Re: [PATCH 1/4] time: Add timespec to microseconds converter

Implement a new function, l_timespec_to_usecs(), that checks for integer overflow in the multiplication and addition operations that occur during the conversion of the timespec members to microseconds. --- ell/ell.sym | 1 + ell/time.c | 24 ++++++++++++++++++++++++ ell/time.h | 3 +++ 3 files changed, 28 insertions(+)

diff --git a/ell/ell.sym b/ell/ell.sym index 0c83b87..776a94c 100644 --- a/ell/ell.sym +++ b/ell/ell.sym @@ -526,6 +526,7 @@ global: l_ecdh_generate_key_pair; l_ecdh_generate_shared_secret; /* time */ + l_timespec_to_usecs; l_time_now; /* gpio */ l_gpio_chips_with_line_label; diff --git a/ell/time.c b/ell/time.c index 6150d03..becf985 100644 --- a/ell/time.c +++ b/ell/time.c @@ -30,6 +30,30 @@ #include "time.h" #include "private.h" +/** + * l_timespec_to_usecs() - convert timespec value to microseconds + * @t: pointer to timespec value to be converted to microseconds. + * + * Convert the timespec value @t to microseconds, being careful to + * avoid integer overflows during the conversion. + * + * Return: Number of microseconds in @t, UINT64_MAX on overflow, and + * zero if @t is NULL. + */ +LIB_EXPORT uint64_t l_timespec_to_usecs(const struct timespec *t) +{ + if (!t) + return 0; + + uint64_t usecs = t->tv_sec * L_USEC_PER_SEC; + + /* check overflow */ + if (usecs / L_USEC_PER_SEC != t->tv_sec)

+ return UINT64_MAX; + + return l_time_offset(usecs, t->tv_nsec / L_NSEC_PER_USEC); +} + /** * l_time_now: * diff --git a/ell/time.h b/ell/time.h index 6976280..6011b80 100644 --- a/ell/time.h +++ b/ell/time.h @@ -38,6 +38,9 @@ extern "C" { #define L_NSEC_PER_USEC 1000ULL #define L_TIME_INVALID ((uint64_t) -1) +struct timespec; + +uint64_t l_timespec_to_usecs(const struct timespec *t); uint64_t l_time_now(void); static inline bool l_time_after(uint64_t a, uint64_t b)