All Databases Inside Mac - Basic Toolbox

ResolveAliasFile

Resolve an alias file

#include <Aliases.h> Finder Interface

OSErr ResolveAliasFile (theSpec, resolvedAliasChains, targetIsFolder,

wasAliased);

FSSpec *theSpec ; pointer to a file system specification record

Boolean resolvedAliasChains ; TRUE = resolve all aliases in a chain

Boolean * targetIsFolder ; TRUE = target is a folder

Boolean *wasAliased ; TRUE = target was aliased

ResolveAliasFile, like all other Alias Manager routines, accepts and

returns file specifications only in the form of file system specification records

defined by the FSSpec data type. The file system specification record

represents a simple and complete description of a file system object. It

contains a volume reference number, a parent directory ID, and a name. Use

the File Manager function MakeFSSpec to convert other forms of file

identification, such as full pathnames, into file system specifications.

You specify the file or directory you plan to open by passing a file system

specification record in the parameter theSpec. ResolveAliasFile returns the

name and location of the target file in theSpec.

ResolveAliasFile can follow a chain of aliases, up to a reasonable maximum

defined for the system, to the ultimate target. Set the resolveAliasChains

parameter to TRUE if you want ResolveAliasFile to resolve all aliases in a

chain, stopping only when it reaches the target file. Set it to FALSE if you want

to resolve only one alias file, even if the target is another alias file.

The parameters targetIsFolder and wasAliased are return parameters only.

ResolveAliasFile always initializes these parameters to FALSE. It sets

targetIsFolder to TRUE if the parameter theSpec points to a directory or a

volume. It sets wasAliased to TRUE if the file originally passed in the

parameter theSpec points to an alias file.

ResolveAliasFile first checks the catalog entry for the file or directory

specified in theSpec to determine whether it is an alias and whether it is a file

or a directory. If the object is not an alias, ResolveAliasFile leaves theSpec

un changed, sets the targetIsFolder parameter to TRUE for a directory or

volume and FALSE for a file, sets wasAliased to FALSE, and returns noErr. If

the object is an alias, ResolveAliasFile resolves it, places the target in the

parameter theSpec, and sets the wasAliased flag to TRUE.

When ResolveAliasFile finds the specified volume and parent directory but

fails to find the target file or directory in that location, ResolveAliasFile

returns a result code of fnfErr and fills in the parameter theSpec with a

complete file system specification record describing the target (that is, the

volume reference number, parent directory ID, and filename or folder name).

The file system specification record is valid, although the object it describes

does not exist. This information is intended as a “hint” that lets you explore

possible solutions to the resolution failure. You can, for example, use the file

system specification record to create a replacement for a missing file with the

File Manager function FSpCreate.

If ResolveAliasFile receives an error code while resolving an alias, it

leaves the input parameters as they are and exits, returning the error code. In

addition to any of these result codes, ResolveAliasFile can also return any

Resource Manager or File Manager errors.

Note: When opening a file without going through the Finder or the

Standard File Package, you call ResolveAliasFile immediately

before opening the file. In the following code example, the customized open

function, MyOpen, ensures that the file to be opened is the target file, and

then opens the data fork with the FSpOpenDF function.

Returns: an Error code. It will be one of the following:

nsvErr (-35) Volume not found

fnfErr (-43 Target not found, but volume and parent directory

found, and theSpec parameter contains a valid file

system specification record

dirNFErr (-120) Parent directory not found

The following is an example of using ResolveAliasFile:

Using the ResolveAliasFile function to open a file

// Assuming inclusion of

#include <Aliases.h>

OSErr MyOpen (FSSpec *theSpec, char perm, short * fRefNum)

{

OSErr myErr;

Boolean targetIsFolder,wasAliased;

*fRefNum = -1; // initialize fRefNum

myErr = ResolveAliasFile (theSpec, TRUE, & targetIsFolder,

&wasAliased);

if ( targetIsFolder)

myErr = paramErr; // cannot open a folder

else

if (myErr) // try to open it

myErr = FSpOpenDF(theSpec, perm, fRefNum);

return myErr;

}

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