This is xnu-8019. See this file in:
/*
 * Copyright (c) 2000-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#ifdef KERNEL
#include <sys/systm.h>
#include <libkern/OSKextLib.h>
#include <libkern/OSKextLibPrivate.h>
#else
#include <libc.h>
#include <libkern/OSKextLib.h>
#include <System/libkern/OSKextLibPrivate.h>
#endif /* KERNEL */

#include <libkern/OSKextLibPrivate.h>

#define VERS_MAJOR_DIGITS        (4)
#define VERS_MINOR_DIGITS        (4)
#define VERS_REVISION_DIGITS     (4)
#define VERS_STAGE_DIGITS        (1)
#define VERS_STAGE_LEVEL_DIGITS  (3)

#define VERS_MAJOR_MAX           (9999)
#define VERS_STAGE_LEVEL_MAX      (255)

#define VERS_MAJOR_MULT  (1000000000000)
#define VERS_MINOR_MULT      (100000000)
#define VERS_REVISION_MULT       (10000)
#define VERS_STAGE_MULT           (1000)


typedef enum {
	kOSKextVersionStageInvalid     = 0,
	kOSKextVersionStageDevelopment = 1,
	kOSKextVersionStageAlpha       = 3,
	kOSKextVersionStageBeta        = 5,
	kOSKextVersionStageCandidate   = 7,
	kOSKextVersionStageRelease     = 9,
} OSKextVersionStage;


/*********************************************************************
*********************************************************************/
static int
__vers_isdigit(char c)
{
	return c == '0' ||
	       c == '1' || c == '2' || c == '3' ||
	       c == '4' || c == '5' || c == '6' ||
	       c == '7' || c == '8' || c == '9';
}

/*********************************************************************
*********************************************************************/
static int
__vers_isspace(char c)
{
	return c == ' ' ||
	       c == '\t' ||
	       c == '\r' ||
	       c == '\n';
}

/*********************************************************************
*********************************************************************/
static int
__vers_digit_for_char(char c)
{
	switch (c) {
	case '0': return 0;
	case '1': return 1;
	case '2': return 2;
	case '3': return 3;
	case '4': return 4;
	case '5': return 5;
	case '6': return 6;
	case '7': return 7;
	case '8': return 8;
	case '9': return 9;
	default:  return -1;
	}
}

/*********************************************************************
*********************************************************************/
static int
__VERS_isreleasestate(char c)
{
	return c == 'd' || c == 'a' || c == 'b' || c == 'f';
}


/*********************************************************************
*********************************************************************/
static OSKextVersionStage
__OSKextVersionStageForString(const char ** string_p)
{
	const char * string;

	if (!string_p || !*string_p) {
		return kOSKextVersionStageInvalid;
	}

	string = *string_p;

	if (__vers_isspace(string[0]) || string[0] == '\0') {
		return kOSKextVersionStageRelease;
	} else {
		switch (string[0]) {
		case 'd':
			if (__vers_isdigit(string[1])) {
				*string_p = &string[1];
				return kOSKextVersionStageDevelopment;
			}
			break;
		case 'a':
			if (__vers_isdigit(string[1])) {
				*string_p = &string[1];
				return kOSKextVersionStageAlpha;
			}
			break;
		case 'b':
			if (__vers_isdigit(string[1])) {
				*string_p = &string[1];
				return kOSKextVersionStageBeta;
			}
			break;
		case 'f':
			if (__vers_isdigit(string[1])) {
				*string_p = &string[1];
				return kOSKextVersionStageCandidate;
			} else if (string[1] == 'c' && __vers_isdigit(string[2])) {
				*string_p = &string[2];
				return kOSKextVersionStageCandidate;
			} else {
				return kOSKextVersionStageInvalid;
			}
		default:
			return kOSKextVersionStageInvalid;
		}
	}

	return kOSKextVersionStageInvalid;
}

/*********************************************************************
*********************************************************************/
static const char *
__OSKextVersionStringForStage(OSKextVersion stage)
{
	switch (stage) {
	default:
		OS_FALLTHROUGH;
	case kOSKextVersionStageInvalid:     return NULL;
	case kOSKextVersionStageDevelopment: return "d";
	case kOSKextVersionStageAlpha:       return "a";
	case kOSKextVersionStageBeta:        return "b";
	case kOSKextVersionStageCandidate:   return "f";
	case kOSKextVersionStageRelease:     return "";
	}
}

/*********************************************************************
*********************************************************************/
OSKextVersion
OSKextParseVersionString(const char * versionString)
{
	OSKextVersion   result             = -1;
	int             vers_digit         = -1;
	int             num_digits_scanned = 0;
	OSKextVersion   vers_major         = 0;
	OSKextVersion   vers_minor         = 0;
	OSKextVersion   vers_revision      = 0;
	OSKextVersionStage   vers_stage         = 0;
	OSKextVersion   vers_stage_level   = 0;
	const char    * current_char_p;

	if (!versionString || *versionString == '\0') {
		return -1;
	}

	current_char_p = (const char *)&versionString[0];

