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Avoid signed integer overflow in timelib_ts_at_start_of_year() #163

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Avoid signed integer overflow in timelib_ts_at_start_of_year() #163

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8 changes: 8 additions & 0 deletions parse_posix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -490,6 +490,14 @@ timelib_sll timelib_ts_at_start_of_year(timelib_sll year)
timelib_sll epoch_leap_years = count_leap_years(1970);
timelib_sll current_leap_years = count_leap_years(year);

/* FIXME: handle error instead of clamping result */
if (year < (TIMELIB_SLL_MIN / SECS_PER_DAY + epoch_leap_years - current_leap_years) / DAYS_PER_YEAR + 1970) {
return TIMELIB_SLL_MIN;
}
if (year > (TIMELIB_SLL_MAX / SECS_PER_DAY + epoch_leap_years - current_leap_years) / DAYS_PER_YEAR + 1970) {
return TIMELIB_SLL_MAX;
}

return SECS_PER_DAY * (
((year-1970) * DAYS_PER_YEAR)
+ current_leap_years
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4 changes: 4 additions & 0 deletions timelib.h
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Expand Up @@ -65,10 +65,14 @@ typedef uint32_t timelib_ulong;
typedef uint64_t timelib_ull;
typedef int64_t timelib_sll;
# define TIMELIB_LL_CONST(n) n ## i64
# define TIMELIB_SLL_MIN INT64_MIN
# define TIMELIB_SLL_MAX INT64_MAX
#else
typedef unsigned long long timelib_ull;
typedef signed long long timelib_sll;
# define TIMELIB_LL_CONST(n) n ## ll
# define TIMELIB_SLL_MIN LLONG_MIN
# define TIMELIB_SLL_MAX LLONG_MAX
#endif

typedef struct _ttinfo ttinfo;
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