Python/pystrtod.c

   1 /* -*- Mode: C; c-file-style: "python" -*- */
   2
   3 #include <Python.h>
   4 #include <locale.h>
   5
   6 /* ascii character tests (as opposed to locale tests) */
   7 #define ISSPACE(c)  ((c) == ' ' || (c) == '\f' || (c) == '\n' || \
   8                      (c) == '\r' || (c) == '\t' || (c) == '\v')
   9 #define ISDIGIT(c)  ((c) >= '0' && (c) <= '9')
  10 #define ISXDIGIT(c) (ISDIGIT(c) || ((c) >= 'a' && (c) <= 'f') || ((c) >= 'A' && (c) <= 'F'))
  11
  12
  13 /**
  14  * PyOS_ascii_strtod:
  15  * @nptr:    the string to convert to a numeric value.
  16  * @endptr:  if non-%NULL, it returns the character after
  17  *           the last character used in the conversion.
  18  *
  19  * Converts a string to a #gdouble value.
  20  * This function behaves like the standard strtod() function
  21  * does in the C locale. It does this without actually
  22  * changing the current locale, since that would not be
  23  * thread-safe.
  24  *
  25  * This function is typically used when reading configuration
  26  * files or other non-user input that should be locale independent.
  27  * To handle input from the user you should normally use the
  28  * locale-sensitive system strtod() function.
  29  *
  30  * If the correct value would cause overflow, plus or minus %HUGE_VAL
  31  * is returned (according to the sign of the value), and %ERANGE is
  32  * stored in %errno. If the correct value would cause underflow,
  33  * zero is returned and %ERANGE is stored in %errno.
  34  * If memory allocation fails, %ENOMEM is stored in %errno.
  35  *
  36  * This function resets %errno before calling strtod() so that
  37  * you can reliably detect overflow and underflow.
  38  *
  39  * Return value: the #gdouble value.
  40  **/
  41 double
  42 PyOS_ascii_strtod(const char *nptr, char **endptr)
  43 {
  44         char *fail_pos;
  45         double val = -1.0;
  46         struct lconv *locale_data;
  47         const char *decimal_point;
  48         size_t decimal_point_len;
  49         const char *p, *decimal_point_pos;
  50         const char *end = NULL; /* Silence gcc */
  51
  52         assert(nptr != NULL);
  53
  54         fail_pos = NULL;
  55
  56         locale_data = localeconv();
  57         decimal_point = locale_data->decimal_point;
  58         decimal_point_len = strlen(decimal_point);
  59
  60         assert(decimal_point_len != 0);
  61
  62         decimal_point_pos = NULL;
  63         if (decimal_point[0] != '.' ||
  64             decimal_point[1] != 0)
  65         {
  66                 p = nptr;
  67                   /* Skip leading space */
  68                 while (ISSPACE(*p))
  69                         p++;
  70
  71                   /* Skip leading optional sign */
  72                 if (*p == '+' || *p == '-')
  73                         p++;
  74
  75                 while (ISDIGIT(*p))
  76                         p++;
  77
  78                 if (*p == '.')
