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  1. /* SEC_MERGE support.
  2.    Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
  3.    Free Software Foundation, Inc.
  4.    Written by Jakub Jelinek <jakub@redhat.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 3 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,
  21.    MA 02110-1301, USA.  */
  22.  
  23.  
  24. /* This file contains support for merging duplicate entities within sections,
  25.    as used in ELF SHF_MERGE.  */
  26.  
  27. #include "sysdep.h"
  28. #include "bfd.h"
  29. #include "libbfd.h"
  30. #include "hashtab.h"
  31. #include "libiberty.h"
  32.  
  33. struct sec_merge_sec_info;
  34.  
  35. /* An entry in the section merge hash table.  */
  36.  
  37. struct sec_merge_hash_entry
  38. {
  39.   struct bfd_hash_entry root;
  40.   /* Length of this entry.  This includes the zero terminator.  */
  41.   unsigned int len;
  42.   /* Start of this string needs to be aligned to
  43.      alignment octets (not 1 << align).  */
  44.   unsigned int alignment;
  45.   union
  46.   {
  47.     /* Index within the merged section.  */
  48.     bfd_size_type index;
  49.     /* Entry this is a suffix of (if alignment is 0).  */
  50.     struct sec_merge_hash_entry *suffix;
  51.   } u;
  52.   /* Which section is it in.  */
  53.   struct sec_merge_sec_info *secinfo;
  54.   /* Next entity in the hash table.  */
  55.   struct sec_merge_hash_entry *next;
  56. };
  57.  
  58. /* The section merge hash table.  */
  59.  
  60. struct sec_merge_hash
  61. {
  62.   struct bfd_hash_table table;
  63.   /* Next available index.  */
  64.   bfd_size_type size;
  65.   /* First entity in the SEC_MERGE sections of this type.  */
  66.   struct sec_merge_hash_entry *first;
  67.   /* Last entity in the SEC_MERGE sections of this type.  */
  68.   struct sec_merge_hash_entry *last;
  69.   /* Entity size.  */
  70.   unsigned int entsize;
  71.   /* Are entries fixed size or zero terminated strings?  */
  72.   bfd_boolean strings;
  73. };
  74.  
  75. struct sec_merge_info
  76. {
  77.   /* Chain of sec_merge_infos.  */
  78.   struct sec_merge_info *next;
  79.   /* Chain of sec_merge_sec_infos.  */
  80.   struct sec_merge_sec_info *chain;
  81.   /* A hash table used to hold section content.  */
  82.   struct sec_merge_hash *htab;
  83. };
  84.  
  85. struct sec_merge_sec_info
  86. {
  87.   /* Chain of sec_merge_sec_infos.  */
  88.   struct sec_merge_sec_info *next;
  89.   /* The corresponding section.  */
  90.   asection *sec;
  91.   /* Pointer to merge_info pointing to us.  */
  92.   void **psecinfo;
  93.   /* A hash table used to hold section content.  */
  94.   struct sec_merge_hash *htab;
  95.   /* First string in this section.  */
  96.   struct sec_merge_hash_entry *first_str;
  97.   /* Original section content.  */
  98.   unsigned char contents[1];
  99. };
  100.  
  101.  
  102. /* Routine to create an entry in a section merge hashtab.  */
  103.  
  104. static struct bfd_hash_entry *
  105. sec_merge_hash_newfunc (struct bfd_hash_entry *entry,
  106.                         struct bfd_hash_table *table, const char *string)
  107. {
  108.   /* Allocate the structure if it has not already been allocated by a
  109.      subclass.  */
  110.   if (entry == NULL)
  111.     entry = (struct bfd_hash_entry *)
  112.         bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry));
  113.   if (entry == NULL)
  114.     return NULL;
  115.  
  116.   /* Call the allocation method of the superclass.  */
  117.   entry = bfd_hash_newfunc (entry, table, string);
  118.  
  119.   if (entry != NULL)
  120.     {
  121.       /* Initialize the local fields.  */
  122.       struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
  123.  
  124.       ret->u.suffix = NULL;
  125.       ret->alignment = 0;
  126.       ret->secinfo = NULL;
  127.       ret->next = NULL;
  128.     }
  129.  
