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  *
  35  * This function resets %errno before calling strtod() so that
  36  * you can reliably detect overflow and underflow.
  37  *
  38  * Return value: the #gdouble value.
  39  **/
  40 double
  41 PyOS_ascii_strtod(const char *nptr, char **endptr)
  42 {
  43         char *fail_pos;
  44         double val = -1.0;
  45         struct lconv *locale_data;
  46         const char *decimal_point;
  47         size_t decimal_point_len;
  48         const char *p, *decimal_point_pos;
  49         const char *end = NULL; /* Silence gcc */
  50
  51         assert(nptr != NULL);
  52
  53         fail_pos = NULL;
  54
  55         locale_data = localeconv();
  56         decimal_point = locale_data->decimal_point;
  57         decimal_point_len = strlen(decimal_point);
  58
  59         assert(decimal_point_len != 0);
  60
  61         decimal_point_pos = NULL;
  62         if (decimal_point[0] != '.' ||
  63             decimal_point[1] != 0)
  64         {
  65                 p = nptr;
  66                   /* Skip leading space */
  67                 while (ISSPACE(*p))
  68                         p++;
  69
  70                   /* Skip leading optional sign */
  71                 if (*p == '+' || *p == '-')
  72                         p++;
  73
  74                 while (ISDIGIT(*p))
  75                         p++;
  76
  77                 if (*p == '.')
  78                 {
  79                         decimal_point_pos = p++;
  80
  81                         while (ISDIGIT(*p))
  82                                 p++;
  83
  84                         if (*p == 'e' || *p == 'E')
  85                                 p++;
  86                         if (*p == '+' || *p == '-')
  87                                 p++;
  88                         while (ISDIGIT(*p))
  89                                 p++;
  90                         end = p;
  91                 }
  92                 /* For the other cases, we need not convert the decimal point */
  93         }
  94
  95         /* Set errno to zero, so that we can distinguish zero results
  96            and underflows */
  97         errno = 0;
  98
  99         if (decimal_point_pos)
 100         {
 101                 char *copy, *c;
 102
 103                 /* We need to convert the '.' to the locale specific decimal point */
 104                 copy = malloc(end - nptr + 1 + decimal_point_len);
 105
 106                 c = copy;
 107                 memcpy(c, nptr, decimal_point_pos - nptr);
 108                 c += decimal_point_pos - nptr;
 109                 memcpy(c, decimal_point, decimal_point_len);
 110                 c += decimal_point_len;
 111                 memcpy(c, decimal_point_pos + 1, end - (decimal_point_pos + 1));
 112                 c += end - (decimal_point_pos + 1);
 113                 *c = 0;
 114
 115                 val = strtod(copy, &fail_pos);
 116
 117                 if (fail_pos)
 118                 {
 119                         if (fail_pos > decimal_point_pos)
 120                                 fail_pos = (char *)nptr + (fail_pos - copy) - (decimal_point_len - 1);
 121                         else
 122                                 fail_pos = (char *)nptr + (fail_pos - copy);
 123                 }
 124
 125                 free(copy);
 126
 127         }
 128         else {
 129                 unsigned i = 0;
 130                 if (nptr[i] == '-')
 131                         i++;
 132                 if (nptr[i] == '0' && (nptr[i+1] == 'x' || nptr[i+1] == 'X'))
 133                         fail_pos = (char*)nptr;
 134                 else
 135                         val = strtod(nptr, &fail_pos);
 136         }
 137
 138         if (endptr)
 139                 *endptr = fail_pos;
 140
 141         return val;
 142 }
 143
 144
 145 /**
 146  * PyOS_ascii_formatd:
 147  * @buffer: A buffer to place the resulting string in
 148  * @buf_len: The length of the buffer.
 149  * @format: The printf()-style format to use for the
 150  *          code to use for converting.
 151  * @d: The #gdouble to convert
 152  *
 153  * Converts a #gdouble to a string, using the '.' as
 154  * decimal point. To format the number you pass in
 155  * a printf()-style format string. Allowed conversion
 156  * specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.
 157  *
 158  * Return value: The pointer to the buffer with the converted string.
 159  **/
 160 char *
 161 PyOS_ascii_formatd(char       *buffer,
 162                    size_t      buf_len,
 163                    const char *format,
 164                    double      d)
 165 {
 166         struct lconv *locale_data;
 167         const char *decimal_point;
 168         size_t decimal_point_len, rest_len;
 169         char *p;
 170         char format_char;
 171
 172 /*      g_return_val_if_fail (buffer != NULL, NULL); */
 173 /*      g_return_val_if_fail (format[0] == '%', NULL); */
 174 /*      g_return_val_if_fail (strpbrk (format + 1, "'l%") == NULL, NULL); */
 175
 176         format_char = format[strlen(format) - 1];
 177
 178 /*      g_return_val_if_fail (format_char == 'e' || format_char == 'E' || */
 179 /*                            format_char == 'f' || format_char == 'F' || */
 180 /*                            format_char == 'g' || format_char == 'G', */
 181 /*                            NULL); */
 182
 183         if (format[0] != '%')
 184                 return NULL;
 185
 186         if (strpbrk(format + 1, "'l%"))
 187                 return NULL;
 188
 189         if (!(format_char == 'e' || format_char == 'E' ||
 190               format_char == 'f' || format_char == 'F' ||
 191               format_char == 'g' || format_char == 'G'))
 192                 return NULL;
 193
 194
 195         PyOS_snprintf(buffer, buf_len, format, d);
 196
 197         locale_data = localeconv();
 198         decimal_point = locale_data->decimal_point;
 199         decimal_point_len = strlen(decimal_point);
 200
 201         assert(decimal_point_len != 0);
 202
 203         if (decimal_point[0] != '.' ||
 204             decimal_point[1] != 0)
 205         {
 206                 p = buffer;
 207
 208                 if (*p == '+' || *p == '-')
 209                         p++;
 210
 211                 while (isdigit((unsigned char)*p))
 212                         p++;
 213
 214                 if (strncmp(p, decimal_point, decimal_point_len) == 0)
 215                 {
 216                         *p = '.';
 217                         p++;
 218                         if (decimal_point_len > 1) {
 219                                 rest_len = strlen(p + (decimal_point_len - 1));
 220                                 memmove(p, p + (decimal_point_len - 1),
 221                                         rest_len);
 222                                 p[rest_len] = 0;
 223                         }
 224                 }
 225         }
 226
 227         return buffer;
 228 }
 229
 230 double
 231 PyOS_ascii_atof(const char *nptr)
 232 {
 233         return PyOS_ascii_strtod(nptr, NULL);
 234 }