gcc/libiberty
Andrew Burgess 5e1d530da8 libiberty/buildargv: handle input consisting of only white space
GDB makes use of the libiberty function buildargv for splitting the
inferior (program being debugged) argument string in the case where
the inferior is not being started under a shell.

I have recently been working to improve this area of GDB, and noticed
some unexpected behaviour to the libiberty function buildargv, when
the input is a string consisting only of white space.

What I observe is that if the input to buildargv is a string
containing only white space, then buildargv will return an argv list
containing a single empty argument, e.g.:

  char **argv = buildargv (" ");
  assert (*argv[0] == '\0');
  assert (argv[1] == NULL);

We get the same output from buildargv if the input is a single space,
or multiple spaces.  Other white space characters give the same
results.

This doesn't seem right to me, and in fact, there appears to be a work
around for this issue in expandargv where we have this code:

  /* If the file is empty or contains only whitespace, buildargv would
     return a single empty argument.  In this context we want no arguments,
     instead.  */
  if (only_whitespace (buffer))
    {
      file_argv = (char **) xmalloc (sizeof (char *));
      file_argv[0] = NULL;
    }
  else
    /* Parse the string.  */
    file_argv = buildargv (buffer);

I think that the correct behaviour in this situation is to return an
empty argv array, e.g.:

  char **argv = buildargv (" ");
  assert (argv[0] == NULL);

And it turns out that this is a trivial change to buildargv.  The diff
does look big, but this is because I've re-indented a block.  Check
with 'git diff -b' to see the minimal changes.  I've also removed the
work around from expandargv.

When testing this sort of thing I normally write the tests first, and
then fix the code.  In this case test-expandargv.c has sort-of been
used as a mechanism for testing the buildargv function (expandargv
does call buildargv most of the time), however, for this particular
issue the work around in expandargv (mentioned above) masked the
buildargv bug.

I did consider adding a new test-buildargv.c file, however, this would
have basically been a copy & paste of test-expandargv.c (with some
minor changes to call buildargv).  This would be fine now, but feels
like we would eventually end up with one file not being updated as
much as the other, and so test coverage would suffer.

Instead, I have added some explicit buildargv testing to the
test-expandargv.c file, this reuses the test input that is already
defined for expandargv.

Of course, once I removed the work around from expandargv then we now
do always call buildargv from expandargv, and so the bug I'm fixing
would impact both expandargv and buildargv, so maybe the new testing
is redundant?  I tend to think more testing is always better, so I've
left it in for now.

