diff options
Diffstat (limited to 'bfd/merge.c')
-rw-r--r-- | bfd/merge.c | 606 |
1 files changed, 606 insertions, 0 deletions
diff --git a/bfd/merge.c b/bfd/merge.c new file mode 100644 index 0000000..ace069e --- /dev/null +++ b/bfd/merge.c @@ -0,0 +1,606 @@ +/* SEC_MERGE support. + Copyright 2001 Free Software Foundation, Inc. + Written by Jakub Jelinek <jakub@redhat.com>. + +This file is part of BFD, the Binary File Descriptor library. + +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 of the License, 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, write to the Free Software +Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +/* This file contains support for merging duplicate entities within sections, + as used in ELF SHF_MERGE. */ + +#include "bfd.h" +#include "sysdep.h" +#include "libbfd.h" + +#include <ctype.h> + +/* An entry in the section merge hash table. */ + +struct sec_merge_hash_entry +{ + struct bfd_hash_entry root; + /* Length of this entry. */ + unsigned int len; + /* Index within the merged section. */ + bfd_size_type index; + /* Which section is it in. */ + asection *sec; + /* Next entity in the hash table. */ + struct sec_merge_hash_entry *next; +}; + +/* The section merge hash table. */ + +struct sec_merge_hash +{ + struct bfd_hash_table table; + /* Next available index. */ + bfd_size_type size; + /* First entity in the SEC_MERGE sections of this type. */ + struct sec_merge_hash_entry *first; + /* Last entity in the SEC_MERGE sections of this type. */ + struct sec_merge_hash_entry *last; + /* Entity size. */ + unsigned int entsize; + /* Start of each string needs to be aligned to 1 << alignment_power + octets. */ + unsigned int alignment_power; + /* Are entries fixed size or zero terminated strings? */ + boolean strings; +}; + +struct sec_merge_info +{ + /* Chain of sec_merge_infos. */ + struct sec_merge_info *next; + /* A hash table used to hold section content. */ + struct sec_merge_hash *htab; + /* The last section attempted for merge. */ + asection *last; +}; + +struct sec_merge_sec_info +{ + /* A hash table used to hold section content. */ + struct sec_merge_hash *htab; + /* First string in this section. */ + struct sec_merge_hash_entry *first; + /* Original section content. */ + unsigned char contents[1]; +}; + +static struct bfd_hash_entry *sec_merge_hash_newfunc + PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *)); +static struct sec_merge_hash_entry *sec_merge_hash_lookup + PARAMS ((struct sec_merge_hash *, const char *, boolean)); +static struct sec_merge_hash *sec_merge_init + PARAMS ((unsigned int, unsigned int, boolean)); +static struct sec_merge_hash_entry *sec_merge_add + PARAMS ((struct sec_merge_hash *, const char *)); +static boolean sec_merge_emit + PARAMS ((bfd *, struct sec_merge_hash *, struct sec_merge_hash_entry *)); + +/* Routine to create an entry in a section merge hashtab. */ + +static struct bfd_hash_entry * +sec_merge_hash_newfunc (entry, table, string) + struct bfd_hash_entry *entry; + struct bfd_hash_table *table; + const char *string; +{ + struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry; + + /* Allocate the structure if it has not already been allocated by a + subclass. */ + if (ret == (struct sec_merge_hash_entry *) NULL) + ret = ((struct sec_merge_hash_entry *) + bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry))); + if (ret == (struct sec_merge_hash_entry *) NULL) + return NULL; + + /* Call the allocation method of the superclass. */ + ret = ((struct sec_merge_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->sec = NULL; + ret->next = NULL; + } + + return (struct bfd_hash_entry *)ret; +} + +/* Look up an entry in a section merge hash table. */ + +static struct sec_merge_hash_entry * +sec_merge_hash_lookup (table, string, create) + struct sec_merge_hash *table; + const char *string; + boolean create; +{ + register const unsigned char *s; + register unsigned long hash; + register unsigned int c; + struct sec_merge_hash_entry *hashp; + unsigned int len, i; + unsigned int index; + + hash = 0; + len = 0; + s = (const unsigned char *) string; + if (table->strings) + { + if (table->entsize == 1) + { + while ((c = *s++) != '\0') + { + hash += c + (c << 17); + hash ^= hash >> 2; + ++len; + } + hash += len + (len << 17); + } + else + { + for (;;) + { + for (i = 0; i < table->entsize; ++i) + if (s[i] != '\0') + break; + if (i == table->entsize) + break; + for (i = 0; i < table->entsize; ++i) + { + c = *s++; + hash += c + (c << 17); + hash ^= hash >> 2; + } + ++len; + } + hash += len + (len << 17); + len *= table->entsize; + } + hash ^= hash >> 2; + len += table->entsize; + } + else + { + for (i = 0; i < table->entsize; ++i) + { + c = *s++; + hash += c + (c << 17); + hash ^= hash >> 2; + } + len = table->entsize; + } + + index = hash % table->table.size; + for (hashp = (struct sec_merge_hash_entry *) table->table.table[index]; + hashp != (struct sec_merge_hash_entry *) NULL; + hashp = (struct sec_merge_hash_entry *) hashp->next) + { + if (hashp->root.hash == hash + && len == hashp->len + && memcmp (hashp->root.string, string, len) == 0) + return hashp; + } + + if (! create) + return (struct sec_merge_hash_entry *) NULL; + + hashp = (struct sec_merge_hash_entry *) + sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL, + (struct bfd_hash_table *) table, string); + if (hashp == (struct sec_merge_hash_entry *) NULL) + return (struct sec_merge_hash_entry *) NULL; + hashp->root.string = string; + hashp->root.hash = hash; + hashp->len = len; + hashp->root.next = table->table.table[index]; + table->table.table[index] = (struct bfd_hash_entry *) hashp; + + return hashp; +} + +/* Create a new hash table. */ + +static struct sec_merge_hash * +sec_merge_init (alignment_power, entsize, strings) + unsigned int alignment_power, entsize; + boolean strings; +{ + struct sec_merge_hash *table; + + table = ((struct sec_merge_hash *) + bfd_malloc (sizeof (struct sec_merge_hash))); + if (table == NULL) + return NULL; + + if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc)) + { + free (table); + return NULL; + } + + table->size = 0; + table->first = NULL; + table->last = NULL; + table->alignment_power = alignment_power; + table->entsize = entsize; + table->strings = strings; + + return table; +} + +/* Get the index of an entity in a hash table, adding it if it is not + already present. */ + +static struct sec_merge_hash_entry * +sec_merge_add (tab, str) + struct sec_merge_hash *tab; + const char *str; +{ + register struct sec_merge_hash_entry *entry; + + entry = sec_merge_hash_lookup (tab, str, true); + if (entry == NULL) + return NULL; + + if (entry->index == (bfd_size_type) -1) + { + entry->index = tab->size; + tab->size += entry->len; + tab->size = align_power (tab->size, tab->alignment_power); + if (tab->first == NULL) + tab->first = entry; + else + tab->last->next = entry; + tab->last = entry; + } + + return entry; +} + +static boolean +sec_merge_emit (abfd, tab, entry) + register bfd *abfd; + struct sec_merge_hash *tab; + struct sec_merge_hash_entry *entry; +{ + asection *sec = entry->sec; + char *pad = ""; + + if (tab->alignment_power) + pad = bfd_zmalloc (1 << tab->alignment_power); + + for (; entry != NULL && entry->sec == sec; entry = entry->next) + { + register const char *str; + register size_t len; + + str = entry->root.string; + len = entry->len; + + if (bfd_write ((PTR) str, 1, len, abfd) != len) + break; + + if (tab->alignment_power) + { + len &= (1 << tab->alignment_power) - 1; + if (len && bfd_write ((PTR) pad, 1, + (1 << tab->alignment_power) - len, + abfd) != (1 << tab->alignment_power) - len) + break; + } + } + + if (tab->alignment_power) + free (pad); + + return entry == NULL || entry->sec != sec; +} + +/* This function is called for each input file from the add_symbols + pass of the linker. */ + +boolean +_bfd_merge_section (abfd, psinfo, sec, psecinfo) + bfd *abfd; + PTR *psinfo; + asection *sec; + PTR *psecinfo; +{ + boolean first, nul; + struct sec_merge_info *sinfo; + struct sec_merge_sec_info *secinfo; + unsigned char *p, *end; + bfd_vma mask; + unsigned int align; + unsigned int i; + + if (sec->_raw_size == 0 + || (sec->flags & SEC_MERGE) == 0 + || sec->entsize == 0) + return true; + + if ((sec->flags & SEC_RELOC) != 0) + { + /* We aren't prepared to handle relocations in merged sections. */ + return true; + } + + if (sec->output_section != NULL + && bfd_is_abs_section (sec->output_section)) + { + /* The section is being discarded from the link, so we should + just ignore it. */ + return true; + } + + align = bfd_get_section_alignment (abfd, sec); + if ((sec->flags & SEC_STRINGS) + && ((sec->entsize < (unsigned int)(1 << align) + && (sec->entsize & (sec->entsize - 1))) + || (sec->entsize > (unsigned int)(1 << align) + && (sec->entsize & ((1 << align) - 1))))) + { + /* Sanity check. If string character size is smaller than + alignment, then we require character size to be a power + of 2, otherwise character size must be integer multiple + of alignment. */ + return true; + } + + first = false; + + for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next) + if (! ((sinfo->last->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS)) + && sinfo->last->entsize == sec->entsize + && ! strcmp (sinfo->last->name, sec->name) + && bfd_get_section_alignment (abfd, sinfo->last) == align) + break; + + if (sinfo == NULL) + { + /* Initialize the information we need to keep track of. */ + first = true; + sinfo = (struct sec_merge_info *) + bfd_alloc (abfd, sizeof (struct sec_merge_info)); + if (sinfo == NULL) + goto error_return; + sinfo->next = (struct sec_merge_info *) *psinfo; + *psinfo = (PTR) sinfo; + sinfo->htab = + sec_merge_init ((sec->flags & SEC_STRINGS) ? align : 0, + sec->entsize, (sec->flags & SEC_STRINGS)); + if (sinfo->htab == NULL) + goto error_return; + } + + /* Read the section from abfd. */ + + *psecinfo = bfd_alloc (abfd, sizeof (struct sec_merge_sec_info) + + sec->_raw_size - 1); + if (*psecinfo == NULL) + goto error_return; + + secinfo = (struct sec_merge_sec_info *)*psecinfo; + secinfo->htab = sinfo->htab; + sinfo->htab->size = 0; + secinfo->first = NULL; + + if (! bfd_get_section_contents (abfd, sec, secinfo->contents, 0, + sec->_raw_size)) + goto error_return; + + end = secinfo->contents + sec->_raw_size; + nul = false; + mask = ((bfd_vma)1 << sinfo->htab->alignment_power) - 1; + if (sec->flags & SEC_STRINGS) + { + for (p = secinfo->contents; p < end;) + { + struct sec_merge_hash_entry *entry; + + entry = sec_merge_add (sinfo->htab, p); + if (entry->sec == NULL) + { + if (secinfo->first == NULL) + secinfo->first = entry; + entry->sec = sec; + } + p += entry->len; + if (sec->entsize == 1) + { + while (p < end && *p == 0) + { + if (!nul && !