BootX-59.1.1.tar.gz

[apple/bootx.git] / bootx.tproj / sl.subproj / drivers.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * 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. 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_LICENSE_HEADER_END@
 */
/*
 *  drivers.c - Driver Loading Functions.
 *
 *  Copyright (c) 2000 Apple Computer, Inc.
 *
 *  DRI: Josh de Cesare
 */

#include <sl.h>

#define DRIVER_DEBUG 0

enum {
  kTagTypeNone = 0,
  kTagTypeDict,
  kTagTypeKey,
  kTagTypeString,
  kTagTypeInteger,
  kTagTypeData,
  kTagTypeDate,
  kTagTypeFalse,
  kTagTypeTrue,
  kTagTypeArray
};

#define kXMLTagPList   "plist "
#define kXMLTagDict    "dict"
#define kXMLTagKey     "key"
#define kXMLTagString  "string"
#define kXMLTagInteger "integer"
#define kXMLTagData    "data"
#define kXMLTagDate    "date"
#define kXMLTagFalse   "false/"
#define kXMLTagTrue    "true/"
#define kXMLTagArray   "array"

#define kPropCFBundleIdentifier ("CFBundleIdentifier")
#define kPropCFBundleExecutable ("CFBundleExecutable")
#define kPropOSBundleRequired   ("OSBundleRequired")
#define kPropOSBundleLibraries  ("OSBundleLibraries")
#define kPropIOKitPersonalities ("IOKitPersonalities")
#define kPropIONameMatch        ("IONameMatch")

struct Tag {
  long       type;
  char       *string;
  struct Tag *tag;
  struct Tag *tagNext;
};
typedef struct Tag Tag, *TagPtr;

struct Module {  
  struct Module *nextModule;
  long          willLoad;
  TagPtr        dict;
  char          *plistAddr;
  long          plistLength;
  char          *driverPath;
};
typedef struct Module Module, *ModulePtr;

struct DriverInfo {
  char *plistAddr;
  long plistLength;
  void *moduleAddr;
  long moduleLength;
};
typedef struct DriverInfo DriverInfo, *DriverInfoPtr;

#define kDriverPackageSignature1 'MKXT'
#define kDriverPackageSignature2 'MOSX'

struct DriversPackage {
  unsigned long signature1;
  unsigned long signature2;
  unsigned long length;
  unsigned long alder32;
  unsigned long version;
  unsigned long numDrivers;
  unsigned long reserved1;
  unsigned long reserved2;
};
typedef struct DriversPackage DriversPackage;

enum {
  kCFBundleType2,
  kCFBundleType3
};

static long FileLoadDrivers(char *dirSpec, long plugin);
static long NetLoadDrivers(char *dirSpec);
static long LoadDriverMKext(char *fileSpec);
static long LoadDriverPList(char *dirSpec, char *name, long bundleType);
static long LoadMatchedModules(void);
static long MatchPersonalities(void);
static long MatchLibraries(void);
static TagPtr GetProperty(TagPtr dict, char *key);
static ModulePtr FindModule(char *name);
static long ParseXML(char *buffer, ModulePtr *module, TagPtr *personalities);
static long ParseNextTag(char *buffer, TagPtr *tag);
static long ParseTagList(char *buffer, TagPtr *tag, long type, long empty);
static long ParseTagKey(char *buffer, TagPtr *tag);
static long ParseTagString(char *buffer, TagPtr *tag);
static long ParseTagInteger(char *buffer, TagPtr *tag);
static long ParseTagData(char *buffer, TagPtr *tag);
static long ParseTagDate(char *buffer, TagPtr *tag);
static long ParseTagBoolean(char *buffer, TagPtr *tag, long type);
static long GetNextTag(char *buffer, char **tag, long *start);
static long FixDataMatchingTag(char *buffer, char *tag);
static TagPtr NewTag(void);
static void FreeTag(TagPtr tag);
static char *NewSymbol(char *string);
static void FreeSymbol(char *string);
#if DRIVER_DEBUG
static void DumpTag(TagPtr tag, long depth);
#endif

static ModulePtr gModuleHead, gModuleTail;
static TagPtr    gPersonalityHead, gPersonalityTail;
static char      gDriverSpec[4096];
static char      gFileSpec[4096];
static char      gTempSpec[4096];
static char      gFileName[4096];

