Documenting our reference count management

1 files changed, 161 insertions, 3 deletions

diff --git a/doc/FileSystem.3 b/doc/FileSystem.3
index 0a3aeef..4e901e0 100644
--- a/doc/FileSystem.3
+++ b/doc/FileSystem.3
@@ -45,7 +45,7 @@ int
 \fBTcl_FSDeleteFile\fR(\fIpathPtr\fR)
 .sp
 int
-\fBTcl_FSRemoveDirectory\fR(\fIpathPtr, int recursive, errorPtr\fR)
+\fBTcl_FSRemoveDirectory\fR(\fIpathPtr, recursive, errorPtr\fR)
 .sp
 int
 \fBTcl_FSRenameFile\fR(\fIsrcPathPtr, destPathPtr\fR)
@@ -79,10 +79,10 @@ int
 \fBTcl_FSUtime\fR(\fIpathPtr, tval\fR)
 .sp
 int
-\fBTcl_FSFileAttrsGet\fR(\fIinterp, int index, pathPtr, objPtrRef\fR)
+\fBTcl_FSFileAttrsGet\fR(\fIinterp, index, pathPtr, objPtrRef\fR)
 .sp
 int
-\fBTcl_FSFileAttrsSet\fR(\fIinterp, int index, pathPtr, Tcl_Obj *objPtr\fR)
+\fBTcl_FSFileAttrsSet\fR(\fIinterp, index, pathPtr, objPtr\fR)
 .sp
 const char *const *
 \fBTcl_FSFileAttrStrings\fR(\fIpathPtr, objPtrRef\fR)
@@ -197,6 +197,8 @@ rename operation.
 .AP Tcl_Obj *destPathPtr in
 As for \fIpathPtr\fR, but used for the destination filename for a copy or
 rename operation.
+.AP int recursive in
+Whether to remove subdirectories and their contents as well.
 .AP "const char" *encodingName in
 The encoding of the data stored in the
 file identified by \fIpathPtr\fR and to be evaluated.
@@ -224,6 +226,10 @@ be joined together. If negative, then all elements are joined.
 .AP Tcl_Obj **errorPtr out
 In the case of an error, filled with a value containing the name of
 the file which caused an error in the various copy/rename operations.
+.AP int index in
+The index of the attribute in question.
+.AP Tcl_Obj *objPtr in
+The value to set in the operation.
 .AP Tcl_Obj **objPtrRef out
 Filled with a value containing the result of the operation.
 .AP Tcl_Obj *resultPtr out
@@ -1628,6 +1634,158 @@ typedef int \fBTcl_FSChdirProc\fR(
 The \fBTcl_FSChdirProc\fR changes the applications current working
 directory to the value specified in \fIpathPtr\fR. The function returns
 -1 on error or 0 on success.
+.SH "REFERENCE COUNT MANAGEMENT"
+.SS "PUBLIC API CALLS"
+.PP
+For all of these functions, \fIpathPtr\fR (including the \fIsrcPathPtr\fR and
+\fIdestPathPtr\fR arguments to \fBTcl_FSCopyFile\fR,
+\fBTcl_FSCopyDirectory\fR, and \fBTcl_FSRenameFile\fR, the \fIfirstPtr\fR and
+\fIsecondPtr\fR arguments to \fBTcl_FSEqualPaths\fR, and the \fIlinkNamePtr\fR
+and \fItoPtr\fR arguments to \fBTcl_FSLink\fR) must not be a zero reference
+count value; references may be retained in internal caches even for
+theoretically read-only operations.  These functions may also manipulate the
+interpreter result (if they take and are given a non-NULL \fIinterp\fR
+argument); you must not count on the interpreter result to hold the reference
+count of any argument value over these calls and should manage your own
+references there. However, references held by the arguments to a Tcl command
+\fIare\fR suitable for reference count management purposes for the duration of
+the implementation of that command.
+.PP
+The \fIerrorPtr\fR argument to \fBTcl_FSCopyDirectory\fR and
+\fBTcl_FSRemoveDirectory\fR is, when an object is set into it at all, set to
+an object with a non-zero reference count that should be passed to
+\fBTcl_DecrRefCount\fR when no longer needed.
+.PP
+\fBTcl_FSListVolumes\fR always returns a zero-reference object, much
+like \fBTcl_NewObj\fR.
+.PP
+\fBTcl_FSLink\fR always returns a non-zero-reference object when it is
+asked to read; you must call \fBTcl_DecrRefCount\fR on the object
+once you no longer need it.
+.PP
+\fBTcl_FSGetCwd\fR always returns a non-zero-reference object; you
+must call \fBTcl_DecrRefCount\fR on the object once you no longer need
+it.
+.PP
+\fBTcl_FSPathSeparator\fR always returns a zero-reference object, much
+like \fBTcl_NewObj\fR.
+.PP
+\fBTcl_FSJoinPath\fR always returns a zero-reference object, much
+like \fBTcl_NewObj\fR. Its \fIlistObj\fR argument can have any reference
+count; it is only read by this function.
+.PP
+\fBTcl_FSSplitPath\fR always returns a zero-reference object, much
+like \fBTcl_NewObj\fR.
