src/lib/string/parse_int.c

   1 /* Copyright (c) 2003, Roger Dingledine
   2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   3  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   4 /* See LICENSE for licensing information */
   5
   6 /**
   7  * \file parse_int.c
   8  * \brief Convert strings into the integers they encode, with bounds checking.
   9  **/
  10
  11 #include "lib/string/parse_int.h"
  12 #include "lib/cc/compat_compiler.h"
  13
  14 #include <errno.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17
  18 /* Helper: common code to check whether the result of a strtol or strtoul or
  19  * strtoll is correct. */
  20 #define CHECK_STRTOX_RESULT()                           \
  21   STMT_BEGIN                                            \
  22   /* Did an overflow occur? */                          \
  23   if (errno == ERANGE)                                  \
  24     goto err;                                           \
  25   /* Was at least one character converted? */           \
  26   if (endptr == s)                                      \
  27     goto err;                                           \
  28   /* Were there unexpected unconverted characters? */   \
  29   if (!next && *endptr)                                 \
  30     goto err;                                           \
  31   /* Illogical (max, min) inputs? */                    \
  32   if (max < min)                                        \
  33     goto err;                                           \
  34   /* Is r within limits? */                             \
  35   if (r < min || r > max)                               \
  36     goto err;                                           \
  37   if (ok) *ok = 1;                                      \
  38   if (next) *next = endptr;                             \
  39   return r;                                             \
  40  err:                                                   \
  41   if (ok) *ok = 0;                                      \
  42   if (next) *next = endptr;                             \
  43   return 0;                                             \
  44   STMT_END
  45
  46 /** Extract a long from the start of <b>s</b>, in the given numeric
  47  * <b>base</b>.  If <b>base</b> is 0, <b>s</b> is parsed as a decimal,
  48  * octal, or hex number in the syntax of a C integer literal.  If
  49  * there is unconverted data and <b>next</b> is provided, set
  50  * *<b>next</b> to the first unconverted character.  An error has
  51  * occurred if no characters are converted; or if there are
  52  * unconverted characters and <b>next</b> is NULL; or if the parsed
  53  * value is not between <b>min</b> and <b>max</b>.  When no error
  54  * occurs, return the parsed value and set *<b>ok</b> (if provided) to
  55  * 1.  When an error occurs, return 0 and set *<b>ok</b> (if provided)
  56  * to 0.
  57  */
  58 long
  59 tor_parse_long(const char *s, int base, long min, long max,
  60                int *ok, char **next)
  61 {
  62   char *endptr;
  63   long r;
  64
  65   if (base < 0) {
  66     if (ok)
  67       *ok = 0;
  68     return 0;
  69   }
  70
  71   errno = 0;
  72   r = strtol(s, &endptr, base);
  73   CHECK_STRTOX_RESULT();
  74 }
  75
  76 /** As tor_parse_long(), but return an unsigned long. */
  77 unsigned long
  78 tor_parse_ulong(const char *s, int base, unsigned long min,
  79                 unsigned long max, int *ok, char **next)
  80 {
  81   char *endptr;
  82   unsigned long r;
  83
  84   if (base < 0) {
  85     if (ok)
  86       *ok = 0;
  87     return 0;
  88   }
  89
  90   errno = 0;
  91   r = strtoul(s, &endptr, base);
  92   CHECK_STRTOX_RESULT();
  93 }
  94
  95 /** As tor_parse_long(), but return a double. */
  96 double
  97 tor_parse_double(const char *s, double min, double max, int *ok, char **next)
  98 {
  99   char *endptr;
 100   double r;
 101
 102   errno = 0;
 103   r = strtod(s, &endptr);
 104   CHECK_STRTOX_RESULT();
 105 }
 106
 107 /** As tor_parse_long, but return a uint64_t.  Only base 10 is guaranteed to
 108  * work for now. */
 109 uint64_t
 110 tor_parse_uint64(const char *s, int base, uint64_t min,
 111                  uint64_t max, int *ok, char **next)
 112 {
 113   char *endptr;
 114   uint64_t r;
 115
 116   if (base < 0) {
 117     if (ok)
 118       *ok = 0;
 119     return 0;
 120   }
 121
 122   errno = 0;
 123 #ifdef HAVE_STRTOULL
 124   r = (uint64_t)strtoull(s, &endptr, base);
 125 #elif defined(_WIN32)
 126   r = (uint64_t)_strtoui64(s, &endptr, base);
 127 #elif SIZEOF_LONG == 8
 128   r = (uint64_t)strtoul(s, &endptr, base);
 129 #else
 130 #error "I don't know how to parse 64-bit numbers."
 131 #endif /* defined(HAVE_STRTOULL) || ... */
 132
 133   CHECK_STRTOX_RESULT();
 134 }