34 #define POSSIBLE_SPECIFIERS ALPHANUMERICAL "%"
  35
  36 int specifier_printf(const char *text, size_t max_length, const Specifier table[], const char *root, const void *userdata, char **ret) {
  37         _cleanup_free_ char *result = NULL;
  38         bool percent = false;
  39         size_t l;
  40         char *t;
  41         int r;
  42
  43         assert(ret);
  44         assert(text);
  45         assert(table);
  46
  47         l = strlen(text);
  48         if (!GREEDY_REALLOC(result, l + 1))
  49                 return -ENOMEM;
  50         t = result;
  51
  52         for (const char *f = text; *f != '\0'; f++, l--) {
  53                 if (percent) {
  54                         percent = false;
  55
  56                         if (*f == '%')
  57                                 *(t++) = '%';
  58                         else {
  59                                 const Specifier *i;
  60
  61                                 for (i = table; i->specifier; i++)
  62                                         if (i->specifier == *f)
  63                                                 break;
  64
  65                                 if (i->lookup) {
  66                                         _cleanup_free_ char *w = NULL;
  67                                         size_t k, j;
  68
  69                                         r = i->lookup(i->specifier, i->data, root, userdata, &w);
  70                                         if (r < 0)
  71                                                 return r;
  72                                         if (isempty(w))
  73                                                 continue;
  74
  75                                         j = t - result;
  76                                         k = strlen(w);
  77
  78                                         if (!GREEDY_REALLOC(result, j + k + l + 1))
  79                                                 return -ENOMEM;
  80                                         memcpy(result + j, w, k);
  81                                         t = result + j + 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         char *n = NULL;
 115
 116         assert(ret);
 117
 118         if (!isempty(data)) {
 119                 n = strdup(data);
 120                 if (!n)
 121                         return -ENOMEM;
 122         }
 123
 124         *ret = n;
 125         return 0;
 126 }
 127
 128 int specifier_real_path(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 129         const char *path = data;
 130
 131         assert(ret);
 132
 133         if (!path)
 134                 return -ENOENT;
 135
 136         return chase_symlinks(path, root, 0, ret, NULL);
 137 }
 138
 139 int specifier_real_directory(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 140         _cleanup_free_ char *path = NULL;
 141         int r;
 142
 143         assert(ret);
 144
 145         r = specifier_real_path(specifier, data, root, userdata, &path);
 146         if (r < 0)
 147                 return r;
 148
 149         assert(path);
 150         return path_extract_directory(path, ret);
 151 }
 152
 153 int specifier_machine_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 154         sd_id128_t id;
 155         char *n;
 156         int r;
 157
 158         assert(ret);
 159
 160         if (root) {
 161                 _cleanup_close_ int fd = -1;
 162
 163                 fd = chase_symlinks_and_open("/etc/machine-id", root, CHASE_PREFIX_ROOT, O_RDONLY|O_CLOEXEC|O_NOCTTY, NULL);
 164                 if (fd < 0)
 165                         return fd;
 166
 167                 r = id128_read_fd(fd, ID128_PLAIN, &id);
 168         } else
 169                 r = sd_id128_get_machine(&id);
 170         if (r < 0)
 171                 return r;
 172
 173         n = new(char, SD_ID128_STRING_MAX);
 174         if (!n)
 175                 return -ENOMEM;
 176
 177         *ret = sd_id128_to_string(id, n);
 178         return 0;
 179 }
 180
 181 int specifier_boot_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 182         sd_id128_t id;
 183         char *n;
 184         int r;
 185
 186         assert(ret);
 187
 188         r = sd_id128_get_boot(&id);
 189         if (r < 0)
 190                 return r;
 191
 192         n = new(char, SD_ID128_STRING_MAX);
 193         if (!n)
 194                 return -ENOMEM;
 195
 196         *ret = sd_id128_to_string(id, n);
 197         return 0;
 198 }
 199
 200 int specifier_host_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 201         char *n;
 202
 203         assert(ret);
 204
 205         n = gethostname_malloc();
 206         if (!n)
 207                 return -ENOMEM;
 208
 209         *ret = n;
 210         return 0;
 211 }
 212
 213 int specifier_short_host_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 214         char *n;
 215
 216         assert(ret);
 217
 218         n = gethostname_short_malloc();
 219         if (!n)
 220                 return -ENOMEM;
 221
 222         *ret = n;
 223         return 0;
 224 }
 225
 226 int specifier_pretty_host_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 227         char *n = NULL;
 228
 229         assert(ret);
 230
 231         if (get_pretty_hostname(&n) < 0) {
 232                 n = gethostname_short_malloc();
 233                 if (!n)
 234                         return -ENOMEM;
 235         }
 236
 237         *ret = n;
 238         return 0;
 239 }
 240
 241 int specifier_kernel_release(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 242         struct utsname uts;
 243         char *n;
 244
 245         assert(ret);
 246
 247         if (uname(&uts) < 0)
