gas/sb.c

   1 /* sb.c - string buffer manipulation routines
   2    Copyright (C) 1994-2021 Free Software Foundation, Inc.
   3
   4    Written by Steve and Judy Chamberlain of Cygnus Support,
   5       sac@cygnus.com
   6
   7    This file is part of GAS, the GNU Assembler.
   8
   9    GAS is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3, or (at your option)
  12    any later version.
  13
  14    GAS is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with GAS; see the file COPYING.  If not, write to the Free
  21    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  22    02110-1301, USA.  */
  23
  24 #include "as.h"
  25 #include "sb.h"
  26
  27 #include <limits.h>
  28 #ifndef CHAR_BIT
  29 #define CHAR_BIT 8
  30 #endif
  31
  32 /* These routines are about manipulating strings.
  33
  34    They are managed in things called `sb's which is an abbreviation
  35    for string buffers.  An sb has to be created, things can be glued
  36    on to it, and at the end of it's life it should be freed.  The
  37    contents should never be pointed at whilst it is still growing,
  38    since it could be moved at any time
  39
  40    eg:
  41    sb_new (&foo);
  42    sb_grow... (&foo,...);
  43    use foo->ptr[*];
  44    sb_kill (&foo);  */
  45
  46 /* Buffers start at INIT_ALLOC size, and roughly double each time we
  47    go over the current allocation.  MALLOC_OVERHEAD is a guess at the
  48    system malloc overhead.  We aim to not waste any memory in the
  49    underlying page/chunk allocated by the system malloc.  */
  50 #define MALLOC_OVERHEAD (2 * sizeof (size_t))
  51 #define INIT_ALLOC (64 - MALLOC_OVERHEAD - 1)
  52
  53 static void sb_check (sb *, size_t);
  54
  55 /* Initializes an sb.  */
  56
  57 void
  58 sb_build (sb *ptr, size_t size)
  59 {
  60   ptr->ptr = XNEWVEC (char, size + 1);
  61   ptr->max = size;
  62   ptr->len = 0;
  63 }
  64
  65 void
  66 sb_new (sb *ptr)
  67 {
  68   sb_build (ptr, INIT_ALLOC);
  69 }
  70
  71 /* Deallocate the sb at ptr.  */
  72
  73 void
  74 sb_kill (sb *ptr)
  75 {
  76   free (ptr->ptr);
  77 }
  78
  79 /* Add the sb at s to the end of the sb at ptr.  */
  80
  81 void
  82 sb_add_sb (sb *ptr, sb *s)
  83 {
  84   sb_check (ptr, s->len);
  85   memcpy (ptr->ptr + ptr->len, s->ptr, s->len);
  86   ptr->len += s->len;
  87 }
  88
  89 /* Helper for sb_scrub_and_add_sb.  */
  90
  91 static sb *sb_to_scrub;
  92 static char *scrub_position;
  93 static size_t
  94 scrub_from_sb (char *buf, size_t buflen)
  95 {
  96   size_t copy;
  97   copy = sb_to_scrub->len - (scrub_position - sb_to_scrub->ptr);
  98   if (copy > buflen)
  99     copy = buflen;
 100   memcpy (buf, scrub_position, copy);
 101   scrub_position += copy;
 102   return copy;
 103 }
 104
 105 /* Run the sb at s through do_scrub_chars and add the result to the sb
 106    at ptr.  */
 107
 108 void
 109 sb_scrub_and_add_sb (sb *ptr, sb *s)
 110 {
 111   sb_to_scrub = s;
 112   scrub_position = s->ptr;
 113
 114   sb_check (ptr, s->len);
 115   ptr->len += do_scrub_chars (scrub_from_sb, ptr->ptr + ptr->len, s->len);
 116
 117   sb_to_scrub = 0;
 118   scrub_position = 0;
 119 }
 120
 121 /* Make sure that the sb at ptr has room for another len characters,
 122    and grow it if it doesn't.  */
 123
 124 static void
 125 sb_check (sb *ptr, size_t len)
 126 {
 127   size_t want = ptr->len + len;
 128
 129   if (want > ptr->max)
 130     {
 131       size_t max;
 132
 133       want += MALLOC_OVERHEAD + 1;
 134       if ((ssize_t) want < 0)
 135         as_fatal ("string buffer overflow");
 136 #if GCC_VERSION >= 3004
 137       max = (size_t) 1 << (CHAR_BIT * sizeof (want)
 138                            - (sizeof (want) <= sizeof (long)
 139                               ? __builtin_clzl ((long) want)
 140                               : __builtin_clzll ((long long) want)));
 141 #else
 142       max = 128;
 143       while (want > max)
 144         max <<= 1;
 145 #endif
 146       max -= MALLOC_OVERHEAD + 1;
 147       ptr->max = max;
 148       ptr->ptr = XRESIZEVEC (char, ptr->ptr, max + 1);
 149     }
 150 }
 151
 152 /* Make the sb at ptr point back to the beginning.  */
 153
 154 void
 155 sb_reset (sb *ptr)
 156 {
 157   ptr->len = 0;
 158 }
 159
 160 /* Add character c to the end of the sb at ptr.  */
 161
 162 void
 163 sb_add_char (sb *ptr, size_t c)
 164 {
 165   sb_check (ptr, 1);
 166   ptr->ptr[ptr->len++] = c;
 167 }
 168
 169 /* Add null terminated string s to the end of sb at ptr.  */
 170
 171 void
 172 sb_add_string (sb *ptr, const char *s)
 173 {
 174   size_t len = strlen (s);
 175   sb_check (ptr, len);
 176   memcpy (ptr->ptr + ptr->len, s, len);
 177   ptr->len += len;
 178 }
 179
 180 /* Add string at s of length len to sb at ptr */
 181
 182 void
 183 sb_add_buffer (sb *ptr, const char *s, size_t len)
 184 {
 185   sb_check (ptr, len);
 186   memcpy (ptr->ptr + ptr->len, s, len);
 187   ptr->len += len;
 188 }
 189
 190 /* Write terminating NUL and return string.  */
 191
 192 char *
 193 sb_terminate (sb *in)
 194 {
 195   in->ptr[in->len] = 0;
 196   return in->ptr;
 197 }
 198
 199 /* Start at the index idx into the string in sb at ptr and skip
 200    whitespace. return the index of the first non whitespace character.  */
 201
 202 size_t
 203 sb_skip_white (size_t idx, sb *ptr)
 204 {
 205   while (idx < ptr->len
 206          && (ptr->ptr[idx] == ' '
 207              || ptr->ptr[idx] == '\t'))
 208     idx++;
 209   return idx;
 210 }
 211
 212 /* Start at the index idx into the sb at ptr. skips whitespace,
 213    a comma and any following whitespace. returns the index of the
 214    next character.  */
 215
 216 size_t
 217 sb_skip_comma (size_t idx, sb *ptr)
 218 {
 219   while (idx < ptr->len
 220          && (ptr->ptr[idx] == ' '
 221              || ptr->ptr[idx] == '\t'))
 222     idx++;
 223
 224   if (idx < ptr->len
 225       && ptr->ptr[idx] == ',')
 226     idx++;
 227
 228   while (idx < ptr->len
 229          && (ptr->ptr[idx] == ' '
 230              || ptr->ptr[idx] == '\t'))
 231     idx++;
 232
 233   return idx;
 234 }