2024-07-16  Andrew Burgess  <aburgess@redhat.com>

libiberty/

	* argv.c (buildargv): Treat input of only whitespace as an empty
	argument list.
	(expandargv): Remove work around for intput that is only
	whitespace.
	* testsuite/test-expandargv.c: Add new tests 10, 11, and 12.
	Extend testing to call buildargv in more cases.
2024-07-16 13:52:03 +01:00
..
config
testsuite libiberty/buildargv: handle input consisting of only white space 2024-07-16 13:52:03 +01:00
_doprnt.c Update copyright years. 2024-01-03 12:19:35 +01:00
.gitignore
acinclude.m4 Update copyright years. 2024-01-03 12:19:35 +01:00
aclocal.m4 libiberty: Disable hwcaps for sha1.o 2023-11-30 10:06:23 +01:00
alloca.c
argv.c libiberty/buildargv: handle input consisting of only white space 2024-07-16 13:52:03 +01:00
asprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
at-file.texi
atexit.c
basename.c
bcmp.c
bcopy.c
bsearch_r.c
bsearch.c
bzero.c
calloc.c
ChangeLog Daily bump. 2024-04-03 00:17:29 +00:00
ChangeLog.jit
choose-temp.c Update copyright years. 2024-01-03 12:19:35 +01:00
clock.c Update copyright years. 2024-01-03 12:19:35 +01:00
concat.c Update copyright years. 2024-01-03 12:19:35 +01:00
config.h-vms
config.in libiberty: Use x86 HW optimized sha1 2023-11-28 13:14:05 +01:00
configure libiberty: Fix build with GCC < 7 2023-12-05 23:32:19 +01:00
configure.ac libiberty: Fix build with GCC < 7 2023-12-05 23:32:19 +01:00
configure.com
copying-lib.texi Update copyright years. 2024-01-03 12:19:35 +01:00
COPYING.LIB
copysign.c
cp-demangle.c c++, demangle: Implement https://github.com/itanium-cxx-abi/cxx-abi/issues/148 non-proposal 2024-01-13 10:23:53 +01:00
cp-demangle.h Update copyright years. 2024-01-03 12:19:35 +01:00
cp-demint.c Update copyright years. 2024-01-03 12:19:35 +01:00
cplus-dem.c libiberty: Invoke D demangler when --format=auto 2024-04-02 13:30:19 -06:00
crc32.c Update copyright years. 2024-01-03 12:19:35 +01:00
d-demangle.c Update copyright years. 2024-01-03 12:19:35 +01:00
dwarfnames.c Update copyright years. 2024-01-03 12:19:35 +01:00
dyn-string.c Fix up duplicated words mostly in comments, part 1 2024-04-02 13:39:11 +02:00
fdmatch.c Update copyright years. 2024-01-03 12:19:35 +01:00
ffs.c
fibheap.c Update copyright years. 2024-01-03 12:19:35 +01:00
filedescriptor.c Update copyright years. 2024-01-03 12:19:35 +01:00
filename_cmp.c Update copyright years. 2024-01-03 12:19:35 +01:00
floatformat.c Update copyright years. 2024-01-03 12:19:35 +01:00
fnmatch.c Update copyright years. 2024-01-03 12:19:35 +01:00
fnmatch.txh
fopen_unlocked.c Update copyright years. 2024-01-03 12:19:35 +01:00
functions.texi
gather-docs Update copyright years. 2024-01-03 12:19:35 +01:00
getcwd.c
getopt1.c Update copyright years. 2024-01-03 12:19:35 +01:00
getopt.c Update copyright years. 2024-01-03 12:19:35 +01:00
getpagesize.c
getpwd.c
getruntime.c Update copyright years. 2024-01-03 12:19:35 +01:00
gettimeofday.c
hashtab.c [libiberty] remove TBAA violation in iterative_hash, improve code-gen 2024-02-15 09:14:22 +01:00
hex.c Update copyright years. 2024-01-03 12:19:35 +01:00
index.c
insque.c
lbasename.c Update copyright years. 2024-01-03 12:19:35 +01:00
libiberty.texi Update copyright years. 2024-01-03 12:19:35 +01:00
lrealpath.c Update copyright years. 2024-01-03 12:19:35 +01:00
maint-tool Update copyright years. 2024-01-03 12:19:35 +01:00
make-relative-prefix.c Update copyright years. 2024-01-03 12:19:35 +01:00
make-temp-file.c Update copyright years. 2024-01-03 12:19:35 +01:00
Makefile.in Update copyright years. 2024-01-03 12:19:35 +01:00
makefile.vms
md5.c Update copyright years. 2024-01-03 12:19:35 +01:00
memchr.c
memcmp.c
memcpy.c
memmem.c Update copyright years. 2024-01-03 12:19:35 +01:00
memmove.c
mempcpy.c Update copyright years. 2024-01-03 12:19:35 +01:00
memset.c
mkstemps.c Update copyright years. 2024-01-03 12:19:35 +01:00
msdos.c
objalloc.c Update copyright years. 2024-01-03 12:19:35 +01:00
obstack.c Update copyright years. 2024-01-03 12:19:35 +01:00
obstacks.texi
partition.c Update copyright years. 2024-01-03 12:19:35 +01:00
pex-common.c Update copyright years. 2024-01-03 12:19:35 +01:00
pex-common.h Update copyright years. 2024-01-03 12:19:35 +01:00
pex-djgpp.c Update copyright years. 2024-01-03 12:19:35 +01:00
pex-msdos.c Update copyright years. 2024-01-03 12:19:35 +01:00
pex-one.c Update copyright years. 2024-01-03 12:19:35 +01:00
pex-unix.c libiberty: Fix error return value in pex_unix_exec_child [PR113957]. 2024-02-19 20:13:30 +00:00
pex-win32.c Update copyright years. 2024-01-03 12:19:35 +01:00
pexecute.c Update copyright years. 2024-01-03 12:19:35 +01:00
pexecute.txh
physmem.c Update copyright years. 2024-01-03 12:19:35 +01:00
putenv.c Update copyright years. 2024-01-03 12:19:35 +01:00
random.c
README
regex.c Fix up duplicated words mostly in comments, part 1 2024-04-02 13:39:11 +02:00
rename.c
rindex.c
rust-demangle.c Update copyright years. 2024-01-03 12:19:35 +01:00
safe-ctype.c Update copyright years. 2024-01-03 12:19:35 +01:00
setenv.c Update copyright years. 2024-01-03 12:19:35 +01:00
setproctitle.c Update copyright years. 2024-01-03 12:19:35 +01:00
sha1.c Update copyright years. 2024-01-03 12:19:35 +01:00
sigsetmask.c
simple-object-coff.c Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object-common.h Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object-elf.c Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object-mach-o.c Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object-xcoff.c Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object.c Update copyright years. 2024-01-03 12:19:35 +01:00
simple-object.txh
snprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
sort.c Update copyright years. 2024-01-03 12:19:35 +01:00
spaces.c Update copyright years. 2024-01-03 12:19:35 +01:00
splay-tree.c Update copyright years. 2024-01-03 12:19:35 +01:00
stack-limit.c Update copyright years. 2024-01-03 12:19:35 +01:00
stpcpy.c Update copyright years. 2024-01-03 12:19:35 +01:00
stpncpy.c Update copyright years. 2024-01-03 12:19:35 +01:00
strcasecmp.c
strchr.c
strdup.c
strerror.c
strncasecmp.c
strncmp.c
strndup.c Update copyright years. 2024-01-03 12:19:35 +01:00
strnlen.c
strrchr.c
strsignal.c
strstr.c
strtod.c Update copyright years. 2024-01-03 12:19:35 +01:00
strtol.c
strtoll.c
strtoul.c
strtoull.c
strverscmp.c Update copyright years. 2024-01-03 12:19:35 +01:00
timeval-utils.c Update copyright years. 2024-01-03 12:19:35 +01:00
tmpnam.c
unlink-if-ordinary.c Update copyright years. 2024-01-03 12:19:35 +01:00
vasprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
vfork.c
vfprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
vprintf-support.c libiberty: Fix up libiberty_vprintf_buffer_size 2024-02-12 18:50:16 +01:00
vprintf-support.h Update copyright years. 2024-01-03 12:19:35 +01:00
vprintf.c
vsnprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
vsprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
waitpid.c
xasprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00
xatexit.c
xexit.c Update copyright years. 2024-01-03 12:19:35 +01:00
xmalloc.c Update copyright years. 2024-01-03 12:19:35 +01:00
xmemdup.c
xstrdup.c
xstrerror.c
xstrndup.c Update copyright years. 2024-01-03 12:19:35 +01:00
xvasprintf.c Update copyright years. 2024-01-03 12:19:35 +01:00

