stdio-common/printf-parse.h

   1 /* Internal header for parsing printf format strings.
   2 Copyright (C) 1995 Free Software Foundation, Inc.
   3 This file is part of th GNU C Library.
   4
   5 The GNU C Library is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 License, or (at your option) any later version.
   9
  10 The GNU C Library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #include <ctype.h>
  21 #include <printf.h>
  22 #include <string.h>
  23 #include <stddef.h>
  24
  25 #define NDEBUG 1
  26 #include <assert.h>
  27
  28 #define MAX(a,b)        ({typeof(a) _a = (a); typeof(b) _b = (b);             \
  29                           _a > _b ? _a : _b; })
  30 #define MIN(a,b)        ({typeof(a) _a = (a); typeof(b) _b = (b);             \
  31                           _a < _b ? _a : _b; })
  32
  33 struct printf_spec
  34   {
  35     /* Information parsed from the format spec.  */
  36     struct printf_info info;
  37
  38     /* Pointers into the format string for the end of this format
  39        spec and the next (or to the end of the string if no more).  */
  40     const char *end_of_fmt, *next_fmt;
  41
  42     /* Position of arguments for precision and width, or -1 if `info' has
  43        the constant value.  */
  44     int prec_arg, width_arg;
  45
  46     int data_arg;               /* Position of data argument.  */
  47     int data_arg_type;          /* Type of first argument.  */
  48     /* Number of arguments consumed by this format specifier.  */
  49     size_t ndata_args;
  50   };
  51
  52
  53 /* The various kinds off arguments that can be passed to printf.  */
  54 union printf_arg
  55   {
  56     unsigned char pa_char;
  57     short int pa_short_int;
  58     int pa_int;
  59     long int pa_long_int;
  60     long long int pa_long_long_int;
  61     unsigned short int pa_u_short_int;
  62     unsigned int pa_u_int;
  63     unsigned long int pa_u_long_int;
  64     unsigned long long int pa_u_long_long_int;
  65     float pa_float;
  66     double pa_double;
  67     long double pa_long_double;
  68     const char *pa_string;
  69     void *pa_pointer;
  70   };
  71
  72
  73 /* Read a simple integer from a string and update the string pointer.
  74    It is assumed that the first character is a digit.  */
  75 static inline unsigned int
  76 read_int (const char * *pstr)
  77 {
  78   unsigned int retval = **pstr - '0';
  79
  80   while (isdigit (*++(*pstr)))
  81     {
  82       retval *= 10;
  83       retval += **pstr - '0';
  84     }
  85
  86   return retval;
  87 }
  88
  89
  90
  91 /* Find the next spec in FORMAT, or the end of the string.  Returns
  92    a pointer into FORMAT, to a '%' or a '\0'.  */
  93 static inline const char *
  94 find_spec (const char *format)
  95 {
  96   while (*format != '\0' && *format != '%')
  97     {
  98       int len;
  99
 100       if (isascii (*format) || (len = mblen (format, MB_CUR_MAX)) <= 0)
 101         ++format;
 102       else
 103         format += len;
 104     }
 105   return format;
 106 }
 107
 108
 109 /* This is defined in reg-printf.c.  */
 110 extern printf_arginfo_function **__printf_arginfo_table;
 111
 112
 113 /* FORMAT must point to a '%' at the beginning of a spec.  Fills in *SPEC
 114    with the parsed details.  POSN is the number of arguments already
 115    consumed.  At most MAXTYPES - POSN types are filled in TYPES.  Return
 116    the number of args consumed by this spec; *MAX_REF_ARG is updated so it
 117    remains the highest argument index used.  */
 118 static inline size_t
 119 parse_one_spec (const char *format, size_t posn, struct printf_spec *spec,
 120                 size_t *max_ref_arg)
 121 {
 122   unsigned int n;
 123   size_t nargs = 0;
 124
 125   /* Skip the '%'.  */
 126   ++format;
 127
 128   /* Clear information structure.  */
 129   spec->data_arg = -1;
 130   spec->info.alt = 0;
 131   spec->info.space = 0;
 132   spec->info.left = 0;
 133   spec->info.showsign = 0;
 134   spec->info.group = 0;
 135   spec->info.pad = ' ';
 136
 137   /* Test for positional argument.  */
 138   if (isdigit (*format))
 139     {
 140       const char *begin = format;
 141
 142       n = read_int (&format);
 143
 144       if (n > 0 && *format == '$')
 145         /* Is positional parameter.  */
 146         {
 147           ++format;             /* Skip the '$'.  */
 148           spec->data_arg = n - 1;
 149           *max_ref_arg = MAX (*max_ref_arg, n);
 150         }
 151       else
 152         /* Oops; that was actually the width and/or 0 padding flag.