// Public Functions

long LoadDrivers(char *dirSpec)
{
  if (gBootFileType == kNetworkDeviceType) {
    NetLoadDrivers(dirSpec);
  } else if (gBootFileType == kBlockDeviceType) {
    FileLoadDrivers(dirSpec, 0);
  } else {
    return 0;
  }
  
  MatchPersonalities();
  
  MatchLibraries();
  
  LoadMatchedModules();
  
  return 0;
}

// Private Functions

static long FileLoadDrivers(char *dirSpec, long plugin)
{
  long ret, length, index, flags, time, time2, bundleType;
  char *name;
  
  if (!plugin) {
    ret = GetFileInfo(dirSpec, "Extensions.mkext", &flags, &time);
    if ((ret == 0) && ((flags & kFileTypeMask) == kFileTypeFlat)) {
      ret = GetFileInfo(dirSpec, "Extensions", &flags, &time2);
      if ((ret != 0) || ((flags & kFileTypeMask) != kFileTypeDirectory) ||
	  (((gBootMode & kBootModeSafe) == 0) && (time > time2))) {
	sprintf(gDriverSpec, "%sExtensions.mkext", dirSpec);
	printf("LoadDrivers: Loading from [%s]\n", gDriverSpec);
	if (LoadDriverMKext(gDriverSpec) == 0) return 0;
      }
    }
    
    strcat(dirSpec, "Extensions");
  }
  
  printf("LoadDrivers: Loading from [%s]\n", dirSpec);
  
  index = 0;
  while (1) {
    ret = GetDirEntry(dirSpec, &index, &name, &flags, &time);
    if (ret == -1) break;
    
    // Make sure this is a directory.
    if ((flags & kFileTypeMask ) != kFileTypeDirectory) continue;
    
    // Make sure this is a kext.
    length = strlen(name);
    if (strcmp(name + length - 5, ".kext")) continue;
    
    // Save the file name.
    strcpy(gFileName, name);
    
    // Determine the bundle type.
    sprintf(gTempSpec, "%s\\%s", dirSpec, gFileName);
    ret = GetFileInfo(gTempSpec, "Contents", &flags, &time);
    if (ret == 0) bundleType = kCFBundleType2;
    else bundleType = kCFBundleType3;
    
    if (!plugin) {
      sprintf(gDriverSpec, "%s\\%s\\%sPlugIns", dirSpec, gFileName,
	      (bundleType == kCFBundleType2) ? "Contents\\" : "");
    }
    
    ret = LoadDriverPList(dirSpec, gFileName, bundleType);
    if (ret != 0) {
      printf("LoadDrivers: failed\n");
    }
    
    if (!plugin) {
      ret = FileLoadDrivers(gDriverSpec, 1);
    }
  }
  
  return 0;
}


static long NetLoadDrivers(char *dirSpec)
{
  long tries, cnt;
  
  // Get the name of the kernel
  cnt = strlen(gBootFile);
  while (cnt--) {
    if ((gBootFile[cnt] == '\\')  || (gBootFile[cnt] == ',')) {
      cnt++;
      break;
    }
  }
  
  sprintf(gDriverSpec, "%s%s.mkext", dirSpec, gBootFile + cnt);
  
  printf("NetLoadDrivers: Loading from [%s]\n", gDriverSpec);
  
  tries = 10;
  while (tries--) {
    if (LoadDriverMKext(gDriverSpec) == 0) break;
  }
  if (tries == -1) return -1;
  
  return 0;
}


static long LoadDriverMKext(char *fileSpec)
{
  unsigned long  driversAddr, driversLength, length;
  char           segName[32];
  DriversPackage *package = (DriversPackage *)kLoadAddr;
  