	/*****
	 * Check for an initial digit of the major release number.
	 */
	vers_major = __vers_digit_for_char(*current_char_p);
	if (vers_major < 0) {
		return -1;
	}

	current_char_p++;
	num_digits_scanned = 1;

	/* Complete scan for major version number. Legal characters are
	 * any digit, period, any buildstage letter.
	 */
	while (num_digits_scanned < VERS_MAJOR_DIGITS) {
		if (__vers_isspace(*current_char_p) || *current_char_p == '\0') {
			vers_stage = kOSKextVersionStageRelease;
			goto finish;
		} else if (__vers_isdigit(*current_char_p)) {
			vers_digit = __vers_digit_for_char(*current_char_p);
			if (vers_digit < 0) {
				return -1;
			}
			vers_major = (vers_major) * 10 + vers_digit;
			current_char_p++;
			num_digits_scanned++;
		} else if (__VERS_isreleasestate(*current_char_p)) {
			goto release_state;
		} else if (*current_char_p == '.') {
			current_char_p++;
			goto minor_version;
		} else {
			return -1;
		}
	}

	/* Check for too many digits.
	 */
	if (num_digits_scanned == VERS_MAJOR_DIGITS) {
		if (*current_char_p == '.') {
			current_char_p++;
		} else if (__vers_isdigit(*current_char_p)) {
			return -1;
		}
	}

minor_version:

	num_digits_scanned = 0;

	/* Scan for minor version number. Legal characters are
	 * any digit, period, any buildstage letter.
	 */
	while (num_digits_scanned < VERS_MINOR_DIGITS) {
		if (__vers_isspace(*current_char_p) || *current_char_p == '\0') {
			vers_stage = kOSKextVersionStageRelease;
			goto finish;
		} else if (__vers_isdigit(*current_char_p)) {
			vers_digit = __vers_digit_for_char(*current_char_p);
			if (vers_digit < 0) {
				return -1;
			}
			vers_minor = (vers_minor) * 10 + vers_digit;
			current_char_p++;
			num_digits_scanned++;
		} else if (__VERS_isreleasestate(*current_char_p)) {
			goto release_state;
		} else if (*current_char_p == '.') {
			current_char_p++;
			goto revision;
		} else {
			return -1;
		}
	}

	/* Check for too many digits.
	 */
	if (num_digits_scanned == VERS_MINOR_DIGITS) {
		if (*current_char_p == '.') {
			current_char_p++;
		} else if (__vers_isdigit(*current_char_p)) {
			return -1;
		}
	}

revision:

	num_digits_scanned = 0;

	/* Scan for revision version number. Legal characters are
	 * any digit, any buildstage letter (NOT PERIOD).
	 */
	while (num_digits_scanned < VERS_REVISION_DIGITS) {
		if (__vers_isspace(*current_char_p) || *current_char_p == '\0') {
			vers_stage = kOSKextVersionStageRelease;
			goto finish;
		} else if (__vers_isdigit(*current_char_p)) {
			vers_digit = __vers_digit_for_char(*current_char_p);
			if (vers_digit < 0) {
				return -1;
			}
			vers_revision = (vers_revision) * 10 + vers_digit;
			current_char_p++;
			num_digits_scanned++;
		} else if (__VERS_isreleasestate(*current_char_p)) {
			goto release_state;
		} else {
			return -1;
		}
	}

	/* Check for too many digits.
	 */
	if (num_digits_scanned == VERS_REVISION_DIGITS) {
		if (*current_char_p == '.') {
			current_char_p++;
		} else if (__vers_isdigit(*current_char_p)) {
			return -1;
		}
	}

release_state:

	/*****
	 * Check for the release state.
	 */
	if (__vers_isspace(*current_char_p) || *current_char_p == '\0') {
		vers_stage = kOSKextVersionStageRelease;
		goto finish;
	} else {
		vers_stage = __OSKextVersionStageForString(&current_char_p);
		if (vers_stage == kOSKextVersionStageInvalid) {
			return -1;
		}
	}


// stage level

	num_digits_scanned = 0;

	/* Scan for stage level number. Legal characters are
	 * any digit only.
	 */
	while (num_digits_scanned < VERS_STAGE_LEVEL_DIGITS) {
		if (__vers_isspace(*current_char_p) || *current_char_p == '\0') {
			if (num_digits_scanned) {
				goto finish;
			} else {
				return -1;
			}
		} else if (__vers_isdigit(*current_char_p)) {
			vers_digit = __vers_digit_for_char(*current_char_p);
			if (vers_digit < 0) {
				return -1;
			}
			vers_stage_level = (vers_stage_level) * 10 + vers_digit;
			current_char_p++;
			num_digits_scanned++;
		} else {
			return -1;
		}
	}

