Apple II
Technical Notes
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                                                  Developer Technical Support
Apple IIgs
#14: Standard File Screwiness

Revised by: Dave Lyons                                               May 1992
Written by: Guillermo Ortiz, Matt Deatherage, & Dave Lyons          June 1987

This Technical Note describes known anomalies in Standard File.

CHANGES SINCE DECEMBER 1991:  Updated for System 6.0. Problems with the
infinite loop and SFMultiGet2 reply record are fixed.
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PREFIX CHECK IS CASE SENSITIVE

When you advance to the next volume using Command-Tab (or just Tab, before
6.0), Standard File checks your prefix against the name of the volume now in
the same device you were just using, to see if you switched disks (this is
possible on a 5.25 drive, for example).  If the name doesn't match, you stay
at the same device.

Unfortunately, the comparison in 6.0 and earlier is case sensitive.  If you
have a volume called "MyDisk" and prefix zero is set to ":MYDISK", advancing
to the next volume doesn't get you anywhere the first time (but the prefix
changes from ":MYDISK" to ":MyDisk").

The following two problems are fixed in System 6.0:

INFINITE LOOP WITH EMPTY PREFIXES

In System Software versions 5.0 through 5.0.4, all Standard File dialogs can
hang if both prefixes 0 and 8 are empty (GS/OS uses prefix 8 to expand partial
pathnames if prefix 0 is empty).

If this affects your software, use GetPrefix to check for empty prefixes
before calling Standard File.  If 0 and 8 are both empty, set prefix 0 to "*:"
(or any other convenient pathname).

SFMultiGet2 (AND SFPMultiGet2) REPLY RECORD

SFMultiGet2 and SFPMultiGet2 in System 5.0.4 and earlier accidentally validate
the multi-file reply record as if it were a regular new-style reply record (as
for SFGetFile2, for example).  The validation is a check that the words at
offsets $08 and $0E in the record are not $0002 (these are nameRefDesc and
pathRefDesc in a new-style reply record).

To ensure that Standard File does not erroneously reject your multi-file reply
record (and return error $1704), you may include ten bytes of $00 following
the six-byte record.

Further Reference
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   o   Apple IIgs Toolbox Reference, Volumes 2 & 3