xref: /NextBSD/contrib/binutils/bfd/hash.c (revision eb1a5f8de9f7ea602c373a710f531abbf81141c4)
1 /* hash.c -- hash table routines for BFD
2    Copyright 1993, 1994, 1995, 1997, 1999, 2001, 2002, 2003, 2004, 2005,
3    2006, 2007 Free Software Foundation, Inc.
4    Written by Steve Chamberlain <sac@cygnus.com>
5 
6    This file is part of BFD, the Binary File Descriptor library.
7 
8    This program is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 2 of the License, or
11    (at your option) any later version.
12 
13    This program is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17 
18    You should have received a copy of the GNU General Public License
19    along with this program; if not, write to the Free Software
20    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
21 
22 #include "sysdep.h"
23 #include "bfd.h"
24 #include "libbfd.h"
25 #include "objalloc.h"
26 #include "libiberty.h"
27 
28 /*
29 SECTION
30 	Hash Tables
31 
32 @cindex Hash tables
33 	BFD provides a simple set of hash table functions.  Routines
34 	are provided to initialize a hash table, to free a hash table,
35 	to look up a string in a hash table and optionally create an
36 	entry for it, and to traverse a hash table.  There is
37 	currently no routine to delete an string from a hash table.
38 
39 	The basic hash table does not permit any data to be stored
40 	with a string.  However, a hash table is designed to present a
41 	base class from which other types of hash tables may be
42 	derived.  These derived types may store additional information
43 	with the string.  Hash tables were implemented in this way,
44 	rather than simply providing a data pointer in a hash table
45 	entry, because they were designed for use by the linker back
46 	ends.  The linker may create thousands of hash table entries,
47 	and the overhead of allocating private data and storing and
48 	following pointers becomes noticeable.
49 
50 	The basic hash table code is in <<hash.c>>.
51 
52 @menu
53 @* Creating and Freeing a Hash Table::
54 @* Looking Up or Entering a String::
55 @* Traversing a Hash Table::
56 @* Deriving a New Hash Table Type::
57 @end menu
58 
59 INODE
60 Creating and Freeing a Hash Table, Looking Up or Entering a String, Hash Tables, Hash Tables
61 SUBSECTION
62 	Creating and freeing a hash table
63 
64 @findex bfd_hash_table_init
65 @findex bfd_hash_table_init_n
66 	To create a hash table, create an instance of a <<struct
67 	bfd_hash_table>> (defined in <<bfd.h>>) and call
68 	<<bfd_hash_table_init>> (if you know approximately how many
69 	entries you will need, the function <<bfd_hash_table_init_n>>,
70 	which takes a @var{size} argument, may be used).
71 	<<bfd_hash_table_init>> returns <<FALSE>> if some sort of
72 	error occurs.
73 
74 @findex bfd_hash_newfunc
75 	The function <<bfd_hash_table_init>> take as an argument a
76 	function to use to create new entries.  For a basic hash
77 	table, use the function <<bfd_hash_newfunc>>.  @xref{Deriving
78 	a New Hash Table Type}, for why you would want to use a
79 	different value for this argument.
80 
81 @findex bfd_hash_allocate
82 	<<bfd_hash_table_init>> will create an objalloc which will be
83 	used to allocate new entries.  You may allocate memory on this
84 	objalloc using <<bfd_hash_allocate>>.
85 
86 @findex bfd_hash_table_free
87 	Use <<bfd_hash_table_free>> to free up all the memory that has
88 	been allocated for a hash table.  This will not free up the
89 	<<struct bfd_hash_table>> itself, which you must provide.
90 
91 @findex bfd_hash_set_default_size
92 	Use <<bfd_hash_set_default_size>> to set the default size of
93 	hash table to use.
94 
95 INODE
96 Looking Up or Entering a String, Traversing a Hash Table, Creating and Freeing a Hash Table, Hash Tables
97 SUBSECTION
98 	Looking up or entering a string
99 
100 @findex bfd_hash_lookup
101 	The function <<bfd_hash_lookup>> is used both to look up a
102 	string in the hash table and to create a new entry.
103 
104 	If the @var{create} argument is <<FALSE>>, <<bfd_hash_lookup>>
105 	will look up a string.  If the string is found, it will
106 	returns a pointer to a <<struct bfd_hash_entry>>.  If the
107 	string is not found in the table <<bfd_hash_lookup>> will
108 	return <<NULL>>.  You should not modify any of the fields in
109 	the returns <<struct bfd_hash_entry>>.
