1 files changed, 307 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/errors.c b/drivers/md/dm-vdo/errors.c
new file mode 100644
index 0000000000..6f89eb1c63
--- /dev/null
+++ b/drivers/md/dm-vdo/errors.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "errors.h"
+
+#include <linux/compiler.h>
+#include <linux/errno.h>
+
+#include "logger.h"
+#include "permassert.h"
+#include "string-utils.h"
+
+static const struct error_info successful = { "UDS_SUCCESS", "Success" };
+
+static const char *const message_table[] = {
+	[EPERM] = "Operation not permitted",
+	[ENOENT] = "No such file or directory",
+	[ESRCH] = "No such process",
+	[EINTR] = "Interrupted system call",
+	[EIO] = "Input/output error",
+	[ENXIO] = "No such device or address",
+	[E2BIG] = "Argument list too long",
+	[ENOEXEC] = "Exec format error",
+	[EBADF] = "Bad file descriptor",
+	[ECHILD] = "No child processes",
+	[EAGAIN] = "Resource temporarily unavailable",
+	[ENOMEM] = "Cannot allocate memory",
+	[EACCES] = "Permission denied",
+	[EFAULT] = "Bad address",
+	[ENOTBLK] = "Block device required",
+	[EBUSY] = "Device or resource busy",
+	[EEXIST] = "File exists",
+	[EXDEV] = "Invalid cross-device link",
+	[ENODEV] = "No such device",
+	[ENOTDIR] = "Not a directory",
+	[EISDIR] = "Is a directory",
+	[EINVAL] = "Invalid argument",
+	[ENFILE] = "Too many open files in system",
+	[EMFILE] = "Too many open files",
+	[ENOTTY] = "Inappropriate ioctl for device",
+	[ETXTBSY] = "Text file busy",
+	[EFBIG] = "File too large",
+	[ENOSPC] = "No space left on device",
+	[ESPIPE] = "Illegal seek",
+	[EROFS] = "Read-only file system",
+	[EMLINK] = "Too many links",
+	[EPIPE] = "Broken pipe",
+	[EDOM] = "Numerical argument out of domain",
+	[ERANGE] = "Numerical result out of range"
+};
+
+static const struct error_info error_list[] = {
+	{ "UDS_OVERFLOW", "Index overflow" },
+	{ "UDS_INVALID_ARGUMENT", "Invalid argument passed to internal routine" },
+	{ "UDS_BAD_STATE", "UDS data structures are in an invalid state" },
+	{ "UDS_DUPLICATE_NAME", "Attempt to enter the same name into a delta index twice" },
+	{ "UDS_ASSERTION_FAILED", "Assertion failed" },
+	{ "UDS_QUEUED", "Request queued" },
+	{ "UDS_ALREADY_REGISTERED", "Error range already registered" },
+	{ "UDS_OUT_OF_RANGE", "Cannot access data outside specified limits" },
+	{ "UDS_DISABLED", "UDS library context is disabled" },
+	{ "UDS_UNSUPPORTED_VERSION", "Unsupported version" },
+	{ "UDS_CORRUPT_DATA", "Some index structure is corrupt" },
+	{ "UDS_NO_INDEX", "No index found" },
+	{ "UDS_INDEX_NOT_SAVED_CLEANLY", "Index not saved cleanly" },
+};
+
+struct error_block {
+	const char *name;
+	int base;
+	int last;
+	int max;
+	const struct error_info *infos;
+};
+
+#define MAX_ERROR_BLOCKS 6
+
+static struct {
+	int allocated;
+	int count;
+	struct error_block blocks[MAX_ERROR_BLOCKS];
+} registered_errors = {
+	.allocated = MAX_ERROR_BLOCKS,
+	.count = 1,
+	.blocks = { {
+			.name = "UDS Error",
+			.base = UDS_ERROR_CODE_BASE,
+			.last = UDS_ERROR_CODE_LAST,
+			.max = UDS_ERROR_CODE_BLOCK_END,
+			.infos = error_list,
+		  } },
+};
+
+/* Get the error info for an error number. Also returns the name of the error block, if known. */
+static const char *get_error_info(int errnum, const struct error_info **info_ptr)
+{
+	struct error_block *block;
+
+	if (errnum == UDS_SUCCESS) {
+		*info_ptr = &successful;
+		return NULL;
+	}
+
+	for (block = registered_errors.blocks;
+	     block < registered_errors.blocks + registered_errors.count;
+	     block++) {
+		if ((errnum >= block->base) && (errnum < block->last)) {
+			*info_ptr = block->infos + (errnum - block->base);
+			return block->name;
+		} else if ((errnum >= block->last) && (errnum < block->max)) {
+			*info_ptr = NULL;
+			return block->name;
+		}
+	}
+
+	return NULL;
+}
+
+/* Return a string describing a system error message. */
+static const char *system_string_error(int errnum, char *buf, size_t buflen)
+{
+	size_t len;
+	const char *error_string = NULL;
+
+	if ((errnum > 0) && (errnum < ARRAY_SIZE(message_table)))
+		error_string = message_table[errnum];
+
+	len = ((error_string == NULL) ?