  130.   return entry;
  131. }
  132.  
  133. /* Look up an entry in a section merge hash table.  */
  134.  
  135. static struct sec_merge_hash_entry *
  136. sec_merge_hash_lookup (struct sec_merge_hash *table, const char *string,
  137.                        unsigned int alignment, bfd_boolean create)
  138. {
  139.   const unsigned char *s;
  140.   unsigned long hash;
  141.   unsigned int c;
  142.   struct sec_merge_hash_entry *hashp;
  143.   unsigned int len, i;
  144.   unsigned int _index;
  145.  
  146.   hash = 0;
  147.   len = 0;
  148.   s = (const unsigned char *) string;
  149.   if (table->strings)
  150.     {
  151.       if (table->entsize == 1)
  152.         {
  153.           while ((c = *s++) != '\0')
  154.             {
  155.               hash += c + (c << 17);
  156.               hash ^= hash >> 2;
  157.               ++len;
  158.             }
  159.           hash += len + (len << 17);
  160.         }
  161.       else
  162.         {
  163.           for (;;)
  164.             {
  165.               for (i = 0; i < table->entsize; ++i)
  166.                 if (s[i] != '\0')
  167.                   break;
  168.               if (i == table->entsize)
  169.                 break;
  170.               for (i = 0; i < table->entsize; ++i)
  171.                 {
  172.                   c = *s++;
  173.                   hash += c + (c << 17);
  174.                   hash ^= hash >> 2;
  175.                 }
  176.               ++len;
  177.             }
  178.           hash += len + (len << 17);
  179.           len *= table->entsize;
  180.         }
  181.       hash ^= hash >> 2;
  182.       len += table->entsize;
  183.     }
  184.   else
  185.     {
  186.       for (i = 0; i < table->entsize; ++i)
  187.         {
  188.           c = *s++;
  189.           hash += c + (c << 17);
  190.           hash ^= hash >> 2;
  191.         }
  192.       len = table->entsize;
  193.     }
  194.  
  195.   _index = hash % table->table.size;
  196.   for (hashp = (struct sec_merge_hash_entry *) table->table.table[_index];
  197.        hashp != NULL;
  198.        hashp = (struct sec_merge_hash_entry *) hashp->root.next)
  199.     {
  200.       if (hashp->root.hash == hash
  201.           && len == hashp->len
  202.           && memcmp (hashp->root.string, string, len) == 0)
  203.         {
  204.           /* If the string we found does not have at least the required
  205.              alignment, we need to insert another copy.  */
  206.           if (hashp->alignment < alignment)
  207.             {
  208.               if (create)
  209.                 {
  210.                   /*  Mark the less aligned copy as deleted.  */
  211.                   hashp->len = 0;
  212.                   hashp->alignment = 0;
  213.                 }
  214.               break;
  215.             }
  216.           return hashp;
  217.         }
  218.     }
  219.  
  220.   if (! create)
  221.     return NULL;
  222.  
  223.   hashp = ((struct sec_merge_hash_entry *)
  224.            bfd_hash_insert (&table->table, string, hash));
  225.   if (hashp == NULL)
  226.     return NULL;
  227.   hashp->len = len;
  228.   hashp->alignment = alignment;
  229.   return hashp;
  230. }
  231.  
  232. /* Create a new hash table.  */
  233.  
  234. static struct sec_merge_hash *
  235. sec_merge_init (unsigned int entsize, bfd_boolean strings)
  236. {
  237.   struct sec_merge_hash *table;
  238.  
  239.   table = (struct sec_merge_hash *) bfd_malloc (sizeof (struct sec_merge_hash));
  240.   if (table == NULL)
  241.     return NULL;
  242.  
  243.   if (! bfd_hash_table_init_n (&table->table, sec_merge_hash_newfunc,
  244.                                sizeof (struct sec_merge_hash_entry), 16699))
  245.     {
  246.       free (table);
  247.       return NULL;
  248.     }
  249.  
  250.   table->size = 0;
  251.   table->first = NULL;
  252.   table->last = NULL;
  253.   table->entsize = entsize;
  254.   table->strings = strings;
  255.  
  256.   return table;
  257. }
  258.  