 248                 return -errno;
 249
 250         n = strdup(uts.release);
 251         if (!n)
 252                 return -ENOMEM;
 253
 254         *ret = n;
 255         return 0;
 256 }
 257
 258 int specifier_architecture(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 259         char *t;
 260
 261         assert(ret);
 262
 263         t = strdup(architecture_to_string(uname_architecture()));
 264         if (!t)
 265                 return -ENOMEM;
 266
 267         *ret = t;
 268         return 0;
 269 }
 270
 271 /* Note: fields in /etc/os-release might quite possibly be missing, even if everything is entirely valid
 272  * otherwise. We'll return an empty value or NULL in that case from the functions below. */
 273
 274 int specifier_os_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 275         assert(ret);
 276         return parse_os_release(root, "ID", ret);
 277 }
 278
 279 int specifier_os_version_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 280         assert(ret);
 281         return parse_os_release(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         assert(ret);
 286         return parse_os_release(root, "BUILD_ID", ret);
 287 }
 288
 289 int specifier_os_variant_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 290         assert(ret);
 291         return parse_os_release(root, "VARIANT_ID", ret);
 292 }
 293
 294 int specifier_os_image_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 295         assert(ret);
 296         return parse_os_release(root, "IMAGE_ID", ret);
 297 }
 298
 299 int specifier_os_image_version(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 300         assert(ret);
 301         return parse_os_release(root, "IMAGE_VERSION", ret);
 302 }
 303
 304 int specifier_group_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 305         char *t;
 306
 307         assert(ret);
 308
 309         t = gid_to_name(getgid());
 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         assert(ret);
 319
 320         if (asprintf(ret, UID_FMT, getgid()) < 0)
 321                 return -ENOMEM;
 322
 323         return 0;
 324 }
 325
 326 int specifier_user_name(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 327         char *t;
 328
 329         assert(ret);
 330
 331         /* If we are UID 0 (root), this will not result in NSS, otherwise it might. This is good, as we want to be able
 332          * to run this in PID 1, where our user ID is 0, but where NSS lookups are not allowed.
 333
 334          * We don't use getusername_malloc() here, because we don't want to look at $USER, to remain consistent with
 335          * specifer_user_id() below.
 336          */
 337
 338         t = uid_to_name(getuid());
 339         if (!t)
 340                 return -ENOMEM;
 341
 342         *ret = t;
 343         return 0;
 344 }
 345
 346 int specifier_user_id(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 347         assert(ret);
 348
 349         if (asprintf(ret, UID_FMT, getuid()) < 0)
 350                 return -ENOMEM;
 351
 352         return 0;
 353 }
 354
 355 int specifier_user_home(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 356         assert(ret);
 357
 358         /* On PID 1 (which runs as root) this will not result in NSS,
 359          * which is good. See above */
 360
 361         return get_home_dir(ret);
 362 }
 363
 364 int specifier_user_shell(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 365         assert(ret);
 366
 367         /* On PID 1 (which runs as root) this will not result in NSS,
 368          * which is good. See above */
 369
 370         return get_shell(ret);
 371 }
 372
 373 int specifier_tmp_dir(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 374         const char *p;
 375         char *copy;
 376         int r;
 377
 378         assert(ret);
 379
 380         if (root) /* If root dir is set, don't honour $TMP or similar */
 381                 p = "/tmp";
 382         else {
 383                 r = tmp_dir(&p);
 384                 if (r < 0)
 385                         return r;
 386         }
 387         copy = strdup(p);
 388         if (!copy)
 389                 return -ENOMEM;
 390
 391         *ret = copy;
 392         return 0;
 393 }
 394
 395 int specifier_var_tmp_dir(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
 396         const char *p;
 397         char *copy;
 398         int r;
 399
 400         assert(ret);
 401
 402         if (root)
 403                 p = "/var/tmp";
 404         else {
 405                 r = var_tmp_dir(&p);
 406                 if (r < 0)
 407                         return r;
 408         }
 409         copy = strdup(p);
 410         if (!copy)
 411                 return -ENOMEM;
 412
 413         *ret = copy;
 414         return 0;
 415 }
 416
 417 int specifier_escape_strv(char **l, char ***ret) {
 418         char **z, **p, **q;
 419
 420         assert(ret);
 421
 422         if (strv_isempty(l)) {
 423                 *ret = NULL;
 424                 return 0;
 425         }
 426
 427         z = new(char*, strv_length(l)+1);
 428         if (!z)
 429                 return -ENOMEM;
 430
 431         for (p = l, q = z; *p; p++, q++) {
 432
 433                 *q = specifier_escape(*p);
 434                 if (!*q) {
 435                         strv_free(z);
 436                         return -ENOMEM;
 437                 }
 438         }
 439
 440         *q = NULL;
 441         *ret = z;
 442
 443         return 0;
 444 }
 445
 446 const Specifier system_and_tmp_specifier_table[] = {
 447         COMMON_SYSTEM_SPECIFIERS,
 448         COMMON_TMP_SPECIFIERS,
 449         {}
 450 };