 153            Step back and read it again.  */
 154         format = begin;
 155     }
 156
 157   /* Check for spec modifiers.  */
 158   while (*format == ' ' || *format == '+' || *format == '-' ||
 159          *format == '#' || *format == '0' || *format == '\'')
 160     switch (*format++)
 161       {
 162       case ' ':
 163         /* Output a space in place of a sign, when there is no sign.  */
 164         spec->info.space = 1;
 165         break;
 166       case '+':
 167         /* Always output + or - for numbers.  */
 168         spec->info.showsign = 1;
 169         break;
 170       case '-':
 171         /* Left-justify things.  */
 172         spec->info.left = 1;
 173         break;
 174       case '#':
 175         /* Use the "alternate form":
 176            Hex has 0x or 0X, FP always has a decimal point.  */
 177         spec->info.alt = 1;
 178         break;
 179       case '0':
 180         /* Pad with 0s.  */
 181         spec->info.pad = '0';
 182         break;
 183       case '\'':
 184         /* Show grouping in numbers if the locale information
 185            indicates any.  */
 186         spec->info.group = 1;
 187         break;
 188       }
 189   if (spec->info.left)
 190     spec->info.pad = ' ';
 191
 192   /* Get the field width.  */
 193   spec->width_arg = -1;
 194   spec->info.width = 0;
 195   if (*format == '*')
 196     {
 197       /* The field width is given in an argument.
 198          A negative field width indicates left justification.  */
 199       const char *begin = ++format;
 200
 201       if (isdigit (*format))
 202         {
 203           /* The width argument might be found in a positional parameter.  */
 204           n = read_int (&format);
 205
 206           if (n > 0 && *format == '$')
 207             {
 208               spec->width_arg = n - 1;
 209               *max_ref_arg = MAX (*max_ref_arg, n);
 210               ++format;         /* Skip '$'.  */
 211             }
 212         }
 213
 214       if (spec->width_arg < 0)
 215         {
 216           /* Not in a positional parameter.  Consume one argument.  */
 217           spec->width_arg = posn++;
 218           ++nargs;
 219           format = begin;       /* Step back and reread.  */
 220         }
 221     }
 222   else if (isdigit (*format))
 223     /* Constant width specification.  */
 224     spec->info.width = read_int (&format);
 225
 226   /* Get the precision.  */
 227   spec->prec_arg = -1;
 228   /* -1 means none given; 0 means explicit 0.  */
 229   spec->info.prec = -1;
 230   if (*format == '.')
