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OvmfPkg: introduce QemuFwCfgSimpleParserLib 

We already parse some boolean and integer values from named fw_cfg files
(usually into PCDs), and we're going to cover more. Add a dedicated
library for centralizing the parsing logic.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Per Sundstrom <per_sundstrom@yahoo.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2681
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200424075353.8489-2-lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
This commit is contained in:
Laszlo Ersek 2020-04-24 09:53:47 +02:00 committed by mergify[bot]
parent 64ab457d1f
commit 611c7f1101
7 changed files with 560 additions and 0 deletions
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128
OvmfPkg/Include/Library/QemuFwCfgSimpleParserLib.h Normal file
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/** @file
Parse the contents of named fw_cfg files as simple (scalar) data types.
Copyright (C) 2020, Red Hat, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#ifndef QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_
#define QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_
#include <Base.h>
/**
Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
file into a small array with automatic storage duration. Parse the array as
the textual representation of a BOOLEAN.
@param[in] FileName The name of the fw_cfg file to look up and parse.
@param[out] Value On success, Value is TRUE if the contents of the fw_cfg
file case-insensitively match "true", "yes", "y",
"enable", "enabled", "1".
On success, Value is FALSE if the contents of the fw_cfg
file case-insensitively match "false", "no", "n",
"disable", "disabled", "0".
On failure, Value is not changed.
@retval RETURN_SUCCESS Parsing successful. Value has been set.
@retval RETURN_UNSUPPORTED Firmware configuration is unavailable.
@retval RETURN_PROTOCOL_ERROR Parsing failed. Value has not been changed.
@return Error codes propagated from
QemuFwCfgFindFile(). Value has not been
changed.
**/
RETURN_STATUS
EFIAPI
QemuFwCfgParseBool (
IN CONST CHAR8 *FileName,
OUT BOOLEAN *Value
);
/**
Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
file into a small array with automatic storage duration. Parse the array as
the textual representation of a UINT8.
@param[in] FileName The name of the fw_cfg file to look up and parse.
@param[in] ParseAsHex If TRUE, call BaseLib's AsciiStrHexToUint64S() for
parsing the fw_cfg file.
If FALSE, call BaseLib's AsciiStrDecimalToUint64S()
for parsing the fw_cfg file.
@param[out] Value On success, Value has been parsed with the BaseLib
function determined by ParseAsHex, and also
range-checked for [0, MAX_UINT8].
On failure, Value is not changed.
@retval RETURN_SUCCESS Parsing successful. Value has been set.
@retval RETURN_UNSUPPORTED Firmware configuration is unavailable.
@retval RETURN_PROTOCOL_ERROR Parsing failed. Value has not been changed.
@retval RETURN_PROTOCOL_ERROR Parsing succeeded, but the result does not fit
in the [0, MAX_UINT8] range. Value has not
been changed.
@return Error codes propagated from
QemuFwCfgFindFile() and from the BaseLib
function selected by ParseAsHex. Value has not
been changed.
**/
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint8 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT8 *Value
);
//
// The following functions behave identically to QemuFwCfgParseUint8(),
// only their range checks use MAX_UINT16, MAX_UINT32, MAX_UINT64, MAX_UINTN,
// respectively.
//
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint16 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT16 *Value
);
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint32 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT32 *Value
);
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint64 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT64 *Value
);
RETURN_STATUS
EFIAPI
QemuFwCfgParseUintn (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINTN *Value
);
#endif // QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_

