[Bug server/25893] New: gdbserver incorrectly handles program args containing space

[Bug server/25893] New: gdbserver incorrectly handles program args containing space

[m.weghorn at posteo dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

            Bug ID: 25893
           Summary: gdbserver incorrectly handles program args containing
                    space
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: server
          Assignee: unassigned at sourceware dot org
          Reporter: m.weghorn at posteo dot de
  Target Milestone: ---

gdbserver cannot handle program arguments containing space, but splits such
arguments into separate ones.

# Steps to reproduce:

1) compile small sample program ("test.cxx") given below:
   g++ -g -O0 -o  test test.cxx

2) run with gdbserver, passing an arg containing space
  gdbserver localhost:50505 test "hello world"

3) attach with GDB, and inspect the program arguments:

(gdb) target remote localhost:50505
[...]
(gdb) break main
Breakpoint 1 at 0x555555555174: file test.cxx, line 3.
(gdb) c
Continuing.
[...]
Breakpoint 1, main (argc=3, argv=0x7fffffffddf8) at test.cxx:3
3           std::cout << argv[1] << std::endl;
(gdb) p argc
$1 = 3
(gdb) p argv[1]
$2 = 0x7fffffffe1a6 "hello"
(gdb) p argv[2]
$3 = 0x7fffffffe1ac "world"
(gdb) 


# Actual result:

Instead of showing a single argument "hello world", two separate arguments
("hello", "world") are shown.

# Expected result:

A single argument "hello world" should have been passed to the program, as is
the case when using "plain" gdb instead of gdbserver:

$ gdb --args test "hello world"
[...]
(gdb) break main
Breakpoint 1 at 0x1174: file test.cxx, line 3.
(gdb) r
Starting program: /home/michi/temp/2020-04-24_gdb_gdbserver_args/test hello\
world

Breakpoint 1, main (argc=2, argv=0x7fffffffddd8) at test.cxx:3
3           std::cout << argv[1] << std::endl;
(gdb) p argc
$1 = 2
(gdb) p argv[1]
$2 = 0x7fffffffe197 "hello world"


# Further notes

I initially experienced this bug with gdb version 9.1 in Debian testing
(amd64), but it's also reproducible with current git master, as of commit
0b2f8a3bbb595a99dd7977caa6382aab25630115.

I plan to submit patches that show a potential approach to fix this.

# Sample program "test.cxx":

  #include <iostream>
  int main(int argc, char** argv) {
      std::cout << argv[1] << std::endl;
      return 0;
  }

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[Bug server/25893] gdbserver incorrectly handles program args containing space

[m.weghorn at posteo dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

Michael Weghorn <m.weghorn at posteo dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |m.weghorn at posteo dot de

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[Bug server/25893] gdbserver incorrectly handles program args containing space

[m.weghorn at posteo dot de]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

--- Comment #1 from Michael Weghorn <m.weghorn at posteo dot de> ---
I've sent patches with a potential solution to the gdb-patches mailing list,
thread starts at
https://sourceware.org/pipermail/gdb-patches/2020-April/168037.html

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[Bug server/25893] gdbserver incorrectly handles program args containing space

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Marchi <simark@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=bea571ebd78ee29cb94adf648fbcda1e109e1be6

commit bea571ebd78ee29cb94adf648fbcda1e109e1be6
Author: Michael Weghorn <m.weghorn@posteo.de>
Date:   Mon May 25 11:39:43 2020 -0400

    Use construct_inferior_arguments which handles special chars

    Use the construct_inferior_arguments function instead of
    stringify_argv to construct a string from the program
    arguments in those places where that one is then passed
    to fork_inferior (linux-low, lyn-low), since
    construct_inferior_arguments properly takes care of
    special characters, while stringify_argv does not.
    Using construct_inferior_arguments seems "natural", since its
    documentation also mentions that it "does the
    same shell processing as fork_inferior".

    Since construct_inferior_args has been extended to do
    proper quoting for Windows shells in commit
    5d60742e2dd3c9b475dce54b56043a358751bbb8
    ("Fix quoting of special characters for the MinGW build.",
    2012-06-12), use it for the Windows case as well.
    (I could not test that case myself, though.)

    Adapt handling of empty args in function 'handle_v_run'
    in gdbserver/server.cc to just insert an empty string
    for an empty arg, since that one is now properly handled
    in 'construct_inferior_arguments' already (and inserting
    a "''" string in 'handle_v_run' would otherwise
    cause that one to be treated as a string literally
    containing two quote characters, which
    'construct_inferior_args' would preserve by adding
    extra escaping).

    This makes gdbserver properly handle program args containing special
    characters (like spaces), e.g. (example from PR25893)

      $ gdbserver localhost:50505 myprogram "hello world"

    now properly handles "hello world" as a single arg, not two separate
    ones ("hello", "world").

    gdbserver/ChangeLog:

            PR gdbserver/25893
            * linux-low.cc (linux_process_target::create_inferior),
            lynx-low.cc (lynx_process_target::create_inferior),
            win32-low.cc (win32_process_target::create_inferior): Use
            construct_inferior_arguments instead of stringify_argv
            to get string representation which properly escapes
            special characters.
            * server.cc (handle_v_run): Just pass empty program arg
            as such, since any further processing is now handled via
            construct_inferior_arguments.

    Change-Id: Ibf963fcd51415c948840fb463289516b3479b0c3

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[Bug server/25893] gdbserver incorrectly handles program args containing space

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simark at simark dot ca
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from Simon Marchi <simark at simark dot ca> ---
Fixed.

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[Bug server/25893] gdbserver incorrectly handles program args containing space

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=25893

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org
   Target Milestone|---                         |10.1

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