[PATCH] Fix "list" when control characters are seen

[PATCH] Fix "list" when control characters are seen

[Tom Tromey]

PR symtab/24423 points out that control characters in a source file
cause a hang in the "list" command, a regression introduced by the
styling changes.

This patch, from the PR, fixes the bug.  I've included a minimal
change to the "list" test that exercises this code.

I recall that this bug was discussed on gdb-patches, and I thought
there was a patch there as well, but I was unable to find it.

gdb/ChangeLog
2019-04-09  Ilya Yu. Malakhov  <malakhov@mcst.ru>

	PR symtab/24423:
	* source.c (print_source_lines_base): Advance "iter" when a
	control character is seen.

gdb/testsuite/ChangeLog
2019-04-09  Tom Tromey  <tromey@adacore.com>

	PR symtab/24423:
	* gdb.base/list0.h (foo): Add a control-l character.
---
 gdb/ChangeLog                  | 6 ++++++
 gdb/source.c                   | 8 ++++++--
 gdb/testsuite/ChangeLog        | 5 +++++
 gdb/testsuite/gdb.base/list0.h | 2 +-
 4 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/gdb/source.c b/gdb/source.c
index f99215f9810..b61880ab503 100644
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -1368,7 +1368,7 @@ print_source_lines_base (struct symtab *s, int line, int stopline,
 	      char c = *iter;
 	      if (c == '\033' && skip_ansi_escape (iter, &skip_bytes))
 		iter += skip_bytes;
-	      else if (c < 040 && c != '\t')
+	      else if (c >= 0 && c < 040 && c != '\t')
 		break;
 	      else if (c == 0177)
 		break;
@@ -1397,9 +1397,13 @@ print_source_lines_base (struct symtab *s, int line, int stopline,
 	    {
 	      xsnprintf (buf, sizeof (buf), "^%c", *iter + 0100);
 	      uiout->text (buf);
+	      ++iter;
 	    }
 	  else if (*iter == 0177)
-	    uiout->text ("^?");
+	    {
+	      uiout->text ("^?");
+	      ++iter;
+	    }
 	}
       uiout->text ("\n");
     }
diff --git a/gdb/testsuite/gdb.base/list0.h b/gdb/testsuite/gdb.base/list0.h
index 42a4fe0f03a..6f280935509 100644
--- a/gdb/testsuite/gdb.base/list0.h
+++ b/gdb/testsuite/gdb.base/list0.h
@@ -3,7 +3,7 @@
 extern void bar(int);
 static void foo (int x)
 /* !
-   !
+\f
    ! */
 {
     bar (x++);
-- 
2.20.1

Re: [PATCH] Fix "list" when control characters are seen

[Andreas Schwab]

On Apr 09 2019, Tom Tromey <tromey@adacore.com> wrote:

> diff --git a/gdb/source.c b/gdb/source.c
> index f99215f9810..b61880ab503 100644
> --- a/gdb/source.c
> +++ b/gdb/source.c
> @@ -1368,7 +1368,7 @@ print_source_lines_base (struct symtab *s, int line, int stopline,
>  	      char c = *iter;
>  	      if (c == '\033' && skip_ansi_escape (iter, &skip_bytes))
>  		iter += skip_bytes;
> -	      else if (c < 040 && c != '\t')
> +	      else if (c >= 0 && c < 040 && c != '\t')

Does this give a warning when char is unsigned?

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Re: [PATCH] Fix "list" when control characters are seen

[Tom Tromey]

>> +	      else if (c >= 0 && c < 040 && c != '\t')

Andreas> Does this give a warning when char is unsigned?

I tried with -funsigned-char, and did not get a warning.

Tom

Re: [PATCH] Fix "list" when control characters are seen

[Tom Tromey]

>>>>> "Tom" == Tom Tromey <tromey@adacore.com> writes:

Tom> PR symtab/24423 points out that control characters in a source file
Tom> cause a hang in the "list" command, a regression introduced by the
Tom> styling changes.

Tom> This patch, from the PR, fixes the bug.  I've included a minimal
Tom> change to the "list" test that exercises this code.

Tom> I recall that this bug was discussed on gdb-patches, and I thought
Tom> there was a patch there as well, but I was unable to find it.

I'm going to check this in to master and the 8.3 branch now.

Tom

Re: [PATCH] Fix "list" when control characters are seen

[Pedro Alves]

On 4/9/19 7:54 PM, Tom Tromey wrote:
> --- a/gdb/testsuite/gdb.base/list0.h
> +++ b/gdb/testsuite/gdb.base/list0.h
> @@ -3,7 +3,7 @@
>  extern void bar(int);
>  static void foo (int x)
>  /* !
> -   !
> +

This seems pretty obscure without the context of the patch around.

Should we add a comment here?

Thanks,
Pedro Alves

Re: [PATCH] Fix "list" when control characters are seen

[Tom Tromey]

>> static void foo (int x)
>> /* !
>> -   !
>> +

Pedro> This seems pretty obscure without the context of the patch around.

Pedro> Should we add a comment here?

Good idea, how's this?

Tom

commit d20ed5fd574ce1b72543c2963fa53946eb2225de
Author: Tom Tromey <tromey@adacore.com>
Date:   Tue Jun 18 09:27:45 2019 -0600

    Add comment to list0.h
    
    Pedro suggested adding a comment to list0.h to explain the control
    character.
    
    Tested on x86-64 Fedora 29.
    
    gdb/testsuite/ChangeLog
    2019-06-18  Tom Tromey  <tromey@adacore.com>
    
            * gdb.base/list0.h: Add comment explaining control character.

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index b6fcf58c7dd..75adad35f48 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2019-06-18  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.base/list0.h: Add comment explaining control character.
+
 2019-06-18  Tom de Vries  <tdevries@suse.de>
 
 	* boards/fission.exp: Break up long debug_flags line.
diff --git a/gdb/testsuite/gdb.base/list0.h b/gdb/testsuite/gdb.base/list0.h
index 6f280935509..ba18e29268e 100644
--- a/gdb/testsuite/gdb.base/list0.h
+++ b/gdb/testsuite/gdb.base/list0.h
@@ -2,7 +2,7 @@
 
 extern void bar(int);
 static void foo (int x)
-/* !
+/* ! the next line has a control character, see PR symtab/24423.
 \f
    ! */
 {

Re: [PATCH] Fix "list" when control characters are seen

[Pedro Alves]

On 6/18/19 4:29 PM, Tom Tromey wrote:
>>> static void foo (int x)
>>> /* !
>>> -   !
>>> +
> 
> Pedro> This seems pretty obscure without the context of the patch around.
> 
> Pedro> Should we add a comment here?
> 
> Good idea, how's this?

Looks great, thanks.

Pedro Alves