unify.c

   1 /*
   2  * Copyright (C) 2002 Andrew Tridgell
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; either version 3 of the License, or (at your option)
   7  * any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 51
  16  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 /*
  20  * C/C++ unifier
  21  *
  22  * The idea is that changes that don't affect the resulting C code should not
  23  * change the hash. This is achieved by folding white-space and other
  24  * non-semantic fluff in the input into a single unified format.
  25  *
  26  * This unifier was design to match the output of the unifier in compilercache,
  27  * which is flex based. The major difference is that this unifier is much
  28  * faster (about 2x) and more forgiving of syntactic errors. Continuing on
  29  * syntactic errors is important to cope with C/C++ extensions in the local
  30  * compiler (for example, inline assembly systems).
  31  */
  32
  33 #include "ccache.h"
  34
  35 static const char *const s_tokens[] = {
  36         "...", ">>=", "<<=", "+=", "-=", "*=", "/=", "%=", "&=", "^=",
  37         "|=",  ">>",  "<<",  "++", "--", "->", "&&", "||", "<=", ">=",
  38         "==",  "!=",  ";",   "{",  "<%", "}",  "%>", ",",  ":",  "=",
  39         "(",   ")",   "[",   "<:", "]",  ":>", ".",  "&",  "!",  "~",
  40         "-",   "+",   "*",   "/",  "%",  "<",  ">",  "^",  "|",  "?",
  41         0
  42 };
  43
  44 #define C_ALPHA 1
  45 #define C_SPACE 2
  46 #define C_TOKEN 4
  47 #define C_QUOTE 8
  48 #define C_DIGIT 16
  49 #define C_HEX   32
  50 #define C_FLOAT 64
  51 #define C_SIGN  128
  52
  53 static struct {
  54         unsigned char type;
  55         unsigned char num_toks;
  56         const char *toks[7];
  57 } tokens[256];
  58
  59 /* build up the table used by the unifier */
  60 static void
  61 build_table(void)
  62 {
  63         unsigned char c;
  64         int i;
  65         static bool done;
  66
  67         if (done) {
  68                 return;
  69         }
  70         done = true;
  71
  72         memset(tokens, 0, sizeof(tokens));
  73         for (c = 0; c < 128; c++) {
  74                 if (isalpha(c) || c == '_') {
  75                         tokens[c].type |= C_ALPHA;
  76                 }
  77                 if (isdigit(c)) {
  78                         tokens[c].type |= C_DIGIT;
  79                 }
  80                 if (isspace(c)) {
  81                         tokens[c].type |= C_SPACE;
  82                 }
  83                 if (isxdigit(c)) {
  84                         tokens[c].type |= C_HEX;
  85                 }
  86         }
  87         tokens['\''].type |= C_QUOTE;
  88         tokens['"'].type |= C_QUOTE;
  89         tokens['l'].type |= C_FLOAT;
  90         tokens['L'].type |= C_FLOAT;
  91         tokens['f'].type |= C_FLOAT;
  92         tokens['F'].type |= C_FLOAT;
  93         tokens['U'].type |= C_FLOAT;
  94         tokens['u'].type |= C_FLOAT;
  95
  96         tokens['-'].type |= C_SIGN;
  97         tokens['+'].type |= C_SIGN;
  98
  99         for (i = 0; s_tokens[i]; i++) {
 100                 c = s_tokens[i][0];
 101                 tokens[c].type |= C_TOKEN;
 102                 tokens[c].toks[tokens[c].num_toks] = s_tokens[i];
 103                 tokens[c].num_toks++;
 104         }
 105 }
 106
 107 /* buffer up characters before hashing them */
 108 static void
 109 pushchar(struct mdfour *hash, unsigned char c)
 110 {
 111         static unsigned char buf[64];
 112         static size_t len;
 113
 114         if (c == 0) {
 115                 if (len > 0) {
 116                         hash_buffer(hash, (char *)buf, len);
 117                         len = 0;
 118                 }
 119                 hash_buffer(hash, NULL, 0);
 120                 return;
 121         }
 122
 123         buf[len++] = c;
 124         if (len == 64) {
 125                 hash_buffer(hash, (char *)buf, len);
 126                 len = 0;
 127         }
 128 }
 129
 130 /* hash some C/C++ code after unifying */
 131 static void
 132 unify(struct mdfour *hash, unsigned char *p, size_t size)
 133 {
 134         size_t ofs;
 135         unsigned char q;
 136         int i;
 137
 138         build_table();
 139
 140         for (ofs = 0; ofs < size; ) {
 141                 if (p[ofs] == '#') {
 142                         if ((size-ofs) > 2 && p[ofs+1] == ' ' && isdigit(p[ofs+2])) {
 143                                 do {
 144                                         ofs++;
 145                                 } while (ofs < size && p[ofs] != '\n');
 146                                 ofs++;
 147                         } else {
 148                                 do {
 149                                         pushchar(hash, p[ofs]);
 150                                         ofs++;
 151                                 } while (ofs < size && p[ofs] != '\n');
 152                                 pushchar(hash, '\n');
