summaryrefslogtreecommitdiff
path: root/iconv/strtab.c
blob: 9504c14748720b159aa8d1899e9071436d4e7718 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
/* C string table handling.
   Copyright (C) 2000-2014 Free Software Foundation, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2000.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <inttypes.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/cdefs.h>
#include <sys/param.h>


struct Strent
{
  const char *string;
  size_t len;
  struct Strent *next;
  struct Strent *left;
  struct Strent *right;
  size_t offset;
  char reverse[0];
};


struct memoryblock
{
  struct memoryblock *next;
  char memory[0];
};


struct Strtab
{
  struct Strent *root;
  struct memoryblock *memory;
  char *backp;
  size_t left;
  size_t total;

  struct Strent null;
};


/* Cache for the pagesize.  We correct this value a bit so that `malloc'
   is not allocating more than a page.  */
static size_t ps;


#include <programs/xmalloc.h>

/* Prototypes for our functions that are used from iconvconfig.c.  If
   you change these, change also iconvconfig.c.  */
/* Create new C string table object in memory.  */
extern struct Strtab *strtabinit (void);

/* Free resources allocated for C string table ST.  */
extern void strtabfree (struct Strtab *st);

/* Add string STR (length LEN is != 0) to C string table ST.  */
extern struct Strent *strtabadd (struct Strtab *st, const char *str,
				 size_t len);

/* Finalize string table ST and store size in *SIZE and return a pointer.  */
extern void *strtabfinalize (struct Strtab *st, size_t *size);

/* Get offset in string table for string associated with SE.  */
extern size_t strtaboffset (struct Strent *se);


struct Strtab *
strtabinit (void)
{
  struct Strtab *ret;

  if (ps == 0)
    {
      ps = sysconf (_SC_PAGESIZE) - 2 * sizeof (void *);
      assert (sizeof (struct memoryblock) < ps);
    }

  ret = (struct Strtab *) calloc (1, sizeof (struct Strtab));
  if (ret != NULL)
    {
      ret->null.len = 1;
      ret->null.string = "";
    }
  return ret;
}


static void
morememory (struct Strtab *st, size_t len)
{
  struct memoryblock *newmem;

  if (len < ps)
    len = ps;
  newmem = (struct memoryblock *) malloc (len);
  if (newmem == NULL)
    abort ();

  newmem->next = st->memory;
  st->memory = newmem;
  st->backp = newmem->memory;
  st->left = len - offsetof (struct memoryblock, memory);
}


void
strtabfree (struct Strtab *st)
{
  struct memoryblock *mb = st->memory;

  while (mb != NULL)
    {
      void *old = mb;
      mb = mb->next;
      free (old);
    }

  free (st);
}


static struct Strent *
newstring (struct Strtab *st, const char *str, size_t len)
{
  struct Strent *newstr;
  size_t align;
  int i;

  /* Compute the amount of padding needed to make the structure aligned.  */
  align = ((__alignof__ (struct Strent)
	    - (((uintptr_t) st->backp)
	       & (__alignof__ (struct Strent) - 1)))
	   & (__alignof__ (struct Strent) - 1));

  /* Make sure there is enough room in the memory block.  */
  if (st->left < align + sizeof (struct Strent) + len)
    {
      morememory (st, sizeof (struct Strent) + len);
      align = 0;
    }

  /* Create the reserved string.  */
  newstr = (struct Strent *) (st->backp + align);
  newstr->string = str;
  newstr->len = len;
  newstr->next = NULL;
  newstr->left = NULL;
  newstr->right = NULL;
  newstr->offset = 0;
  for (i = len - 2; i >= 0; --i)
    newstr->reverse[i] = str[len - 2 - i];
  newstr->reverse[len - 1] = '\0';
  st->backp += align + sizeof (struct Strent) + len;
  st->left -= align + sizeof (struct Strent) + len;

  return newstr;
}


/* XXX This function should definitely be rewritten to use a balancing
   tree algorithm (AVL, red-black trees).  For now a simple, correct
   implementation is enough.  */
static struct Strent **
searchstring (struct Strent **sep, struct Strent *newstr)
{
  int cmpres;