  // Load the MKext.
  length = LoadFile(fileSpec);
  if (length == -1) return -1;
  
  ThinFatBinary((void **)&package, &length);
  
  // Verify the MKext.
  if ((package->signature1 != kDriverPackageSignature1) ||
      (package->signature2 != kDriverPackageSignature2)) return -1;
  if (package->length > kLoadSize) return -1;
  if (package->alder32 != Alder32((char *)&package->version,
				  package->length - 0x10)) return -1;
  
  // Make space for the MKext.
  driversLength = package->length;
  driversAddr = AllocateKernelMemory(driversLength);
  
  // Copy the MKext.
  memcpy((void *)driversAddr, (void *)package, driversLength);
  
  // Add the MKext to the memory map.
  sprintf(segName, "DriversPackage-%x", driversAddr);
  AllocateMemoryRange(segName, driversAddr, driversLength);
  
  return 0;
}


static long LoadDriverPList(char *dirSpec, char *name, long bundleType)
{
  long      length, ret, driverPathLength;
  char      *buffer;
  ModulePtr module;
  TagPtr    personalities;
  char      *tmpDriverPath;
  
  // Reset the malloc zone.
  malloc_init((char *)kMallocAddr, kMallocSize);
  
  // Save the driver path.
  sprintf(gFileSpec, "%s\\%s\\%s", dirSpec, name,
	  (bundleType == kCFBundleType2) ? "Contents\\MacOS\\" : "");
  driverPathLength = strlen(gFileSpec);
  tmpDriverPath = malloc(driverPathLength + 1);
  if (tmpDriverPath == 0) return -1;
  strcpy(tmpDriverPath, gFileSpec);
  
  // Construct the file spec.
  sprintf(gFileSpec, "%s\\%s\\%sInfo.plist", dirSpec, name,
	  (bundleType == kCFBundleType2) ? "Contents\\" : "");
  
  length = LoadFile(gFileSpec);
  if (length == -1) {
    free(tmpDriverPath);
    return -1;
  }
  
  buffer = malloc(length + 1);
  if (buffer == 0) {
    free(tmpDriverPath);
    return -1;
  }
  strncpy(buffer, (char *)kLoadAddr, length);
  
  ret = ParseXML(buffer, &module, &personalities);
  free(buffer);
  if (ret != 0) {
    free(tmpDriverPath);
    return -1;
  }
  
  // Allocate memory for the driver path and the plist.
  module->driverPath = AllocateBootXMemory(driverPathLength + 1);
  module->plistAddr = AllocateBootXMemory(length + 1);
  
  if ((module->driverPath == 0) | (module->plistAddr == 0)) {
    free(tmpDriverPath);
    return -1;
  }
  
  // Save the driver path in the module.
  strcpy(module->driverPath, tmpDriverPath);
  free(tmpDriverPath);
  
  // Add the origin plist to the module.
  strncpy(module->plistAddr, (char *)kLoadAddr, length);
  module->plistLength = length + 1;
  
  // Add the module to the end of the module list.
  if (gModuleHead == 0) gModuleHead = module;
  else gModuleTail->nextModule = module;
  gModuleTail = module;
  
  // Add the persionalities to the personality list.
  if (personalities) personalities = personalities->tag;
  while (personalities != 0) {
    if (gPersonalityHead == 0) gPersonalityHead = personalities->tag;
    else gPersonalityTail->tagNext = personalities->tag;
    gPersonalityTail = personalities->tag;
    
    personalities = personalities->tagNext;
  }
  
  return 0;
}


static long LoadMatchedModules(void)
{
  TagPtr        prop;
  ModulePtr     module;
  char          *fileName, segName[32];
  DriverInfoPtr driver;
  unsigned long length, driverAddr, driverLength;
  void          *driverModuleAddr;
  
  module = gModuleHead;
  while (module != 0) {
    if (module->willLoad) {
      prop = GetProperty(module->dict, kPropCFBundleExecutable);
      if (prop != 0) {
	fileName = prop->string;
	sprintf(gFileSpec, "%s%s", module->driverPath, fileName);
	length = LoadFile(gFileSpec);
      } else length = 0;
      if (length != -1) {
	if (length != 0) {
	  driverModuleAddr = (void *)kLoadAddr;
	  ThinFatBinary(&driverModuleAddr, &length);
	}
	
