.\"***************************************************************************
-.\" Copyright 2018-2021,2023 Thomas E. Dickey *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
.\" Copyright 2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: scr_dump.5,v 1.39 2023/11/25 14:21:48 tom Exp $
-.TH scr_dump 5 2023-11-25 "ncurses 6.4" "File formats"
+.\" $Id: scr_dump.5,v 1.46 2024/03/23 20:42:29 tom Exp $
+.TH scr_dump 5 2024-03-23 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "File formats"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
.SH NAME
scr_dump \-
\fIcurses\fR screen dump
-.SH SYNOPSIS
-.B scr_dump
+.\"SH SYNOPSIS
.SH DESCRIPTION
The curses library provides applications with the ability to write the
contents of a window to an external file using \fBscr_dump\fP or \fBputwin\fP,
because the library truncates or fills the screen as necessary.
.bP
The ncurses6 \fBgetwin\fP reads the legacy screen dumps from ncurses5.
-.SS ncurses5 (legacy)
-The screen-dump feature was added to ncurses in June 1995.
+.SS "ncurses5 (Legacy)"
+The screen-dump feature was added to \fI\%ncurses\fP in June 1995.
While there were fixes and improvements in succeeding years,
the basic scheme was unchanged:
.bP
-The \fBWINDOW\fP structure was written in binary form.
+The \fI\%WINDOW\fP structure was written in binary form.
.bP
-The \fBWINDOW\fP structure refers to lines of data,
-which were written as an array of binary data following the \fBWINDOW\fP.
+The \fI\%WINDOW\fP structure refers to lines of data,
+which were written as an array of binary data following the \fI\%WINDOW\fP.
.bP
When \fBgetwin\fP restored the window,
it would keep track of offsets into the array of line-data
-and adjust the \fBWINDOW\fP structure which was read back into memory.
+and adjust the \fI\%WINDOW\fP structure which was read back into memory.
.PP
This is similar to Unix System\ V,
but does not write a \*(``magic number\*('' to identify the file format.
.SH PORTABILITY
-There is no standard format for \fBputwin\fP.
-This section gives a brief description of the existing formats.
-.SS X/Open Curses
-Refer to \fIX/Open Curses, Issue 7\fP (2009).
-.PP
-X/Open's documentation for \fIenhanced curses\fP says only:
+There is no standard format for
+.I curses
+screen dumps.
+A brief survey of the existing implementations follows.
+.SS "X/Open Curses"
+X/Open Curses, Issue 7 specifies little.
+It says
+(boldface emphasis added)
.RS 3
.PP
-The \fBgetwin(\ ) \fPfunction reads window-related data
-stored in the file by \fIputwin(\ )\fP.
-The function
-then creates and initializes a new window using that data.
+\*(``[t]he \fI\%getwin()\fP function reads window-related data stored in
+the file by \fI\%putwin()\fP.
+The function then creates and initializes a new window using that data.
.PP
-The \fBputwin(\ )\fP function writes all data associated
-with \fIwin\fP into the \fBstdio\fP(3) stream to which \fIfilep\fP
-points, using an \fBunspecified format\fP.
-This information can be retrieved later using \fBgetwin(\ )\fP.
+The \fI\%putwin()\fP function writes all data associated with \fIwin\fP
+into the \fI\%stdio\fP stream to which \fIfilep\fP points,
+using an \fBunspecified format\fP.
+This information can be retrieved later using \fI\%getwin()\fP.\*(''
.RE
.PP
In the mid-1990s when the X/Open Curses document was written,
-there were still systems using older, less capable curses libraries
-(aside from the BSD curses library which was not relevant to X/Open
-because it did not meet the criteria for \fIbase curses\fP).
-The document explained the term \*(``enhanced\*('' as follows:
-.RS 3
-.bP
-Shading is used to identify \fIX/Open Enhanced Curses\fP material,
-relating to interfaces included to provide enhanced capabilities
-for applications originally written to be compiled on systems
-based on the Unix operating system.
