From 70ad8397259f96f53104929b0c416f6617280b69 Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Wed, 21 Mar 2018 16:28:41 +0100 Subject: [PATCH] Clarify the behavior of bignum resize and copy functions --- include/mbedtls/bignum.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h index 3bf02a7ee..31383b1eb 100644 --- a/include/mbedtls/bignum.h +++ b/include/mbedtls/bignum.h @@ -204,6 +204,8 @@ void mbedtls_mpi_free( mbedtls_mpi *X ); /** * \brief Enlarge to the specified number of limbs * + * This function does nothing if the MPI is already large enough. + * * \param X MPI to grow * \param nblimbs The target number of limbs * @@ -215,19 +217,23 @@ int mbedtls_mpi_grow( mbedtls_mpi *X, size_t nblimbs ); /** * \brief Resize down, keeping at least the specified number of limbs * + * If \c X is smaller than \c nblimbs, it is resized up + * instead. + * * \param X MPI to shrink * \param nblimbs The minimum number of limbs to keep * * \return 0 if successful, * MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed + * (this can only happen when resizing up). */ int mbedtls_mpi_shrink( mbedtls_mpi *X, size_t nblimbs ); /** * \brief Copy the contents of Y into X * - * \param X Destination MPI - * \param Y Source MPI + * \param X Destination MPI. It is enlarged if necessary. + * \param Y Source MPI. * * \return 0 if successful, * MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed