Apple Network Setup manual AssertpackedPref != nil assertunpackedPref != nil

C H A P T E R 2

Using Network Setup

static OSStatus MyUnpackTCPInterfacesPref(const OTCfgTCPInterfacesPacked *packedPref, ByteCount packedPrefSize, OTCfgTCPInterfacesUnpacked *unpackedPref)

{

UInt8 *cursor;

assert(packedPref != nil); assert(unpackedPref != nil);

//Put the cursor at the beginning of the packed preference data. cursor = (UInt8 *) packedPref;

//Walk through the packed preference data and extract the fields. unpackedPref->fCount = *((UInt16 *) cursor);

if (unpackedPref->fCount != 1) goto prefDataErr; cursor += sizeof(UInt16);

unpackedPref->fConfigMethod = *cursor; cursor += sizeof(UInt8);

//The following code accesses a long off a word.

//Network Setup is PowerPC only, and the emulated PowerPC processor handles these

//misaligned accesses.

unpackedPref->fIPAddress = *((InetHost *) cursor); cursor += sizeof(InetHost); unpackedPref->fSubnetMask = *((InetHost *) cursor); cursor += sizeof(InetHost);

//fAppleTalkZone is a Str32. A longer string in the 'iitf' preference causes an

error.

if ( *cursor > 32 ) goto prefDataErr;

BlockMoveData(cursor, unpackedPref->fAppleTalkZone, *cursor + 1); cursor += (*cursor + 1);

BlockMoveData(cursor, unpackedPref->path, 36); cursor += 36;

BlockMoveData(cursor, unpackedPref->module, 32); cursor += 32;

unpackedPref->framing = *((UInt32 *) cursor); cursor += sizeof(UInt32);

52Protocol-specific Topics