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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. |
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.. | ||
config | ||
testsuite | ||
_doprnt.c | ||
.gitignore | ||
acinclude.m4 | ||
aclocal.m4 | ||
alloca.c | ||
argv.c | ||
asprintf.c | ||
at-file.texi | ||
atexit.c | ||
basename.c | ||
bcmp.c | ||
bcopy.c | ||
bsearch_r.c | ||
bsearch.c | ||
bzero.c | ||
calloc.c | ||
ChangeLog | ||
ChangeLog.jit | ||
choose-temp.c | ||
clock.c | ||
concat.c | ||
config.h-vms | ||
config.in | ||
configure | ||
configure.ac | ||
configure.com | ||
copying-lib.texi | ||
COPYING.LIB | ||
copysign.c | ||
cp-demangle.c | ||
cp-demangle.h | ||
cp-demint.c | ||
cplus-dem.c | ||
crc32.c | ||
d-demangle.c | ||
dwarfnames.c | ||
dyn-string.c | ||
fdmatch.c | ||
ffs.c | ||
fibheap.c | ||
filedescriptor.c | ||
filename_cmp.c | ||
floatformat.c | ||
fnmatch.c | ||
fnmatch.txh | ||
fopen_unlocked.c | ||
functions.texi | ||
gather-docs | ||
getcwd.c | ||
getopt1.c | ||
getopt.c | ||
getpagesize.c | ||
getpwd.c | ||
getruntime.c | ||
gettimeofday.c | ||
hashtab.c | ||
hex.c | ||
index.c | ||
insque.c | ||
lbasename.c | ||
libiberty.texi | ||
lrealpath.c | ||
maint-tool | ||
make-relative-prefix.c | ||
make-temp-file.c | ||
Makefile.in | ||
makefile.vms | ||
md5.c | ||
memchr.c | ||
memcmp.c | ||
memcpy.c | ||
memmem.c | ||
memmove.c | ||
mempcpy.c | ||
memset.c | ||
mkstemps.c | ||
msdos.c | ||
objalloc.c | ||
obstack.c | ||
obstacks.texi | ||
partition.c | ||
pex-common.c | ||
pex-common.h | ||
pex-djgpp.c | ||
pex-msdos.c | ||
pex-one.c | ||
pex-unix.c | ||
pex-win32.c | ||
pexecute.c | ||
pexecute.txh | ||
physmem.c | ||
putenv.c | ||
random.c | ||
README | ||
regex.c | ||
rename.c | ||
rindex.c | ||
rust-demangle.c | ||
safe-ctype.c | ||
setenv.c | ||
setproctitle.c | ||
sha1.c | ||
sigsetmask.c | ||
simple-object-coff.c | ||
simple-object-common.h | ||
simple-object-elf.c | ||
simple-object-mach-o.c | ||
simple-object-xcoff.c | ||
simple-object.c | ||
simple-object.txh | ||
snprintf.c | ||
sort.c | ||
spaces.c | ||
splay-tree.c | ||
stack-limit.c | ||
stpcpy.c | ||
stpncpy.c | ||
strcasecmp.c | ||
strchr.c | ||
strdup.c | ||
strerror.c | ||
strncasecmp.c | ||
strncmp.c | ||
strndup.c | ||
strnlen.c | ||
strrchr.c | ||
strsignal.c | ||
strstr.c | ||
strtod.c | ||
strtol.c | ||
strtoll.c | ||
strtoul.c | ||
strtoull.c | ||
strverscmp.c | ||
timeval-utils.c | ||
tmpnam.c | ||
unlink-if-ordinary.c | ||
vasprintf.c | ||
vfork.c | ||
vfprintf.c | ||
vprintf-support.c | ||
vprintf-support.h | ||
vprintf.c | ||
vsnprintf.c | ||
vsprintf.c | ||
waitpid.c | ||
xasprintf.c | ||
xatexit.c | ||
xexit.c | ||
xmalloc.c | ||
xmemdup.c | ||
xstrdup.c | ||
xstrerror.c | ||
xstrndup.c | ||
xvasprintf.c |
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.