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[Bug tui/16138] TUI commands when run from emacs exit gdb complaining "Error opening terminal: emacs"
- From: "cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: Wed, 29 Oct 2014 14:33:57 +0000
- Subject: [Bug tui/16138] TUI commands when run from emacs exit gdb complaining "Error opening terminal: emacs"
- Auto-submitted: auto-generated
- References: <bug-16138-4717 at http dot sourceware dot org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=16138
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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=84eda397bcf3ebea00383e4a6a864af59723dafd
commit 84eda397bcf3ebea00383e4a6a864af59723dafd
Author: Pedro Alves <palves@redhat.com>
Date: Wed Oct 29 14:23:57 2014 +0000
PR tui/16138, PR tui/17519, and misc failures to initialize the terminal
PR tui/16138 is about failure to initialize curses resulting in GDB
exiting instead of throwing an error. E.g.:
$ TERM=foo gdb
(gdb) layout asm
Error opening terminal: foo.
$
The problem is that we're calling initscr to initialize the screen.
As mentioned in
http://pubs.opengroup.org/onlinepubs/7908799/xcurses/initscr.html:
If errors occur, initscr() writes an appropriate error message to
standard error and exits.
^^^^^
Instead, we should use newterm:
"A program that needs an indication of error conditions, so it can
continue to run in a line-oriented mode if the terminal cannot support
a screen-oriented program, would also use this function."
After the patch:
$ TERM=foo gdb -q -nx
(gdb) layout asm
Cannot enable the TUI: error opening terminal [TERM=foo]
(gdb)
And then PR tui/17519 is about GDB not validating whether the terminal
has the necessary capabilities when enabling the TUI. If one tries to
enable the TUI with TERM=dumb (and e.g., from a shell within emacs),
GDB ends up with a clear screen, the cursor is placed at the
bottom/right corner of the screen, there's no prompt, typing shows no
echo, and there's no indication of what's going on. c-x,a gets you
out of the TUI, but it's completely non-obvious.
After the patch, we get:
$ TERM=dumb gdb -q -nx
(gdb) layout asm
Cannot enable the TUI: terminal doesn't support cursor addressing
[TERM=dumb]
(gdb)
While at it, I've moved all the tui_allowed_p validation to
tui_enable, and expanded the error messages. Previously we'd get:
$ gdb -q -nx -i=mi
(gdb)
layout asm
&"layout asm\n"
&"TUI mode not allowed\n"
^error,msg="TUI mode not allowed"
and:
$ gdb -q -nx -ex "layout asm" > foo
TUI mode not allowed
While now we get:
$ gdb -q -nx -i=mi
(gdb)
layout asm
&"layout asm\n"
&"Cannot enable the TUI when the interpreter is 'mi'\n"
^error,msg="Cannot enable the TUI when the interpreter is 'mi'"
(gdb)
and:
$ gdb -q -nx -ex "layout asm" > foo
Cannot enable the TUI when output is not a terminal
Tested on x86_64 Fedora 20.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
PR tui/16138
PR tui/17519
* tui/tui-interp.c (tui_is_toplevel): Delete global.
(tui_allowed_p): Delete function.
* tui/tui.c: Include "interps.h".
(tui_enable): Don't use tui_allowed_p. Error out here with
detailed error messages if the TUI is the top level interpreter,
or if output is not a terminal. Use newterm instead of initscr,
and error out if initializing the terminal fails. Also error out if
the terminal doesn't support cursor addressing.
* tui/tui.h (tui_allowed_p): Delete declaration.
-----------------------------------------------------------------------
Summary of changes:
gdb/tui/tui-interp.c | 17 ----------------
gdb/tui/tui.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++---
gdb/tui/tui.h | 4 ---
3 files changed, 49 insertions(+), 25 deletions(-)
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