ref: 2459e34d77e2e21ef829c0dfaafd99433899494f
dir: /man/2/palmfile/
.TH PALMFILE 2
.SH NAME
Palmfile: Categories, DBInfo, Doc, Entry, Pfile, Record \- read Palm™ file formats
.SH SYNOPSIS
.EX
include "bufio.m";
include "palmfile.m";
palmfile := load Palmfile Palmfile->PATH;
Pfile: adt {
fname: string;
appinfo: array of byte;
sortinfo: array of int;
entries: array of ref Entry;
open: fn(name: string, mode: int): (ref Pfile, string);
. # create: fn(nil: string, mode: int, perm: int, nil: ref DBInfo): ref Pfile;
close: fn(pf: self ref Pfile): int;
read: fn(pf: self ref Pfile, index: int): (ref Record, string);
. # append: fn(pf: self ref Pfile, r: ref Record): int;
stat: fn(pf: self ref Pfile): ref DBInfo;
. # wstat: fn(pf: self ref Pfile, nil: ref DBInfo): string;
. # readid: fn(pf: self ref Pfile, nil: int): (ref Record, string);
. # setappinfo: fn(pf: self ref Pfile, nil: array of byte);
. # setsortinfo: fn(pf: self ref Pfile, nil: array of int);
};
DBInfo: adt {
name: string; # database name on Palm
attr: int; # file attributes (defined below)
dtype: string; # database type (byte[4])
version: int; # version of data layout, defined by application
creator: string; # creating application (byte[4])
ctime: int; # creation time
mtime: int; # modification time
btime: int; # last backup
modno: int; # modification number
uidseed: int; # unique record ID seed
new: fn(name: string, attr: int, dtype: string,
version: int, creator: string): ref DBInfo;
};
Entry: adt {
id: int; # resource: id; record: unique ID
offset: int; # offset in file
size: int; # size in bytes
name: int; # resource entry only
attr: int; # record entry only
};
Record: adt {
id: int; # resource: ID; data: unique record ID
index: int; # record index (origin 0)
name: int; # byte[4]: resource record only
attr: int; # attributes, defined below, data record only
cat: int; # category, data record only
data: array of byte; # content of record
. # new: fn(size: int): ref Record;
};
Categories: adt {
renamed: int; # which categories have been renamed
labels: array of string; # category names
uids: array of int; # corresponding unique IDs
lastuid: int; # last unique ID assigned
appdata: array of byte; # remaining application-specific data
new: fn(labels: array of string): ref Categories;
unpack: fn(a: array of byte): ref Categories;
pack: fn(c: self ref Categories): array of byte;
};
Doc: adt {
version: int;
length: int; # uncompressed
nrec: int; # text records only
recsize: int; # uncompressed
position: int;
sizes: array of int; # sizes of uncompressed records
open: fn(file: ref Pfile): (ref Doc, string);
read: fn(doc: self ref Doc, i: int): (string, string);
iscompressed: fn(doc: self ref Doc): int;
unpacktext: fn(doc: self ref Doc, a: array of byte):
(string, string);
textlength: fn(doc: self ref Doc, a: array of byte): int;
};
init: fn(): string;
filename: fn(s: string): string;
dbname: fn(s: string): string;
gets: fn(a: array of byte): string;
puts: fn(a: array of byte, s: string);
get2: fn(a: array of byte): int;
get3: fn(a: array of byte): int;
get4: fn(a: array of byte): int;
put2: fn(a: array of byte, v: int);
put3: fn(a: array of byte, v: int);
put4: fn(a: array of byte, v: int);
.EE
.SH DESCRIPTION
.B Palmfile
provides read-only access to files in the Palm™ database and document formats.
It currently handles three types of files:
Palm Database
.RB ( .pdb )
files, which store data for applications;
Palm Resource
.RB ( .prc )
files, which store code resources and user interface resource elements;
and
Palm Doc
.RB ( .doc )
files, which store compressed documents for the Palm document and e-book readers.
Database and resource files have a similar structure, with slight differences
in representation, and differing mainly in how the contents are used.
.PP
.B Init
must be called before any other function in the file.
It returns a diagnostic if it cannot initialise the module.
.PP
.B Pfile
represents an open Palm file of any type:
.TP
.B open()
Opens file
.I name
with the given
.I mode
(which must currently be
.BR Sys->OREAD )
and returns a tuple
.RI ( pf , err ).
.I Pf
is a new
.B Pfile
instance giving access to the file,
or nil if the open failed, in which case the
.I err
string contains a diagnostic.