110 
111 	If the @var{create} argument is <<TRUE>>, the string will be
112 	entered into the hash table if it is not already there.
113 	Either way a pointer to a <<struct bfd_hash_entry>> will be
114 	returned, either to the existing structure or to a newly
115 	created one.  In this case, a <<NULL>> return means that an
116 	error occurred.
117 
118 	If the @var{create} argument is <<TRUE>>, and a new entry is
119 	created, the @var{copy} argument is used to decide whether to
120 	copy the string onto the hash table objalloc or not.  If
121 	@var{copy} is passed as <<FALSE>>, you must be careful not to
122 	deallocate or modify the string as long as the hash table
123 	exists.
124 
125 INODE
126 Traversing a Hash Table, Deriving a New Hash Table Type, Looking Up or Entering a String, Hash Tables
127 SUBSECTION
128 	Traversing a hash table
129 
130 @findex bfd_hash_traverse
131 	The function <<bfd_hash_traverse>> may be used to traverse a
132 	hash table, calling a function on each element.  The traversal
133 	is done in a random order.
134 
135 	<<bfd_hash_traverse>> takes as arguments a function and a
136 	generic <<void *>> pointer.  The function is called with a
137 	hash table entry (a <<struct bfd_hash_entry *>>) and the
138 	generic pointer passed to <<bfd_hash_traverse>>.  The function
139 	must return a <<boolean>> value, which indicates whether to
140 	continue traversing the hash table.  If the function returns
141 	<<FALSE>>, <<bfd_hash_traverse>> will stop the traversal and
142 	return immediately.
143 
144 INODE
145 Deriving a New Hash Table Type, , Traversing a Hash Table, Hash Tables
146 SUBSECTION
147 	Deriving a new hash table type
148 
149 	Many uses of hash tables want to store additional information
150 	which each entry in the hash table.  Some also find it
151 	convenient to store additional information with the hash table
152 	itself.  This may be done using a derived hash table.
153 
154 	Since C is not an object oriented language, creating a derived
155 	hash table requires sticking together some boilerplate
156 	routines with a few differences specific to the type of hash
157 	table you want to create.
158 
159 	An example of a derived hash table is the linker hash table.
160 	The structures for this are defined in <<bfdlink.h>>.  The
161 	functions are in <<linker.c>>.
162 
163 	You may also derive a hash table from an already derived hash
164 	table.  For example, the a.out linker backend code uses a hash
165 	table derived from the linker hash table.
166 
167 @menu
168 @* Define the Derived Structures::
169 @* Write the Derived Creation Routine::
170 @* Write Other Derived Routines::
171 @end menu
172 
173 INODE
174 Define the Derived Structures, Write the Derived Creation Routine, Deriving a New Hash Table Type, Deriving a New Hash Table Type
175 SUBSUBSECTION
176 	Define the derived structures
177 
178 	You must define a structure for an entry in the hash table,
179 	and a structure for the hash table itself.
180 
181 	The first field in the structure for an entry in the hash
182 	table must be of the type used for an entry in the hash table
183 	you are deriving from.  If you are deriving from a basic hash
184 	table this is <<struct bfd_hash_entry>>, which is defined in
185 	<<bfd.h>>.  The first field in the structure for the hash
186 	table itself must be of the type of the hash table you are
187 	deriving from itself.  If you are deriving from a basic hash
188 	table, this is <<struct bfd_hash_table>>.
189 
190 	For example, the linker hash table defines <<struct
191 	bfd_link_hash_entry>> (in <<bfdlink.h>>).  The first field,
192 	<<root>>, is of type <<struct bfd_hash_entry>>.  Similarly,
193 	the first field in <<struct bfd_link_hash_table>>, <<table>>,
194 	is of type <<struct bfd_hash_table>>.
195 
196 INODE
197 Write the Derived Creation Routine, Write Other Derived Routines, Define the Derived Structures, Deriving a New Hash Table Type
198 SUBSUBSECTION
199 	Write the derived creation routine
200 
201 	You must write a routine which will create and initialize an
202 	entry in the hash table.  This routine is passed as the
203 	function argument to <<bfd_hash_table_init>>.
204 
205 	In order to permit other hash tables to be derived from the
206 	hash table you are creating, this routine must be written in a
207 	standard way.