This directory contains the -liberty library of free software.
It is a collection of subroutines used by various GNU programs.
Current members include:

	getopt -- get options from command line
	obstack -- stacks of arbitrarily-sized objects
	strerror -- error message strings corresponding to errno
	strtol -- string-to-long conversion
	strtoul -- string-to-unsigned-long conversion

We expect many of the GNU subroutines that are floating around to
eventually arrive here.

The library must be configured from the top source directory.  Don't
try to run configure in this directory.  Follow the configuration
instructions in ../README.

Please report bugs to https://gcc.gnu.org/bugzilla/ and send fixes to
"gcc-patches@gcc.gnu.org".  Thank you.

ADDING A NEW FILE
=================

There are two sets of files:  Those that are "required" will be
included in the library for all configurations, while those
that are "optional" will be included in the library only if "needed."

To add a new required file, edit Makefile.in to add the source file
name to CFILES and the object file to REQUIRED_OFILES.

To add a new optional file, it must provide a single function, and the
name of the function must be the same as the name of the file.

    * Add the source file name to CFILES in Makefile.in and the object
      file to CONFIGURED_OFILES.

    * Add the function to name to the funcs shell variable in
      configure.ac.

    * Add the function to the AC_CHECK_FUNCS lists just after the
      setting of the funcs shell variable.  These AC_CHECK_FUNCS calls
      are never executed; they are there to make autoheader work
      better.

    * Consider the special cases of building libiberty; as of this
      writing, the special cases are newlib and VxWorks.  If a
      particular special case provides the function, you do not need
      to do anything.  If it does not provide the function, add the
      object file to LIBOBJS, and add the function name to the case
      controlling whether to define HAVE_func.

Finally, in the build directory of libiberty, configure with
"--enable-maintainer-mode", run "make maint-deps" to update
Makefile.in, and run 'make stamp-functions' to regenerate
functions.texi.

The optional file you've added (e.g. getcwd.c) should compile and work
on all hosts where it is needed.  It does not have to work or even
compile on hosts where it is not needed.

ADDING A NEW CONFIGURATION
==========================

On most hosts you should be able to use the scheme for automatically
figuring out which files are needed.  In that case, you probably
don't need a special Makefile stub for that configuration.

If the fully automatic scheme doesn't work, you may be able to get
by with defining EXTRA_OFILES in your Makefile stub.  This is
a list of object file names that should be treated as required
for this configuration - they will be included in libiberty.a,
regardless of whatever might be in the C library.