/* hash.c -- hash table routines for BFD
- Copyright 1993 Free Software Foundation, Inc.
+ Copyright (C) 1993, 94, 95, 97, 1999 Free Software Foundation, Inc.
Written by Steve Chamberlain <sac@cygnus.com>
-This file is part of GLD, the Gnu Linker.
+This file is part of BFD, the Binary File Descriptor library.
-GLD is free software; you can redistribute it and/or modify
+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.
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
-GLD is distributed in the hope that it will be useful,
+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 GLD; see the file COPYING. If not, write to
-the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#include "bfd.h"
#include "sysdep.h"
#include "libbfd.h"
-#include "obstack.h"
+#include "objalloc.h"
-/* Obstack allocation and deallocation routines. */
-#define obstack_chunk_alloc bfd_xmalloc_by_size_t
-#define obstack_chunk_free free
+/*
+SECTION
+ Hash Tables
+
+@cindex Hash tables
+ BFD provides a simple set of hash table functions. Routines
+ are provided to initialize a hash table, to free a hash table,
+ to look up a string in a hash table and optionally create an
+ entry for it, and to traverse a hash table. There is
+ currently no routine to delete an string from a hash table.
+
+ The basic hash table does not permit any data to be stored
+ with a string. However, a hash table is designed to present a
+ base class from which other types of hash tables may be
+ derived. These derived types may store additional information
+ with the string. Hash tables were implemented in this way,
+ rather than simply providing a data pointer in a hash table
+ entry, because they were designed for use by the linker back
+ ends. The linker may create thousands of hash table entries,
+ and the overhead of allocating private data and storing and
+ following pointers becomes noticeable.
+
+ The basic hash table code is in <<hash.c>>.
+
+@menu
+@* Creating and Freeing a Hash Table::
+@* Looking Up or Entering a String::
+@* Traversing a Hash Table::
+@* Deriving a New Hash Table Type::
+@end menu
+
+INODE
+Creating and Freeing a Hash Table, Looking Up or Entering a String, Hash Tables, Hash Tables
+SUBSECTION
+ Creating and freeing a hash table
+
+@findex bfd_hash_table_init
+@findex bfd_hash_table_init_n
+ To create a hash table, create an instance of a <<struct
+ bfd_hash_table>> (defined in <<bfd.h>>) and call
+ <<bfd_hash_table_init>> (if you know approximately how many
+ entries you will need, the function <<bfd_hash_table_init_n>>,
+ which takes a @var{size} argument, may be used).
+ <<bfd_hash_table_init>> returns <<false>> if some sort of
+ error occurs.
+
+@findex bfd_hash_newfunc
+ The function <<bfd_hash_table_init>> take as an argument a
+ function to use to create new entries. For a basic hash
+ table, use the function <<bfd_hash_newfunc>>. @xref{Deriving
+ a New Hash Table Type}, for why you would want to use a
+ different value for this argument.
+
+@findex bfd_hash_allocate
+ <<bfd_hash_table_init>> will create an objalloc which will be
+ used to allocate new entries. You may allocate memory on this
+ objalloc using <<bfd_hash_allocate>>.
+
+@findex bfd_hash_table_free
+ Use <<bfd_hash_table_free>> to free up all the memory that has
+ been allocated for a hash table. This will not free up the
+ <<struct bfd_hash_table>> itself, which you must provide.
+
+INODE
+Looking Up or Entering a String, Traversing a Hash Table, Creating and Freeing a Hash Table, Hash Tables
+SUBSECTION
+ Looking up or entering a string
+
+@findex bfd_hash_lookup
+ The function <<bfd_hash_lookup>> is used both to look up a
+ string in the hash table and to create a new entry.
+
+ If the @var{create} argument is <<false>>, <<bfd_hash_lookup>>
+ will look up a string. If the string is found, it will
+ returns a pointer to a <<struct bfd_hash_entry>>. If the
+ string is not found in the table <<bfd_hash_lookup>> will
+ return <<NULL>>. You should not modify any of the fields in
+ the returns <<struct bfd_hash_entry>>.
+
+ If the @var{create} argument is <<true>>, the string will be
+ entered into the hash table if it is not already there.
+ Either way a pointer to a <<struct bfd_hash_entry>> will be
+ returned, either to the existing structure or to a newly
+ created one. In this case, a <<NULL>> return means that an
+ error occurred.
