259 lines
7.4 KiB
C
259 lines
7.4 KiB
C
/*
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* PSA ITS simulator over stdio files.
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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#include "common.h"
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#if defined(MBEDTLS_PSA_ITS_FILE_C)
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#include "mbedtls/platform.h"
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#if defined(_WIN32)
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#include <windows.h>
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#endif
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#include "psa_crypto_its.h"
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#include <limits.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#if !defined(PSA_ITS_STORAGE_PREFIX)
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#define PSA_ITS_STORAGE_PREFIX ""
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#endif
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#define PSA_ITS_STORAGE_FILENAME_PATTERN "%08x%08x"
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#define PSA_ITS_STORAGE_SUFFIX ".psa_its"
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#define PSA_ITS_STORAGE_FILENAME_LENGTH \
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(sizeof(PSA_ITS_STORAGE_PREFIX) - 1 + /*prefix without terminating 0*/ \
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16 + /*UID (64-bit number in hex)*/ \
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sizeof(PSA_ITS_STORAGE_SUFFIX) - 1 + /*suffix without terminating 0*/ \
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1 /*terminating null byte*/)
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#define PSA_ITS_STORAGE_TEMP \
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PSA_ITS_STORAGE_PREFIX "tempfile" PSA_ITS_STORAGE_SUFFIX
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/* The maximum value of psa_storage_info_t.size */
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#define PSA_ITS_MAX_SIZE 0xffffffff
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#define PSA_ITS_MAGIC_STRING "PSA\0ITS\0"
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#define PSA_ITS_MAGIC_LENGTH 8
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/* As rename fails on Windows if the new filepath already exists,
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* use MoveFileExA with the MOVEFILE_REPLACE_EXISTING flag instead.
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* Returns 0 on success, nonzero on failure. */
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#if defined(_WIN32)
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#define rename_replace_existing(oldpath, newpath) \
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(!MoveFileExA(oldpath, newpath, MOVEFILE_REPLACE_EXISTING))
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#else
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#define rename_replace_existing(oldpath, newpath) rename(oldpath, newpath)
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#endif
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typedef struct {
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uint8_t magic[PSA_ITS_MAGIC_LENGTH];
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uint8_t size[sizeof(uint32_t)];
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uint8_t flags[sizeof(psa_storage_create_flags_t)];
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} psa_its_file_header_t;
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static void psa_its_fill_filename(psa_storage_uid_t uid, char *filename)
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{
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/* Break up the UID into two 32-bit pieces so as not to rely on
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* long long support in snprintf. */
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mbedtls_snprintf(filename, PSA_ITS_STORAGE_FILENAME_LENGTH,
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"%s" PSA_ITS_STORAGE_FILENAME_PATTERN "%s",
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PSA_ITS_STORAGE_PREFIX,
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(unsigned) (uid >> 32),
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(unsigned) (uid & 0xffffffff),
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PSA_ITS_STORAGE_SUFFIX);
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}
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static psa_status_t psa_its_read_file(psa_storage_uid_t uid,
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struct psa_storage_info_t *p_info,
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FILE **p_stream)
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{
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char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
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psa_its_file_header_t header;
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size_t n;
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*p_stream = NULL;
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psa_its_fill_filename(uid, filename);
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*p_stream = fopen(filename, "rb");
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if (*p_stream == NULL) {
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return PSA_ERROR_DOES_NOT_EXIST;
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}
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/* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
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mbedtls_setbuf(*p_stream, NULL);
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n = fread(&header, 1, sizeof(header), *p_stream);
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if (n != sizeof(header)) {
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return PSA_ERROR_DATA_CORRUPT;
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}
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if (memcmp(header.magic, PSA_ITS_MAGIC_STRING,
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PSA_ITS_MAGIC_LENGTH) != 0) {
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return PSA_ERROR_DATA_CORRUPT;
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}
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p_info->size = (header.size[0] |
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header.size[1] << 8 |
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header.size[2] << 16 |
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header.size[3] << 24);
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p_info->flags = (header.flags[0] |
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header.flags[1] << 8 |
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header.flags[2] << 16 |
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header.flags[3] << 24);
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return PSA_SUCCESS;
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}
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psa_status_t psa_its_get_info(psa_storage_uid_t uid,
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struct psa_storage_info_t *p_info)
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{
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psa_status_t status;
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FILE *stream = NULL;
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status = psa_its_read_file(uid, p_info, &stream);
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if (stream != NULL) {
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fclose(stream);
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}
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return status;
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}
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psa_status_t psa_its_get(psa_storage_uid_t uid,
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uint32_t data_offset,
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uint32_t data_length,
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void *p_data,
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size_t *p_data_length)
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{
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psa_status_t status;
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FILE *stream = NULL;
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size_t n;
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struct psa_storage_info_t info;
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status = psa_its_read_file(uid, &info, &stream);
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if (status != PSA_SUCCESS) {
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goto exit;
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}
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status = PSA_ERROR_INVALID_ARGUMENT;
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if (data_offset + data_length < data_offset) {
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goto exit;
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}
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#if SIZE_MAX < 0xffffffff
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if (data_offset + data_length > SIZE_MAX) {
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goto exit;
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}
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#endif
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if (data_offset + data_length > info.size) {
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goto exit;
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}
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status = PSA_ERROR_STORAGE_FAILURE;
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#if LONG_MAX < 0xffffffff
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while (data_offset > LONG_MAX) {
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if (fseek(stream, LONG_MAX, SEEK_CUR) != 0) {
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goto exit;
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}
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data_offset -= LONG_MAX;
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}
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#endif
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if (fseek(stream, data_offset, SEEK_CUR) != 0) {
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goto exit;
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}
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n = fread(p_data, 1, data_length, stream);
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if (n != data_length) {
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goto exit;
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}
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status = PSA_SUCCESS;
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if (p_data_length != NULL) {
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*p_data_length = n;
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}
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exit:
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if (stream != NULL) {
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fclose(stream);
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}
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return status;
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}
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psa_status_t psa_its_set(psa_storage_uid_t uid,
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uint32_t data_length,
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const void *p_data,
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psa_storage_create_flags_t create_flags)
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{
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if (uid == 0) {
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return PSA_ERROR_INVALID_HANDLE;
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}
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psa_status_t status = PSA_ERROR_STORAGE_FAILURE;
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char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
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FILE *stream = NULL;
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psa_its_file_header_t header;
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size_t n;
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memcpy(header.magic, PSA_ITS_MAGIC_STRING, PSA_ITS_MAGIC_LENGTH);
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MBEDTLS_PUT_UINT32_LE(data_length, header.size, 0);
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MBEDTLS_PUT_UINT32_LE(create_flags, header.flags, 0);
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psa_its_fill_filename(uid, filename);
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stream = fopen(PSA_ITS_STORAGE_TEMP, "wb");
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if (stream == NULL) {
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goto exit;
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}
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/* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
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mbedtls_setbuf(stream, NULL);
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status = PSA_ERROR_INSUFFICIENT_STORAGE;
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n = fwrite(&header, 1, sizeof(header), stream);
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if (n != sizeof(header)) {
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goto exit;
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}
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if (data_length != 0) {
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n = fwrite(p_data, 1, data_length, stream);
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if (n != data_length) {
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goto exit;
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}
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}
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status = PSA_SUCCESS;
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exit:
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if (stream != NULL) {
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int ret = fclose(stream);
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if (status == PSA_SUCCESS && ret != 0) {
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status = PSA_ERROR_INSUFFICIENT_STORAGE;
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}
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}
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if (status == PSA_SUCCESS) {
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if (rename_replace_existing(PSA_ITS_STORAGE_TEMP, filename) != 0) {
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status = PSA_ERROR_STORAGE_FAILURE;
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}
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}
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/* The temporary file may still exist, but only in failure cases where
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* we're already reporting an error. So there's nothing we can do on
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* failure. If the function succeeded, and in some error cases, the
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* temporary file doesn't exist and so remove() is expected to fail.
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* Thus we just ignore the return status of remove(). */
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(void) remove(PSA_ITS_STORAGE_TEMP);
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return status;
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}
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psa_status_t psa_its_remove(psa_storage_uid_t uid)
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{
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char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
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FILE *stream;
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psa_its_fill_filename(uid, filename);
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stream = fopen(filename, "rb");
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if (stream == NULL) {
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return PSA_ERROR_DOES_NOT_EXIST;
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}
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fclose(stream);
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if (remove(filename) != 0) {
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return PSA_ERROR_STORAGE_FAILURE;
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}
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return PSA_SUCCESS;
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}
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#endif /* MBEDTLS_PSA_ITS_FILE_C */
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