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OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParser.c Normal file
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/** @file
Parse the contents of named fw_cfg files as simple (scalar) data types.
Copyright (C) 2020, Red Hat, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Library/QemuFwCfgLib.h>
#include <Library/QemuFwCfgSimpleParserLib.h>
//
// Size of the longest valid UINT64 string, including the terminating NUL.
//
#define UINT64_STRING_MAX_SIZE \
MAX (sizeof "18446744073709551615", sizeof "0xFFFFFFFFFFFFFFFF")
//
// Size of the longest valid BOOL string (see the "mTrueString" and
// "mFalseString" arrays below), including the terminating NUL.
//
#define BOOL_STRING_MAX_SIZE (sizeof "disabled")
//
// Length of "\r\n", not including the terminating NUL.
//
#define CRLF_LENGTH (sizeof "\r\n" - 1)
//
// Words recognized as representing TRUE or FALSE.
//
STATIC CONST CHAR8 * CONST mTrueString[] = {
"true", "yes", "y", "enable", "enabled", "1"
};
STATIC CONST CHAR8 * CONST mFalseString[] = {
"false", "no", "n", "disable", "disabled", "0"
};
//
// Helper functions.
//
/**
Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
file into the caller-provided CHAR8 array. NUL-terminate the array.
@param[in] FileName The name of the fw_cfg file to look up and read.
@param[in,out] BufferSize On input, number of bytes available in Buffer.
On output, the number of bytes that have been
stored to Buffer.
On error, BufferSize is indeterminate.
@param[out] Buffer The buffer to read the fw_cfg file into. If the
fw_cfg file contents are not NUL-terminated, then
a NUL character is placed into Buffer after the
fw_cfg file contents.
On error, Buffer is indeterminate.
@retval RETURN_SUCCESS Buffer has been populated with the fw_cfg file
contents. Buffer is NUL-terminated regardless
of whether the fw_cfg file itself was
NUL-terminated.
@retval RETURN_UNSUPPORTED Firmware configuration is unavailable.
@retval RETURN_PROTOCOL_ERROR The fw_cfg file does not fit into Buffer.
(This is considered a QEMU configuration
error; BufferSize is considered authoritative
for the contents of the fw_cfg file identified
by FileName.)
@retval RETURN_PROTOCOL_ERROR The fw_cfg file contents are not themselves
NUL-terminated, and an extra NUL byte does not
fit into Buffer. (Again a QEMU configuration
error.)
@return Error codes propagated from
QemuFwCfgFindFile().
**/
STATIC
RETURN_STATUS
QemuFwCfgGetAsString (
IN CONST CHAR8 *FileName,
IN OUT UINTN *BufferSize,
OUT CHAR8 *Buffer
)
{
RETURN_STATUS Status;
FIRMWARE_CONFIG_ITEM FwCfgItem;
UINTN FwCfgSize;
if (!QemuFwCfgIsAvailable ()) {
return RETURN_UNSUPPORTED;
}
Status = QemuFwCfgFindFile (FileName, &FwCfgItem, &FwCfgSize);
if (RETURN_ERROR (Status)) {
return Status;
}
if (FwCfgSize > *BufferSize) {
return RETURN_PROTOCOL_ERROR;
}
QemuFwCfgSelectItem (FwCfgItem);
QemuFwCfgReadBytes (FwCfgSize, Buffer);
//
// If Buffer is already NUL-terminated due to fw_cfg contents, we're done.
//
if (FwCfgSize > 0 && Buffer[FwCfgSize - 1] == '\0') {
*BufferSize = FwCfgSize;
return RETURN_SUCCESS;
}
//
// Otherwise, append a NUL byte to Buffer (if we have room for it).
//
if (FwCfgSize == *BufferSize) {
return RETURN_PROTOCOL_ERROR;
}
Buffer[FwCfgSize] = '\0';
*BufferSize = FwCfgSize + 1;
return RETURN_SUCCESS;
}
/**
Remove a trailing \r\n or \n sequence from a string.
@param[in,out] BufferSize On input, the number of bytes in Buffer, including
the terminating NUL.
On output, the adjusted string size (including the
terminating NUL), after stripping the \r\n or \n
suffix.
@param[in,out] Buffer The NUL-terminated string to trim.
**/
STATIC
VOID
StripNewline (
IN OUT UINTN *BufferSize,
IN OUT CHAR8 *Buffer
)
{
UINTN InSize, OutSize;
InSize = *BufferSize;
OutSize = InSize;
if (InSize >= 3 &&
Buffer[InSize - 3] == '\r' && Buffer[InSize - 2] == '\n') {
OutSize = InSize - 2;
} else if (InSize >= 2 && Buffer[InSize - 2] == '\n') {
OutSize = InSize - 1;
}
if (OutSize < InSize) {
Buffer[OutSize - 1] = '\0';
*BufferSize = OutSize;
}
}
/**
Read the fw_cfg file identified by FileName as a string into a small array
with automatic storage duration, using QemuFwCfgGetAsString(). Parse the
string as a UINT64. Perform a range-check on the parsed value.
@param[in] FileName The name of the fw_cfg file to look up and parse.
@param[in] ParseAsHex If TRUE, call BaseLib's AsciiStrHexToUint64S() for
