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  1. /* SEC_MERGE support.
  2.    Copyright (C) 2001-2015 Free Software Foundation, Inc.
  3.    Written by Jakub Jelinek <jakub@redhat.com>.
  4.  
  5.    This file is part of BFD, the Binary File Descriptor library.
  6.  
  7.    This program is free software; you can redistribute it and/or modify
  8.    it under the terms of the GNU General Public License as published by
  9.    the Free Software Foundation; either version 3 of the License, or
  10.    (at your option) any later version.
  11.  
  12.    This program is distributed in the hope that it will be useful,
  13.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.    GNU General Public License for more details.
  16.  
  17.    You should have received a copy of the GNU General Public License
  18.    along with this program; if not, write to the Free Software
  19.    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  20.    MA 02110-1301, USA.  */
  21.  
  22.  
  23. /* This file contains support for merging duplicate entities within sections,
  24.    as used in ELF SHF_MERGE.  */
  25.  
  26. #include "sysdep.h"
  27. #include "bfd.h"
  28. #include "elf-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.                 unsigned char *contents, file_ptr offset)
  289. {
  290.   struct sec_merge_sec_info *secinfo = entry->secinfo;
  291.   asection *sec = secinfo->sec;
  292.   char *pad = NULL;
  293.   bfd_size_type off = 0;
  294.   int alignment_power = sec->output_section->alignment_power;
  295.  
  296.   if (alignment_power)
  297.     {
  298.       pad = (char *) bfd_zmalloc ((bfd_size_type) 1 << alignment_power);
  299.       if (pad == NULL)
  300.         return FALSE;
  301.     }
  302.  
  303.   for (; entry != NULL && entry->secinfo == secinfo; entry = entry->next)
  304.     {
  305.       const char *str;
  306.       bfd_size_type len;
  307.  
  308.       len = -off & (entry->alignment - 1);
  309.       if (len != 0)
  310.         {
  311.           if (contents)
  312.             {
  313.               memcpy (contents + offset, pad, len);
  314.               offset += len;
  315.             }
  316.           else if (bfd_bwrite (pad, len, abfd) != len)
  317.             goto err;
  318.           off += len;
  319.         }
  320.  
  321.       str = entry->root.string;
  322.       len = entry->len;
  323.  
  324.       if (contents)
  325.         {
  326.           memcpy (contents + offset, str, len);
  327.           offset += len;
  328.         }
  329.       else if (bfd_bwrite (str, len, abfd) != len)
  330.         goto err;
  331.  
  332.       off += len;
  333.     }
  334.  
  335.   /* Trailing alignment needed?  */
  336.   off = sec->size - off;
  337.   if (off != 0)
  338.     {
  339.       if (contents)
  340.         memcpy (contents + offset, pad, off);
  341.       else if (bfd_bwrite (pad, off, abfd) != off)
  342.     goto err;
  343.     }
  344.  
  345.   if (pad != NULL)
  346.     free (pad);
  347.   return TRUE;
  348.  
  349.  err:
  350.   if (pad != NULL)
  351.     free (pad);
  352.   return FALSE;
  353. }
  354.  
  355. /* Register a SEC_MERGE section as a candidate for merging.
  356.    This function is called for all non-dynamic SEC_MERGE input sections.  */
  357.  
  358. bfd_boolean
  359. _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
  360.                         void **psecinfo)
  361. {
  362.   struct sec_merge_info *sinfo;
  363.   struct sec_merge_sec_info *secinfo;
  364.   unsigned int align;
  365.   bfd_size_type amt;
  366.   bfd_byte *contents;
  367.  
  368.   if ((abfd->flags & DYNAMIC) != 0
  369.       || (sec->flags & SEC_MERGE) == 0)
  370.     abort ();
  371.  
  372.   if (sec->size == 0
  373.       || (sec->flags & SEC_EXCLUDE) != 0
  374.       || sec->entsize == 0)
  375.     return TRUE;
  376.  
  377.   if ((sec->flags & SEC_RELOC) != 0)
  378.     {
  379.       /* We aren't prepared to handle relocations in merged sections.  */
  380.       return TRUE;
  381.     }
  382.  
