[Bug gdb/16933] New: p omits trailing 0 when printing a range of chars

[Bug gdb/16933] New: p omits trailing 0 when printing a range of chars

[f.heckenbach@fh-soft.de]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

            Bug ID: 16933
           Summary: p omits trailing 0 when printing a range of chars
           Product: gdb
           Version: 7.7
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: f.heckenbach@fh-soft.de

This bug was reported as Debian bug #666216 for gdb 7-0. According to Hector
Oron, it is still reproducable with 7.7-1.

p omits trailing 0 when printing a range of chars.
To reproduce:

# echo 'char foo[5] = { 1, 2, 0, 4, 0 };' > foo.c
# gcc -c -g foo.c
# gdb foo.o
(gdb) p foo[0]@5
$1 = "\001\002\000\004"

What I really wanted would be "{1, 2, 0, 4, 0}", like for other
integer types, since I explicitly selected a single element and gave
a range (@5), but if it must print it as a string, it should at
least print all of the bytes.

I know that's probably due to C's notorious confusion between
integers and characters, and I also know there are other ways to
dump some bytes in gdb.

But still it seems plain wrong to print 4 chars if 5 items were
explicitly requested, just because the last one happens to be 0.
Note that it's not printing a 0-terminated string either: The
embedded "\000" is printed; just one terminating 0 is omitted.

(Which gets very confusing with larger arrays, if you look for
something near the end, thinking the last one printed is the last
one requested and then go hunting your off-by-one bug, only to
realize later there wasn't any ...)

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[Bug gdb/16933] p omits trailing 0 when printing a range of chars

[schwab@linux-m68k.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
"\001\002\000\004\000" would be wrong because that has 6 elements and implies
that there is another zero following.

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[Bug gdb/16933] p omits trailing 0 when printing a range of chars

[f.heckenbach@fh-soft.de]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

--- Comment #2 from Frank Heckenbach <f.heckenbach@fh-soft.de> ---
> https://sourceware.org/bugzilla/show_bug.cgi?id=16933
> 
> --- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> ---
> "\001\002\000\004\000" would be wrong because that has 6 elements and implies
> that there is another zero following.

I see. But for the same reason this is then also wrong:

# echo 'char foo[5] = { 1, 2, 0, 4 };' > foo.c
# gcc -c -g foo.c
# gdb foo.o
(gdb) p foo[0]@4
$1 = "\001\002\000\004"

So AIUI gdb must not print a range of chars as a string at all and
should really print "{1, 2, 0, 4, 0}" or "{1, 2, 0, 4}", resp., as
I'd actually prefer anyway.

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[Bug gdb/16933] p omits trailing 0 when printing a range of chars

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

Hannes Domani <ssbssa at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ssbssa at sourceware dot org

--- Comment #3 from Hannes Domani <ssbssa at sourceware dot org> ---
See also PR16020.

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[Bug gdb/16933] p omits trailing 0 when printing a range of chars

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

Hannes Domani <ssbssa at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dedeco.balaco at yahoo dot com

--- Comment #4 from Hannes Domani <ssbssa at sourceware dot org> ---
*** Bug 21467 has been marked as a duplicate of this bug. ***

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[Bug gdb/16933] p omits trailing 0 when printing a range of chars

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=16933

--- Comment #5 from Hannes Domani <ssbssa at sourceware dot org> ---
(In reply to Hannes Domani from comment #3)
> See also PR16020.

And also PR26842.

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