src/shared/xml.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2013 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <string.h>
  23
  24 #include "util.h"
  25 #include "xml.h"
  26
  27 enum {
  28         STATE_NULL,
  29         STATE_TEXT,
  30         STATE_TAG,
  31         STATE_ATTRIBUTE,
  32 };
  33
  34 static void inc_lines(unsigned *line, const char *s, size_t n) {
  35         const char *p = s;
  36
  37         if (!line)
  38                 return;
  39
  40         for (;;) {
  41                 const char *f;
  42
  43                 f = memchr(p, '\n', n);
  44                 if (!f)
  45                         return;
  46
  47                 n -= (f - p) + 1;
  48                 p = f + 1;
  49                 (*line)++;
  50         }
  51 }
  52
  53 /* We don't actually do real XML here. We only read a simplistic
  54  * subset, that is a bit less strict that XML and lacks all the more
  55  * complex features, like entities, or namespaces. However, we do
  56  * support some HTML5-like simplifications */
  57
  58 int xml_tokenize(const char **p, char **name, void **state, unsigned *line) {
  59         const char *c, *e, *b;
  60         char *ret;
  61         int t;
  62
  63         assert(p);
  64         assert(*p);
  65         assert(name);
  66         assert(state);
  67
  68         t = PTR_TO_INT(*state);
  69         c = *p;
  70
  71         if (t == STATE_NULL) {
  72                 if (line)
  73                         *line = 1;
  74                 t = STATE_TEXT;
  75         }
  76
  77         for (;;) {
  78                 if (*c == 0)
  79                         return XML_END;
  80
  81                 switch (t) {
  82
  83                 case STATE_TEXT: {
  84                         int x;
  85
  86                         e = strchrnul(c, '<');
  87                         if (e > c) {
  88                                 /* More text... */
  89                                 ret = strndup(c, e - c);
  90                                 if (!ret)
  91                                         return -ENOMEM;
  92
  93                                 inc_lines(line, c, e - c);
  94
  95                                 *name = ret;
  96                                 *p = e;
  97                                 *state = INT_TO_PTR(STATE_TEXT);
  98
  99                                 return XML_TEXT;
 100                         }
 101
 102                         assert(*e == '<');
 103                         b = c + 1;
 104
 105                         if (startswith(b, "!--")) {
 106                                 /* A comment */
 107                                 e = strstr(b + 3, "-->");
 108                                 if (!e)
 109                                         return -EINVAL;
 110
 111                                 inc_lines(line, b, e + 3 - b);
 112
 113                                 c = e + 3;
 114                                 continue;
 115                         }
 116
 117                         if (*b == '?') {
 118                                 /* Processing instruction */
 119
 120                                 e = strstr(b + 1, "?>");
 121                                 if (!e)
 122                                         return -EINVAL;
 123
 124                                 inc_lines(line, b, e + 2 - b);
 125
 126                                 c = e + 2;
 127                                 continue;
 128                         }
 129
 130                         if (*b == '!') {
 131                                 /* DTD */
 132
 133                                 e = strchr(b + 1, '>');
 134                                 if (!e)
 135                                         return -EINVAL;
 136
 137                                 inc_lines(line, b, e + 1 - b);
 138
 139                                 c = e + 1;
 140                                 continue;
 141                         }
 142
 143                         if (*b == '/') {
 144                                 /* A closing tag */
 145                                 x = XML_TAG_CLOSE;
 146                                 b++;
 147                         } else
 148                                 x = XML_TAG_OPEN;
 149
 150                         e = strpbrk(b, WHITESPACE "/>");
 151                         if (!e)
 152                                 return -EINVAL;
 153
 154                         ret = strndup(b, e - b);
 155                         if (!ret)
 156                                 return -ENOMEM;
 157
 158                         *name = ret;
 159                         *p = e;
 160                         *state = INT_TO_PTR(STATE_TAG);
 161
 162                         return x;
 163                 }
 164
 165                 case STATE_TAG:
 166
 167                         b = c + strspn(c, WHITESPACE);
 168                         if (*b == 0)
 169                                 return -EINVAL;
 170
 171                         inc_lines(line, c, b - c);
 172
 173                         e = b + strcspn(b, WHITESPACE "=/>");
 174                         if (e > b) {
 175                                 /* An attribute */
 176
 177                                 ret = strndup(b, e - b);
 178                                 if (!ret)
 179                                         return -ENOMEM;
 180
 181                                 *name = ret;
 182                                 *p = e;
 183                                 *state = INT_TO_PTR(STATE_ATTRIBUTE);
 184
 185                                 return XML_ATTRIBUTE_NAME;
 186                         }
 187
 188                         if (startswith(b, "/>")) {
 189                                 /* An empty tag */
 190
 191                                 *name = NULL; /* For empty tags we return a NULL name, the caller must be prepared for that */
 192                                 *p = b + 2;
 193                                 *state = INT_TO_PTR(STATE_TEXT);
 194
 195                                 return XML_TAG_CLOSE_EMPTY;
 196                         }
 197
 198                         if (*b != '>')
 199                                 return -EINVAL;
 200
 201                         c = b + 1;
 202                         t = STATE_TEXT;
 203                         continue;
 204
 205                 case STATE_ATTRIBUTE:
 206
 207                         if (*c == '=') {
 208                                 c++;
 209
 210                                 if (*c == '\'' || *c == '\"') {
 211                                         /* Tag with a quoted value */
 212
 213                                         e = strchr(c+1, *c);
 214                                         if (!e)
 215                                                 return -EINVAL;
 216
 217                                         inc_lines(line, c, e - c);
 218
 219                                         ret = strndup(c+1, e - c - 1);
 220                                         if (!ret)
 221                                                 return -ENOMEM;
 222
 223                                         *name = ret;
 224                                         *p = e + 1;
 225                                         *state = INT_TO_PTR(STATE_TAG);
 226
 227                                         return XML_ATTRIBUTE_VALUE;
 228
 229                                 }
 230
 231                                 /* Tag with a value without quotes */
 232
 233                                 b = strpbrk(c, WHITESPACE ">");
 234                                 if (!b)
 235                                         b = c;
 236
 237                                 ret = strndup(c, b - c);
 238                                 if (!ret)
 239                                         return -ENOMEM;
 240
 241                                 *name = ret;
 242                                 *p = b;
 243                                 *state = INT_TO_PTR(STATE_TAG);
 244                                 return XML_ATTRIBUTE_VALUE;
 245                         }
 246
 247                         t = STATE_TAG;
 248                         continue;
 249                 }
 250
 251         }
 252
 253         assert_not_reached("Bad state");
 254 }