parsing the fw_cfg file.
If FALSE, call BaseLib's AsciiStrDecimalToUint64S()
for parsing the fw_cfg file.
@param[in] Limit The inclusive upper bound on the parsed UINT64 value.
@param[out] Value On success, Value has been parsed with the BaseLib
function determined by ParseAsHex, and has been
range-checked against [0, Limit].
On failure, Value is not changed.
@retval RETURN_SUCCESS Parsing successful. Value has been set.
@retval RETURN_UNSUPPORTED Firmware configuration is unavailable.
@retval RETURN_PROTOCOL_ERROR Parsing failed. Value has not been changed.
@retval RETURN_PROTOCOL_ERROR Parsing succeeded, but the result does not fit
in the [0, Limit] range. Value has not been
changed.
@return Error codes propagated from
QemuFwCfgFindFile() and from the BaseLib
function selected by ParseAsHex. Value has not
been changed.
**/
STATIC
RETURN_STATUS
QemuFwCfgParseUint64WithLimit (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
IN UINT64 Limit,
OUT UINT64 *Value
)
{
UINTN Uint64StringSize;
CHAR8 Uint64String[UINT64_STRING_MAX_SIZE + CRLF_LENGTH];
RETURN_STATUS Status;
CHAR8 *EndPointer;
UINT64 Uint64;
Uint64StringSize = sizeof Uint64String;
Status = QemuFwCfgGetAsString (FileName, &Uint64StringSize, Uint64String);
if (RETURN_ERROR (Status)) {
return Status;
}
StripNewline (&Uint64StringSize, Uint64String);
if (ParseAsHex) {
Status = AsciiStrHexToUint64S (Uint64String, &EndPointer, &Uint64);
} else {
Status = AsciiStrDecimalToUint64S (Uint64String, &EndPointer, &Uint64);
}
if (RETURN_ERROR (Status)) {
return Status;
}
//
// Report a wire protocol error if the subject sequence is empty, or trailing
// garbage is present, or Limit is not honored.
//
if (EndPointer == Uint64String || *EndPointer != '\0' || Uint64 > Limit) {
return RETURN_PROTOCOL_ERROR;
}
*Value = Uint64;
return RETURN_SUCCESS;
}
//
// Public functions.
//
RETURN_STATUS
EFIAPI
QemuFwCfgSimpleParserInit (
VOID
)
{
//
// Do nothing, just participate in constructor dependency ordering.
//
return RETURN_SUCCESS;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseBool (
IN CONST CHAR8 *FileName,
OUT BOOLEAN *Value
)
{
UINTN BoolStringSize;
CHAR8 BoolString[BOOL_STRING_MAX_SIZE + CRLF_LENGTH];
RETURN_STATUS Status;
UINTN Idx;
BoolStringSize = sizeof BoolString;
Status = QemuFwCfgGetAsString (FileName, &BoolStringSize, BoolString);
if (RETURN_ERROR (Status)) {
return Status;
}
StripNewline (&BoolStringSize, BoolString);
for (Idx = 0; Idx < ARRAY_SIZE (mTrueString); ++Idx) {
if (AsciiStriCmp (BoolString, mTrueString[Idx]) == 0) {
*Value = TRUE;
return RETURN_SUCCESS;
}
}
for (Idx = 0; Idx < ARRAY_SIZE (mFalseString); ++Idx) {
if (AsciiStriCmp (BoolString, mFalseString[Idx]) == 0) {
*Value = FALSE;
return RETURN_SUCCESS;
}
}
return RETURN_PROTOCOL_ERROR;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint8 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT8 *Value
)
{
RETURN_STATUS Status;
UINT64 Uint64;
Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT8,
&Uint64);
if (RETURN_ERROR (Status)) {
return Status;
}
*Value = (UINT8)Uint64;
return RETURN_SUCCESS;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint16 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT16 *Value
)
{
RETURN_STATUS Status;
UINT64 Uint64;
Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT16,
&Uint64);
if (RETURN_ERROR (Status)) {
return Status;
}
*Value = (UINT16)Uint64;
return RETURN_SUCCESS;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint32 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT32 *Value
)
{
RETURN_STATUS Status;
UINT64 Uint64;
Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT32,
&Uint64);
if (RETURN_ERROR (Status)) {
return Status;
}
*Value = (UINT32)Uint64;
return RETURN_SUCCESS;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseUint64 (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINT64 *Value
)
{
RETURN_STATUS Status;
UINT64 Uint64;
Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT64,
&Uint64);
if (RETURN_ERROR (Status)) {
return Status;
}
*Value = Uint64;
return RETURN_SUCCESS;
}
RETURN_STATUS
EFIAPI
QemuFwCfgParseUintn (
IN CONST CHAR8 *FileName,
IN BOOLEAN ParseAsHex,
OUT UINTN *Value
)
{
RETURN_STATUS Status;
UINT64 Uint64;
Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINTN,
&Uint64);
if (RETURN_ERROR (Status)) {
return Status;
}
*Value = (UINTN)Uint64;
return RETURN_SUCCESS;
}

