103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
// SPDX-License-Identifier: ISC
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#include <zinnia/assert.h>
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#include <zinnia/chardev.h>
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#include <zinnia/random.h>
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#include <zinnia/utils.h>
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constexpr size_t MEMFILE_CHUNK = 64;
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static const uint8_t zero_chunk[MEMFILE_CHUNK];
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static errno_t memfile_discard(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_written) {
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*out_written = iovec_iter_len(buffer);
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return 0;
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}
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static errno_t memfile_read_zero(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_read) {
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size_t total = 0;
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errno_t status = 0;
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while (iovec_iter_len(buffer)) {
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size_t copied;
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status = iovec_iter_copy_to(buffer, zero_chunk, MIN(iovec_iter_len(buffer), MEMFILE_CHUNK), &copied);
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total += copied;
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if (status)
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break;
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}
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*out_read = total;
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return status;
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}
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static errno_t null_read(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_read) {
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*out_read = 0;
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return 0;
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}
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static const struct vfs_file_ops null_file_ops = {
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.read = null_read,
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.write = memfile_discard,
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};
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static const struct vfs_file_ops zero_file_ops = {
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.read = memfile_read_zero,
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.write = memfile_discard,
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};
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static errno_t full_write(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_written) {
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*out_written = 0;
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return ENOSPC;
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}
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static const struct vfs_file_ops full_file_ops = {
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.read = memfile_read_zero,
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.write = full_write,
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};
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static errno_t random_read(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_read) {
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uint8_t chunk[MEMFILE_CHUNK];
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size_t total = 0;
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errno_t status = 0;
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while (iovec_iter_len(buffer)) {
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const size_t len = MIN(iovec_iter_len(buffer), sizeof(chunk));
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// TODO: This function sucks and is probably not useful for cryptography.
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random_fill(chunk, len);
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size_t copied;
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status = iovec_iter_copy_to(buffer, chunk, len, &copied);
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total += copied;
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if (status)
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break;
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}
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*out_read = total;
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return status;
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}
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static const struct vfs_file_ops random_file_ops = {
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.read = random_read,
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.write = memfile_discard,
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};
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static struct chardev null_dev;
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static struct chardev zero_dev;
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static struct chardev full_dev;
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static struct chardev random_dev;
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static struct chardev urandom_dev;
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static void memfiles_add(const char* name, struct chardev* dev, const struct vfs_file_ops* ops, uint32_t minor) {
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chardev_init(dev, nullptr, ops, 1, minor);
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errno_t status = devtmpfs_add_chardev(name, dev, 0666);
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assert(status == 0, "Unable to create /dev/%s (%i)", name, status);
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}
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static void memfiles_stage_init(struct boot_info* info) {
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memfiles_add("null", &null_dev, &null_file_ops, 3);
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memfiles_add("zero", &zero_dev, &zero_file_ops, 5);
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memfiles_add("full", &full_dev, &full_file_ops, 7);
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memfiles_add("random", &random_dev, &random_file_ops, 8);
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memfiles_add("urandom", &urandom_dev, &random_file_ops, 9);
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}
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INIT_TASK(memfiles_stage, "dev.memfiles", memfiles_stage_init);
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INIT_DEPENDS(memfiles_stage, devtmpfs_stage, random_stage);
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