[nycbug-talk] anyone know why install functions this way?
Matthew Story
matt at tablethotels.com
Mon Dec 12 11:58:56 EST 2011
For anyone interested, there does actually seem to be a valid reason for this behavior, the reason is that you can `install' an existing directory with owner/group flags set. This means that if you are installing to an existing directory, and it fails ... unlink would remove the directory and any contents ... hardly desirable. install -d does the following:
1. byte-wise walk path, stopping at each '/' character
+-> for each sub-path
+----> stat sub-path
+--------> doesn't exist (ENOENT)
+-------------> mkdir with file mode 755 || exit error
+--------> exists but is not a directory && exit error
2. if gid or uid is specified and not equal to effective uid/gid:
+-> chown leaf directory || warn
3. chmod leaf directory || warn
Might be interesting to make this a little more robust for "new" directories, and to exit non-0 even for existing dirs, while preserving content. Will take this up on bugs list for FreeBSD. Thanks for playing along all.
relevant C code below (via: http://svn.freebsd.org/base/stable/8/usr.bin/xinstall/xinstall.c ... web viewable here: http://svnweb.freebsd.org/base/stable/8/usr.bin/xinstall/xinstall.c)
/*
* install_dir --
* build directory hierarchy
*/
void
install_dir(char *path)
{
char *p;
struct stat sb;
int ch;
for (p = path;; ++p)
if (!*p || (p != path && *p == '/')) {
ch = *p;
*p = '\0';
if (stat(path, &sb)) {
if (errno != ENOENT || mkdir(path, 0755) < 0) {
err(EX_OSERR, "mkdir %s", path);
/* NOTREACHED */
} else if (verbose)
(void)printf("install: mkdir %s\n",
path);
} else if (!S_ISDIR(sb.st_mode))
errx(EX_OSERR, "%s exists but is not a directory", path);
if (!(*p = ch))
break;
}
if ((gid != (gid_t)-1 || uid != (uid_t)-1) && chown(path, uid, gid))
warn("chown %u:%u %s", uid, gid, path);
if (chmod(path, mode))
warn("chmod %o %s", mode, path);
}
On Dec 12, 2011, at 9:55 AM, Matthew Story wrote:
> one correction below ...
>
> On Dec 12, 2011, at 9:41 AM, Matthew Story wrote:
>
>> [snip...]
>> A couple of work-arounds I'm using for now below (if anyone is interested) ...
>>
>> # assume success until failure method ...
>> shout() { echo "$0: $*" >&2; }
>> barf() { shout "$*"; exit 111; }
>> cleanup() {
>> rc="$?"
>> [ ! -z "$working" -a -e "$working" ] && rm -r "$working"
>> exit "$rc"
>> }
>> dir_install() {
>> eval working=\"\$$#\"
>> trap cleanup INT TERM EXIT
> install "$@" 2>&1 | {
>> read err
>> [ -z "$err" ] || barf "cannot install dir: $working"
>> } || exit $?
>> trap "" INT TERM EXIT
>> }
>> dir_install -o foo -d "some.dir"
>>
>> # test for failure up front, with a file
>> test_file="test_install-d.$$.`hostname`.`date +%s`"
>> install -o "user" -g "group" "$test_file"|| rc=$?
>> [ -e "$test_file" ] && rm "$test_file"
>> [ 0 -ne "$rc" ] && exit "$rc"
>> install -o "user" -g "group" -d "$dir" || exit $?
>>
>>
>> On Dec 9, 2011, at 8:08 PM, Matthew Story wrote:
>>
>>> Know this isn't a bug list or anything like that, but figured I'd throw this out there ... the only thing I found on the interweb was regarding RPMs on CentOS ... so this is apparently not even a BSDism, but it makes writing my installer scripts vastly less reliable. Lots more below, but the gist is this:
>>>
>>> install -o root -d foo/
>>>
>>> Will create the directory with my user and effective group id, and my umask ... and yield an error message ... but still exit 0 (success). At the very least I would expect the directory to linger with these permissions and exit non-zero (failure) ... this is also not consistant with the behavior of files.
>>>
>>> Anyway ... anyone know a historical reason for this, or have a good hack around this ... getting patches into section 1 to trickle down into my world takes a while, assuming the behavior is even a bug ...
>>>
>>> ------------------------lots of copy-paste below----------------------------------
>>>
>>> [matt ~]$ mkdir install-showcase
>>> [matt ~]$ cd install-showcase/
>>> [matt ~/install-showcase]$ who am i
>>> matt 14 Dec 9 19:52
>>> [matt ~/install-showcase]$ install -d ./test.dir; echo $? # install a directory as me, success!
>>> 0
>>> [matt ~/install-showcase]$ ls -d ./test.dir; echo $? # see, success!
>>> ./test.dir
>>> 0
>>> [matt ~/install-showcase]$ install -o root -d ./test.dir.1; echo $? # install a directory as root, success?!
>>> install: chown 0:4294967295 ./test.dir.1: Operation not permitted
>>> 0
>>> [matt ~/install-showcase]$ ls -d ./test.dir.1 # see, success!
>>> ./test.dir.1
>>> [matt ~/install-showcase]$ ls -d ./test.dir.1; echo $? # see, success!
>>> ./test.dir.1
>>> 0
>>> [matt ~/install-showcase]$ install -o doesnotexist -d ./test.dir.2; echo $? # install directory as a user that doesn't exist, failure!
>>> install: doesnotexist: Invalid argument
>>> 67
>>> [matt ~/install-showcase]$ touch filetobeinstalled; ls filetobeinstalled; echo $? # but does it work with files?
>>> filetobeinstalled
>>> 0
>>> [matt ~/install-showcase]$ install filetobeinstalled test.file; echo $? # install a file as me, success!
>>> 0
>>> [matt ~/install-showcase]$ ls filetobeinstalled; echo $?
>>> filetobeinstalled
>>> 0
>>> [matt ~/install-showcase]$ install -o root filetobeinstalled test.file.1; echo $? # install a file as root, success?
>>> install: test.file.1: chown/chgrp: Operation not permitted
>>> 71
>>> [matt ~/install-showcase]$ ls test.file.1; echo $? # not even a lingering file
>>> ls: test.file.1: No such file or directory
>>> 1
>>> [matt ~/install-showcase]$ install -S -o root -d test.dir.2; echo $? # how about a directory in safe mode?
>>> install: chown 0:4294967295 test.dir.2: Operation not permitted
>>> 0
>>> [matt ~/install-showcase]$ ls -d test.dir.2; echo $? # yup ... safe mode too ... :(
>>> test.dir.2
>>> 0
>>> [matt ~/install-showcase]$ install -S -o root -d test.dir.2; echo $? # how about a directory in safe mode ... with an existing target
>>> install: chown 0:4294967295 test.dir.2: Operation not permitted
>>> 0
>>> [matt ~/install-showcase]$ ls -ld test.dir.2; echo $? # yup ... safe mode too ... :(
>>> drwxr-xr-x 2 matt matt 2 Dec 9 20:00 test.dir.2
>>> 0
>>> [matt ~/install-showcase]$ install -S -o root -d test.dir.2; echo $? # how about a directory in safe mode ... with an existing target
>>> install: chown 0:4294967295 test.dir.2: Operation not permitted
>>> 0
>>> _______________________________________________
>>> talk mailing list
>>> talk at lists.nycbug.org
>>> http://lists.nycbug.org/mailman/listinfo/talk
>>>
>>
>>
>
>
More information about the talk
mailing list