208 
209 	The first argument to the creation routine is a pointer to a
210 	hash table entry.  This may be <<NULL>>, in which case the
211 	routine should allocate the right amount of space.  Otherwise
212 	the space has already been allocated by a hash table type
213 	derived from this one.
214 
215 	After allocating space, the creation routine must call the
216 	creation routine of the hash table type it is derived from,
217 	passing in a pointer to the space it just allocated.  This
218 	will initialize any fields used by the base hash table.
219 
220 	Finally the creation routine must initialize any local fields
221 	for the new hash table type.
222 
223 	Here is a boilerplate example of a creation routine.
224 	@var{function_name} is the name of the routine.
225 	@var{entry_type} is the type of an entry in the hash table you
226 	are creating.  @var{base_newfunc} is the name of the creation
227 	routine of the hash table type your hash table is derived
228 	from.
229 
230 EXAMPLE
231 
232 .struct bfd_hash_entry *
233 .@var{function_name} (struct bfd_hash_entry *entry,
234 .                     struct bfd_hash_table *table,
235 .                     const char *string)
236 .{
237 .  struct @var{entry_type} *ret = (@var{entry_type} *) entry;
238 .
239 . {* Allocate the structure if it has not already been allocated by a
240 .    derived class.  *}
241 .  if (ret == NULL)
242 .    {
243 .      ret = bfd_hash_allocate (table, sizeof (* ret));
244 .      if (ret == NULL)
245 .        return NULL;
246 .    }
247 .
248 . {* Call the allocation method of the base class.  *}
249 .  ret = ((@var{entry_type} *)
250 .	 @var{base_newfunc} ((struct bfd_hash_entry *) ret, table, string));
251 .
252 . {* Initialize the local fields here.  *}
253 .
254 .  return (struct bfd_hash_entry *) ret;
255 .}
256 
257 DESCRIPTION
258 	The creation routine for the linker hash table, which is in
259 	<<linker.c>>, looks just like this example.
260 	@var{function_name} is <<_bfd_link_hash_newfunc>>.
261 	@var{entry_type} is <<struct bfd_link_hash_entry>>.
262 	@var{base_newfunc} is <<bfd_hash_newfunc>>, the creation
263 	routine for a basic hash table.
264 
265 	<<_bfd_link_hash_newfunc>> also initializes the local fields
266 	in a linker hash table entry: <<type>>, <<written>> and
267 	<<next>>.
268 
269 INODE
270 Write Other Derived Routines, , Write the Derived Creation Routine, Deriving a New Hash Table Type
271 SUBSUBSECTION
272 	Write other derived routines
273 
274 	You will want to write other routines for your new hash table,
275 	as well.
276 
277 	You will want an initialization routine which calls the
278 	initialization routine of the hash table you are deriving from
279 	and initializes any other local fields.  For the linker hash
280 	table, this is <<_bfd_link_hash_table_init>> in <<linker.c>>.
281 
282 	You will want a lookup routine which calls the lookup routine
283 	of the hash table you are deriving from and casts the result.
284 	The linker hash table uses <<bfd_link_hash_lookup>> in
285 	<<linker.c>> (this actually takes an additional argument which
286 	it uses to decide how to return the looked up value).
287 
288 	You may want a traversal routine.  This should just call the
289 	traversal routine of the hash table you are deriving from with
290 	appropriate casts.  The linker hash table uses
291 	<<bfd_link_hash_traverse>> in <<linker.c>>.
292 
293 	These routines may simply be defined as macros.  For example,
294 	the a.out backend linker hash table, which is derived from the
295 	linker hash table, uses macros for the lookup and traversal
296 	routines.  These are <<aout_link_hash_lookup>> and
297 	<<aout_link_hash_traverse>> in aoutx.h.
298 */
299 
300 /* The default number of entries to use when creating a hash table.  */
301 #define DEFAULT_SIZE 4051
302 
303 /* The following function returns a nearest prime number which is
304    greater than N, and near a power of two.  Copied from libiberty.