 153                                 ofs++;
 154                         }
 155                         continue;
 156                 }
 157
 158                 if (tokens[p[ofs]].type & C_ALPHA) {
 159                         do {
 160                                 pushchar(hash, p[ofs]);
 161                                 ofs++;
 162                         } while (ofs < size && (tokens[p[ofs]].type & (C_ALPHA|C_DIGIT)));
 163                         pushchar(hash, '\n');
 164                         continue;
 165                 }
 166
 167                 if (tokens[p[ofs]].type & C_DIGIT) {
 168                         do {
 169                                 pushchar(hash, p[ofs]);
 170                                 ofs++;
 171                         } while (ofs < size &&
 172                                  ((tokens[p[ofs]].type & C_DIGIT) || p[ofs] == '.'));
 173                         if (ofs < size && (p[ofs] == 'x' || p[ofs] == 'X')) {
 174                                 do {
 175                                         pushchar(hash, p[ofs]);
 176                                         ofs++;
 177                                 } while (ofs < size && (tokens[p[ofs]].type & C_HEX));
 178                         }
 179                         if (ofs < size && (p[ofs] == 'E' || p[ofs] == 'e')) {
 180                                 pushchar(hash, p[ofs]);
 181                                 ofs++;
 182                                 while (ofs < size && (tokens[p[ofs]].type & (C_DIGIT|C_SIGN))) {
 183                                         pushchar(hash, p[ofs]);
 184                                         ofs++;
 185                                 }
 186                         }
 187                         while (ofs < size && (tokens[p[ofs]].type & C_FLOAT)) {
 188                                 pushchar(hash, p[ofs]);
 189                                 ofs++;
 190                         }
 191                         pushchar(hash, '\n');
 192                         continue;
 193                 }
 194
 195                 if (tokens[p[ofs]].type & C_SPACE) {
 196                         do {
 197                                 ofs++;
 198                         } while (ofs < size && (tokens[p[ofs]].type & C_SPACE));
 199                         continue;
 200                 }
 201
 202                 if (tokens[p[ofs]].type & C_QUOTE) {
 203                         q = p[ofs];
 204                         pushchar(hash, p[ofs]);
 205                         do {
 206                                 ofs++;
 207                                 while (ofs < size-1 && p[ofs] == '\\') {
 208                                         pushchar(hash, p[ofs]);
 209                                         pushchar(hash, p[ofs+1]);
 210                                         ofs += 2;
 211                                 }
 212                                 pushchar(hash, p[ofs]);
 213                         } while (ofs < size && p[ofs] != q);
 214                         pushchar(hash, '\n');
 215                         ofs++;
 216                         continue;
 217                 }
 218
 219                 if (tokens[p[ofs]].type & C_TOKEN) {
 220                         q = p[ofs];
 221                         for (i = 0; i < tokens[q].num_toks; i++) {
 222                                 unsigned char *s = (unsigned char *)tokens[q].toks[i];
 223                                 int len = strlen((char *)s);
 224                                 if (size >= ofs+len && memcmp(&p[ofs], s, len) == 0) {
 225                                         int j;
 226                                         for (j = 0; s[j]; j++) {
 227                                                 pushchar(hash, s[j]);
 228                                                 ofs++;
 229                                         }
 230                                         pushchar(hash, '\n');
 231                                         break;
 232                                 }
 233                         }
 234                         if (i < tokens[q].num_toks) {
 235                                 continue;
 236                         }
 237                 }
 238
 239                 pushchar(hash, p[ofs]);
 240                 pushchar(hash, '\n');
 241                 ofs++;
 242         }
 243         pushchar(hash, 0);
 244 }
 245
 246
 247 /* hash a file that consists of preprocessor output, but remove any line
 248    number information from the hash
 249  */
 250 int
 251 unify_hash(struct mdfour *hash, const char *fname)
 252 {
 253         char *data;
 254         size_t size;
 255
 256         if (!read_file(fname, 0, &data, &size)) {
 257                 stats_update(STATS_PREPROCESSOR);
 258                 return -1;
 259         }
 260         unify(hash, (unsigned char *)data, size);
 261         free(data);
 262         return 0;
 263 }