src/basic/proc-cmdline.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 Lennart Poettering
   6 ***/
   7
   8 #include <stdbool.h>
   9 #include <stddef.h>
  10 #include <string.h>
  11
  12 #include "alloc-util.h"
  13 #include "extract-word.h"
  14 #include "fileio.h"
  15 #include "macro.h"
  16 #include "parse-util.h"
  17 #include "proc-cmdline.h"
  18 #include "process-util.h"
  19 #include "special.h"
  20 #include "string-util.h"
  21 #include "util.h"
  22 #include "virt.h"
  23
  24 int proc_cmdline(char **ret) {
  25         const char *e;
  26         assert(ret);
  27
  28         /* For testing purposes it is sometimes useful to be able to override what we consider /proc/cmdline to be */
  29         e = secure_getenv("SYSTEMD_PROC_CMDLINE");
  30         if (e) {
  31                 char *m;
  32
  33                 m = strdup(e);
  34                 if (!m)
  35                         return -ENOMEM;
  36
  37                 *ret = m;
  38                 return 0;
  39         }
  40
  41         if (detect_container() > 0)
  42                 return get_process_cmdline(1, 0, false, ret);
  43         else
  44                 return read_one_line_file("/proc/cmdline", ret);
  45 }
  46
  47 int proc_cmdline_parse(proc_cmdline_parse_t parse_item, void *data, unsigned flags) {
  48
  49         _cleanup_free_ char *line = NULL;
  50         const char *p;
  51         int r;
  52
  53         assert(parse_item);
  54
  55         r = proc_cmdline(&line);
  56         if (r < 0)
  57                 return r;
  58
  59         p = line;
  60         for (;;) {
  61                 _cleanup_free_ char *word = NULL;
  62                 char *value, *key, *q;
  63
  64                 r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
  65                 if (r < 0)
  66                         return r;
  67                 if (r == 0)
  68                         break;
  69
  70                 key = word;
  71
  72                 /* Filter out arguments that are intended only for the initrd */
  73                 q = startswith(word, "rd.");
  74                 if (q) {
  75                         if (!in_initrd())
  76                                 continue;
  77
  78                         if (flags & PROC_CMDLINE_STRIP_RD_PREFIX)
  79                                 key = q;
  80                 }
  81
  82                 value = strchr(key, '=');
  83                 if (value)
  84                         *(value++) = 0;
  85
  86                 r = parse_item(key, value, data);
  87                 if (r < 0)
  88                         return r;
  89         }
  90
  91         return 0;
  92 }
  93
  94 static bool relaxed_equal_char(char a, char b) {
  95
  96         return a == b ||
  97                 (a == '_' && b == '-') ||
  98                 (a == '-' && b == '_');
  99 }
 100
 101 char *proc_cmdline_key_startswith(const char *s, const char *prefix) {
 102
 103         assert(s);
 104         assert(prefix);
 105
 106         /* Much like startswith(), but considers "-" and "_" the same */
 107
 108         for (; *prefix != 0; s++, prefix++)
 109                 if (!relaxed_equal_char(*s, *prefix))
 110                         return NULL;
 111
 112         return (char*) s;
 113 }
 114
 115 bool proc_cmdline_key_streq(const char *x, const char *y) {
 116         assert(x);
 117         assert(y);
 118
 119         /* Much like streq(), but considers "-" and "_" the same */
 120
 121         for (; *x != 0 || *y != 0; x++, y++)
 122                 if (!relaxed_equal_char(*x, *y))
 123                         return false;
 124
 125         return true;
 126 }
 127
 128 int proc_cmdline_get_key(const char *key, unsigned flags, char **value) {
 129         _cleanup_free_ char *line = NULL, *ret = NULL;
 130         bool found = false;
 131         const char *p;
 132         int r;
 133
 134         /* Looks for a specific key on the kernel command line. Supports two modes:
 135          *
 136          * a) The "value" parameter is used. In this case a parameter beginning with the "key" string followed by "="
 137          *    is searched, and the value following this is returned in "value".
 138          *
 139          * b) as above, but the PROC_CMDLINE_VALUE_OPTIONAL flag is set. In this case if the key is found as a
 140          *    separate word (i.e. not followed by "=" but instead by whitespace or the end of the command line), then
 141          *    this is also accepted, and "value" is returned as NULL.
 142          *
 143          * c) The "value" parameter is NULL. In this case a search for the exact "key" parameter is performed.