+
+ If the @var{create} argument is <<true>>, and a new entry is
+ created, the @var{copy} argument is used to decide whether to
+ copy the string onto the hash table objalloc or not. If
+ @var{copy} is passed as <<false>>, you must be careful not to
+ deallocate or modify the string as long as the hash table
+ exists.
+
+INODE
+Traversing a Hash Table, Deriving a New Hash Table Type, Looking Up or Entering a String, Hash Tables
+SUBSECTION
+ Traversing a hash table
+
+@findex bfd_hash_traverse
+ The function <<bfd_hash_traverse>> may be used to traverse a
+ hash table, calling a function on each element. The traversal
+ is done in a random order.
+
+ <<bfd_hash_traverse>> takes as arguments a function and a
+ generic <<void *>> pointer. The function is called with a
+ hash table entry (a <<struct bfd_hash_entry *>>) and the
+ generic pointer passed to <<bfd_hash_traverse>>. The function
+ must return a <<boolean>> value, which indicates whether to
+ continue traversing the hash table. If the function returns
+ <<false>>, <<bfd_hash_traverse>> will stop the traversal and
+ return immediately.
+
+INODE
+Deriving a New Hash Table Type, , Traversing a Hash Table, Hash Tables
+SUBSECTION
+ Deriving a new hash table type
+
+ Many uses of hash tables want to store additional information
+ which each entry in the hash table. Some also find it
+ convenient to store additional information with the hash table
+ itself. This may be done using a derived hash table.
+
+ Since C is not an object oriented language, creating a derived
+ hash table requires sticking together some boilerplate
+ routines with a few differences specific to the type of hash
+ table you want to create.
+
+ An example of a derived hash table is the linker hash table.
+ The structures for this are defined in <<bfdlink.h>>. The
+ functions are in <<linker.c>>.
+
+ You may also derive a hash table from an already derived hash
+ table. For example, the a.out linker backend code uses a hash
+ table derived from the linker hash table.
+
+@menu
+@* Define the Derived Structures::
+@* Write the Derived Creation Routine::
+@* Write Other Derived Routines::
+@end menu
+
+INODE
+Define the Derived Structures, Write the Derived Creation Routine, Deriving a New Hash Table Type, Deriving a New Hash Table Type
+SUBSUBSECTION
+ Define the derived structures
+
+ You must define a structure for an entry in the hash table,
+ and a structure for the hash table itself.
+
+ The first field in the structure for an entry in the hash
+ table must be of the type used for an entry in the hash table
+ you are deriving from. If you are deriving from a basic hash
+ table this is <<struct bfd_hash_entry>>, which is defined in
+ <<bfd.h>>. The first field in the structure for the hash
+ table itself must be of the type of the hash table you are
+ deriving from itself. If you are deriving from a basic hash
+ table, this is <<struct bfd_hash_table>>.
+
+ For example, the linker hash table defines <<struct
+ bfd_link_hash_entry>> (in <<bfdlink.h>>). The first field,
+ <<root>>, is of type <<struct bfd_hash_entry>>. Similarly,
+ the first field in <<struct bfd_link_hash_table>>, <<table>>,
+ is of type <<struct bfd_hash_table>>.
+
+INODE
+Write the Derived Creation Routine, Write Other Derived Routines, Define the Derived Structures, Deriving a New Hash Table Type
+SUBSUBSECTION
+ Write the derived creation routine
+
+ You must write a routine which will create and initialize an
+ entry in the hash table. This routine is passed as the
+ function argument to <<bfd_hash_table_init>>.
+
+ In order to permit other hash tables to be derived from the
+ hash table you are creating, this routine must be written in a
+ standard way.
+
+ The first argument to the creation routine is a pointer to a
+ hash table entry. This may be <<NULL>>, in which case the
+ routine should allocate the right amount of space. Otherwise
+ the space has already been allocated by a hash table type
+ derived from this one.
+
+ After allocating space, the creation routine must call the
+ creation routine of the hash table type it is derived from,
+ passing in a pointer to the space it just allocated. This
+ will initialize any fields used by the base hash table.
+
+ Finally the creation routine must initialize any local fields
+ for the new hash table type.
+
+ Here is a boilerplate example of a creation routine.