  259. /* Get the index of an entity in a hash table, adding it if it is not
  260.    already present.  */
  261.  
  262. static struct sec_merge_hash_entry *
  263. sec_merge_add (struct sec_merge_hash *tab, const char *str,
  264.                unsigned int alignment, struct sec_merge_sec_info *secinfo)
  265. {
  266.   struct sec_merge_hash_entry *entry;
  267.  
  268.   entry = sec_merge_hash_lookup (tab, str, alignment, TRUE);
  269.   if (entry == NULL)
  270.     return NULL;
  271.  
  272.   if (entry->secinfo == NULL)
  273.     {
  274.       tab->size++;
  275.       entry->secinfo = secinfo;
  276.       if (tab->first == NULL)
  277.         tab->first = entry;
  278.       else
  279.         tab->last->next = entry;
  280.       tab->last = entry;
  281.     }
  282.  
  283.   return entry;
  284. }
  285.  
  286. static bfd_boolean
  287. sec_merge_emit (bfd *abfd, struct sec_merge_hash_entry *entry)
  288. {
  289.   struct sec_merge_sec_info *secinfo = entry->secinfo;
  290.   asection *sec = secinfo->sec;
  291.   char *pad = NULL;
  292.   bfd_size_type off = 0;
  293.   int alignment_power = sec->output_section->alignment_power;
  294.  
  295.   if (alignment_power)
  296.     {
  297.       pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
  298.       if (pad == NULL)
  299.         return FALSE;
  300.     }
  301.  
  302.   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
  303.     {
  304.       const char *str;
  305.       bfd_size_type len;
  306.  
  307.       len = -off & (entry->alignment - 1);
  308.       if (len != 0)
  309.         {
  310.           if (bfd_bwrite (pad, len, abfd) != len)
  311.             goto err;
  312.           off += len;
  313.         }
  314.  
  315.       str = entry->root.string;
  316.       len = entry->len;
  317.  
  318.       if (bfd_bwrite (str, len, abfd) != len)
  319.         goto err;
  320.  
  321.       off += len;
  322.     }
  323.  
  324.   /* Trailing alignment needed?  */
  325.   off = sec->size - off;
  326.   if (off != 0
  327.       && bfd_bwrite (pad, off, abfd) != off)
  328.     goto err;
  329.  
  330.   if (pad != NULL)
  331.     free (pad);
  332.   return TRUE;
  333.  
  334.  err:
  335.   if (pad != NULL)
  336.     free (pad);
  337.   return FALSE;
  338. }
  339.  
  340. /* Register a SEC_MERGE section as a candidate for merging.
  341.    This function is called for all non-dynamic SEC_MERGE input sections.  */
  342.  
  343. bfd_boolean
  344. _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
  345.                         void **psecinfo)
  346. {
  347.   struct sec_merge_info *sinfo;
  348.   struct sec_merge_sec_info *secinfo;
  349.   unsigned int align;
  350.   bfd_size_type amt;
  351.   bfd_byte *contents;
  352.  
  353.   if ((abfd->flags & DYNAMIC) != 0
  354.       || (sec->flags & SEC_MERGE) == 0)
  355.     abort ();
  356.  
  357.   if (sec->size == 0
  358.       || (sec->flags & SEC_EXCLUDE) != 0
  359.       || sec->entsize == 0)
  360.     return TRUE;
  361.  
  362.   if ((sec->flags & SEC_RELOC) != 0)
  363.     {
  364.       /* We aren't prepared to handle relocations in merged sections.  */
  365.       return TRUE;
  366.     }
  367.  
  368.   align = sec->alignment_power;
  369.   if ((sec->entsize < (unsigned) 1 << align
  370.        && ((sec->entsize & (sec->entsize - 1))
  371.            || !(sec->flags & SEC_STRINGS)))
  372.       || (sec->entsize > (unsigned) 1 << align
  373.           && (sec->entsize & (((unsigned) 1 << align) - 1))))
  374.     {
  375.       /* Sanity check.  If string character size is smaller than
  376.          alignment, then we require character size to be a power
  377.          of 2, otherwise character size must be integer multiple
  378.          of alignment.  For non-string constants, alignment must
  379.          be smaller than or equal to entity size and entity size
  380.          must be integer multiple of alignment.  */
  381.       return TRUE;
  382.     }
  383.  