((p - secinfo->contents) & mask)) + { + nul = true; + entry = sec_merge_add (sinfo->htab, ""); + if (entry->sec == NULL) + { + if (secinfo->first == NULL) + secinfo->first = entry; + entry->sec = sec; + } + } + p++; + } + } + else + { + while (p < end) + { + for (i = 0; i < sec->entsize; i++) + if (p[i] != '\0') + break; + if (i != sec->entsize) + break; + if (!nul && !((p - secinfo->contents) & mask)) + { + nul = true; + entry = sec_merge_add (sinfo->htab, p); + if (entry->sec == NULL) + { + if (secinfo->first == NULL) + secinfo->first = entry; + entry->sec = sec; + } + } + p += sec->entsize; + } + } + } + } + else + { + for (p = secinfo->contents; p < end; p += sec->entsize) + { + struct sec_merge_hash_entry *entry; + + entry = sec_merge_add (sinfo->htab, p); + if (entry->sec == NULL) + { + if (secinfo->first == NULL) + secinfo->first = entry; + entry->sec = sec; + } + } + } + + sec->_cooked_size = sinfo->htab->size; + if (!sec->_cooked_size) + sec->flags |= SEC_EXCLUDE; + sinfo->last = sec; + return true; + + error_return: + if (*psecinfo != NULL) + free (*psecinfo); + *psecinfo = NULL; + return false; +} + +/* Write out the merged section. */ + +boolean +_bfd_write_merged_section (output_bfd, sec, psecinfo) + bfd *output_bfd; + asection *sec; + PTR psecinfo; +{ + struct sec_merge_sec_info *secinfo; + + secinfo = (struct sec_merge_sec_info *) psecinfo; + + if (!secinfo->first) + return true; + + if (bfd_seek (output_bfd, + (sec->output_section->filepos + sec->output_offset), + SEEK_SET) != 0) + return false; + + if (! sec_merge_emit (output_bfd, secinfo->htab, secinfo->first)) + return false; + + return true; +} + +/* Adjust an address in the SEC_MERGE section. Given OFFSET within + *PSEC, this returns the new offset in the adjusted SEC_MERGE + section and writes the new section back into *PSEC. */ + +bfd_vma +_bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend) + bfd *output_bfd ATTRIBUTE_UNUSED; + asection **psec; + PTR psecinfo; + bfd_vma offset, addend; +{ + struct sec_merge_sec_info *secinfo; + struct sec_merge_hash_entry *entry; + unsigned char *p; + asection *sec = *psec; + + secinfo = (struct sec_merge_sec_info *) psecinfo; + + if (offset + addend >= sec->_raw_size) + { + if (offset + addend > sec->_raw_size) + (*_bfd_error_handler) (_("%s: access beyond end of merged section (%ld + %ld)"), + bfd_get_filename (sec->owner), (long)offset, + (long) addend); + return (secinfo->first ? sec->_cooked_size : 0); + } + + if (secinfo->htab->strings) + { + if (sec->entsize == 1) + { + p = secinfo->contents + offset + addend - 1; + while (*p && p >= secinfo->contents) + --p; + ++p; + } + else + { + p = secinfo->contents + + ((offset + addend) / sec->entsize) * sec->entsize; + p -= sec->entsize; + while (p >= secinfo->contents) + { + unsigned int i; + + for (i = 0; i < sec->entsize; ++i) + if (p[i] != '\0') + break; + if (i == sec->entsize) + break; + p -= sec->entsize; + } + p += sec->entsize; + } + } + else + { + p = secinfo->contents + + ((offset + addend) / sec->entsize) * sec->entsize; + } + entry = sec_merge_hash_lookup (secinfo->htab, p, false); + if (!entry) + { + if (! secinfo->htab->strings) + abort (); + /* This should only happen if somebody points into the padding + after a NUL character but before next entity. */ + if (*p) + abort (); + if (! secinfo->htab->first) + abort (); + entry = secinfo->htab->first; + p = secinfo->contents + + ((offset + addend) / sec->entsize + 1) * sec->entsize + - entry->len; + } + + *psec = entry->sec; + return entry->index + (secinfo->contents + offset - p); +} |