 231     {
 232       ++format;
 233       if (*format == '*')
 234         {
 235           /* The precision is given in an argument.  */
 236           const char *begin = ++format;
 237
 238           if (isdigit (*format))
 239             {
 240               n = read_int (&format);
 241
 242               if (n > 0 && *format == '$')
 243                 {
 244                   spec->prec_arg = n - 1;
 245                   *max_ref_arg = MAX (*max_ref_arg, n);
 246                   ++format;
 247                 }
 248             }
 249
 250           if (spec->prec_arg < 0)
 251             {
 252               /* Not in a positional parameter.  */
 253               spec->prec_arg = posn++;
 254               ++nargs;
 255               format = begin;
 256             }
 257         }
 258       else if (isdigit (*format))
 259         spec->info.prec = read_int (&format);
 260       else
 261         /* "%.?" is treated like "%.0?".  */
 262         spec->info.prec = 0;
 263     }
 264
 265   /* Check for type modifiers.  */
 266 #define is_longlong is_long_double
 267   spec->info.is_long_double = 0;
 268   spec->info.is_short = 0;
 269   spec->info.is_long = 0;
 270
 271   while (*format == 'h' || *format == 'l' || *format == 'L' ||
 272          *format == 'Z' || *format == 'q')
 273     switch (*format++)
 274       {
 275       case 'h':
 276         /* int's are short int's.  */
 277         spec->info.is_short = 1;
 278         break;
 279       case 'l':
 280         if (spec->info.is_long)
 281           /* A double `l' is equivalent to an `L'.  */
 282           spec->info.is_longlong = 1;
 283         else
 284           /* int's are long int's.  */
 285           spec->info.is_long = 1;
 286         break;
 287       case 'L':
 288         /* double's are long double's, and int's are long long int's.  */
 289         spec->info.is_long_double = 1;
 290         break;
 291       case 'Z':
 292         /* int's are size_t's.  */
 293         assert (sizeof(size_t) <= sizeof(unsigned long long int));
 294         spec->info.is_longlong = sizeof(size_t) > sizeof(unsigned long int);
 295         spec->info.is_long = sizeof(size_t) > sizeof(unsigned int);
 296         break;
 297       case 'q':
 298         /* 4.4 uses this for long long.  */
 299         spec->info.is_longlong = 1;
 300         break;
 301       }
 302
 303   /* Get the format specification.  */
 304   spec->info.spec = *format++;
 305   if (__printf_arginfo_table != NULL &&
 306       __printf_arginfo_table[spec->info.spec] != NULL)
 307     /* We don't try to get the types for all arguments if the format
 308        uses more than one.  The normal case is covered though.  */
 309     spec->ndata_args = (*__printf_arginfo_table[spec->info.spec])
 310       (&spec->info, 1, &spec->data_arg_type);
 311   else
 312     {
 313       /* Find the data argument types of a built-in spec.  */
 314       spec->ndata_args = 1;
 315
 316       switch (spec->info.spec)
 317         {
 318         case 'i':
 319         case 'd':
 320         case 'u':
 321         case 'o':
 322         case 'X':
 323         case 'x':
 324           if (spec->info.is_longlong)
 325             spec->data_arg_type = PA_INT|PA_FLAG_LONG_LONG;
 326           else if (spec->info.is_long)
 327             spec->data_arg_type = PA_INT|PA_FLAG_LONG;
 328           else if (spec->info.is_short)
 329             spec->data_arg_type = PA_INT|PA_FLAG_SHORT;
 330           else
 331             spec->data_arg_type = PA_INT;
 332           break;
 333         case 'e':
 334         case 'E':
 335         case 'f':
 336         case 'g':
 337         case 'G':
 338           if (spec->info.is_long_double)
 339             spec->data_arg_type = PA_DOUBLE|PA_FLAG_LONG_DOUBLE;
 340           else
 341             spec->data_arg_type = PA_DOUBLE;
 342           break;
 343         case 'c':
 344           spec->data_arg_type = PA_CHAR;
 345           break;
 346         case 's':
 347           spec->data_arg_type = PA_STRING;
 348           break;
 349         case 'p':
 350           spec->data_arg_type = PA_POINTER;
 351           break;
 352         case 'n':
 353           spec->data_arg_type = PA_INT|PA_FLAG_PTR;
 354           break;
 355
 356         case 'm':
 357         default:
 358           /* An unknown spec will consume no args.  */
 359           spec->ndata_args = 0;
 360           break;
 361         }
 362
 363       if (spec->data_arg == -1 && spec->ndata_args > 0)
 364         {
 365           /* There are args consumed, but no positional spec.
 366              Use the next sequential arg position.  */
 367           spec->data_arg = posn;
 368           posn += spec->ndata_args;
 369           nargs += spec->ndata_args;
 370         }
 371     }
 372
 373   if (spec->info.spec == '\0')
 374     /* Format ended before this spec was complete.  */
 375     spec->end_of_fmt = spec->next_fmt = format - 1;
 376   else
 377     {
 378       /* Find the next format spec.  */
 379       spec->end_of_fmt = format;
 380       spec->next_fmt = find_spec (format);
 381     }
 382
 383   return nargs;
 384 }