+ @var{function_name} is the name of the routine.
+ @var{entry_type} is the type of an entry in the hash table you
+ are creating. @var{base_newfunc} is the name of the creation
+ routine of the hash table type your hash table is derived
+ from.
+
+EXAMPLE
+
+.struct bfd_hash_entry *
+.@var{function_name} (entry, table, string)
+. struct bfd_hash_entry *entry;
+. struct bfd_hash_table *table;
+. const char *string;
+.{
+. struct @var{entry_type} *ret = (@var{entry_type} *) entry;
+.
+. {* Allocate the structure if it has not already been allocated by a
+. derived class. *}
+. if (ret == (@var{entry_type} *) NULL)
+. {
+. ret = ((@var{entry_type} *)
+. bfd_hash_allocate (table, sizeof (@var{entry_type})));
+. if (ret == (@var{entry_type} *) NULL)
+. return NULL;
+. }
+.
+. {* Call the allocation method of the base class. *}
+. ret = ((@var{entry_type} *)
+. @var{base_newfunc} ((struct bfd_hash_entry *) ret, table, string));
+.
+. {* Initialize the local fields here. *}
+.
+. return (struct bfd_hash_entry *) ret;
+.}
+
+DESCRIPTION
+ The creation routine for the linker hash table, which is in
+ <<linker.c>>, looks just like this example.
+ @var{function_name} is <<_bfd_link_hash_newfunc>>.
+ @var{entry_type} is <<struct bfd_link_hash_entry>>.
+ @var{base_newfunc} is <<bfd_hash_newfunc>>, the creation
+ routine for a basic hash table.
+
+ <<_bfd_link_hash_newfunc>> also initializes the local fields
+ in a linker hash table entry: <<type>>, <<written>> and
+ <<next>>.
+
+INODE
+Write Other Derived Routines, , Write the Derived Creation Routine, Deriving a New Hash Table Type
+SUBSUBSECTION
+ Write other derived routines
+
+ You will want to write other routines for your new hash table,
+ as well.
+
+ You will want an initialization routine which calls the
+ initialization routine of the hash table you are deriving from
+ and initializes any other local fields. For the linker hash
+ table, this is <<_bfd_link_hash_table_init>> in <<linker.c>>.
+
+ You will want a lookup routine which calls the lookup routine
+ of the hash table you are deriving from and casts the result.
+ The linker hash table uses <<bfd_link_hash_lookup>> in
+ <<linker.c>> (this actually takes an additional argument which
+ it uses to decide how to return the looked up value).
+
+ You may want a traversal routine. This should just call the
+ traversal routine of the hash table you are deriving from with
+ appropriate casts. The linker hash table uses
+ <<bfd_link_hash_traverse>> in <<linker.c>>.
+
+ These routines may simply be defined as macros. For example,
+ the a.out backend linker hash table, which is derived from the
+ linker hash table, uses macros for the lookup and traversal
+ routines. These are <<aout_link_hash_lookup>> and
+ <<aout_link_hash_traverse>> in aoutx.h.
