contrib/sendmail/libsm/strl.c

   1 /*
   2  * Copyright (c) 1999-2002 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  *
   5  * By using this file, you agree to the terms and conditions set
   6  * forth in the LICENSE file which can be found at the top level of
   7  * the sendmail distribution.
   8  *
   9  */
  10
  11 #include <sm/gen.h>
  12 SM_RCSID("@(#)$Id: strl.c,v 1.31 2002/01/20 01:41:25 gshapiro Exp $")
  13 #include <sm/config.h>
  14 #include <sm/string.h>
  15
  16 /*
  17 **  Notice: this file is used by libmilter. Please try to avoid
  18 **      using libsm specific functions.
  19 */
  20
  21 /*
  22 **  XXX the type of the length parameter has been changed
  23 **  from size_t to ssize_t to avoid theoretical problems with negative
  24 **  numbers passed into these functions.
  25 **  The real solution to this problem is to make sure that this doesn't
  26 **  happen, but for now we'll use this workaround.
  27 */
  28
  29 /*
  30 **  SM_STRLCPY -- size bounded string copy
  31 **
  32 **      This is a bounds-checking variant of strcpy.
  33 **      If size > 0, copy up to size-1 characters from the nul terminated
  34 **      string src to dst, nul terminating the result.  If size == 0,
  35 **      the dst buffer is not modified.
  36 **      Additional note: this function has been "tuned" to run fast and tested
  37 **      as such (versus versions in some OS's libc).
  38 **
  39 **      The result is strlen(src).  You can detect truncation (not all
  40 **      of the characters in the source string were copied) using the
  41 **      following idiom:
  42 **
  43 **              char *s, buf[BUFSIZ];
  44 **              ...
  45 **              if (sm_strlcpy(buf, s, sizeof(buf)) >= sizeof(buf))
  46 **                      goto overflow;
  47 **
  48 **      Parameters:
  49 **              dst -- destination buffer
  50 **              src -- source string
  51 **              size -- size of destination buffer
  52 **
  53 **      Returns:
  54 **              strlen(src)
  55 */
  56
  57 size_t
  58 sm_strlcpy(dst, src, size)
  59         register char *dst;
  60         register const char *src;
  61         ssize_t size;
  62 {
  63         register ssize_t i;
  64
  65         if (size-- <= 0)
  66                 return strlen(src);
  67         for (i = 0; i < size && (dst[i] = src[i]) != 0; i++)
  68                 continue;
  69         dst[i] = '\0';
  70         if (src[i] == '\0')
  71                 return i;
  72         else
  73                 return i + strlen(src + i);
  74 }
  75
  76 /*
  77 **  SM_STRLCAT -- size bounded string concatenation
  78 **
  79 **      This is a bounds-checking variant of strcat.
  80 **      If strlen(dst) < size, then append at most size - strlen(dst) - 1
  81 **      characters from the source string to the destination string,
  82 **      nul terminating the result.  Otherwise, dst is not modified.
  83 **
  84 **      The result is the initial length of dst + the length of src.
  85 **      You can detect overflow (not all of the characters in the
  86 **      source string were copied) using the following idiom:
  87 **
  88 **              char *s, buf[BUFSIZ];
  89 **              ...
  90 **              if (sm_strlcat(buf, s, sizeof(buf)) >= sizeof(buf))
  91 **                      goto overflow;
  92 **
  93 **      Parameters:
  94 **              dst -- nul-terminated destination string buffer
  95 **              src -- nul-terminated source string
  96 **              size -- size of destination buffer
  97 **
  98 **      Returns:
  99 **              total length of the string tried to create
 100 **              (= initial length of dst + length of src)
 101 */
 102
 103 size_t
 104 sm_strlcat(dst, src, size)
 105         register char *dst;
 106         register const char *src;
 107         ssize_t size;
 108 {
 109         register ssize_t i, j, o;
 110
 111         o = strlen(dst);
 112         if (size < o + 1)
 113                 return o + strlen(src);
 114         size -= o + 1;
 115         for (i = 0, j = o; i < size && (dst[j] = src[i]) != 0; i++, j++)
 116                 continue;
 117         dst[j] = '\0';
 118         if (src[i] == '\0')
 119                 return j;
 120         else
 121                 return j + strlen(src + i);
 122 }
 123 /*
 124 **  SM_STRLCAT2 -- append two strings to dst obeying length and
 125 **              '\0' terminate it
 126 **
 127 **              strlcat2 will append at most len - strlen(dst) - 1 chars.
 128 **              terminates with '\0' if len > 0
 129 **              dst = dst "+" src1 "+" src2
 130 **              use this instead of sm_strlcat(dst,src1); sm_strlcat(dst,src2);
 131 **              for better speed.
 132 **
 133 **      Parameters:
 134 **              dst -- "destination" string.
 135 **              src1 -- "from" string 1.
 136 **              src2 -- "from" string 2.
 137 **              len -- max. length of "destination" string.
 138 **
 139 **      Returns:
 140 **              total length of the string tried to create
 141 **              (= initial length of dst + length of src)
 142 **              if this is greater than len then an overflow would have
 143 **              occurred.