 144          *
 145          * In all three cases, > 0 is returned if the key is found, 0 if not. */
 146
 147         if (isempty(key))
 148                 return -EINVAL;
 149
 150         if ((flags & PROC_CMDLINE_VALUE_OPTIONAL) && !value)
 151                 return -EINVAL;
 152
 153         r = proc_cmdline(&line);
 154         if (r < 0)
 155                 return r;
 156
 157         p = line;
 158         for (;;) {
 159                 _cleanup_free_ char *word = NULL;
 160                 const char *e;
 161
 162                 r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
 163                 if (r < 0)
 164                         return r;
 165                 if (r == 0)
 166                         break;
 167
 168                 /* Automatically filter out arguments that are intended only for the initrd, if we are not in the
 169                  * initrd. */
 170                 if (!in_initrd() && startswith(word, "rd."))
 171                         continue;
 172
 173                 if (value) {
 174                         e = proc_cmdline_key_startswith(word, key);
 175                         if (!e)
 176                                 continue;
 177
 178                         if (*e == '=') {
 179                                 r = free_and_strdup(&ret, e+1);
 180                                 if (r < 0)
 181                                         return r;
 182
 183                                 found = true;
 184
 185                         } else if (*e == 0 && (flags & PROC_CMDLINE_VALUE_OPTIONAL))
 186                                 found = true;
 187
 188                 } else {
 189                         if (streq(word, key))
 190                                 found = true;
 191                 }
 192         }
 193
 194         if (value)
 195                 *value = TAKE_PTR(ret);
 196
 197         return found;
 198 }
 199
 200 int proc_cmdline_get_bool(const char *key, bool *ret) {
 201         _cleanup_free_ char *v = NULL;
 202         int r;
 203
 204         assert(ret);
 205
 206         r = proc_cmdline_get_key(key, PROC_CMDLINE_VALUE_OPTIONAL, &v);
 207         if (r < 0)
 208                 return r;
 209         if (r == 0) {
 210                 *ret = false;
 211                 return 0;
 212         }
 213
 214         if (v) { /* parameter passed */
 215                 r = parse_boolean(v);
 216                 if (r < 0)
 217                         return r;
 218                 *ret = r;
 219         } else /* no parameter passed */
 220                 *ret = true;
 221
 222         return 1;
 223 }
 224
 225 int shall_restore_state(void) {
 226         bool ret;
 227         int r;
 228
 229         r = proc_cmdline_get_bool("systemd.restore_state", &ret);
 230         if (r < 0)
 231                 return r;
 232
 233         return r > 0 ? ret : true;
 234 }
 235
 236 static const char * const rlmap[] = {
 237         "emergency", SPECIAL_EMERGENCY_TARGET,
 238         "-b",        SPECIAL_EMERGENCY_TARGET,
 239         "rescue",    SPECIAL_RESCUE_TARGET,
 240         "single",    SPECIAL_RESCUE_TARGET,
 241         "-s",        SPECIAL_RESCUE_TARGET,
 242         "s",         SPECIAL_RESCUE_TARGET,
 243         "S",         SPECIAL_RESCUE_TARGET,
 244         "1",         SPECIAL_RESCUE_TARGET,
 245         "2",         SPECIAL_MULTI_USER_TARGET,
 246         "3",         SPECIAL_MULTI_USER_TARGET,
 247         "4",         SPECIAL_MULTI_USER_TARGET,
 248         "5",         SPECIAL_GRAPHICAL_TARGET,
 249         NULL
 250 };
 251
 252 static const char * const rlmap_initrd[] = {
 253         "emergency", SPECIAL_EMERGENCY_TARGET,
 254         "rescue",    SPECIAL_RESCUE_TARGET,
 255         NULL
 256 };
 257
 258 const char* runlevel_to_target(const char *word) {
 259         const char * const *rlmap_ptr;
 260         size_t i;
 261
 262         if (!word)
 263                 return NULL;
 264
 265         if (in_initrd()) {
 266                 word = startswith(word, "rd.");
 267                 if (!word)
 268                         return NULL;
 269         }
 270
 271         rlmap_ptr = in_initrd() ? rlmap_initrd : rlmap;
 272
 273         for (i = 0; rlmap_ptr[i]; i += 2)
 274                 if (streq(word, rlmap_ptr[i]))
 275                         return rlmap_ptr[i+1];
 276
 277         return NULL;
 278 }