	// Make make in the image area.
	driverLength = sizeof(DriverInfo) + module->plistLength + length;
	driverAddr = AllocateKernelMemory(driverLength);
	
	// Set up the DriverInfo.
	driver = (DriverInfoPtr)driverAddr;
	driver->plistAddr = (char *)(driverAddr + sizeof(DriverInfo));
	driver->plistLength = module->plistLength;
	if (length != 0) {
	  driver->moduleAddr   = (void *)(driverAddr + sizeof(DriverInfo) +
					module->plistLength);
	  driver->moduleLength = length;
	} else {
	  driver->moduleAddr   = 0;
	  driver->moduleLength = 0;
	}
	
	// Save the plist and module.
	strcpy(driver->plistAddr, module->plistAddr);
	if (length != 0) {
	  memcpy(driver->moduleAddr, driverModuleAddr, driver->moduleLength);
	}
	
	// Add an entry to the memory map.
	sprintf(segName, "Driver-%x", driver);
	AllocateMemoryRange(segName, driverAddr, driverLength);
      }
    }
    
    module = module->nextModule;
  }
  
  return 0;
}


static long MatchPersonalities(void)
{
  TagPtr    persionality;
  TagPtr    prop;
  ModulePtr module;
  CICell    ph;
  
  // Try to match each of the personalities.
  for(persionality = gPersonalityHead; persionality != 0;
	persionality = persionality->tagNext) {
    // Get the module name. Make sure it exists and has not
    // already been marked for loading.
    prop = GetProperty(persionality, kPropCFBundleIdentifier);
    if (prop == 0) continue;
    module = FindModule(prop->string);
    if (module == 0) continue;
    if (module->willLoad) continue;
    
    // Look for the exact match property.
    // Try to match with it.
    
    // Look for the old match property.
    // Try to match with it.
    ph = 0;
    prop = GetProperty(persionality, kPropIONameMatch);
    if ((prop != 0) && (prop->tag != 0)) prop = prop->tag;
    while (prop != 0) {
      ph = SearchForNodeMatching(0, 1, prop->string);
      if (ph != 0) break;
      
      prop = prop->tagNext;
    }
    
    // If a node was found mark the module to be loaded.
    if (ph != 0) {
      module->willLoad = 1;
    }
  }
  
  return 0;
}


static long MatchLibraries(void)
{
  TagPtr        prop, prop2;
  ModulePtr     module, module2;
  long          done;
  
  do {
    done = 1;
    module = gModuleHead;
    while (module != 0) {
      if (module->willLoad == 1) {
	prop = GetProperty(module->dict, kPropOSBundleLibraries);
	if (prop != 0) {
	  prop = prop->tag;
	  while (prop != 0) {
	    module2 = gModuleHead;
	    while (module2 != 0) {
	      prop2 = GetProperty(module2->dict, kPropCFBundleIdentifier);
	      if ((prop2 != 0) && (!strcmp(prop->string, prop2->string))) {
		if (module2->willLoad == 0) module2->willLoad = 1;
		break;
	      }
	      module2 = module2->nextModule;
	    }
	    prop = prop->tagNext;
	  }
	}
	module->willLoad = 2;
	done = 0;
      }
      module = module->nextModule;
    }
  } while (!done);
  
  return 0;
}


static TagPtr GetProperty(TagPtr dict, char *key)
{
  TagPtr tagList, tag;
  
  if (dict->type != kTagTypeDict) return 0;
  
  tag = 0;
  tagList = dict->tag;
  while (tagList) {
    tag = tagList;
    tagList = tag->tagNext;
    
