gas/sb.c

   1 /* sb.c - string buffer manipulation routines
   2    Copyright (C) 1994-2024 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   /* do_scrub_chars can expand text, for example when replacing
 115      # 123 "filename"
 116      with
 117      \t.linefile 123 "filename"
 118      or when replacing a 'c with the decimal ascii number for c.
 119      So we loop until the input S is consumed.  */
 120   while (1)
 121     {
 122       size_t copy = s->len - (scrub_position - s->ptr) + do_scrub_pending ();
 123       if (copy == 0)
 124         break;
 125       sb_check (ptr, copy);
 126       ptr->len += do_scrub_chars (scrub_from_sb, ptr->ptr + ptr->len,
 127                                   ptr->max - ptr->len, false);
 128     }
 129
 130   sb_to_scrub = 0;
 131   scrub_position = 0;
 132 }
 133
 134 /* Make sure that the sb at ptr has room for another len characters,
 135    and grow it if it doesn't.  */
 136
 137 static void
 138 sb_check (sb *ptr, size_t len)
 139 {
 140   size_t want = ptr->len + len;
 141
 142   if (want > ptr->max)
 143     {
 144       size_t max;
 145
 146       want += MALLOC_OVERHEAD + 1;
 147       if ((ssize_t) want < 0)
 148         as_fatal ("string buffer overflow");
 149 #if GCC_VERSION >= 3004
 150       max = (size_t) 1 << (CHAR_BIT * sizeof (want)
 151                            - (sizeof (want) <= sizeof (long)
 152                               ? __builtin_clzl ((long) want)
 153                               : __builtin_clzll ((long long) want)));
 154 #else
 155       max = 128;
 156       while (want > max)
 157         max <<= 1;
 158 #endif
 159       max -= MALLOC_OVERHEAD + 1;
 160       ptr->max = max;
 161       ptr->ptr = XRESIZEVEC (char, ptr->ptr, max + 1);
 162     }
 163 }
 164
 165 /* Make the sb at ptr point back to the beginning.  */
 166
 167 void
 168 sb_reset (sb *ptr)
 169 {
 170   ptr->len = 0;
 171 }
 172
 173 /* Add character c to the end of the sb at ptr.  */
 174
 175 void
 176 sb_add_char (sb *ptr, char c)
 177 {
 178   sb_check (ptr, 1);
 179   ptr->ptr[ptr->len++] = c;
 180 }
 181
 182 /* Add null terminated string s to the end of sb at ptr.  */
 183
 184 void
 185 sb_add_string (sb *ptr, const char *s)
 186 {
 187   size_t len = strlen (s);
 188   sb_check (ptr, len);
 189   memcpy (ptr->ptr + ptr->len, s, len);
 190   ptr->len += len;
 191 }
 192
 193 /* Add string at s of length len to sb at ptr */
 194
 195 void
 196 sb_add_buffer (sb *ptr, const char *s, size_t len)
 197 {
 198   sb_check (ptr, len);
 199   memcpy (ptr->ptr + ptr->len, s, len);
 200   ptr->len += len;
 201 }
 202
 203 /* Write terminating NUL and return string.  */
 204
 205 char *
 206 sb_terminate (sb *in)
 207 {
 208   in->ptr[in->len] = 0;
 209   return in->ptr;
 210 }
 211
 212 /* Start at the index idx into the string in sb at ptr and skip
 213    whitespace. return the index of the first non whitespace character.  */
 214
 215 size_t
 216 sb_skip_white (size_t idx, sb *ptr)
 217 {
 218   while (idx < ptr->len
 219          && (ptr->ptr[idx] == ' '
 220              || ptr->ptr[idx] == '\t'))
 221     idx++;
 222   return idx;
 223 }
 224
 225 /* Start at the index idx into the sb at ptr. skips whitespace,
 226    a comma and any following whitespace. returns the index of the
 227    next character.  */
 228
 229 size_t
 230 sb_skip_comma (size_t idx, sb *ptr)
 231 {
 232   while (idx < ptr->len
 233          && (ptr->ptr[idx] == ' '
 234              || ptr->ptr[idx] == '\t'))
 235     idx++;
 236
 237   if (idx < ptr->len
 238       && ptr->ptr[idx] == ',')
 239     idx++;
 240
 241   while (idx < ptr->len
 242          && (ptr->ptr[idx] == ' '
 243              || ptr->ptr[idx] == '\t'))
 244     idx++;
 245
 246   return idx;
 247 }