I found quite a lot of bugs, so I ended up pretty much rewriting as I
followed the spec¹.
Now, it works as follows:
- Determine a mask (who) of bits that can be modified for the subsequent
operations. If none are specified, select all file mode bits.
- In a loop, determine which operation (+, -, =) to apply.
- If the next character is a permcopy (u, g, o), set the new permissions
(perm) corresponding to the bits set in the user, group or other parts
of the existing mode.
- Otherwise, set the new permissions by looping through the next r, w,
x, s, t characters.
- Now, the set of bits we want to add or remove is (who & perm). Set or
remove these bits according the the operation (first clearing the
appropriate bits if the operation is =).
- Continue from the top if the next character is a comma, otherwise,
process the next operation.
I tested this on some made up inputs, and I believe it is working
correctly now:
parsemode("g+w", 0644, 0), before: 0606, now: 0664, fixed
parsemode("u+rx", 0222, 0), before: 0077, now: 0722, fixed
parsemode("+x", 0644, 023), before: 0754, now: 0754, still works
parsemode("+w", 0444, 022), before: 0644, now: 0644, still works
parsemode("+w", 0444, 0), before: 0666, now: 0666, still works
parsemode("+s", 0755, 0), before: 0755, now: 6755, fixed
parsemode("u+s", 0755, 0), before: 0055, now: 4755, fixed
parsemode("g+s", 0755, 0), before: 0705, now: 2755, fixed
parsemode("g=u", 0700, 0), before: 0000, now: 0770, fixed
parsemode("go=u-w", 0700, 0), before: 0000, now: 0755, fixed
parsemode("o+u-g", 0641, 0), before: 0000, now: 0643, fixed
parsemode("u=rx,o+w,g-r", 0654, 0) before: error, now: 0516, fixed
parsemode(",", 0654, 0), before: error, now: error, still works
¹ http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chmod.html
sbase - suckless unix tools
===========================
sbase is a collection of unix tools that are inherently portable
across UNIX and UNIX-like systems.
The following programs are currently implemented:
basename
cal
cat
chgrp
chmod
chown
chroot
cksum
cmp
col
cols
comm
cp
csplit
cut
date
dirname
du
echo
env
expand
expr
false
fold
grep
head
hostname
kill
link
ln
logname
ls
md5sum
mkdir
mkfifo
mktemp
mv
nice
nl
nohup
paste
printenv
printf
pwd
readlink
renice
rm
rmdir
sleep
setsid
sort
split
sponge
strings
sync
tail
tar
tee
test
touch
tr
true
tty
uudecode
uuencode
uname
unexpand
uniq
unlink
seq
sha1sum
sha256sum
sha512sum
wc
xargs
yes
The complement of sbase is ubase[1] which is Linux-specific and
provides all the non-portable tools. Together they are intended to
form a base system similar to busybox but much smaller and suckless.
Building
--------
To build sbase, simply type make. You may have to fiddle with
config.mk depending on your system.
You can also build sbase-box, which generates a single binary
containing all the required tools. You can then symlink the
individual tools to sbase-box.
Ideally you will want to statically link sbase. If you are on Linux
we recommend using musl-libc[2].
Portability
-----------
sbase has been compiled on a variety of different operating systems,
including Linux, *BSD, OSX, Haiku, Solaris, SCO OpenServer and others.
sbase also compiles and runs on minix3 with slight modifications.
They do not provide mmap()/munmap() so you need to use minix_mmap()
and minix_munmap() respectively.
Various combinations of operating systems and architectures have also
been built.
You can build sbase with gcc, clang, tcc, nwcc and pcc.
[1] http://git.suckless.org/ubase/
[2] http://www.musl-libc.org/
6164445cce