+		 snprintf(buf, buflen, "Unknown error %d", errnum) :
+		 snprintf(buf, buflen, "%s", error_string));
+	if (len < buflen)
+		return buf;
+
+	buf[0] = '\0';
+	return "System error";
+}
+
+/* Convert an error code to a descriptive string. */
+const char *uds_string_error(int errnum, char *buf, size_t buflen)
+{
+	char *buffer = buf;
+	char *buf_end = buf + buflen;
+	const struct error_info *info = NULL;
+	const char *block_name;
+
+	if (buf == NULL)
+		return NULL;
+
+	if (errnum < 0)
+		errnum = -errnum;
+
+	block_name = get_error_info(errnum, &info);
+	if (block_name != NULL) {
+		if (info != NULL) {
+			buffer = vdo_append_to_buffer(buffer, buf_end, "%s: %s",
+						      block_name, info->message);
+		} else {
+			buffer = vdo_append_to_buffer(buffer, buf_end, "Unknown %s %d",
+						      block_name, errnum);
+		}
+	} else if (info != NULL) {
+		buffer = vdo_append_to_buffer(buffer, buf_end, "%s", info->message);
+	} else {
+		const char *tmp = system_string_error(errnum, buffer, buf_end - buffer);
+
+		if (tmp != buffer)
+			buffer = vdo_append_to_buffer(buffer, buf_end, "%s", tmp);
+		else
+			buffer += strlen(tmp);
+	}
+
+	return buf;
+}
+
+/* Convert an error code to its name. */
+const char *uds_string_error_name(int errnum, char *buf, size_t buflen)
+{
+	char *buffer = buf;
+	char *buf_end = buf + buflen;
+	const struct error_info *info = NULL;
+	const char *block_name;
+
+	if (errnum < 0)
+		errnum = -errnum;
+
+	block_name = get_error_info(errnum, &info);
+	if (block_name != NULL) {
+		if (info != NULL) {
+			buffer = vdo_append_to_buffer(buffer, buf_end, "%s", info->name);
+		} else {
+			buffer = vdo_append_to_buffer(buffer, buf_end, "%s %d",
+						      block_name, errnum);
+		}
+	} else if (info != NULL) {
+		buffer = vdo_append_to_buffer(buffer, buf_end, "%s", info->name);
+	} else {
+		const char *tmp;
+
+		tmp = system_string_error(errnum, buffer, buf_end - buffer);
+		if (tmp != buffer)
+			buffer = vdo_append_to_buffer(buffer, buf_end, "%s", tmp);
+		else
+			buffer += strlen(tmp);
+	}
+
+	return buf;
+}
+
+/*
+ * Translate an error code into a value acceptable to the kernel. The input error code may be a
+ * system-generated value (such as -EIO), or an internal UDS status code. The result will be a
+ * negative errno value.
+ */
+int uds_status_to_errno(int error)
+{
+	char error_name[VDO_MAX_ERROR_NAME_SIZE];
+	char error_message[VDO_MAX_ERROR_MESSAGE_SIZE];
+
+	/* 0 is success, and negative values are already system error codes. */
+	if (likely(error <= 0))
+		return error;
+
+	if (error < 1024) {
+		/* This is probably an errno from userspace. */
+		return -error;
+	}
+
+	/* Internal UDS errors */
+	switch (error) {
+	case UDS_NO_INDEX:
+	case UDS_CORRUPT_DATA:
+		/* The index doesn't exist or can't be recovered. */
+		return -ENOENT;
+
+	case UDS_INDEX_NOT_SAVED_CLEANLY:
+	case UDS_UNSUPPORTED_VERSION:
+		/*
+		 * The index exists, but can't be loaded. Tell the client it exists so they don't
+		 * destroy it inadvertently.
+		 */
+		return -EEXIST;
+
+	case UDS_DISABLED:
+		/* The session is unusable; only returned by requests. */
+		return -EIO;
+
+	default:
+		/* Translate an unexpected error into something generic. */
+		vdo_log_info("%s: mapping status code %d (%s: %s) to -EIO",
+			     __func__, error,
+			     uds_string_error_name(error, error_name,
+						   sizeof(error_name)),
+			     uds_string_error(error, error_message,
+					      sizeof(error_message)));
+		return -EIO;
+	}
+}
+
+/*
+ * Register a block of error codes.
+ *
+ * @block_name: the name of the block of error codes
+ * @first_error: the first error code in the block
+ * @next_free_error: one past the highest possible error in the block
+ * @infos: a pointer to the error info array for the block
+ * @info_size: the size of the error info array
+ */
+int uds_register_error_block(const char *block_name, int first_error,
+			     int next_free_error, const struct error_info *infos,
+			     size_t info_size)
+{
+	int result;
+	struct error_block *block;
+	struct error_block new_block = {
+		.name = block_name,
+		.base = first_error,
+		.last = first_error + (info_size / sizeof(struct error_info)),
+		.max = next_free_error,
+		.infos = infos,
+	};
+
+	result = VDO_ASSERT(first_error < next_free_error,
+			    "well-defined error block range");
+	if (result != VDO_SUCCESS)
+		return result;
+
+	if (registered_errors.count == registered_errors.allocated) {
+		/* This should never happen. */
+		return UDS_OVERFLOW;
+	}
+
+	for (block = registered_errors.blocks;
+	     block < registered_errors.blocks + registered_errors.count;
+	     block++) {
+		if (strcmp(block_name, block->name) == 0)
+			return UDS_DUPLICATE_NAME;
+
+		/* Ensure error ranges do not overlap. */
+		if ((first_error < block->max) && (next_free_error > block->base))
+			return UDS_ALREADY_REGISTERED;
+	}
+
+	registered_errors.blocks[registered_errors.count++] = new_block;
+	return UDS_SUCCESS;
+}