  383.   align = sec->alignment_power;
  384.   if ((sec->entsize < (unsigned) 1 << align
  385.        && ((sec->entsize & (sec->entsize - 1))
  386.            || !(sec->flags & SEC_STRINGS)))
  387.       || (sec->entsize > (unsigned) 1 << align
  388.           && (sec->entsize & (((unsigned) 1 << align) - 1))))
  389.     {
  390.       /* Sanity check.  If string character size is smaller than
  391.          alignment, then we require character size to be a power
  392.          of 2, otherwise character size must be integer multiple
  393.          of alignment.  For non-string constants, alignment must
  394.          be smaller than or equal to entity size and entity size
  395.          must be integer multiple of alignment.  */
  396.       return TRUE;
  397.     }
  398.  
  399.   for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
  400.     if ((secinfo = sinfo->chain)
  401.         && ! ((secinfo->sec->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
  402.         && secinfo->sec->entsize == sec->entsize
  403.         && secinfo->sec->alignment_power == sec->alignment_power
  404.         && secinfo->sec->output_section == sec->output_section)
  405.       break;
  406.  
  407.   if (sinfo == NULL)
  408.     {
  409.       /* Initialize the information we need to keep track of.  */
  410.       sinfo = (struct sec_merge_info *)
  411.           bfd_alloc (abfd, sizeof (struct sec_merge_info));
  412.       if (sinfo == NULL)
  413.         goto error_return;
  414.       sinfo->next = (struct sec_merge_info *) *psinfo;
  415.       sinfo->chain = NULL;
  416.       *psinfo = sinfo;
  417.       sinfo->htab = sec_merge_init (sec->entsize, (sec->flags & SEC_STRINGS));
  418.       if (sinfo->htab == NULL)
  419.         goto error_return;
  420.     }
  421.  
  422.   /* Read the section from abfd.  */
  423.  
  424.   amt = sizeof (struct sec_merge_sec_info) - 1 + sec->size;
  425.   if (sec->flags & SEC_STRINGS)
  426.     /* Some versions of gcc may emit a string without a zero terminator.
  427.        See http://gcc.gnu.org/ml/gcc-patches/2006-06/msg01004.html
  428.        Allocate space for an extra zero.  */
  429.     amt += sec->entsize;
  430.   *psecinfo = bfd_alloc (abfd, amt);
  431.   if (*psecinfo == NULL)
  432.     goto error_return;
  433.  
  434.   secinfo = (struct sec_merge_sec_info *) *psecinfo;
  435.   if (sinfo->chain)
  436.     {
  437.       secinfo->next = sinfo->chain->next;
  438.       sinfo->chain->next = secinfo;
  439.     }
  440.   else
  441.     secinfo->next = secinfo;
  442.   sinfo->chain = secinfo;
  443.   secinfo->sec = sec;
  444.   secinfo->psecinfo = psecinfo;
  445.   secinfo->htab = sinfo->htab;
  446.   secinfo->first_str = NULL;
  447.  
  448.   sec->rawsize = sec->size;
  449.   if (sec->flags & SEC_STRINGS)
  450.     memset (secinfo->contents + sec->size, 0, sec->entsize);
  451.   contents = secinfo->contents;
  452.   if (! bfd_get_full_section_contents (sec->owner, sec, &contents))
  453.     goto error_return;
  454.  
  455.   return TRUE;
  456.  
  457.  error_return:
  458.   *psecinfo = NULL;
  459.   return FALSE;
  460. }
  461.  
  462. /* Record one section into the hash table.  */
  463. static bfd_boolean
  464. record_section (struct sec_merge_info *sinfo,
  465.                 struct sec_merge_sec_info *secinfo)
  466. {
  467.   asection *sec = secinfo->sec;
  468.   struct sec_merge_hash_entry *entry;
  469.   bfd_boolean nul;
  470.   unsigned char *p, *end;
  471.   bfd_vma mask, eltalign;
  472.   unsigned int align, i;
  473.  