  /* More strings?  */
  if (*sep == NULL)
    {
      *sep = newstr;
      return sep;
    }

  /* Compare the strings.  */
  cmpres = memcmp ((*sep)->reverse, newstr->reverse,
		   MIN ((*sep)->len, newstr->len) - 1);
  if (cmpres == 0)
    /* We found a matching string.  */
    return sep;
  else if (cmpres > 0)
    return searchstring (&(*sep)->left, newstr);
  else
    return searchstring (&(*sep)->right, newstr);
}


/* Add new string.  The actual string is assumed to be permanent.  */
struct Strent *
strtabadd (struct Strtab *st, const char *str, size_t len)
{
  struct Strent *newstr;
  struct Strent **sep;

  /* Compute the string length if the caller doesn't know it.  */
  if (len == 0)
    len = strlen (str) + 1;

  /* Make sure all "" strings get offset 0.  */
  if (len == 1)
    return &st->null;

  /* Allocate memory for the new string and its associated information.  */
  newstr = newstring (st, str, len);

  /* Search in the array for the place to insert the string.  If there
     is no string with matching prefix and no string with matching
     leading substring, create a new entry.  */
  sep = searchstring (&st->root, newstr);
  if (*sep != newstr)
    {
      /* This is not the same entry.  This means we have a prefix match.  */
      if ((*sep)->len > newstr->len)
	{
	  struct Strent *subs;

	  for (subs = (*sep)->next; subs; subs = subs->next)
	    if (subs->len == newstr->len)
	      {
		/* We have an exact match with a substring.  Free the memory
		   we allocated.  */
		st->left += st->backp - (char *) newstr;
		st->backp = (char *) newstr;

		return subs;
	      }

	  /* We have a new substring.  This means we don't need the reverse
	     string of this entry anymore.  */
	  st->backp -= newstr->len;
	  st->left += newstr->len;

	  newstr->next = (*sep)->next;
	  (*sep)->next = newstr;
	}
      else if ((*sep)->len != newstr->len)
	{
	  /* When we get here it means that the string we are about to
	     add has a common prefix with a string we already have but
	     it is longer.  In this case we have to put it first.  */
	  st->total += newstr->len - (*sep)->len;
	  newstr->next = *sep;
	  newstr->left = (*sep)->left;
	  newstr->right = (*sep)->right;
	  *sep = newstr;
	}
      else
	{
	  /* We have an exact match.  Free the memory we allocated.  */
	  st->left += st->backp - (char *) newstr;
	  st->backp = (char *) newstr;

	  newstr = *sep;
	}
    }
  else
    st->total += newstr->len;

  return newstr;
}


static void
copystrings (struct Strent *nodep, char **freep, size_t *offsetp)
{
  struct Strent *subs;

  if (nodep->left != NULL)
    copystrings (nodep->left, freep, offsetp);

  /* Process the current node.  */
  nodep->offset = *offsetp;
  *freep = (char *) mempcpy (*freep, nodep->string, nodep->len);
  *offsetp += nodep->len;

  for (subs = nodep->next; subs != NULL; subs = subs->next)
    {
      assert (subs->len < nodep->len);
      subs->offset = nodep->offset + nodep->len - subs->len;
    }

  if (nodep->right != NULL)
    copystrings (nodep->right, freep, offsetp);
}


void *
strtabfinalize (struct Strtab *st, size_t *size)
{
  size_t copylen;
  char *endp;
  char *retval;

  /* Fill in the information.  */
  endp = retval = (char *) xmalloc (st->total + 1);

  /* Always put an empty string at the beginning so that a zero offset
     can mean error.  */
  *endp++ = '\0';

  /* Now run through the tree and add all the string while also updating
     the offset members of the elfstrent records.  */
  copylen = 1;
  copystrings (st->root, &endp, &copylen);
  assert (copylen == st->total + 1);
  assert (endp == retval + st->total + 1);
  *size = copylen;

  return retval;
}


size_t
strtaboffset (struct Strent *se)
{
  return se->offset;
}