  384.   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
  385.     if ((secinfo = sinfo->chain)
  386.         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
  387.         && secinfo->sec->entsize == sec->entsize
  388.         && secinfo->sec->alignment_power == sec->alignment_power
  389.         && secinfo->sec->output_section == sec->output_section)
  390.       break;
  391.  
  392.   if (sinfo == NULL)
  393.     {
  394.       /* Initialize the information we need to keep track of.  */
  395.       sinfo = (struct sec_merge_info *)
  396.           bfd_alloc (abfd, sizeof (struct sec_merge_info));
  397.       if (sinfo == NULL)
  398.         goto error_return;
  399.       sinfo->next = (struct sec_merge_info *) *psinfo;
  400.       sinfo->chain = NULL;
  401.       *psinfo = sinfo;
  402.       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
  403.       if (sinfo->htab == NULL)
  404.         goto error_return;
  405.     }
  406.  
  407.   /* Read the section from abfd.  */
  408.  
  409.   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
  410.   if (sec->flags & SEC_STRINGS)
  411.     /* Some versions of gcc may emit a string without a zero terminator.
  412.        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
  413.        Allocate space for an extra zero.  */
  414.     amt += sec->entsize;
  415.   *psecinfo = bfd_alloc (abfd, amt);
  416.   if (*psecinfo == NULL)
  417.     goto error_return;
  418.  
  419.   secinfo = (struct sec_merge_sec_info *) *psecinfo;
  420.   if (sinfo->chain)
  421.     {
  422.       secinfo->next = sinfo->chain->next;
  423.       sinfo->chain->next = secinfo;
  424.     }
  425.   else
  426.     secinfo->next = secinfo;
  427.   sinfo->chain = secinfo;
  428.   secinfo->sec = sec;
  429.   secinfo->psecinfo = psecinfo;
  430.   secinfo->htab = sinfo->htab;
  431.   secinfo->first_str = NULL;
  432.  
  433.   sec->rawsize = sec->size;
  434.   if (sec->flags & SEC_STRINGS)
  435.     memset (secinfo->contents + sec->size, 0, sec->entsize);
  436.   contents = secinfo->contents;
  437.   if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
  438.     goto error_return;
  439.  
  440.   return TRUE;
  441.  
  442.  error_return:
  443.   *psecinfo = NULL;
  444.   return FALSE;
  445. }
  446.  
  447. /* Record one section into the hash table.  */
  448. static bfd_boolean
  449. record_section (struct sec_merge_info *sinfo,
  450.                 struct sec_merge_sec_info *secinfo)
  451. {
  452.   asection *sec = secinfo->sec;
  453.   struct sec_merge_hash_entry *entry;
  454.   bfd_boolean nul;
  455.   unsigned char *p, *end;
  456.   bfd_vma mask, eltalign;
  457.   unsigned int align, i;
  458.  
  459.   align = sec->alignment_power;
  460.   end = secinfo->contents + sec->size;
  461.   nul = FALSE;
  462.   mask = ((bfd_vma) 1 << align) - 1;
  463.   if (sec->flags & SEC_STRINGS)
  464.     {
  465.       for (p = secinfo->contents; p < end; )
  466.         {
  467.           eltalign = p - secinfo->contents;
  468.           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
  469.           if (!eltalign || eltalign > mask)
  470.             eltalign = mask + 1;
  471.           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
  472.                                  secinfo);
  473.           if (! entry)
  474.             goto error_return;
  475.           p += entry->len;
  476.           if (sec->entsize == 1)
  477.             {
  478.               while (p < end && *p == 0)
  479.                 {
  480.                   if (!nul && !((p - secinfo->contents) & mask))
  481.                     {
  482.                       nul = TRUE;
  483.                       entry = sec_merge_add (sinfo->htab, "",
  484.                                              (unsigned) mask + 1, secinfo);
  485.                       if (! entry)
  486.                         goto error_return;
  487.                     }
  488.                   p++;
  489.                 }
  490.             }
  491.           else
  492.             {
  493.               while (p < end)
  494.                 {
  495.                   for (i = 0; i < sec->entsize; i++)
  496.                     if (p[i] != '\0')
  497.                       break;
  498.                   if (i != sec->entsize)
  499.                     break;
  500.                   if (!nul && !((p - secinfo->contents) & mask))
  501.                     {
  502.                       nul = TRUE;
  503.                       entry = sec_merge_add (sinfo->htab, (char *) p,
  504.                                              (unsigned) mask + 1, secinfo);
  505.                       if (! entry)
  506.                         goto error_return;
  507.                     }
  508.                   p += sec->entsize;
  509.                 }
  510.             }
  511.         }
  512.     }
  513.   else
  514.     {
  515.       for (p = secinfo->contents; p < end; p += sec->entsize)
  516.         {
  517.           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
  518.           if (! entry)
  519.             goto error_return;
  520.         }
  521.     }
  522.  
  523.   return TRUE;
  524.  
  525. error_return:
  526.   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  527.     *secinfo->psecinfo = NULL;
  528.   return FALSE;
  529. }
  530.  
  531. static int
  532. strrevcmp (const void *a, const void *b)
  533. {
  534.   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  535.   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  536.   unsigned int lenA = A->len;
  537.   unsigned int lenB = B->len;
  538.   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  539.   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  540.   int l = lenA < lenB ? lenA : lenB;
  541.  
  542.   while (l)
  543.     {
  544.       if (*s != *t)
  545.         return (int) *s - (int) *t;
  546.       s--;
  547.       t--;
  548.       l--;
  549.     }
  550.   return lenA - lenB;
  551. }
  552.  
  553. /* Like strrevcmp, but for the case where all strings have the same
  554.    alignment > entsize.  */
  555.  
  556. static int
  557. strrevcmp_align (const void *a, const void *b)
  558. {
  559.   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  560.   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  561.   unsigned int lenA = A->len;
  562.   unsigned int lenB = B->len;
  563.   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  564.   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  565.   int l = lenA < lenB ? lenA : lenB;
  566.   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
  567.  
  568.   if (tail_align != 0)
  569.     return tail_align;
  570.  
  571.   while (l)
  572.     {
  573.       if (*s != *t)
  574.         return (int) *s - (int) *t;
  575.       s--;
  576.       t--;
  577.       l--;
  578.     }
  579.   return lenA - lenB;
  580. }
  581.  
  582. static inline int
  583. is_suffix (const struct sec_merge_hash_entry *A,
  584.            const struct sec_merge_hash_entry *B)
  585. {
  586.   if (A->len <= B->len)
  587.     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
  588.        not to be equal by the hash table.  */
  589.     return 0;
  590.  
  591.   return memcmp (A->root.string + (A->len - B->len),
  592.                  B->root.string, B->len) == 0;
  593. }
  594.  
  595. /* This is a helper function for _bfd_merge_sections.  It attempts to
  596.    merge strings matching suffixes of longer strings.  */
  597. static void
  598. merge_strings (struct sec_merge_info *sinfo)
  599. {
  600.   struct sec_merge_hash_entry **array, **a, *e;
  601.   struct sec_merge_sec_info *secinfo;
  602.   bfd_size_type size, amt;
  603.   unsigned int alignment = 0;
  604.  
  605.   /* Now sort the strings */
  606.   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
  607.   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
  608.   if (array == NULL)
  609.     goto alloc_failure;
  610.  
  611.   for (e = sinfo->htab->first, a = array; e; e = e->next)
  612.     if (e->alignment)
  613.       {
  614.         *a++ = e;
  615.         /* Adjust the length to not include the zero terminator.  */
  616.         e->len -= sinfo->htab->entsize;
  617.         if (alignment != e->alignment)
  618.           {
  619.             if (alignment == 0)
  620.               alignment = e->alignment;
  621.             else
  622.               alignment = (unsigned) -1;
  623.           }
  624.       }
  625.  
  626.   sinfo->htab->size = a - array;
  627.   if (sinfo->htab->size != 0)
  628.     {
  629.       qsort (array, (size_t) sinfo->htab->size,
  630.              sizeof (struct sec_merge_hash_entry *),
  631.              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
  632.               ? strrevcmp_align : strrevcmp));
  633.  
