my_strtoll10.cc

/* Copyright (c) 2003, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
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   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   You should have received a copy of the GNU General Public License
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#include "mysql/strings/my_strtoll10.h"

#include <climits>
#include <cstdint>

#include "my_sys.h" /* Needed for MY_ERRNO_ERANGE */

#define MAX_NEGATIVE_NUMBER ((unsigned long long)0x8000000000000000LL)
#define INIT_CNT 9
#define LFACTOR 1000000000ULL
#define LFACTOR1 10000000000ULL
#define LFACTOR2 100000000000ULL

static unsigned long lfactor[9] = {
    1L, 10L, 100L, 1000L, 10000L, 100000L, 1000000L, 10000000L, 100000000L};

/*
  Convert a string to an to unsigned long long integer value

  SYNOPSIS
    my_strtoll10()
      nptr     in       pointer to the string to be converted
      endptr   in/out   pointer to the end of the string/
                        pointer to the stop character
      error    out      returned error code

  DESCRIPTION
    This function takes the decimal representation of integer number
    from string nptr and converts it to an signed or unsigned
    long long integer value.
    Space characters and tab are ignored.
    A sign character might precede the digit characters. The number
    may have any number of pre-zero digits.

    The function stops reading the string nptr at the first character
    that is not a decimal digit. If endptr is not NULL then the function
    will not read characters after *endptr.

  RETURN VALUES
    Value of string as a signed/unsigned long long integer

    if no error and endptr != NULL, it will be set to point at the character
    after the number

    The error parameter contains information how things went:
    -1		Number was an ok negative number
    0	 	ok
    ERANGE	If the the value of the converted number exceeded the
                maximum negative/unsigned long long integer.
                In this case the return value is ~0 if value was
                positive and LLONG_MIN if value was negative.
    EDOM	If the string didn't contain any digits. In this case
                the return value is 0.

    If endptr is not NULL the function will store the end pointer to
    the stop character here.
*/

long long my_strtoll10(const char *nptr, const char **endptr, int *error) {
  const char *s, *end, *start, *n_end, *true_end;
  const char *dummy;
  uint8_t c = 0;
  unsigned long i, j, k;
  unsigned long long li = 0;
  int negative;
  unsigned long cutoff = 0;
  unsigned long cutoff2 = 0;
  unsigned long cutoff3 = 0;

  s = nptr;
  /* If fixed length string */
  if (endptr) {
    end = *endptr;
    while (s != end && (*s == ' ' || *s == '\t')) s++;
    if (s == end) goto no_conv;
  } else {
    endptr = &dummy; /* Easier end test */
    while (*s == ' ' || *s == '\t') s++;
    if (!*s) goto no_conv;
    /* This number must be big to guard against a lot of pre-zeros */
    end = s + 65535; /* Can't be longer than this */
  }

  /* Check for a sign.	*/
  negative = 0;
  if (*s == '-') {
    *error = -1; /* Mark as negative number */
    negative = 1;
    if (++s == end) goto no_conv;
    cutoff = MAX_NEGATIVE_NUMBER / LFACTOR2;
    cutoff2 = (MAX_NEGATIVE_NUMBER % LFACTOR2) / 100;
    cutoff3 = MAX_NEGATIVE_NUMBER % 100;
  } else {
    *error = 0;
    if (*s == '+') {
      if (++s == end) goto no_conv;
    }
    cutoff = ULLONG_MAX / LFACTOR2;
    cutoff2 = ULLONG_MAX % LFACTOR2 / 100;
    cutoff3 = ULLONG_MAX % 100;
  }

  /* Handle case where we have a lot of pre-zero */
  if (*s == '0') {
    i = 0;
    do {
      if (++s == end) goto end_i; /* Return 0 */
    } while (*s == '0');
    n_end = s + INIT_CNT;
  } else {
    /* Read first digit to check that it's a valid number */
    if ((c = (*s - '0')) > 9) goto no_conv;
    i = c;
    n_end = ++s + INIT_CNT - 1;
  }

  /* Handle first 9 digits and store them in i */
  if (n_end > end) n_end = end;
  for (; s != n_end; s++) {
    if ((c = (*s - '0')) > 9) goto end_i;
    i = i * 10 + c;
  }
  if (s == end) goto end_i;

  /* Handle next 9 digits and store them in j */
  j = 0;
  start = s; /* Used to know how much to shift i */
  n_end = true_end = s + INIT_CNT;
  if (n_end > end) n_end = end;
  do {
    if ((c = (*s - '0')) > 9) goto end_i_and_j;
    j = j * 10 + c;
  } while (++s != n_end);
  if (s == end) {
    if (s != true_end) goto end_i_and_j;
    goto end3;
  }
  if ((c = (*s - '0')) > 9) goto end3;

  /* Handle the next 1 or 2 digits and store them in k */
  k = c;
  if (++s == end || (c = (*s - '0')) > 9) goto end4;
  k = k * 10 + c;
  *endptr = ++s;

  /* number string should have ended here */
  if (s != end && (c = (*s - '0')) <= 9) goto overflow;

  /* Check that we didn't get an overflow with the last digit */
  if (i > cutoff ||
      (i == cutoff && (j > cutoff2 || (j == cutoff2 && k > cutoff3))))
    goto overflow;
  li = i * LFACTOR2 + (unsigned long long)j * 100 + k;
  return (long long)li;

overflow: /* *endptr is set here */
  *error = MY_ERRNO_ERANGE;
  return negative ? LLONG_MIN : (long long)ULLONG_MAX;

end_i:
  *endptr = s;
  return (negative ? ((long long)-(long)i) : (long long)i);

end_i_and_j:
  li = (unsigned long long)i * lfactor[(unsigned)(s - start)] + j;
  *endptr = s;
  return (negative ? -((long long)li) : (long long)li);

end3:
  li = (unsigned long long)i * LFACTOR + (unsigned long long)j;
  *endptr = s;
  return (negative ? -((long long)li) : (long long)li);

end4:
  li = (unsigned long long)i * LFACTOR1 + (unsigned long long)j * 10 + k;
  *endptr = s;
  if (negative) {
    if (li > MAX_NEGATIVE_NUMBER) goto overflow;
    if (li == MAX_NEGATIVE_NUMBER) return LLONG_MIN;
    return -((long long)li);
  }
  return (long long)li;

no_conv:
  /* There was no number to convert.  */
  *error = MY_ERRNO_EDOM;
  *endptr = nptr;
  return 0;
}