    if ((tag->type != kTagTypeKey) || (tag->string == 0)) continue;
    
    if (!strcmp(tag->string, key)) return tag->tag;
  }
  
  return 0;
}


static ModulePtr FindModule(char *name)
{
  ModulePtr module;
  TagPtr    prop;
  
  module = gModuleHead;
  
  while (module != 0) {
    prop = GetProperty(module->dict, kPropCFBundleIdentifier);
    if ((prop != 0) && !strcmp(name, prop->string)) break;
    module = module->nextModule;
  }
  
  return module;
}


static long ParseXML(char *buffer, ModulePtr *module, TagPtr *personalities)
{
  long           length, pos;
  TagPtr         moduleDict, required;
  ModulePtr      tmpModule;
  
  pos = 0;
  while (1) {
    length = ParseNextTag(buffer + pos, &moduleDict);
    if (length == -1) break;
    pos += length;
    
    if (moduleDict == 0) continue;
    
    if (moduleDict->type == kTagTypeDict) break;
    
    FreeTag(moduleDict);
  }
  
  if (length == -1) return -1;
  
  required = GetProperty(moduleDict, kPropOSBundleRequired);
  if ((required == 0) || (required->type != kTagTypeString) ||
      !strcmp(required->string, "Safe Boot")) {
    FreeTag(moduleDict);
    return -1;
  }
  
  tmpModule = AllocateBootXMemory(sizeof(Module));
  if (tmpModule == 0) {
    FreeTag(moduleDict);
    return -1;
  }
  tmpModule->dict = moduleDict;
  
  // For now, load any module that has OSBundleRequired != "Safe Boot".
  tmpModule->willLoad = 1;
  
  *module = tmpModule;
  
  // Get the personalities.
  *personalities = GetProperty(moduleDict, kPropIOKitPersonalities);
  
  return 0;
}


static long ParseNextTag(char *buffer, TagPtr *tag)
{
  long length, pos;
  char *tagName;
  
  length = GetNextTag(buffer, &tagName, 0);
  if (length == -1) return -1;
  
  pos = length;
  if (!strncmp(tagName, kXMLTagPList, 6)) {
    length = 0;
  } else if (!strcmp(tagName, kXMLTagDict)) {
    length = ParseTagList(buffer + pos, tag, kTagTypeDict, 0);
  } else if (!strcmp(tagName, kXMLTagDict "/")) {
    length = ParseTagList(buffer + pos, tag, kTagTypeDict, 1);
  } else if (!strcmp(tagName, kXMLTagKey)) {
    length = ParseTagKey(buffer + pos, tag);
  } else if (!strcmp(tagName, kXMLTagString)) {
    length = ParseTagString(buffer + pos, tag);
  } else if (!strcmp(tagName, kXMLTagInteger)) {
    length = ParseTagInteger(buffer + pos, tag);
  } else if (!strcmp(tagName, kXMLTagData)) {
    length = ParseTagData(buffer + pos, tag);
  } else if (!strcmp(tagName, kXMLTagDate)) {
    length = ParseTagDate(buffer + pos, tag);
  } else if (!strcmp(tagName, kXMLTagFalse)) {
    length = ParseTagBoolean(buffer + pos, tag, kTagTypeFalse);
  } else if (!strcmp(tagName, kXMLTagTrue)) {
    length = ParseTagBoolean(buffer + pos, tag, kTagTypeTrue);
  } else if (!strcmp(tagName, kXMLTagArray)) {
    length = ParseTagList(buffer + pos, tag, kTagTypeArray, 0);
  } else if (!strcmp(tagName, kXMLTagArray "/")) {
    length = ParseTagList(buffer + pos, tag, kTagTypeArray, 1);
  } else {
    *tag = 0;
    length = 0;
  }
  
  if (length == -1) return -1;
  
  return pos + length;
}


static long ParseTagList(char *buffer, TagPtr *tag, long type, long empty)
{
  long   length, pos;
  TagPtr tagList, tmpTag;
  