  474.   align = sec->alignment_power;
  475.   end = secinfo->contents + sec->size;
  476.   nul = FALSE;
  477.   mask = ((bfd_vma) 1 << align) - 1;
  478.   if (sec->flags & SEC_STRINGS)
  479.     {
  480.       for (p = secinfo->contents; p < end; )
  481.         {
  482.           eltalign = p - secinfo->contents;
  483.           eltalign = ((eltalign ^ (eltalign - 1)) + 1) >> 1;
  484.           if (!eltalign || eltalign > mask)
  485.             eltalign = mask + 1;
  486.           entry = sec_merge_add (sinfo->htab, (char *) p, (unsigned) eltalign,
  487.                                  secinfo);
  488.           if (! entry)
  489.             goto error_return;
  490.           p += entry->len;
  491.           if (sec->entsize == 1)
  492.             {
  493.               while (p < end && *p == 0)
  494.                 {
  495.                   if (!nul && !((p - secinfo->contents) & mask))
  496.                     {
  497.                       nul = TRUE;
  498.                       entry = sec_merge_add (sinfo->htab, "",
  499.                                              (unsigned) mask + 1, secinfo);
  500.                       if (! entry)
  501.                         goto error_return;
  502.                     }
  503.                   p++;
  504.                 }
  505.             }
  506.           else
  507.             {
  508.               while (p < end)
  509.                 {
  510.                   for (i = 0; i < sec->entsize; i++)
  511.                     if (p[i] != '\0')
  512.                       break;
  513.                   if (i != sec->entsize)
  514.                     break;
  515.                   if (!nul && !((p - secinfo->contents) & mask))
  516.                     {
  517.                       nul = TRUE;
  518.                       entry = sec_merge_add (sinfo->htab, (char *) p,
  519.                                              (unsigned) mask + 1, secinfo);
  520.                       if (! entry)
  521.                         goto error_return;
  522.                     }
  523.                   p += sec->entsize;
  524.                 }
  525.             }
  526.         }
  527.     }
  528.   else
  529.     {
  530.       for (p = secinfo->contents; p < end; p += sec->entsize)
  531.         {
  532.           entry = sec_merge_add (sinfo->htab, (char *) p, 1, secinfo);
  533.           if (! entry)
  534.             goto error_return;
  535.         }
  536.     }
  537.  
  538.   return TRUE;
  539.  
  540. error_return:
  541.   for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  542.     *secinfo->psecinfo = NULL;
  543.   return FALSE;
  544. }
  545.  
  546. static int
  547. strrevcmp (const void *a, const void *b)
  548. {
  549.   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  550.   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  551.   unsigned int lenA = A->len;
  552.   unsigned int lenB = B->len;
  553.   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  554.   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  555.   int l = lenA < lenB ? lenA : lenB;
  556.  
  557.   while (l)
  558.     {
  559.       if (*s != *t)
  560.         return (int) *s - (int) *t;
  561.       s--;
  562.       t--;
  563.       l--;
  564.     }
  565.   return lenA - lenB;
  566. }
  567.  
  568. /* Like strrevcmp, but for the case where all strings have the same
  569.    alignment > entsize.  */
  570.  
  571. static int
  572. strrevcmp_align (const void *a, const void *b)
  573. {
  574.   struct sec_merge_hash_entry *A = *(struct sec_merge_hash_entry **) a;
  575.   struct sec_merge_hash_entry *B = *(struct sec_merge_hash_entry **) b;
  576.   unsigned int lenA = A->len;
  577.   unsigned int lenB = B->len;
  578.   const unsigned char *s = (const unsigned char *) A->root.string + lenA - 1;
  579.   const unsigned char *t = (const unsigned char *) B->root.string + lenB - 1;
  580.   int l = lenA < lenB ? lenA : lenB;
  581.   int tail_align = (lenA & (A->alignment - 1)) - (lenB & (A->alignment - 1));
  582.  
  583.   if (tail_align != 0)
  584.     return tail_align;
  585.  
  586.   while (l)
  587.     {
  588.       if (*s != *t)
  589.         return (int) *s - (int) *t;
  590.       s--;
  591.       t--;
  592.       l--;
  593.     }
  594.   return lenA - lenB;
  595. }
  596.  