+*/
/* The default number of entries to use when creating a hash table. */
#define DEFAULT_SIZE (4051)
unsigned int alloc;
alloc = size * sizeof (struct bfd_hash_entry *);
- obstack_begin (&table->memory, alloc);
+
+ table->memory = (PTR) objalloc_create ();
+ if (table->memory == NULL)
+ {
+ bfd_set_error (bfd_error_no_memory);
+ return false;
+ }
table->table = ((struct bfd_hash_entry **)
- obstack_alloc (&table->memory, alloc));
+ objalloc_alloc ((struct objalloc *) table->memory, alloc));
+ if (table->table == NULL)
+ {
+ bfd_set_error (bfd_error_no_memory);
+ return false;
+ }
memset ((PTR) table->table, 0, alloc);
table->size = size;
table->newfunc = newfunc;
bfd_hash_table_free (table)
struct bfd_hash_table *table;
{
- obstack_free (&table->memory, (PTR) NULL);
+ objalloc_free ((struct objalloc *) table->memory);
+ table->memory = NULL;
}
/* Look up a string in a hash table. */
{
char *new;
- new = (char *) obstack_alloc (&table->memory, len + 1);
+ new = (char *) objalloc_alloc ((struct objalloc *) table->memory,
+ len + 1);
+ if (!new)
+ {
+ bfd_set_error (bfd_error_no_memory);
+ return (struct bfd_hash_entry *) NULL;
+ }
strcpy (new, string);
string = new;
}
return hashp;
}
+/* Replace an entry in a hash table. */
+
+void
+bfd_hash_replace (table, old, nw)
+ struct bfd_hash_table *table;
+ struct bfd_hash_entry *old;
+ struct bfd_hash_entry *nw;
+{
+ unsigned int index;
+ struct bfd_hash_entry **pph;
+
+ index = old->hash % table->size;
+ for (pph = &table->table[index];
+ (*pph) != (struct bfd_hash_entry *) NULL;
+ pph = &(*pph)->next)
+ {
+ if (*pph == old)
+ {
+ *pph = nw;
+ return;
+ }
+ }
+
+ abort ();
+}
+
/* Base method for creating a new hash table entry. */
/*ARGSUSED*/
bfd_hash_newfunc (entry, table, string)
struct bfd_hash_entry *entry;
struct bfd_hash_table *table;
- const char *string;
+ const char *string ATTRIBUTE_UNUSED;
{
if (entry == (struct bfd_hash_entry *) NULL)
entry = ((struct bfd_hash_entry *)
PTR
bfd_hash_allocate (table, size)
struct bfd_hash_table *table;
- size_t size;
+ unsigned int size;
{
- return obstack_alloc (&table->memory, size);
+ PTR ret;
+
+ ret = objalloc_alloc ((struct objalloc *) table->memory, size);
+ if (ret == NULL && size != 0)
+ bfd_set_error (bfd_error_no_memory);
+ return ret;
}
/* Traverse a hash table. */
}
}
}
+\f
+/* A few different object file formats (a.out, COFF, ELF) use a string
+ table. These functions support adding strings to a string table,
+ returning the byte offset, and writing out the table.
+
+ Possible improvements:
+ + look for strings matching trailing substrings of other strings
+ + better data structures? balanced trees?
+ + look at reducing memory use elsewhere -- maybe if we didn't have
+ to construct the entire symbol table at once, we could get by
+ with smaller amounts of VM? (What effect does that have on the
+ string table reductions?) */
+
+/* An entry in the strtab hash table. */
+
+struct strtab_hash_entry
+{
+ struct bfd_hash_entry root;
+ /* Index in string table. */
+ bfd_size_type index;
+ /* Next string in strtab. */
+ struct strtab_hash_entry *next;
+};
+
+/* The strtab hash table. */
+
+struct bfd_strtab_hash
+{
+ struct bfd_hash_table table;
+ /* Size of strtab--also next available index. */
+ bfd_size_type size;
+ /* First string in strtab. */
+ struct strtab_hash_entry *first;
+ /* Last string in strtab. */
+ struct strtab_hash_entry *last;
+ /* Whether to precede strings with a two byte length, as in the
+ XCOFF .debug section. */
+ boolean xcoff;
+};
+
+static struct bfd_hash_entry *strtab_hash_newfunc
+ PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
+
+/* Routine to create an entry in a strtab. */
+
+static struct bfd_hash_entry *
+strtab_hash_newfunc (entry, table, string)
+ struct bfd_hash_entry *entry;
+ struct bfd_hash_table *table;
+ const char *string;
+{
+ struct strtab_hash_entry *ret = (struct strtab_hash_entry *) entry;
