stringToNum.diff

   1     A new StringToNum() function without a call to sscanf()
   2
   3     It seems a shame to scan a string twice, as the older version does.
   4
   5 ---
   6
   7  source/interpret.c |   43 +++++++++++++++++++++++++++++++------------
   8  1 files changed, 31 insertions(+), 12 deletions(-)
   9
  10 diff --quilt old/source/interpret.c new/source/interpret.c
  11 --- old/source/interpret.c
  12 +++ new/source/interpret.c
  13 @@ -2821,37 +2821,56 @@ static int execError(const char *s1, con
  14      msg[MAX_ERR_MSG_LEN - 1] = '\0';
  15      ErrMsg = msg;
  16      return STAT_ERROR;
  17  }
  18
  19 +/*
  20 +** read an integer from a string, returning True if successful. The string must
  21 +** not contain anything other than the number (perhaps surrounded by spaces).
  22 +*/
  23  int StringToNum(const char *string, int *number)
  24  {
  25      const char *c = string;
  26 +    int n = 0, new_n;
  27 +    int sign = 1;
  28 +    int haveDigit = False;
  29
  30      while (*c == ' ' || *c == '\t') {
  31          ++c;
  32      }
  33 -    if (*c == '+' || *c == '-') {
  34 +    if (*c == '+') {
  35          ++c;
  36 -    }
  37 -    while (isdigit((unsigned char)*c)) {
  38 +    } else if (*c == '-') {
  39          ++c;
  40 +        sign = -1;
  41      }
  42 -    while (*c == ' ' || *c == '\t') {
  43 -        ++c;
  44 +    if (isdigit((unsigned char)*c)) {
  45 +        haveDigit = True;               /* now pick up any other digits */
  46 +        do {
  47 +            new_n = 10 * n + *c - '0';  /* evaluate the number as we go */
  48 +            if (new_n == INT_MIN) {
  49 +                if (sign != -1) {
  50 +                    return False;       /* special case: INT_MIN must be < 0 */
  51 +                }
  52 +            } else if (new_n < n) {
  53 +                return False;           /* overflow: digit sequence too long! */
  54 +            }
  55 +            n = new_n;
  56 +            ++c;
  57 +        } while (isdigit((unsigned char)*c));
  58 +        while (*c == ' ' || *c == '\t') {
  59 +            ++c;
  60 +        }
  61 +    }
  62 +    if (number) {
  63 +        *number = sign * n;
  64      }
  65      if (*c) {
  66          /* if everything went as expected, we should be at end, but we're not */
  67          return False;
  68      }
  69 -    if (number) {
  70 -        if (sscanf(string, "%d", number) != 1) {
  71 -            /* This case is here to support old behavior */
  72 -           *number = 0;
  73 -        }
  74 -    }
  75 -    return True;
  76 +    return haveDigit;
  77  }
  78
  79  #ifdef DEBUG_DISASSEMBLER   /* dumping values in disassembly or stack dump */
  80  static void dumpVal(DataValue dv)
  81  {