  tagList = 0;
  pos = 0;
  
  if (!empty) {
    while (1) {
      length = ParseNextTag(buffer + pos, &tmpTag);
      if (length == -1) break;
      pos += length;
      
      if (tmpTag == 0) break;
      tmpTag->tagNext = tagList;
      tagList = tmpTag;
    }
    
    if (length == -1) {
      FreeTag(tagList);
      return -1;
    }
  }
  
  tmpTag = NewTag();
  if (tmpTag == 0) {
    FreeTag(tagList);
    return -1;
  }
  
  tmpTag->type = type;
  tmpTag->string = 0;
  tmpTag->tag = tagList;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return pos;
}


static long ParseTagKey(char *buffer, TagPtr *tag)
{
  long   length, length2;
  char   *string;
  TagPtr tmpTag, subTag;
  
  length = FixDataMatchingTag(buffer, kXMLTagKey);
  if (length == -1) return -1;
  
  length2 = ParseNextTag(buffer + length, &subTag);
  if (length2 == -1) return -1;
  
  tmpTag = NewTag();
  if (tmpTag == 0) {
    FreeTag(subTag);
    return -1;
  }
  
  string = NewSymbol(buffer);
  if (string == 0) {
    FreeTag(subTag);
    FreeTag(tmpTag);
    return -1;
  }
  
  tmpTag->type = kTagTypeKey;
  tmpTag->string = string;
  tmpTag->tag = subTag;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return length + length2;
}


static long ParseTagString(char *buffer, TagPtr *tag)
{
  long   length;
  char   *string;
  TagPtr tmpTag;
  
  length = FixDataMatchingTag(buffer, kXMLTagString);
  if (length == -1) return -1;
  
  tmpTag = NewTag();
  if (tmpTag == 0) return -1;
  
  string = NewSymbol(buffer);
  if (string == 0) {
    FreeTag(tmpTag);
    return -1;
  }
  
  tmpTag->type = kTagTypeString;
  tmpTag->string = string;
  tmpTag->tag = 0;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return length;
}


static long ParseTagInteger(char *buffer, TagPtr *tag)
{
  long   length, integer;
  TagPtr tmpTag;
  
  length = FixDataMatchingTag(buffer, kXMLTagInteger);
  if (length == -1) return -1;
  
  tmpTag = NewTag();
  if (tmpTag == 0) return -1;
  
  integer = 0;
  
  tmpTag->type = kTagTypeInteger;
  tmpTag->string = (char *)integer;
  tmpTag->tag = 0;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return length;
}


static long ParseTagData(char *buffer, TagPtr *tag)
{
  long   length;
  TagPtr tmpTag;
  
  length = FixDataMatchingTag(buffer, kXMLTagData);
  if (length == -1) return -1;
  
  tmpTag = NewTag();
  if (tmpTag == 0) return -1;
  
  tmpTag->type = kTagTypeData;
  tmpTag->string = 0;
  tmpTag->tag = 0;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return length;
}


static long ParseTagDate(char *buffer, TagPtr *tag)
{
  long   length;
  TagPtr tmpTag;
  
  length = FixDataMatchingTag(buffer, kXMLTagDate);
  if (length == -1) return -1;
  
  tmpTag = NewTag();
  if (tmpTag == 0) return -1;
  
  tmpTag->type = kTagTypeDate;
  tmpTag->string = 0;
  tmpTag->tag = 0;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return length;
}


static long ParseTagBoolean(char *buffer, TagPtr *tag, long type)
{
  TagPtr tmpTag;
  
  tmpTag = NewTag();
  if (tmpTag == 0) return -1;
  
  tmpTag->type = type;
  tmpTag->string = 0;
  tmpTag->tag = 0;
  tmpTag->tagNext = 0;
  
  *tag = tmpTag;
  
  return 0;
}


static long GetNextTag(char *buffer, char **tag, long *start)
{
  long cnt, cnt2;
  
  if (tag == 0) return -1;
  