-Therefore, the features described may not be present on systems
-that conform to \fBXPG4 or to earlier XPG releases\fP.
-The relevant reference pages may provide additional
-or more specific portability warnings about use of the material.
-.RE
-.PP
-In the foregoing, emphasis was added to \fBunspecified format\fP
-and to \fBXPG4 or to earlier XPG releases\fP,
-for clarity.
-.SS Unix System V
-Unix System\ V curses identified the file format by writing a
-\*(``magic number\*('' at the beginning of the dump.
-The \fBWINDOW\fP data and the lines of text follow, all in binary form.
+there were still System\ V systems using older,
+less capable
+.I curses
+libraries.
+BSD
+.I curses
+was not relevant to X/Open because it did not meet the criteria
+for base-level conformance;
+see \fB\%ncurses\fP(3X).
+.SS "System V"
+System\ V
+.I curses
+identified the file format by writing a \*(``magic number\*('' at the
+beginning of the dump.
+The \fI\%WINDOW\fP data and the lines of text follow, all in binary form.
.PP
-The Solaris curses source has these definitions:
+Solaris
+.I curses
+has the following definitions.
.PP
.RS 4
.EX
.PP
That is, the feature was likely introduced in SVr2 (1984),
and improved in SVr3 (1987).
-The Solaris curses source has no magic number for SVr4 (1989).
-Other operating systems (AIX and HP-UX) use a magic number which would
-correspond to this definition:
+Solaris
+.I curses
+has no magic number for SVr4 (1989).
+Other System\ V operating systems
+(AIX and HP-UX)
+use a magic number that would correspond to the following.
.PP
.RS 4
.EX
.RE
.PP
That octal number in bytes is 001, 035.
-Because most Unix vendors use big-endian hardware,
-the magic number is written with the high-order byte first, e.g.,
+Because most Unix vendors at the time used big-endian hardware,
+the magic number is written with the high-order byte first.
.PP
.RS 4
.EX
.EE
.RE
.PP
-After the magic number, the \fBWINDOW\fP structure and line-data are
-written in binary format.
-While the magic number used by the Unix systems can be seen using \fBod\fP(1),
-none of the Unix systems documents the format used for screen-dumps.
+After the magic number,
+the \fI\%WINDOW\fP structure and line data are written in binary format.
+While the magic number used by these systems can be observed with
+\fIod\fP(1),
+none of them documents the format used for screen dumps.
.PP
-The Unix systems do not use identical formats.
-While collecting information for for this manual page,
-the \fIsavescreen\fP test-program
-produced dumps of different size
-(all on 64-bit hardware, on 40x80 screens):
+Nor do they use an identical format,
+even with the System\ V family.
+The
+.I \%ncurses
+.I \%savescreen
+test program was used to collect information for this manual page.
+It produced dumps of different size
+(all on 64-bit hardware,
+on 40x80 screens):
.bP
AIX (51817 bytes)
.bP
.bP
Solaris 10 (13273 bytes)
.bP
-ncurses5 (12888 bytes)
+\fI\%ncurses\fP5 (12888 bytes)
.SS Solaris
-As noted above, Solaris curses has no magic number corresponding
-to SVr4 curses.
-This is odd since Solaris was the first operating system
-to pass the SVr4 guidelines.
-Solaris has two versions of curses:
+As noted above,
+Solaris
+.I curses
+has no magic number corresponding to SVr4
+.IR curses .
+This is odd,
+since Solaris was the first operating system to meet the SVr4
+guidelines.
+Solaris furthermore supplies two versions of
+.IR curses .
.bP
-The default curses library uses the SVr3 magic number.
+The default
+.I curses
+library uses the SVr3 magic number.
.bP
-There is an alternate curses library in \fB/usr/xpg4\fP.
-This uses a textual format with no magic number.