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OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf Normal file
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## @file
# Parse the contents of named fw_cfg files as simple (scalar) data types.
#
# Copyright (C) 2020, Red Hat, Inc.
#
# SPDX-License-Identifier: BSD-2-Clause-Patent
##
[Defines]
INF_VERSION = 1.29
BASE_NAME = QemuFwCfgSimpleParserLib
FILE_GUID = a9a1211d-061e-4b64-af30-5dd0cac9dc99
MODULE_TYPE = BASE
VERSION_STRING = 1.0
LIBRARY_CLASS = QemuFwCfgSimpleParserLib
CONSTRUCTOR = QemuFwCfgSimpleParserInit
[Sources]
QemuFwCfgSimpleParser.c
[Packages]
MdePkg/MdePkg.dec
OvmfPkg/OvmfPkg.dec
[LibraryClasses]
BaseLib
QemuFwCfgLib

4
OvmfPkg/OvmfPkg.dec
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@ -60,6 +60,10 @@
#
QemuFwCfgS3Lib|Include/Library/QemuFwCfgS3Lib.h
## @libraryclass Parse the contents of named fw_cfg files as simple
# (scalar) data types.
QemuFwCfgSimpleParserLib|Include/Library/QemuFwCfgSimpleParserLib.h
## @libraryclass Rewrite the BootOrder NvVar based on QEMU's "bootorder"
# fw_cfg file.
#

1
OvmfPkg/OvmfPkgIa32.dsc
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@ -160,6 +160,7 @@
UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf

1
OvmfPkg/OvmfPkgIa32X64.dsc
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@ -164,6 +164,7 @@
UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf

1
OvmfPkg/OvmfPkgX64.dsc
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@ -164,6 +164,7 @@
UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf