/** @brief Reads an entire file into \c result, stopping after \c size bytes or
* EOF. It will read until EOF if size is 0. */
static posix_errno_t read_file(efile_data_t *d, size_t size, ErlNifBinary *result) {
size_t initial_buffer_size;
ssize_t bytes_read;
if(size == 0) {
initial_buffer_size = 16 << 10;
} else {
initial_buffer_size = size;
}
if(!enif_alloc_binary(initial_buffer_size, result)) {
return ENOMEM;
}
bytes_read = 0;
for(;;) {
ssize_t block_bytes_read;
SysIOVec read_vec[1];
read_vec[0].iov_base = result->data + bytes_read;
read_vec[0].iov_len = result->size - bytes_read;
block_bytes_read = efile_readv(d, read_vec, 1);
if(block_bytes_read < 0) {
enif_release_binary(result);
return d->posix_errno;
}
bytes_read += block_bytes_read;
if(block_bytes_read < (result->size - bytes_read)) {
/* EOF */
break;
} else if(bytes_read == size) {
break;
}
if(!enif_realloc_binary(result, bytes_read * 2)) {
enif_release_binary(result);
return ENOMEM;
}
}
/* The file may have shrunk since we queried its size, so we have to do
* this even when the size is known. */
if(bytes_read < result->size && !enif_realloc_binary(result, bytes_read)) {
ERTS_INTERNAL_ERROR("Failed to shrink read_file result.");
}
return 0;
}
static ERL_NIF_TERM read_nif_impl(efile_data_t *d, ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[]) {
Sint64 bytes_read, block_size;
SysIOVec read_vec[1];
ErlNifBinary result;
ASSERT(argc == 1);
if(!enif_is_number(env, argv[0])) {
return enif_make_badarg(env);
}
if(!enif_get_int64(env, argv[0], &block_size) || block_size < 0) {
return posix_error_to_tuple(env, EINVAL);
}
if(!enif_alloc_binary(block_size, &result)) {
return posix_error_to_tuple(env, ENOMEM);
}
read_vec[0].iov_base = result.data;
read_vec[0].iov_len = result.size;
bytes_read = efile_readv(d, read_vec, 1);
ASSERT(bytes_read <= block_size);
if(bytes_read < 0) {
enif_release_binary(&result);
return posix_error_to_tuple(env, d->posix_errno);
} else if(bytes_read == 0) {
enif_release_binary(&result);
return am_eof;
}
if(bytes_read < block_size && !enif_realloc_binary(&result, bytes_read)) {
ERTS_INTERNAL_ERROR("Failed to shrink read result.");
}
return enif_make_tuple2(env, am_ok, enif_make_binary(env, &result));
}