  597. static inline int
  598. is_suffix (const struct sec_merge_hash_entry *A,
  599.            const struct sec_merge_hash_entry *B)
  600. {
  601.   if (A->len <= B->len)
  602.     /* B cannot be a suffix of A unless A is equal to B, which is guaranteed
  603.        not to be equal by the hash table.  */
  604.     return 0;
  605.  
  606.   return memcmp (A->root.string + (A->len - B->len),
  607.                  B->root.string, B->len) == 0;
  608. }
  609.  
  610. /* This is a helper function for _bfd_merge_sections.  It attempts to
  611.    merge strings matching suffixes of longer strings.  */
  612. static void
  613. merge_strings (struct sec_merge_info *sinfo)
  614. {
  615.   struct sec_merge_hash_entry **array, **a, *e;
  616.   struct sec_merge_sec_info *secinfo;
  617.   bfd_size_type size, amt;
  618.   unsigned int alignment = 0;
  619.  
  620.   /* Now sort the strings */
  621.   amt = sinfo->htab->size * sizeof (struct sec_merge_hash_entry *);
  622.   array = (struct sec_merge_hash_entry **) bfd_malloc (amt);
  623.   if (array == NULL)
  624.     goto alloc_failure;
  625.  
  626.   for (e = sinfo->htab->first, a = array; e; e = e->next)
  627.     if (e->alignment)
  628.       {
  629.         *a++ = e;
  630.         /* Adjust the length to not include the zero terminator.  */
  631.         e->len -= sinfo->htab->entsize;
  632.         if (alignment != e->alignment)
  633.           {
  634.             if (alignment == 0)
  635.               alignment = e->alignment;
  636.             else
  637.               alignment = (unsigned) -1;
  638.           }
  639.       }
  640.  
  641.   sinfo->htab->size = a - array;
  642.   if (sinfo->htab->size != 0)
  643.     {
  644.       qsort (array, (size_t) sinfo->htab->size,
  645.              sizeof (struct sec_merge_hash_entry *),
  646.              (alignment != (unsigned) -1 && alignment > sinfo->htab->entsize
  647.               ? strrevcmp_align : strrevcmp));
  648.  
  649.       /* Loop over the sorted array and merge suffixes */
  650.       e = *--a;
  651.       e->len += sinfo->htab->entsize;
  652.       while (--a >= array)
  653.         {
  654.           struct sec_merge_hash_entry *cmp = *a;
  655.  
  656.           cmp->len += sinfo->htab->entsize;
  657.           if (e->alignment >= cmp->alignment
  658.               && !((e->len - cmp->len) & (cmp->alignment - 1))
  659.               && is_suffix (e, cmp))
  660.             {
  661.               cmp->u.suffix = e;
  662.               cmp->alignment = 0;
  663.             }
  664.           else
  665.             e = cmp;
  666.         }
  667.     }
  668.  
  669. alloc_failure:
  670.   if (array)
  671.     free (array);
  672.  
  673.   /* Now assign positions to the strings we want to keep.  */
  674.   size = 0;
  675.   secinfo = sinfo->htab->first->secinfo;
  676.   for (e = sinfo->htab->first; e; e = e->next)
  677.     {
  678.       if (e->secinfo != secinfo)
  679.         {
  680.           secinfo->sec->size = size;
  681.           secinfo = e->secinfo;
  682.         }
  683.       if (e->alignment)
  684.         {
  685.           if (e->secinfo->first_str == NULL)
  686.             {
  687.               e->secinfo->first_str = e;
  688.               size = 0;
  689.             }
  690.           size = (size + e->alignment - 1) & ~((bfd_vma) e->alignment - 1);
  691.           e->u.index = size;
  692.           size += e->len;
  693.         }
  694.     }
  695.   secinfo->sec->size = size;
  696.   if (secinfo->sec->alignment_power != 0)
  697.     {
  698.       bfd_size_type align = (bfd_size_type) 1 << secinfo->sec->alignment_power;
  699.       secinfo->sec->size = (secinfo->sec->size + align - 1) & -align;
  700.     }
  701.  
  702.   /* And now adjust the rest, removing them from the chain (but not hashtable)
  703.      at the same time.  */
  704.   for (a = &sinfo->htab->first, e = *a; e; e = e->next)
  705.     if (e->alignment)
  706.       a = &e->next;
  707.     else
  708.       {
  709.         *a = e->next;
  710.         if (e->len)
  711.           {
  712.             e->secinfo = e->u.suffix->secinfo;
  713.             e->alignment = e->u.suffix->alignment;
  714.             e->u.index = e->u.suffix->u.index + (e->u.suffix->len - e->len);
  715.           }
  716.       }
  717. }
  718.  
  719. /* This function is called once after all SEC_MERGE sections are registered
  720.    with _bfd_merge_section.  */
  721.  
  722. bfd_boolean
  723. _bfd_merge_sections (bfd *abfd,
  724.                      struct bfd_link_info *info ATTRIBUTE_UNUSED,
  725.                      void *xsinfo,
  726.                      void (*remove_hook) (bfd *, asection *))
  727. {
  728.   struct sec_merge_info *sinfo;
  729.  
  730.   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
  731.     {
  732.       struct sec_merge_sec_info * secinfo;
  733.  
  734.       if (! sinfo->chain)
  735.         continue;
  736.  
  737.       /* Move sinfo->chain to head of the chain, terminate it.  */
  738.       secinfo = sinfo->chain;
  739.       sinfo->chain = secinfo->next;
  740.       secinfo->next = NULL;
  741.  
  742.       /* Record the sections into the hash table.  */
  743.       for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  744.         if (secinfo->sec->flags & SEC_EXCLUDE)
  745.           {
  746.             *secinfo->psecinfo = NULL;
  747.             if (remove_hook)
  748.               (*remove_hook) (abfd, secinfo->sec);
  749.           }
  750.         else if (! record_section (sinfo, secinfo))
  751.           break;
  752.  
  753.       if (secinfo)
  754.         continue;
  755.  
  756.       if (sinfo->htab->first == NULL)
  757.         continue;
  758.  
  759.       if (sinfo->htab->strings)
  760.         merge_strings (sinfo);
  761.       else
  762.         {
  763.           struct sec_merge_hash_entry *e;
  764.           bfd_size_type size = 0;
  765.  
  766.           /* Things are much simpler for non-strings.
  767.              Just assign them slots in the section.  */
  768.           secinfo = NULL;
  769.           for (e = sinfo->htab->first; e; e = e->next)
  770.             {
  771.               if (e->secinfo->first_str == NULL)
  772.                 {
  773.                   if (secinfo)
  774.                     secinfo->sec->size = size;
  775.                   e->secinfo->first_str = e;
  776.                   size = 0;
  777.                 }
  778.               size = (size + e->alignment - 1)
  779.                      & ~((bfd_vma) e->alignment - 1);
  780.               e->u.index = size;
  781.               size += e->len;
  782.               secinfo = e->secinfo;
  783.             }
  784.           secinfo->sec->size = size;
  785.         }
  786.  
  787.         /* Finally remove all input sections which have not made it into
  788.            the hash table at all.  */
  789.         for (secinfo = sinfo->chain; secinfo; secinfo = secinfo->next)
  790.           if (secinfo->first_str == NULL)
  791.             secinfo->sec->flags |= SEC_EXCLUDE | SEC_KEEP;
  792.     }
  793.  
  794.   return TRUE;
  795. }
  796.  
  797. /* Write out the merged section.  */
  798.  
  799. bfd_boolean
  800. _bfd_write_merged_section (bfd *output_bfd, asection *sec, void *psecinfo)
  801. {
  802.   struct sec_merge_sec_info *secinfo;
  803.   file_ptr pos;
  804.   unsigned char *contents;
  805.   Elf_Internal_Shdr *hdr;
  806.  
  807.   secinfo = (struct sec_merge_sec_info *) psecinfo;
  808.  
  809.   if (!secinfo)
  810.     return FALSE;
  811.  
  812.   if (secinfo->first_str == NULL)
  813.     return TRUE;
  814.  