.TP
.IB pf .close()
Close the file (needed only when writing to a file is eventually supported).
.TP
.IB pf .read( index )
Returns a tuple
.RI ( rec,\ err )
where
.I rec
is a
.B Record
containing the data of the record
with the given
.I index
(origin 0), or
nil if no such record index exists or it cannot be read.
In the latter case,
.I err
is a diagnostic string.
.TP
.IB pf .stat()
Return the database information for
.IR pf .
.TP
.B entries
An array of
.B Entry
values (see below), one per record.
The length of the array is consequently the length of
the file in records.
It can be nil or empty.
.TP
.B appinfo
Optional application-specific data (see
.B Categories
below).
.TP
.B sortinfo
Optional application-specific data (typically
an array of record IDs in a chosen sorting order).
.TP
.B fname
File name given to
.BR Pfile.open .
.PP
.B DBInfo
gives the database information for a file:
.TF creator
.PD
.TP
.B name
Database name used on the Palm, maximum of 31 characters.
.TP
.B attr
A bit set of file attributes, containing the following values:
.RS
.TF Fappinfodirty
.PD
.TP
.B Fresource
File is a resource file
.RB ( .prc )
not a database file
.RB ( .pdb ).
.TP
.B Fronly
File is read only.
.TP
.B Fappinfodirty
Application information has changed.
.TP
.B Fbackup
No conduit program exists (the whole file must be backed up).
.TP
.B Foverwrite
Overwrite older copy if present.
.TP
.B Freset
Reset PDA after installing this file.
.TP
.B Fprivate
Don't allow copy of this file to be beamed.
.RE
.TP
.B dtype
String identifying database type (up to 4 characters).
It is usually the string
\f5"appI"\fP for resource files.
.TP
.B version
Identifies the version of the data format (application specific).
.TP
.B creator
String identifying creating application (up to 4 characters).
.TP
.B ctime
File creation time, in seconds from the Inferno epoch (see
.IR daytime (2)).
.TP
.B mtime
Time file last modified, in seconds from the epoch.
.TP
.B btime
Time file last backed up, in seconds from the epoch.
.TP
.B uidseed
Seed for generating unique record IDs (typically set to 0 for database files,
always 0 for resource files).
.TP
.BI new( name,\ attr,\ dtype,\ creator )
Return a new
.B DBInfo
with the given values.
.PP
In some applications, it is useful to use a data base name
(ie,
.BR DBInfo.name )
as a component of an Inferno file name.
The device allows space and slash characters in names, though,
which makes it hard to use the name directly.
.B Filename
maps each space character
in
.I s
to U+00A0 (unpaddable space)
and each slash character to U+2215 (`division /'),
and returns the result.
.B Dbname
maps the other way.
.SS Entries and Records
Each record in the file is represented by an
.B Entry
in memory, which holds the record's essential attributes,
leaving the data on file.
The meaning of some of the elements depends on whether
the file is a data file or a resource file.
.TF offset
.PD
.TP
.B id
Resource ID, 16 bits (resource file); unique record ID, 24 bits (data file).
.TP
.B offset
Offset in file, in bytes.
.TP
.B size
Size of record in bytes.
.TP
.B name
Name of the resource (resource record only).
.TP
.B attrs
Record attributes (data record only):
.RS
.TF Rarchive
.PD
.TP
.B Rdelete
Delete the record when file next synchronised.
.TP
.B Rdirty
Record has been modified.
.TP
.B Rinuse
Record in use (not typically used in Inferno).
.TP
.B Rsecret
Record is secret (shown on the device only with use of a password).
.TP
.B Rarchive
Archive this record when file next synchronised.
.TP
.B Rmcat
Mask for the 4-bit category field (in
.B Entry.attrs
only).
.RE
.PP
Records read from the file are represented by a
.B Record
adt containing its data and associated values.
Some fields are valid only for particular classes of records.
.TF index
.PD
.TP
.B id
Resource or record ID, as for
.BR Entry .
.TP
.B index
Index (origin 0) of the record in the file.
.TP
.B name
Resource name (resource record only).
.TP
.B attr
Record attributes, as above (data record only).
.TP
.B cat
Record's category ID (data record only).
.TP
.B data
The actual data.
.SS Application data
The contents of both the ``application information'' and ``sort information'' sections of the file
are defined by an application in general.
Even so, both have conventional uses with many Palm applications.