	/* Check for too many digits.
	 */
	if ((num_digits_scanned == VERS_STAGE_LEVEL_DIGITS) &&
	    !(__vers_isspace(*current_char_p) || (*current_char_p == '\0'))) {
		return -1;
	}

	if (vers_stage_level > VERS_STAGE_LEVEL_MAX) {
		return -1;
	}

finish:

	if (vers_stage == kOSKextVersionStageCandidate && vers_stage_level == 0) {
		return -1;
	}

	result = (vers_major * VERS_MAJOR_MULT) +
	    (vers_minor * VERS_MINOR_MULT) +
	    (vers_revision * VERS_REVISION_MULT) +
	    (vers_stage * VERS_STAGE_MULT) +
	    vers_stage_level;

	return result;
}

/*********************************************************************
* This function must be safe to call in panic context.
*********************************************************************/
Boolean
OSKextVersionGetString(
	OSKextVersion   aVersion,
	char          * buffer,
	uint32_t        bufferLength)
{
	int             cpos = 0;
	OSKextVersion   vers_major = 0;
	OSKextVersion   vers_minor = 0;
	OSKextVersion   vers_revision = 0;
	OSKextVersion   vers_stage = 0;
	OSKextVersion   vers_stage_level = 0;
	const char    * stage_string = NULL;// don't free

	/* No buffer or length less than longest possible vers string,
	 * return 0.
	 */
	if (!buffer || bufferLength < kOSKextVersionMaxLength) {
		return FALSE;
	}

	bzero(buffer, bufferLength * sizeof(char));

	if (aVersion < 0) {
		strlcpy(buffer, "(invalid)", bufferLength);
		return TRUE;
	}
	if (aVersion == 0) {
		strlcpy(buffer, "(missing)", bufferLength);
		return TRUE;
	}

	vers_major = aVersion / VERS_MAJOR_MULT;
	if (vers_major > VERS_MAJOR_MAX) {
		strlcpy(buffer, "(invalid)", bufferLength);
		return TRUE;
	}

	vers_minor = aVersion - (vers_major * VERS_MAJOR_MULT);
	vers_minor /= VERS_MINOR_MULT;

	vers_revision = aVersion -
	    ((vers_major * VERS_MAJOR_MULT) + (vers_minor * VERS_MINOR_MULT));
	vers_revision /= VERS_REVISION_MULT;

	vers_stage = aVersion -
	    ((vers_major * VERS_MAJOR_MULT) + (vers_minor * VERS_MINOR_MULT) +
	    (vers_revision * VERS_REVISION_MULT));
	vers_stage /= VERS_STAGE_MULT;

	vers_stage_level = aVersion -
	    ((vers_major * VERS_MAJOR_MULT) + (vers_minor * VERS_MINOR_MULT) +
	    (vers_revision * VERS_REVISION_MULT) + (vers_stage * VERS_STAGE_MULT));
	if (vers_stage_level > VERS_STAGE_LEVEL_MAX) {
		strlcpy(buffer, "(invalid)", bufferLength);
		return TRUE;
	}

	cpos = scnprintf(buffer, bufferLength, "%u", (uint32_t)vers_major);

	/* Always include the minor version; it just looks weird without.
	 */
	buffer[cpos] = '.';
	cpos++;
	cpos += scnprintf(buffer + cpos, bufferLength - cpos, "%u", (uint32_t)vers_minor);

	/* The revision is displayed only if nonzero.
	 */
	if (vers_revision) {
		buffer[cpos] = '.';
		cpos++;
		cpos += scnprintf(buffer + cpos, bufferLength - cpos, "%u",
		    (uint32_t)vers_revision);
	}

	stage_string = __OSKextVersionStringForStage(vers_stage);
	if (!stage_string) {
		strlcpy(buffer, "(invalid)", bufferLength);
		return TRUE;
	}
	if (stage_string[0]) {
		strlcat(buffer, stage_string, bufferLength);
		cpos += strlen(stage_string);
	}

	if (vers_stage < kOSKextVersionStageRelease) {
		snprintf(buffer + cpos, bufferLength - cpos, "%u", (uint32_t)vers_stage_level);
	}

	return TRUE;
}

/*********************************************************************
*********************************************************************/
#ifndef KERNEL
OSKextVersion
OSKextParseVersionCFString(CFStringRef versionString)
{
	OSKextVersion result = -1;
	char         versBuffer[kOSKextVersionMaxLength];

	if (CFStringGetCString(versionString, versBuffer,
	    sizeof(versBuffer), kCFStringEncodingASCII)) {
		result = OSKextParseVersionString(versBuffer);
	}
	return result;
}
#endif