305    Returns zero for ridiculously large N to signify an error.  */
306 
307 static unsigned long
higher_prime_number(unsigned long n)308 higher_prime_number (unsigned long n)
309 {
310   /* These are primes that are near, but slightly smaller than, a
311      power of two.  */
312   static const unsigned long primes[] = {
313     (unsigned long) 127,
314     (unsigned long) 2039,
315     (unsigned long) 32749,
316     (unsigned long) 65521,
317     (unsigned long) 131071,
318     (unsigned long) 262139,
319     (unsigned long) 524287,
320     (unsigned long) 1048573,
321     (unsigned long) 2097143,
322     (unsigned long) 4194301,
323     (unsigned long) 8388593,
324     (unsigned long) 16777213,
325     (unsigned long) 33554393,
326     (unsigned long) 67108859,
327     (unsigned long) 134217689,
328     (unsigned long) 268435399,
329     (unsigned long) 536870909,
330     (unsigned long) 1073741789,
331     (unsigned long) 2147483647,
332 					/* 4294967291L */
333     ((unsigned long) 2147483647) + ((unsigned long) 2147483644),
334   };
335 
336   const unsigned long *low = &primes[0];
337   const unsigned long *high = &primes[sizeof (primes) / sizeof (primes[0])];
338 
339   while (low != high)
340     {
341       const unsigned long *mid = low + (high - low) / 2;
342       if (n >= *mid)
343 	low = mid + 1;
344       else
345 	high = mid;
346     }
347 
348   if (n >= *low)
349     return 0;
350 
351   return *low;
352 }
353 
354 static size_t bfd_default_hash_table_size = DEFAULT_SIZE;
355 
356 /* Create a new hash table, given a number of entries.  */
357 
358 bfd_boolean
bfd_hash_table_init_n(struct bfd_hash_table * table,struct bfd_hash_entry * (* newfunc)(struct bfd_hash_entry *,struct bfd_hash_table *,const char *),unsigned int entsize,unsigned int size)359 bfd_hash_table_init_n (struct bfd_hash_table *table,
360 		       struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,
361 							  struct bfd_hash_table *,
362 							  const char *),
363 		       unsigned int entsize,
364 		       unsigned int size)
365 {
366   unsigned int alloc;
367 
368   alloc = size * sizeof (struct bfd_hash_entry *);
369 
370   table->memory = (void *) objalloc_create ();
371   if (table->memory == NULL)
372     {
373       bfd_set_error (bfd_error_no_memory);
374       return FALSE;
375     }
376   table->table = objalloc_alloc ((struct objalloc *) table->memory, alloc);
377   if (table->table == NULL)
378     {
379       bfd_set_error (bfd_error_no_memory);
380       return FALSE;
381     }
382   memset ((void *) table->table, 0, alloc);
383   table->size = size;
384   table->entsize = entsize;
385   table->count = 0;
386   table->frozen = 0;
387   table->newfunc = newfunc;
388   return TRUE;
389 }
390 
391 /* Create a new hash table with the default number of entries.  */
392 
393 bfd_boolean
bfd_hash_table_init(struct bfd_hash_table * table,struct bfd_hash_entry * (* newfunc)(struct bfd_hash_entry *,struct bfd_hash_table *,const char *),unsigned int entsize)394 bfd_hash_table_init (struct bfd_hash_table *table,
395 		     struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,
396 							struct bfd_hash_table *,
397 							const char *),
398 		     unsigned int entsize)
399 {
400   return bfd_hash_table_init_n (table, newfunc, entsize,
401 				bfd_default_hash_table_size);
402 }
403 
404 /* Free a hash table.  */
405 
406 void
bfd_hash_table_free(struct bfd_hash_table * table)407 bfd_hash_table_free (struct bfd_hash_table *table)
408 {
409   objalloc_free (table->memory);
410   table->memory = NULL;
411 }
412 
413 /* Look up a string in a hash table.  */
414 
415 struct bfd_hash_entry *
bfd_hash_lookup(struct bfd_hash_table * table,const char * string,bfd_boolean create,bfd_boolean copy)416 bfd_hash_lookup (struct bfd_hash_table *table,
417 		 const char *string,
418 		 bfd_boolean create,
419 		 bfd_boolean copy)
420 {
421   const unsigned char *s;
422   unsigned long hash;
423   unsigned int c;
424   struct bfd_hash_entry *hashp;
425   unsigned int len;
426   unsigned int index;
427 
428   hash = 0;
429   len = 0;
430   s = (const unsigned char *) string;
431   while ((c = *s++) != '\0')
432     {
433       hash += c + (c << 17);
434       hash ^= hash >> 2;
435     }
436   len = (s - (const unsigned char *) string) - 1;
437   hash += len + (len << 17);
438   hash ^= hash >> 2;
439 
440   index = hash % table->size;
441   for (hashp = table->table[index];
442        hashp != NULL;
443        hashp = hashp->next)
444     {
445       if (hashp->hash == hash
446 	  && strcmp (hashp->string, string) == 0)
447 	return hashp;
448     }
449 
450   if (! create)
451     return NULL;
452 
453   hashp = (*table->newfunc) (NULL, table, string);
454   if (hashp == NULL)
455     return NULL;
456   if (copy)
457     {
458       char *new;
459 
460       new = objalloc_alloc ((struct objalloc *) table->memory, len + 1);
461       if (!new)
462 	{
463 	  bfd_set_error (bfd_error_no_memory);
464 	  return NULL;
465 	}
466       memcpy (new, string, len + 1);
467       string = new;
468     }
469   hashp->string = string;
470   hashp->hash = hash;
471   hashp->next = table->table[index];
472   table->table[index] = hashp;
473   table->count++;
474 
475   if (!table->frozen && table->count > table->size * 3 / 4)
476     {
477       unsigned long newsize = higher_prime_number (table->size);
478       struct bfd_hash_entry **newtable;
479       unsigned int hi;
480       unsigned long alloc = newsize * sizeof (struct bfd_hash_entry *);
481 
482       /* If we can't find a higher prime, or we can't possibly alloc
483 	 that much memory, don't try to grow the table.  */
484       if (newsize == 0 || alloc / sizeof (struct bfd_hash_entry *) != newsize)
485 	{
486 	  table->frozen = 1;
487 	  return hashp;
488 	}
489 
490       newtable = ((struct bfd_hash_entry **)
491 		  objalloc_alloc ((struct objalloc *) table->memory, alloc));
492       memset ((PTR) newtable, 0, alloc);
493 
494       for (hi = 0; hi < table->size; hi ++)
495 	while (table->table[hi])
496 	  {
497 	    struct bfd_hash_entry *chain = table->table[hi];
498 	    struct bfd_hash_entry *chain_end = chain;
499 	    int index;
500 
501 	    while (chain_end->next && chain_end->next->hash == chain->hash)
502 	      chain_end = chain_end->next;
503 
504 	    table->table[hi] = chain_end->next;
505 	    index = chain->hash % newsize;
506 	    chain_end->next = newtable[index];
507 	    newtable[index] = chain;
508 	  }
509       table->table = newtable;
510       table->size = newsize;
511     }
512 
513   return hashp;
514 }
515 
516 /* Replace an entry in a hash table.  */
517 
518 void
bfd_hash_replace(struct bfd_hash_table * table,struct bfd_hash_entry * old,struct bfd_hash_entry * nw)519 bfd_hash_replace (struct bfd_hash_table *table,
520 		  struct bfd_hash_entry *old,
521 		  struct bfd_hash_entry *nw)
522 {
523   unsigned int index;
524   struct bfd_hash_entry **pph;
525 
526   index = old->hash % table->size;
527   for (pph = &table->table[index];
528        (*pph) != NULL;
529        pph = &(*pph)->next)
530     {
531       if (*pph == old)
532 	{
533 	  *pph = nw;
534 	  return;
535 	}
536     }
537 
538   abort ();
539 }
540 
541 /* Allocate space in a hash table.  */
542 
543 void *
bfd_hash_allocate(struct bfd_hash_table * table,unsigned int size)544 bfd_hash_allocate (struct bfd_hash_table *table,
545 		   unsigned int size)
546 {
547   void * ret;
548 
549   ret = objalloc_alloc ((struct objalloc *) table->memory, size);
550   if (ret == NULL && size != 0)
551     bfd_set_error (bfd_error_no_memory);
552   return ret;
553 }
554 
555 /* Base method for creating a new hash table entry.  */
556 
557 struct bfd_hash_entry *
bfd_hash_newfunc(struct bfd_hash_entry * entry,struct bfd_hash_table * table,const char * string ATTRIBUTE_UNUSED)558 bfd_hash_newfunc (struct bfd_hash_entry *entry,
559 		  struct bfd_hash_table *table,
560 		  const char *string ATTRIBUTE_UNUSED)
561 {