  // Find the start of the tag.
  cnt = 0;
  while ((buffer[cnt] != '\0') && (buffer[cnt] != '<')) cnt++;
  if (buffer[cnt] == '\0') return -1;
  
  // Find the end of the tag.
  cnt2 = cnt + 1;
  while ((buffer[cnt2] != '\0') && (buffer[cnt2] != '>')) cnt2++;
  if (buffer[cnt2] == '\0') return -1;
  
  // Fix the tag data.
  *tag = buffer + cnt + 1;
  buffer[cnt2] = '\0';
  if (start) *start = cnt;
  
  return cnt2 + 1;
}


static long FixDataMatchingTag(char *buffer, char *tag)
{
  long length, start, stop;
  char *endTag;
  
  start = 0;
  while (1) {
    length = GetNextTag(buffer + start, &endTag, &stop);
    if (length == -1) return -1;
    
    if ((*endTag == '/') && !strcmp(endTag + 1, tag)) break;
    start += length;
  }
  
  buffer[start + stop] = '\0';
  
  return start + length;
}


#define kTagsPerBlock (0x1000)

static TagPtr gTagsFree;

static TagPtr NewTag(void)
{
  long   cnt;
  TagPtr tag;
  
  if (gTagsFree == 0) {
    tag = (TagPtr)AllocateBootXMemory(kTagsPerBlock * sizeof(Tag));
    if (tag == 0) return 0;
    
    // Initalize the new tags.
    for (cnt = 0; cnt < kTagsPerBlock; cnt++) {
      tag[cnt].type = kTagTypeNone;
      tag[cnt].string = 0;
      tag[cnt].tag = 0;
      tag[cnt].tagNext = tag + cnt + 1;
    }
    tag[kTagsPerBlock - 1].tagNext = 0;
    
    gTagsFree = tag;
  }
  
  tag = gTagsFree;
  gTagsFree = tag->tagNext;
  
  return tag;
}


static void FreeTag(TagPtr tag)
{
  return;
  if (tag == 0) return;
  
  if (tag->string) FreeSymbol(tag->string);
  
  FreeTag(tag->tag);
  FreeTag(tag->tagNext);
  
  // Clear and free the tag.
  tag->type = kTagTypeNone;
  tag->string = 0;
  tag->tag = 0;
  tag->tagNext = gTagsFree;
  gTagsFree = tag;
}


struct Symbol {
  long          refCount;
  struct Symbol *next;
  char          string[1];
};
typedef struct Symbol Symbol, *SymbolPtr;

static SymbolPtr FindSymbol(char *string, SymbolPtr *prevSymbol);

static SymbolPtr gSymbolsHead;


static char *NewSymbol(char *string)
{
  SymbolPtr symbol;
  
  // Look for string in the list of symbols.
  symbol = FindSymbol(string, 0);
  
  // Add the new symbol.
  if (symbol == 0) {
    symbol = AllocateBootXMemory(sizeof(Symbol) + strlen(string));
    if (symbol == 0) return 0;
    
    // Set the symbol's data.
    symbol->refCount = 0;
    strcpy(symbol->string, string);
    
    // Add the symbol to the list.
    symbol->next = gSymbolsHead;
    gSymbolsHead = symbol;
  }
  
  // Update the refCount and return the string.
  symbol->refCount++;
  return symbol->string;
}


static void FreeSymbol(char *string)
{ 
#if 0
  SymbolPtr symbol, prev;
  
  // Look for string in the list of symbols.
  symbol = FindSymbol(string, &prev);
  if (symbol == 0) return;
  
  // Update the refCount.
  symbol->refCount--;
  
  if (symbol->refCount != 0) return;
  
  // Remove the symbol from the list.
  if (prev != 0) prev->next = symbol->next;
  else gSymbolsHead = symbol->next;
  