  815.   /* FIXME: octets_per_byte.  */
  816.   hdr = &elf_section_data (sec->output_section)->this_hdr;
  817.   if (hdr->sh_offset == (file_ptr) -1)
  818.     {
  819.       /* We must compress this section.  Write output to the
  820.          buffer.  */
  821.       contents = hdr->contents;
  822.       if ((sec->output_section->flags & SEC_ELF_COMPRESS) == 0
  823.           || contents == NULL)
  824.         abort ();
  825.     }
  826.   else
  827.     {
  828.       contents = NULL;
  829.   pos = sec->output_section->filepos + sec->output_offset;
  830.   if (bfd_seek (output_bfd, pos, SEEK_SET) != 0)
  831.     return FALSE;
  832.     }
  833.  
  834.   if (! sec_merge_emit (output_bfd, secinfo->first_str, contents,
  835.                         sec->output_offset))
  836.     return FALSE;
  837.  
  838.   return TRUE;
  839. }
  840.  
  841. /* Adjust an address in the SEC_MERGE section.  Given OFFSET within
  842.    *PSEC, this returns the new offset in the adjusted SEC_MERGE
  843.    section and writes the new section back into *PSEC.  */
  844.  
  845. bfd_vma
  846. _bfd_merged_section_offset (bfd *output_bfd ATTRIBUTE_UNUSED, asection **psec,
  847.                             void *psecinfo, bfd_vma offset)
  848. {
  849.   struct sec_merge_sec_info *secinfo;
  850.   struct sec_merge_hash_entry *entry;
  851.   unsigned char *p;
  852.   asection *sec = *psec;
  853.  
  854.   secinfo = (struct sec_merge_sec_info *) psecinfo;
  855.  
  856.   if (!secinfo)
  857.     return offset;
  858.  
  859.   if (offset >= sec->rawsize)
  860.     {
  861.       if (offset > sec->rawsize)
  862.         {
  863.           (*_bfd_error_handler)
  864.             (_("%s: access beyond end of merged section (%ld)"),
  865.              bfd_get_filename (sec->owner), (long) offset);
  866.         }
  867.       return secinfo->first_str ? sec->size : 0;
  868.     }
  869.  
  870.   if (secinfo->htab->strings)
  871.     {
  872.       if (sec->entsize == 1)
  873.         {
  874.           p = secinfo->contents + offset - 1;
  875.           while (p >= secinfo->contents && *p)
  876.             --p;
  877.           ++p;
  878.         }
  879.       else
  880.         {
  881.           p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
  882.           p -= sec->entsize;
  883.           while (p >= secinfo->contents)
  884.             {
  885.               unsigned int i;
  886.  
  887.               for (i = 0; i < sec->entsize; ++i)
  888.                 if (p[i] != '\0')
  889.                   break;
  890.               if (i == sec->entsize)
  891.                 break;
  892.               p -= sec->entsize;
  893.             }
  894.           p += sec->entsize;
  895.         }
  896.     }
  897.   else
  898.     {
  899.       p = secinfo->contents + (offset / sec->entsize) * sec->entsize;
  900.     }
  901.   entry = sec_merge_hash_lookup (secinfo->htab, (char *) p, 0, FALSE);
  902.   if (!entry)
  903.     {
  904.       if (! secinfo->htab->strings)
  905.         abort ();
  906.       /* This should only happen if somebody points into the padding
  907.          after a NUL character but before next entity.  */
  908.       if (*p)
  909.         abort ();
  910.       if (! secinfo->htab->first)
  911.         abort ();
  912.       entry = secinfo->htab->first;
  913.       p = (secinfo->contents + (offset / sec->entsize + 1) * sec->entsize
  914.            - entry->len);
  915.     }
  916.  
  917.   *psec = entry->secinfo->sec;
  918.   return entry->u.index + (secinfo->contents + offset - p);
  919. }
  920.  
  921. /* Tidy up when done.  */
  922.  
  923. void
  924. _bfd_merge_sections_free (void *xsinfo)
  925. {
  926.   struct sec_merge_info *sinfo;
  927.  
  928.   for (sinfo = (struct sec_merge_info *) xsinfo; sinfo; sinfo = sinfo->next)
  929.     {
  930.       bfd_hash_table_free (&sinfo->htab->table);
  931.       free (sinfo->htab);
  932.     }
  933. }
  934.