562   if (entry == NULL)
563     entry = bfd_hash_allocate (table, sizeof (* entry));
564   return entry;
565 }
566 
567 /* Traverse a hash table.  */
568 
569 void
bfd_hash_traverse(struct bfd_hash_table * table,bfd_boolean (* func)(struct bfd_hash_entry *,void *),void * info)570 bfd_hash_traverse (struct bfd_hash_table *table,
571 		   bfd_boolean (*func) (struct bfd_hash_entry *, void *),
572 		   void * info)
573 {
574   unsigned int i;
575 
576   table->frozen = 1;
577   for (i = 0; i < table->size; i++)
578     {
579       struct bfd_hash_entry *p;
580 
581       for (p = table->table[i]; p != NULL; p = p->next)
582 	if (! (*func) (p, info))
583 	  goto out;
584     }
585  out:
586   table->frozen = 0;
587 }
588 
589 void
bfd_hash_set_default_size(bfd_size_type hash_size)590 bfd_hash_set_default_size (bfd_size_type hash_size)
591 {
592   /* Extend this prime list if you want more granularity of hash table size.  */
593   static const bfd_size_type hash_size_primes[] =
594     {
595       251, 509, 1021, 2039, 4051, 8599, 16699, 32749
596     };
597   size_t index;
598 
599   /* Work out best prime number near the hash_size.  */
600   for (index = 0; index < ARRAY_SIZE (hash_size_primes) - 1; ++index)
601     if (hash_size <= hash_size_primes[index])
602       break;
603 
604   bfd_default_hash_table_size = hash_size_primes[index];
605 }
606 
607 /* A few different object file formats (a.out, COFF, ELF) use a string
608    table.  These functions support adding strings to a string table,
609    returning the byte offset, and writing out the table.
610 
611    Possible improvements:
612    + look for strings matching trailing substrings of other strings
613    + better data structures?  balanced trees?
614    + look at reducing memory use elsewhere -- maybe if we didn't have
615      to construct the entire symbol table at once, we could get by
616      with smaller amounts of VM?  (What effect does that have on the
617      string table reductions?)  */
618 
619 /* An entry in the strtab hash table.  */
620 
621 struct strtab_hash_entry
622 {
623   struct bfd_hash_entry root;
624   /* Index in string table.  */
625   bfd_size_type index;
626   /* Next string in strtab.  */
627   struct strtab_hash_entry *next;
628 };
629 
630 /* The strtab hash table.  */
631 
632 struct bfd_strtab_hash
633 {
634   struct bfd_hash_table table;
635   /* Size of strtab--also next available index.  */
636   bfd_size_type size;
637   /* First string in strtab.  */
638   struct strtab_hash_entry *first;
639   /* Last string in strtab.  */
640   struct strtab_hash_entry *last;
641   /* Whether to precede strings with a two byte length, as in the
642      XCOFF .debug section.  */
643   bfd_boolean xcoff;
644 };
645 
646 /* Routine to create an entry in a strtab.  */
647 
648 static struct bfd_hash_entry *
strtab_hash_newfunc(struct bfd_hash_entry * entry,struct bfd_hash_table * table,const char * string)649 strtab_hash_newfunc (struct bfd_hash_entry *entry,
650 		     struct bfd_hash_table *table,
651 		     const char *string)
652 {
653   struct strtab_hash_entry *ret = (struct strtab_hash_entry *) entry;
654 
655   /* Allocate the structure if it has not already been allocated by a
656      subclass.  */
657   if (ret == NULL)
658     ret = bfd_hash_allocate (table, sizeof (* ret));
659   if (ret == NULL)
660     return NULL;
661 
662   /* Call the allocation method of the superclass.  */
663   ret = (struct strtab_hash_entry *)
664 	 bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string);
665 
666   if (ret)
667     {
668       /* Initialize the local fields.  */
669       ret->index = (bfd_size_type) -1;
670       ret->next = NULL;
671     }
672 
673   return (struct bfd_hash_entry *) ret;
674 }
675 
676 /* Look up an entry in an strtab.  */
677 
678 #define strtab_hash_lookup(t, string, create, copy) \
679   ((struct strtab_hash_entry *) \
680    bfd_hash_lookup (&(t)->table, (string), (create), (copy)))
681 
682 /* Create a new strtab.  */