The Palm software often assigns data records to particular categories (eg, ``Business'' or ``Personal''),
and stores up to 16 category names and IDs in the application data in a fixed format
(possibly followed by further data that is application specific).
This is represented by an instance of
.BR Categories ,
which provides the following:
.TF renamed
.PD
.TP
.B renamed
Bit set indicating which categories have been renamed (for category 0, bit
.BR 1<<0 ,
for 1, bit
.BR 1<<1 ,
and so on).
.TP
.B labels
Array of 16 category labels.
.TP
.B uids
Array of 16 category IDs, each in the range 0 to 255.
(It is said that the Palm itself assigns 0 to 127 and desktop applications assign 128 to 255.)
.TP
.B lastuid
Last unique category ID assigned.
.TP
.B appdata
Any data that remained after unpacking the category data.
.TP
.BI new( labels )
Return a new
.B Categories
value for the given array of
.IR labels ,
assigning unique IDs to each in turn, starting from 128.
There can be at most 16 labels; if there are fewer, the remaining labels will be marked as unused
(empty strings).
.TP
.BI unpack( a )
Unpack the application data in array
.I a
(typically
.IB pf .appinfo
for some
.B Pfile
.IR pf ),
returning a reference to a new
.B Categories
instance.
A nil value is returned if the array is too short to hold valid category data.
.TP
.IB c .pack()
Pack
.I c
into a form suitable for writing back to a file's application information area.
.PP
Binary data in Palm files is typically encoded in big-endian form.
.B Palmfile
functions account for that internally, but some Palm applications might use
big-endian data in their own data records.
Several functions are therefore provided to decode and encode big-endian data:
.BI get n
retrieves an integer from the first
.I n
bytes of array
.IR a ;
.BI put n
stores a big-endian representation of the value
.I v
in the first
.I n
bytes of array
.IR a .
.PP
Strings are stored in fixed-length arrays of bytes, always terminated by a zero byte.
The character encoding is (apparently) Latin-1 (ISO 8859-1), not UTF-8,
so functions
.B gets
and
.B puts
are provided to convert between that representation and a Limbo string.
.SS Documents
.B Doc
provides read-only access to Palm documents and (unencrypted) e-books:
.TF position
.PD
.TP
.BI open( file )
Given a
.B Pfile
.IR file ,
return a tuple
.RI ( doc,\ err )
where
.I doc
is a new
.B Doc
instance giving access to the document contents in
.IR file .
If an error occurs, in particular if
.I file
does not appear to be a valid Palm document,
.I doc
is nil and the string
.I err
diagnoses the error.
.TP
.IB doc .iscompressed()
Returns true (non-zero) if the document is compressed; returns false (zero) otherwise.
.TP
.IB doc .read( i )
Read text record with index
.I i
(origin 0),
returning a tuple
.RI ( s,\ err )
where
.I s
is the uncompressed text for record
.IR i ,
or nil if the record does not exist (or there is an error reading it).
On any error,
.I err
is a diagnostic string.
Note that
.I i
is an index into the set of text records, and is not an index into the set of all records.
It must be no greater than
.IB doc .nrec .
.IB doc .unpacktext( a )
Returns a tuple
.RI ( s,\ err )
where
.I s
is the text in array
.IR a ,
after uncompressing if
.I doc
contains compressed records.
Following Palm conventions, the text is assumed to be written in the Latin-1 encoding (ISO-8859-1).
If it is compressed but the data in
.I a
is corrupt (cannot be uncompressed),
.I s
is nil and
.I err
diagnoses the problem.
.TP
.IB doc .textlength( a )
Returns the number of bytes required to store the text in array
.I a
once it has been uncompressed (if necessary).
.TP
.B version
The document's version number.
.TP
.B length
The length of the whole document in bytes, when uncompressed.
.TP
.B nrec
Number of text records in the document.
.TP
.B recsize
Size of uncompressed text records.
.TP
.B position
Possibly records the position where reading last stopped.
.TP
.B sizes
Array giving sizes of all text records, once uncompressed.
.PP
Most document-reading applications require only
.B Doc.open
and
.BR Doc.read ,
and perhaps
.BR Doc.length
to guide the construction of scroll bars (for instance).
.SH SOURCE
.B /appl/lib/palmfile.b
.SH SEE ALSO
.IR "Palm® File Format Specification" ,
Gary Hillerson, Palm Inc.,
Document Number 3008-004,
1 May 2001.
. br
.IR "[Palm®] standard text document file format" ,
Paul Lucas, 18 August 1998.