  79                 {
  80                         decimal_point_pos = p++;
  81
  82                         while (ISDIGIT(*p))
  83                                 p++;
  84
  85                         if (*p == 'e' || *p == 'E')
  86                                 p++;
  87                         if (*p == '+' || *p == '-')
  88                                 p++;
  89                         while (ISDIGIT(*p))
  90                                 p++;
  91                         end = p;
  92                 }
  93                 /* For the other cases, we need not convert the decimal point */
  94         }
  95
  96         /* Set errno to zero, so that we can distinguish zero results
  97            and underflows */
  98         errno = 0;
  99
 100         if (decimal_point_pos)
 101         {
 102                 char *copy, *c;
 103
 104                 /* We need to convert the '.' to the locale specific decimal point */
 105                 copy = (char *)PyMem_MALLOC(end - nptr + 1 + decimal_point_len);
 106                 if (copy == NULL) {
 107                         if (endptr)
 108                                 *endptr = (char *)nptr;
 109                         errno = ENOMEM;
 110                         return val;
 111                 }
 112
 113                 c = copy;
 114                 memcpy(c, nptr, decimal_point_pos - nptr);
 115                 c += decimal_point_pos - nptr;
 116                 memcpy(c, decimal_point, decimal_point_len);
 117                 c += decimal_point_len;
 118                 memcpy(c, decimal_point_pos + 1, end - (decimal_point_pos + 1));
 119                 c += end - (decimal_point_pos + 1);
 120                 *c = 0;
 121
 122                 val = strtod(copy, &fail_pos);
 123
 124                 if (fail_pos)
 125                 {
 126                         if (fail_pos > decimal_point_pos)
 127                                 fail_pos = (char *)nptr + (fail_pos - copy) - (decimal_point_len - 1);
 128                         else
 129                                 fail_pos = (char *)nptr + (fail_pos - copy);
 130                 }
 131
 132                 PyMem_FREE(copy);
 133
 134         }
 135         else {
 136                 unsigned i = 0;
 137                 if (nptr[i] == '-')
 138                         i++;
 139                 if (nptr[i] == '0' && (nptr[i+1] == 'x' || nptr[i+1] == 'X'))
 140                         fail_pos = (char*)nptr;
 141                 else
 142                         val = strtod(nptr, &fail_pos);
 143         }
 144
 145         if (endptr)
 146                 *endptr = fail_pos;
 147
 148         return val;
 149 }
 150
 151
 152 /**
 153  * PyOS_ascii_formatd:
 154  * @buffer: A buffer to place the resulting string in
 155  * @buf_len: The length of the buffer.
 156  * @format: The printf()-style format to use for the
 157  *          code to use for converting.
 158  * @d: The #gdouble to convert
 159  *
 160  * Converts a #gdouble to a string, using the '.' as
 161  * decimal point. To format the number you pass in
 162  * a printf()-style format string. Allowed conversion
 163  * specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.
 164  *
 165  * Return value: The pointer to the buffer with the converted string.
 166  **/
 167 char *
 168 PyOS_ascii_formatd(char       *buffer,
 169                    size_t      buf_len,
 170                    const char *format,
 171                    double      d)
 172 {
 173         struct lconv *locale_data;
 174         const char *decimal_point;
 175         size_t decimal_point_len, rest_len;
 176         char *p;
 177         char format_char;
 178
 179 /*      g_return_val_if_fail (buffer != NULL, NULL); */
 180 /*      g_return_val_if_fail (format[0] == '%', NULL); */
 181 /*      g_return_val_if_fail (strpbrk (format + 1, "'l%") == NULL, NULL); */
 182
 183         format_char = format[strlen(format) - 1];
 184
 185 /*      g_return_val_if_fail (format_char == 'e' || format_char == 'E' || */
 186 /*                            format_char == 'f' || format_char == 'F' || */
 187 /*                            format_char == 'g' || format_char == 'G', */
 188 /*                            NULL); */
 189
 190         if (format[0] != '%')
 191                 return NULL;
 192
 193         if (strpbrk(format + 1, "'l%"))
 194                 return NULL;
 195
 196         if (!(format_char == 'e' || format_char == 'E' ||
 197               format_char == 'f' || format_char == 'F' ||
 198               format_char == 'g' || format_char == 'G'))
 199                 return NULL;
 200
 201
 202         PyOS_snprintf(buffer, buf_len, format, d);
 203
 204         locale_data = localeconv();
 205         decimal_point = locale_data->decimal_point;
 206         decimal_point_len = strlen(decimal_point);
 207
 208         assert(decimal_point_len != 0);
 209
 210         if (decimal_point[0] != '.' ||
 211             decimal_point[1] != 0)
 212         {
 213                 p = buffer;
 214
 215                 if (*p == '+' || *p == '-')
 216                         p++;
 217
 218                 while (isdigit((unsigned char)*p))
 219                         p++;
 220
 221                 if (strncmp(p, decimal_point, decimal_point_len) == 0)
 222                 {
 223                         *p = '.';
 224                         p++;
 225                         if (decimal_point_len > 1) {
 226                                 rest_len = strlen(p + (decimal_point_len - 1));
 227                                 memmove(p, p + (decimal_point_len - 1),
 228                                         rest_len);
 229                                 p[rest_len] = 0;
 230                         }
 231                 }
 232         }
 233
 234         return buffer;
 235 }
 236
 237 double
 238 PyOS_ascii_atof(const char *nptr)
 239 {
 240         return PyOS_ascii_strtod(nptr, NULL);
 241 }