  634.       /* Loop over the sorted array and merge suffixes */
  635.       e = *--a;
  636.       e->len += sinfo->htab->entsize;
  637.       while (--a >= array)
  638.         {
  639.           struct sec_merge_hash_entry *cmp = *a;
  640.  
  641.           cmp->len += sinfo->htab->entsize;
  642.           if (e->alignment >= cmp->alignment
  643.               && !((e->len - cmp->len) & (cmp->alignment - 1))
  644.               && is_suffix (e, cmp))
  645.             {
  646.               cmp->u.suffix = e;
  647.               cmp->alignment = 0;
  648.             }
  649.           else
  650.             e = cmp;
  651.         }
  652.     }
  653.  
  654. alloc_failure:
  655.   if (array)
  656.     free (array);
  657.  
  658.   /* Now assign positions to the strings we want to keep.  */
  659.   size = 0;
  660.   secinfo = sinfo->htab->first->secinfo;
  661.   for (e = sinfo->htab->first; e; e = e->next)
  662.     {
  663.       if (e->secinfo != secinfo)
  664.         {
  665.           secinfo->sec->size = size;
  666.           secinfo = e->secinfo;
  667.         }
  668.       if (e->alignment)
  669.         {
  670.           if (e->secinfo->first_str == NULL)
  671.             {
  672.               e->secinfo->first_str = e;
  673.               size = 0;
  674.             }
  675.           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
  676.           e->u.index = size;
  677.           size += e->len;
  678.         }
  679.     }
  680.   secinfo->sec->size = size;
  681.   if (secinfo->sec->alignment_power != 0)
  682.     {
  683.       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
  684.       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
  685.     }
  686.  
  687.   /* And now adjust the rest, removing them from the chain (but not hashtable)
  688.      at the same time.  */
  689.   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
  690.     if (e->alignment)
  691.       a = &e->next;
  692.     else
  693.       {
  694.         *a = e->next;
  695.         if (e->len)
  696.           {
  697.             e->secinfo = e->u.suffix->secinfo;
  698.             e->alignment = e->u.suffix->alignment;
  699.             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
  700.           }
  701.       }
  702. }
  703.  
  704. /* This function is called once after all SEC_MERGE sections are registered
  705.    with _bfd_merge_section.  */
  706.  
  707. bfd_boolean
  708. _bfd_merge_sections (bfd *abfd,
  709.                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
  710.                      void *xsinfo,
  711.                      void (*remove_hook) (bfd *, asection *))
  712. {
  713.   struct sec_merge_info *sinfo;
  714.  
  715.   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
  716.     {
  717.       struct sec_merge_sec_info * secinfo;
  718.  
  719.       if (! sinfo->chain)
  720.         continue;
  721.  
  722.       /* Move sinfo->chain to head of the chain, terminate it.  */
  723.       secinfo = sinfo->chain;
  724.       sinfo->chain = secinfo->next;
  725.       secinfo->next = NULL;
  726.  
  727.       /* Record the sections into the hash table.  */
  728.       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  729.         if (secinfo->sec->flags & SEC_EXCLUDE)
  730.           {
  731.             *secinfo->psecinfo = NULL;
  732.             if (remove_hook)
  733.               (*remove_hook) (abfd, secinfo->sec);
  734.           }
  735.         else if (! record_section (sinfo, secinfo))
  736.           break;
  737.  
  738.       if (secinfo)
  739.         continue;
  740.  
  741.       if (sinfo->htab->first == NULL)
  742.         continue;
  743.  
  744.       if (sinfo->htab->strings)
  745.         merge_strings (sinfo);
  746.       else
  747.         {
  748.           struct sec_merge_hash_entry *e;
  749.           bfd_size_type size = 0;
  750.  
  751.           /* Things are much simpler for non-strings.
  752.              Just assign them slots in the section.  */
  753.           secinfo = NULL;
  754.           for (e = sinfo->htab->first; e; e = e->next)
  755.             {
  756.               if (e->secinfo->first_str == NULL)
  757.                 {
  758.                   if (secinfo)
  759.                     secinfo->sec->size = size;
  760.                   e->secinfo->first_str = e;
  761.                   size = 0;
  762.                 }
  763.               size = (size + e->alignment - 1)
  764.                      & ~((bfd_vma) e->alignment - 1);
  765.               e->u.index = size;
  766.               size += e->len;
  767.               secinfo = e->secinfo;
  768.             }
  769.           secinfo->sec->size = size;
  770.         }
  771.  