 144 **
 145 */
 146
 147 size_t
 148 sm_strlcat2(dst, src1, src2, len)
 149         register char *dst;
 150         register const char *src1;
 151         register const char *src2;
 152         ssize_t len;
 153 {
 154         register ssize_t i, j, o;
 155
 156         /* current size of dst */
 157         o = strlen(dst);
 158
 159         /* max. size is less than current? */
 160         if (len < o + 1)
 161                 return o + strlen(src1) + strlen(src2);
 162
 163         len -= o + 1;   /* space left in dst */
 164
 165         /* copy the first string; i: index in src1; j: index in dst */
 166         for (i = 0, j = o; i < len && (dst[j] = src1[i]) != 0; i++, j++)
 167                 continue;
 168
 169         /* src1: end reached? */
 170         if (src1[i] != '\0')
 171         {
 172                 /* no: terminate dst; there is space since i < len */
 173                 dst[j] = '\0';
 174                 return j + strlen(src1 + i) + strlen(src2);
 175         }
 176
 177         len -= i;       /* space left in dst */
 178
 179         /* copy the second string; i: index in src2; j: index in dst */
 180         for (i = 0; i < len && (dst[j] = src2[i]) != 0; i++, j++)
 181                 continue;
 182         dst[j] = '\0';  /* terminate dst; there is space since i < len */
 183         if (src2[i] == '\0')
 184                 return j;
 185         else
 186                 return j + strlen(src2 + i);
 187 }
 188
 189 /*
 190 **  SM_STRLCPYN -- concatenate n strings and assign the result to dst
 191 **              while obeying length and '\0' terminate it
 192 **
 193 **              dst = src1 "+" src2 "+" ...
 194 **              use this instead of sm_snprintf() for string values
 195 **              and repeated sm_strlc*() calls for better speed.
 196 **
 197 **      Parameters:
 198 **              dst -- "destination" string.
 199 **              len -- max. length of "destination" string.
 200 **              n -- number of strings
 201 **              strings...
 202 **
 203 **      Returns:
 204 **              total length of the string tried to create
 205 **              (= initial length of dst + length of src)
 206 **              if this is greater than len then an overflow would have
 207 **              occurred.
 208 */
 209
 210 size_t
 211 #ifdef __STDC__
 212 sm_strlcpyn(char *dst, ssize_t len, int n, ...)
 213 #else /* __STDC__ */
 214 sm_strlcpyn(dst, len, n, va_alist)
 215         register char *dst;
 216         ssize_t len;
 217         int n;
 218         va_dcl
 219 #endif /* __STDC__ */
 220 {
 221         register ssize_t i, j;
 222         char *str;
 223         SM_VA_LOCAL_DECL
 224
 225         SM_VA_START(ap, n);
 226
 227         if (len-- <= 0) /* This allows space for the terminating '\0' */
 228         {
 229                 i = 0;
 230                 while (n-- > 0)
 231                         i += strlen(SM_VA_ARG(ap, char *));
 232                 SM_VA_END(ap);
 233                 return i;
 234         }
 235
 236         j = 0;  /* index in dst */
 237
 238         /* loop through all source strings */
 239         while (n-- > 0)
 240         {
 241                 str = SM_VA_ARG(ap, char *);
 242
 243                 /* copy string; i: index in str; j: index in dst */
 244                 for (i = 0; j < len && (dst[j] = str[i]) != 0; i++, j++)
 245                         continue;
 246
 247                 /* str: end reached? */
 248                 if (str[i] != '\0')
 249                 {
 250                         /* no: terminate dst; there is space since j < len */
 251                         dst[j] = '\0';
 252                         j += strlen(str + i);
 253                         while (n-- > 0)
 254                                 j += strlen(SM_VA_ARG(ap, char *));
 255                         SM_VA_END(ap);
 256                         return j;
 257                 }
 258         }
 259         SM_VA_END(ap);
 260
 261         dst[j] = '\0';  /* terminate dst; there is space since j < len */
 262         return j;
 263 }
 264
 265 #if 0
 266 /*
 267 **  SM_STRLAPP -- append string if it fits into buffer.
 268 **
 269 **      If size > 0, copy up to size-1 characters from the nul terminated
 270 **      string src to dst, nul terminating the result.  If size == 0,
 271 **      the dst buffer is not modified.
 272 **
 273 **      This routine is useful for appending strings in a loop, e.g, instead of
 274 **      s = buf;
 275 **      for (ptr, ptr != NULL, ptr = next->ptr)
 276 **      {
 277 **              (void) sm_strlcpy(s, ptr->string, sizeof buf - (s - buf));
 278 **              s += strlen(s);
 279 **      }
 280 **      replace the loop body with:
 281 **              if (!sm_strlapp(*s, ptr->string, sizeof buf - (s - buf)))
 282 **                      break;
 283 **      it's faster...
 284 **
 285 **      XXX interface isn't completely clear (yet), hence this code is
 286 **      not available.
 287 **
 288 **
 289 **      Parameters:
 290 **              dst -- (pointer to) destination buffer
 291 **              src -- source string
 292 **              size -- size of destination buffer
 293 **
 294 **      Returns:
 295 **              true if strlen(src) < size
 296 **
 297 **      Side Effects:
 298 **              modifies dst if append succeeds (enough space).
 299 */
 300
 301 bool
 302 sm_strlapp(dst, src, size)
 303         register char **dst;
 304         register const char *src;
 305         ssize_t size;
 306 {
 307         register size_t i;
 308
 309         if (size-- <= 0)
 310                 return false;
 311         for (i = 0; i < size && ((*dst)[i] = src[i]) != '\0'; i++)
 312                 continue;
 313         (*dst)[i] = '\0';
 314         if (src[i] == '\0')
 315         {
 316                 *dst += i;
 317                 return true;
 318         }
 319
 320         /* undo */
 321         (*dst)[0] = '\0';
 322         return false;
 323 }
 324 #endif /* 0 */