683 
684 struct bfd_strtab_hash *
_bfd_stringtab_init(void)685 _bfd_stringtab_init (void)
686 {
687   struct bfd_strtab_hash *table;
688   bfd_size_type amt = sizeof (* table);
689 
690   table = bfd_malloc (amt);
691   if (table == NULL)
692     return NULL;
693 
694   if (!bfd_hash_table_init (&table->table, strtab_hash_newfunc,
695 			    sizeof (struct strtab_hash_entry)))
696     {
697       free (table);
698       return NULL;
699     }
700 
701   table->size = 0;
702   table->first = NULL;
703   table->last = NULL;
704   table->xcoff = FALSE;
705 
706   return table;
707 }
708 
709 /* Create a new strtab in which the strings are output in the format
710    used in the XCOFF .debug section: a two byte length precedes each
711    string.  */
712 
713 struct bfd_strtab_hash *
_bfd_xcoff_stringtab_init(void)714 _bfd_xcoff_stringtab_init (void)
715 {
716   struct bfd_strtab_hash *ret;
717 
718   ret = _bfd_stringtab_init ();
719   if (ret != NULL)
720     ret->xcoff = TRUE;
721   return ret;
722 }
723 
724 /* Free a strtab.  */
725 
726 void
_bfd_stringtab_free(struct bfd_strtab_hash * table)727 _bfd_stringtab_free (struct bfd_strtab_hash *table)
728 {
729   bfd_hash_table_free (&table->table);
730   free (table);
731 }
732 
733 /* Get the index of a string in a strtab, adding it if it is not
734    already present.  If HASH is FALSE, we don't really use the hash
735    table, and we don't eliminate duplicate strings.  */
736 
737 bfd_size_type
_bfd_stringtab_add(struct bfd_strtab_hash * tab,const char * str,bfd_boolean hash,bfd_boolean copy)738 _bfd_stringtab_add (struct bfd_strtab_hash *tab,
739 		    const char *str,
740 		    bfd_boolean hash,
741 		    bfd_boolean copy)
742 {
743   struct strtab_hash_entry *entry;
744 
745   if (hash)
746     {
747       entry = strtab_hash_lookup (tab, str, TRUE, copy);
748       if (entry == NULL)
749 	return (bfd_size_type) -1;
750     }
751   else
752     {
753       entry = bfd_hash_allocate (&tab->table, sizeof (* entry));
754       if (entry == NULL)
755 	return (bfd_size_type) -1;
756       if (! copy)
757 	entry->root.string = str;
758       else
759 	{
760 	  char *n;
761 
762 	  n = bfd_hash_allocate (&tab->table, strlen (str) + 1);
763 	  if (n == NULL)
764 	    return (bfd_size_type) -1;
765 	  entry->root.string = n;
766 	}
767       entry->index = (bfd_size_type) -1;
768       entry->next = NULL;
769     }
770 
771   if (entry->index == (bfd_size_type) -1)
772     {
773       entry->index = tab->size;
774       tab->size += strlen (str) + 1;
775       if (tab->xcoff)
776 	{
777 	  entry->index += 2;
778 	  tab->size += 2;
779 	}
780       if (tab->first == NULL)
781 	tab->first = entry;
782       else
783 	tab->last->next = entry;
784       tab->last = entry;
785     }
786 
787   return entry->index;
788 }
789 
790 /* Get the number of bytes in a strtab.  */
791 
792 bfd_size_type
_bfd_stringtab_size(struct bfd_strtab_hash * tab)793 _bfd_stringtab_size (struct bfd_strtab_hash *tab)
794 {
795   return tab->size;
796 }
797 
798 /* Write out a strtab.  ABFD must already be at the right location in
799    the file.  */
800 
801 bfd_boolean
_bfd_stringtab_emit(bfd * abfd,struct bfd_strtab_hash * tab)802 _bfd_stringtab_emit (bfd *abfd, struct bfd_strtab_hash *tab)
803 {
804   bfd_boolean xcoff;
805   struct strtab_hash_entry *entry;
806 
807   xcoff = tab->xcoff;
808 
809   for (entry = tab->first; entry != NULL; entry = entry->next)
810     {
811       const char *str;
812       size_t len;
813 
814       str = entry->root.string;
815       len = strlen (str) + 1;
816 
817       if (xcoff)
818 	{
819 	  bfd_byte buf[2];
820 
821 	  /* The output length includes the null byte.  */
822 	  bfd_put_16 (abfd, (bfd_vma) len, buf);
823 	  if (bfd_bwrite ((void *) buf, (bfd_size_type) 2, abfd) != 2)
824 	    return FALSE;
825 	}
826 
827       if (bfd_bwrite ((void *) str, (bfd_size_type) len, abfd) != len)
828 	return FALSE;
829     }
830 
831   return TRUE;
832 }
833