+.PP
+\fBTcl_FSGetNormalizedPath\fR returns an object with a non-zero
+reference count where Tcl is the owner. You should increment its
+reference count if you want to retain it, but do not need to if you
+are just using the value immediately.
+.PP
+\fBTcl_FSJoinToPath\fR always returns a zero-reference object, much like
+\fBTcl_NewObj\fR. Its \fIbasePtr\fR argument follows the rules above for
+\fIpathPtr\fR, as do the values in the \fIobjv\fR argument.
+.PP
+\fBTcl_FSGetTranslatedPath\fR returns a non-zero-reference object (or
+NULL in the error case); you must call \fBTcl_DecrRefCount\fR on the
+object once you no longer need it.
+.PP
+\fBTcl_FSNewNativePath\fR always returns a zero-reference object (or
+NULL), much like \fBTcl_NewObj\fR.
+.PP
+\fBTcl_FSFileSystemInfo\fR always returns a zero-reference object (or
+NULL), much like \fBTcl_NewObj\fR.
+.PP
+The \fIobjPtr\fR and \fIobjPtrRef\fR arguments to \fBTcl_FSFileAttrsGet\fR,
+\fBTcl_FSFileAttrsSet\fR and \fBTcl_FSFileAttrStrings\fR are conventional Tcl
+values; the \fIobjPtr\fR argument will be read but not retained, and the
+\fIobjPtrRef\fR argument will have (on success) a zero-reference value written
+into it (as with \fBTcl_NewObj\fR). \fBTcl_FSFileAttrsGet\fR and
+\fBTcl_FSFileAttrsSet\fR may also manipulate the interpreter result.
+.PP
+The \fIresultPtr\fR argument to \fBTcl_FSMatchInDirectory\fR will not have its
+reference count manipulated, but it should have a reference count of no more
+than 1, and should not be the current interpreter result (as the function may
+overwrite that on error).
+.SS "VIRTUAL FILESYSTEM INTERFACE"
+.PP
+For all virtual filesystem implementation functions, any \fIpathPtr\fR
+arguments should not have their reference counts manipulated. If they take an
+\fIinterp\fR argument, they may set an error message in that, but must not
+manipulate the \fIpathPtr\fR afterwards. Aside from that:
+.TP
+\fIinternalToNormalizedProc\fR
+.
+This should return a zero-reference count value, as if allocated with
+\fBTcl_NewObj\fR.
+.TP
+\fInormalizePathProc\fR
+.
+Unlike with other API implementation functions, the \fIpathPtr\fR argument
+here is guaranteed to be an unshared object that should be updated. Its
+reference count should not be modified.
+.TP
+\fIfilesystemPathTypeProc\fR
+.
+The return value (if non-NULL) either has a reference count of zero or needs
+to be maintained (on a per-thread basis) by the filesystem. Tcl will increment
+the reference count of the value if it wishes to retain it.
+.TP
+\fIfilesystemSeparatorProc\fR
+.
+The return value should be a value with reference count of zero.
+.TP
+\fImatchInDirectoryProc\fR
+.
+The \fIresultPtr\fR argument should be assumed to hold a list that can be
+appended to (i.e., that has a reference count no greater than 1). No reference
+to it should be retained.
+.TP
+\fIlinkProc\fR
+.
+If \fItoPtr\fR is NULL, this should return a value with reference count 1 that
+has just been allocated and passed to \fBTcl_IncrRefCount\fR. If \fItoPtr\fR
+is not NULL, it should be returned on success. 
+.TP
+\fIlistVolumesProc\fR
+.
+The result value should be a list (if non-NULL); it will have its reference
+count decremented once (with \fBTcl_DecrRefCount\fR) by Tcl once done.
+.TP
+\fIfileAttrStringsProc\fR
+.
+If the result is NULL, the \fIobjPtrRef\fR should have a list value written to
+it; that list will have its reference count both incremented (with
+\fBTcl_IncrRefCount\fR) and decremented (with \fBTcl_DecrRefCount\fR).
+.TP
+\fIfileAttrsGetProc\fR
+.
+The \fIobjPtrRef\fR argument should have (on non-error return) a zero
+reference count value written to it (allocated as if with \fBTcl_NewObj\fR).
+.TP
+\fIfileAttrsSetProc\fR
+.
+The \fIobjPtr\fR argument should either just be read or its reference count
+incremented to retain it.
+.TP
+\fIremoveDirectoryProc\fR
+.
+If an error is being reported, the problem filename reported via
+\fIerrorPtr\fR should be newly allocated (as if with \fBTcl_NewObj\fR) and
+have a reference count of 1 (i.e., have been passed to
+\fBTcl_IncrRefCount\fR).
+.TP
+\fIcopyDirectoryProc\fR
+.
+If an error is being reported, the problem filename reported via
+\fIerrorPtr\fR should be newly allocated (as if with \fBTcl_NewObj\fR) and
+have a reference count of 1 (i.e., have been passed to
+\fBTcl_IncrRefCount\fR).
+.TP
+\fIgetCwdProc\fR
+.
+The result will be passed to \fBTcl_DecrRefCount\fR by the implementation of
+\fBTcl_FSGetCwd\fR after it has been normalized.
 .SH "SEE ALSO"
 cd(n), file(n), filename(n), load(n), open(n), pwd(n), source(n), unload(n)
 .SH KEYWORDS