+An alternate
+.I curses
+library
+(which we term
+.I \%xcurses),
+available in
+.IR /usr/xpg4 ,
+uses a textual format with no magic number.
.IP
-According to the copyright notice, the \fIxpg4\fP Solaris curses library was
-developed by MKS (Mortice Kern Systems) from 1990 to 1995.
+According to its copyright notice,
+this
+.I \%xcurses
+library was developed by MKS
+(Mortice Kern Systems) from 1990 to 1995.
.IP
-Like ncurses6, there is a file-header with parameters.
-Unlike ncurses6, the contents of the window are written piecemeal,
-with coordinates and attributes for each chunk of text rather
-than writing the whole window from top to bottom.
+Like ncurses6,
+it includes a header with parameters.
+Unlike ncurses6,
+the contents of the window are written piecemeal,
+with coordinates and attributes for each chunk of text rather than
+writing the whole window from top to bottom.
.SS PDCurses
-PDCurses added support for screen dumps in version 2.7 (2005).
-Like Unix System\ V and ncurses5,
-it writes the \fBWINDOW\fP structure in binary,
+.I \%PDCurses
+added support for screen dumps in version 2.7 (2005).
+Like System\ V and ncurses5,
+it writes the \fI\%WINDOW\fP structure in binary,
but begins the file with its three-byte identifier \*(``PDC\*('',
-followed by a one-byte version,
-e.g.,
+followed by a single-byte version number.
.PP
.RS 4
.EX
.EE
.RE
.SS NetBSD
-As of April 2017, NetBSD curses does
-not support \fBscr_dump\fP and \fBscr_restore\fP
-(or \fBscr_init\fP, \fBscr_set\fP),
-although it has \fBputwin\fP and \fBgetwin\fP.
+As of April 2017,
+NetBSD
+.I curses
+does not support \fB\%scr_dump\fP and \fB\%scr_restore\fP
+(or \fB\%scr_init\fP,
+\fB\%scr_set\fP),
+although it has \fB\%putwin\fP and \fB\%getwin\fP.
.PP
-Like ncurses5, NetBSD \fBputwin\fP does not identify its dumps with a
-useful magic number.
+Like ncurses5,
+NetBSD \fB\%putwin\fP does not identify its dumps with a useful magic
+number.
It writes
.bP
-the curses shared library major and minor versions
-as the first two bytes (e.g., 7 and 1),
+the
+.I curses
+shared library major and minor versions as the first two bytes
+(for example,
+7 and 1),
.bP
-followed by a binary dump of the \fBWINDOW\fP,
+followed by a binary dump of the \fI\%WINDOW\fP,
.bP
-some data for wide-characters referenced by the \fBWINDOW\fP structure, and
+some data for wide characters referenced by the \fI\%WINDOW\fP
+structure,
+and
.bP
-finally, lines as done by other implementations.
+finally,
+lines as done by other implementations.
.SH EXAMPLES
Given a simple program which writes text to the screen
(and for the sake of example, limiting the screen-size to 10x20):
ensure they are not overlooked.
.bP
Attributes are written in escaped curly braces, e.g., \*(``\e{BOLD}\*('',
-and may include a color-pair (C1 or C2 in this example).
+and may include a color pair (C1 or C2 in this example).
.bP
The parameters in the header are written out only if they are nonzero.
When reading back, order does not matter.
.SH AUTHORS
Thomas E. Dickey
.br
-extended screen-dump format for ncurses 6.0 (2015)
+extended screen-dump format for \fI\%ncurses\fP 6.0 (2015)
.sp
Eric S. Raymond
.br
-screen dump feature in ncurses 1.9.2d (1995)
+screen dump feature in \fI\%ncurses\fP 1.9.2d (1995)
.SH SEE ALSO
\fB\%curs_scr_dump\fP(3X),
\fB\%curs_util\fP(3X)
projects / ncurses.git / blobdiff