+
+ /* Allocate the structure if it has not already been allocated by a
+ subclass. */
+ if (ret == (struct strtab_hash_entry *) NULL)
+ ret = ((struct strtab_hash_entry *)
+ bfd_hash_allocate (table, sizeof (struct strtab_hash_entry)));
+ if (ret == (struct strtab_hash_entry *) NULL)
+ return NULL;
+
+ /* Call the allocation method of the superclass. */
+ ret = ((struct strtab_hash_entry *)
+ bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
+
+ if (ret)
+ {
+ /* Initialize the local fields. */
+ ret->index = (bfd_size_type) -1;
+ ret->next = NULL;
+ }
+
+ return (struct bfd_hash_entry *) ret;
+}
+
+/* Look up an entry in an strtab. */
+
+#define strtab_hash_lookup(t, string, create, copy) \
+ ((struct strtab_hash_entry *) \
+ bfd_hash_lookup (&(t)->table, (string), (create), (copy)))
+
+/* Create a new strtab. */
+
+struct bfd_strtab_hash *
+_bfd_stringtab_init ()
+{
+ struct bfd_strtab_hash *table;
+
+ table = ((struct bfd_strtab_hash *)
+ bfd_malloc (sizeof (struct bfd_strtab_hash)));
+ if (table == NULL)
+ return NULL;
+
+ if (! bfd_hash_table_init (&table->table, strtab_hash_newfunc))
+ {
+ free (table);
+ return NULL;
+ }
+
+ table->size = 0;
+ table->first = NULL;
+ table->last = NULL;
+ table->xcoff = false;
+
+ return table;
+}
+
+/* Create a new strtab in which the strings are output in the format
+ used in the XCOFF .debug section: a two byte length precedes each
+ string. */
+
+struct bfd_strtab_hash *
+_bfd_xcoff_stringtab_init ()
+{
+ struct bfd_strtab_hash *ret;
+
+ ret = _bfd_stringtab_init ();
+ if (ret != NULL)
+ ret->xcoff = true;
+ return ret;
+}
+
+/* Free a strtab. */
+
+void
+_bfd_stringtab_free (table)
+ struct bfd_strtab_hash *table;
+{
+ bfd_hash_table_free (&table->table);
+ free (table);
+}
+
+/* Get the index of a string in a strtab, adding it if it is not
+ already present. If HASH is false, we don't really use the hash
+ table, and we don't eliminate duplicate strings. */
+
+bfd_size_type
+_bfd_stringtab_add (tab, str, hash, copy)
+ struct bfd_strtab_hash *tab;
+ const char *str;
+ boolean hash;
+ boolean copy;
+{
+ register struct strtab_hash_entry *entry;
+
+ if (hash)
+ {
+ entry = strtab_hash_lookup (tab, str, true, copy);
+ if (entry == NULL)
+ return (bfd_size_type) -1;
+ }
+ else
+ {
+ entry = ((struct strtab_hash_entry *)
+ bfd_hash_allocate (&tab->table,
+ sizeof (struct strtab_hash_entry)));
+ if (entry == NULL)
+ return (bfd_size_type) -1;
+ if (! copy)
+ entry->root.string = str;
+ else
+ {
+ char *n;
+
+ n = (char *) bfd_hash_allocate (&tab->table, strlen (str) + 1);
+ if (n == NULL)
+ return (bfd_size_type) -1;
+ entry->root.string = n;
+ }
+ entry->index = (bfd_size_type) -1;
+ entry->next = NULL;
+ }
+
+ if (entry->index == (bfd_size_type) -1)
+ {
+ entry->index = tab->size;
+ tab->size += strlen (str) + 1;
+ if (tab->xcoff)
+ {
+ entry->index += 2;
+ tab->size += 2;
+ }
+ if (tab->first == NULL)
+ tab->first = entry;
+ else
+ tab->last->next = entry;
+ tab->last = entry;
+ }
+
+ return entry->index;
+}
+
+/* Get the number of bytes in a strtab. */
+
+bfd_size_type
+_bfd_stringtab_size (tab)
+ struct bfd_strtab_hash *tab;
+{
+ return tab->size;
+}
+
+/* Write out a strtab. ABFD must already be at the right location in
+ the file. */
+
+boolean
+_bfd_stringtab_emit (abfd, tab)
+ register bfd *abfd;
+ struct bfd_strtab_hash *tab;
+{
+ register boolean xcoff;
+ register struct strtab_hash_entry *entry;
+
+ xcoff = tab->xcoff;
+
+ for (entry = tab->first; entry != NULL; entry = entry->next)
+ {
+ register const char *str;
+ register size_t len;
+
+ str = entry->root.string;
+ len = strlen (str) + 1;
+
+ if (xcoff)
+ {
+ bfd_byte buf[2];
+
+ /* The output length includes the null byte. */
+ bfd_put_16 (abfd, len, buf);
+ if (bfd_write ((PTR) buf, 1, 2, abfd) != 2)
+ return false;
+ }
+
+ if (bfd_write ((PTR) str, 1, len, abfd) != len)
+ return false;
+ }
+
+ return true;
+}