gbranden pushed a commit to branch master
in repository groff.
commit a00682e9cb4070e35139f6df59130d9ce12505ce
Author: G. Branden Robinson <[email protected]>
AuthorDate: Thu Jul 25 15:20:55 2024 -0500
[troff]: Enforce minimum page length.
* src/roff/troff/div.cpp (page_length): Clamp `pl` request argument to
the output device's vertical resolution (similarly to the way `ll` and
`lt` behave).
* doc/groff.texi.in (Page Layout):
* NEWS: Document this.
---
ChangeLog | 11 +++++++++++
NEWS | 5 +++++
doc/groff.texi.in | 12 ++++++------
src/roff/troff/div.cpp | 13 ++++++++++---
4 files changed, 32 insertions(+), 9 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 79882167f..a20737e48 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2024-07-25 G. Branden Robinson <[email protected]>
+
+ [troff]: Enforce minimum page length.
+
+ * src/roff/troff/div.cpp (page_length): Clamp `pl` request
+ argument to the output device's vertical resolution (similarly
+ to the way `ll` and `lt` behave).
+
+ * doc/groff.texi.in (Page Layout):
+ * NEWS: Document this.
+
2024-07-25 G. Branden Robinson <[email protected]>
* src/roff/troff/env.cpp (line_length, title_length): Drop use
diff --git a/NEWS b/NEWS
index 90a1646ad..c89f4b55b 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,11 @@ o The `mso` request no longer attempts to open a macro file
named, say,
simply processes the macro search path for a file name matching the
request argument, and succeeds or fails depending on an exact match.
+o GNU troff no longer accepts nonpositive page lengths. Attempting to
+ set one with the `pl` request clamps the page length to the vertical
+ motion quantum as `ll` does with the horizontal motion quantum in AT&T
+ and GNU troffs.
+
o The `color`, `cp`, `linetabs`, and `vpt` requests now interpret
arguments with negative values as instructions to disable the
corresponding feature, using the *roff integer-to-Boolean conversion
diff --git a/doc/groff.texi.in b/doc/groff.texi.in
index 18aff8d8c..1ea82341d 100644
--- a/doc/groff.texi.in
+++ b/doc/groff.texi.in
@@ -10096,12 +10096,12 @@ The formatter permits configuration of the page
length and page number.
@cindex configuring the page length (@code{pl})
@cindex setting the page length (@code{pl})
Change (increase or decrease) the page length per the numeric expression
-@var{length}. The default scaling unit is @samp{v}. A negative
-@var{length} is valid, but an uncommon application:@: it prevents page
-location traps from being sprung,@footnote{@xref{Traps}.} and each
-output line is placed on a new page. If @var{length} is invalid, GNU
-@code{troff} emits a warning in category @samp{number}. If @var{length}
-is absent or invalid, @samp{11i} is assumed.
+@var{length}. The default scaling unit is @samp{v}. If @var{length} is
+invalid, GNU @code{troff} emits a warning in category @samp{number}. If
+@var{length} is absent or invalid, @samp{11i} is assumed. If
+@var{length} is nonpositive, GNU @command{troff} emits a warning in
+category @samp{range} and sets the page length to the device's vertical
+motion quantum; recall @ref{Motion Quanta}.
@cindex page length register (@code{.p})
The read-only register @samp{.p} interpolates the current page length.
diff --git a/src/roff/troff/div.cpp b/src/roff/troff/div.cpp
index 83f10e7bc..5b352a315 100644
--- a/src/roff/troff/div.cpp
+++ b/src/roff/troff/div.cpp
@@ -701,9 +701,16 @@ void page_offset()
void page_length()
{
- vunits n;
- if (has_arg() && get_vunits(&n, 'v', topdiv->get_page_length()))
- topdiv->set_page_length(n);
+ vunits temp;
+ if (has_arg() && get_vunits(&temp, 'v', topdiv->get_page_length())) {
+ if (temp < vresolution) {
+ warning(WARN_RANGE, "setting invalid page length %1u to device"
+ " vertical motion quantum",
+ temp.to_units());
+ temp = vresolution;
+ }
+ topdiv->set_page_length(temp);
+ }
else
topdiv->set_page_length(11*units_per_inch);
skip_line();
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