  772.         /* Finally remove all input sections which have not made it into
  773.            the hash table at all.  */
  774.         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  775.           if (secinfo->first_str == NULL)
  776.             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
  777.     }
  778.  
  779.   return TRUE;
  780. }
  781.  
  782. /* Write out the merged section.  */
  783.  
  784. bfd_boolean
  785. _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
  786. {
  787.   struct sec_merge_sec_info *secinfo;
  788.   file_ptr pos;
  789.  
  790.   secinfo = (struct sec_merge_sec_info *) psecinfo;
  791.  
  792.   if (!secinfo)
  793.     return FALSE;
  794.  
  795.   if (secinfo->first_str == NULL)
  796.     return TRUE;
  797.  
  798.   /* FIXME: octets_per_byte.  */
  799.   pos = sec->output_section->filepos + sec->output_offset;
  800.   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
  801.     return FALSE;
  802.  
  803.   if (! sec_merge_emit (output_bfd, secinfo->first_str))
  804.     return FALSE;
  805.  
  806.   return TRUE;
  807. }
  808.  
  809. /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
  810.    *PSEC, this returns the new offset in the adjusted SEC_MERGE
  811.    section and writes the new section back into *PSEC.  */
  812.  
  813. bfd_vma
  814. _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
  815.                             void *psecinfo, bfd_vma offset)
  816. {
  817.   struct sec_merge_sec_info *secinfo;
  818.   struct sec_merge_hash_entry *entry;
  819.   unsigned char *p;
  820.   asection *sec = *psec;
  821.  
  822.   secinfo = (struct sec_merge_sec_info *) psecinfo;
  823.  
  824.   if (!secinfo)
  825.     return offset;
  826.  
  827.   if (offset >= sec->rawsize)
  828.     {
  829.       if (offset > sec->rawsize)
  830.         {
  831.           (*_bfd_error_handler)
  832.             (_("%s: access beyond end of merged section (%ld)"),
  833.              bfd_get_filename (sec->owner), (long) offset);
  834.         }
  835.       return secinfo->first_str ? sec->size : 0;
  836.     }
  837.  
  838.   if (secinfo->htab->strings)
  839.     {
  840.       if (sec->entsize == 1)
  841.         {
  842.           p = secinfo->contents + offset - 1;
  843.           while (p >= secinfo->contents && *p)
  844.             --p;
  845.           ++p;
  846.         }
  847.       else
  848.         {
  849.           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
  850.           p -= sec->entsize;
  851.           while (p >= secinfo->contents)
  852.             {
  853.               unsigned int i;
  854.  
  855.               for (i = 0; i < sec->entsize; ++i)
  856.                 if (p[i] != '\0')
  857.                   break;
  858.               if (i == sec->entsize)
  859.                 break;
  860.               p -= sec->entsize;
  861.             }
  862.           p += sec->entsize;
  863.         }
  864.     }
  865.   else
  866.     {
  867.       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
  868.     }
  869.   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
  870.   if (!entry)
  871.     {
  872.       if (! secinfo->htab->strings)
  873.         abort ();
  874.       /* This should only happen if somebody points into the padding
  875.          after a NUL character but before next entity.  */
  876.       if (*p)
  877.         abort ();
  878.       if (! secinfo->htab->first)
  879.         abort ();
  880.       entry = secinfo->htab->first;
  881.       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
  882.            - entry->len);
  883.     }
  884.  
  885.   *psec = entry->secinfo->sec;
  886.   return entry->u.index + (secinfo->contents + offset - p);
  887. }
  888.  
  889. /* Tidy up when done.  */
  890.  
  891. void
  892. _bfd_merge_sections_free (void *xsinfo)
  893. {
  894.   struct sec_merge_info *sinfo;
  895.  
  896.   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
  897.     {
  898.       bfd_hash_table_free (&sinfo->htab->table);
  899.       free (sinfo->htab);
  900.     }
  901. }
  902.