  // Free the symbol's memory.
  free(symbol);
#endif
}


static SymbolPtr FindSymbol(char *string, SymbolPtr *prevSymbol)
{
  SymbolPtr symbol, prev;
  
  symbol = gSymbolsHead;
  prev = 0;
  
  while (symbol != 0) {
    if (!strcmp(symbol->string, string)) break;
    
    prev = symbol;
    symbol = symbol->next;
  }
  
  if ((symbol != 0) && (prevSymbol != 0)) *prevSymbol = prev;
  
  return symbol;
}

#if DRIVER_DEBUG
static void DumpTagDict(TagPtr tag, long depth);
static void DumpTagKey(TagPtr tag, long depth);
static void DumpTagString(TagPtr tag, long depth);
static void DumpTagInteger(TagPtr tag, long depth);
static void DumpTagData(TagPtr tag, long depth);
static void DumpTagDate(TagPtr tag, long depth);
static void DumpTagBoolean(TagPtr tag, long depth);
static void DumpTagArray(TagPtr tag, long depth);
static void DumpSpaces(long depth);

static void DumpTag(TagPtr tag, long depth)
{
  if (tag == 0) return;
  
  switch (tag->type) {
  case kTagTypeDict :
    DumpTagDict(tag, depth);
    break;
    
  case kTagTypeKey :
    DumpTagKey(tag, depth);
    break;
    
  case kTagTypeString :
    DumpTagString(tag, depth);
    break;
    
  case kTagTypeInteger :
    DumpTagInteger(tag, depth);
    break;
    
  case kTagTypeData :
    DumpTagData(tag, depth);
    break;
    
  case kTagTypeDate :
    DumpTagDate(tag, depth);
    break;
    
  case kTagTypeFalse :
  case kTagTypeTrue :
    DumpTagBoolean(tag, depth);
    break;
    
  case kTagTypeArray :
    DumpTagArray(tag, depth);
    break;
    
  default :
    break;
  }
}


static void DumpTagDict(TagPtr tag, long depth)
{
  TagPtr tagList;
  
  if (tag->tag == 0) {
    DumpSpaces(depth);
    printf("<%s/>\n", kXMLTagDict);
  } else {
    DumpSpaces(depth);
    printf("<%s>\n", kXMLTagDict);
    
    tagList = tag->tag;
    while (tagList) {
      DumpTag(tagList, depth + 1);
      tagList = tagList->tagNext;
    }
    
    DumpSpaces(depth);
    printf("</%s>\n", kXMLTagDict);
  }
}


static void DumpTagKey(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>%s</%s>\n", kXMLTagKey, tag->string, kXMLTagKey);
  
  DumpTag(tag->tag, depth);
}


static void DumpTagString(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>%s</%s>\n", kXMLTagString, tag->string, kXMLTagString);
}


static void DumpTagInteger(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>%x</%s>\n", kXMLTagInteger, tag->string, kXMLTagInteger);
}


static void DumpTagData(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>%x</%s>\n", kXMLTagData, tag->string, kXMLTagData);
}


static void DumpTagDate(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>%x</%s>\n", kXMLTagDate, tag->string, kXMLTagDate);
}


static void DumpTagBoolean(TagPtr tag, long depth)
{
  DumpSpaces(depth);
  printf("<%s>\n", (tag->type == kTagTypeTrue) ? kXMLTagTrue : kXMLTagFalse);
}


static void DumpTagArray(TagPtr tag, long depth)
{
  TagPtr tagList;
  
  if (tag->tag == 0) {
    DumpSpaces(depth);
    printf("<%s/>\n", kXMLTagArray);
  } else {
    DumpSpaces(depth);
    printf("<%s>\n", kXMLTagArray);
    
    tagList = tag->tag;
    while (tagList) {
      DumpTag(tagList, depth + 1);
      tagList = tagList->tagNext;
    }
    
    DumpSpaces(depth);
    printf("</%s>\n", kXMLTagArray);
  }
}


static void DumpSpaces(long depth)
{
  long cnt;
  
  for (cnt = 0; cnt < (depth * 4); cnt++) putchar(' ');
}
#endif