/* C string table handling.
Copyright (C) 2000-2018 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, ©len);
assert (copylen == st->total + 1);
assert (endp == retval + st->total + 1);
*size = copylen;
return retval;
}
size_t
strtaboffset (struct Strent *se)
{
return se->offset;
}