Nothing new here; only correction of mistakes that I made (I decided to review my e-mail because Ken Brwon took an interrest in the subject matter).
On Fri, 06 Sep 2019 23:53:05, Houder wrote: > To those still interested! :-P [snip] > While I took a closer look at the source code, I found a BUG in > path_conv::check() in winsup/cygwin/path.cc > > https://cygwin.com/ml/cygwin/2019-08/msg00418.html <==== wrong > ( Date: Sun, 01 Sep 2019 19:38:11 +0200 ) Correction: https://cygwin.com/ml/cygwin/2019-09/msg00001.html [snip] > On September 3rd, I discovered that dropping Eric B.'s code snippet, > would introduce a BUG: > > https://cygwin.com/ml/cygwin/2019-09/msg00015.html > ( Date: Tue, 03 Sep 2019 10:39:54 +0200 ) > > 64-@@ ln -s aap noot > .. > 64-@@ rmdir aap > 64-@@ mkdir noot > mkdir: cannot create directory ‘noot’: File exists > 64-@@ mkdir noot/ <==== Whao! So that is what Eric indicated in his commit! > 64-@@ ls -ld aap <==== WRONG! WRONG! > drwxr-xr-x+ 1 Henri None 0 Sep 3 10:28 aap > > Different from Posix, Linux does not allow the creation of the directory > aap ... (btw, neither should rmdir delete an existing directory aap if > noot/ is specified) Correction: Linux is in agreement w/ Posix. Cygwin is NOT in agreement w/ Posix (and Linux)i wrt to rmdir(2). > While waiting for a reaction by Eric Blake, I decided to take a closer > look at path_conv::check() ... Could a solution be found in this method? > > (path arguments to (all?) commands are processed by this method) > > Basically, this method consists of a 'double loop', as follows: > > for (;;) // outer loop > for (;;) // inner loop > > - the inner loop tests whether or not a path component is a symlnk > - if it is, the outer loop is reentered, where the symlnk part of > the path is replaced by the target > - finally, the algorithm bails out of both loops if a "real" path > is found (or not) > > Or something very near to this explanation ... > > In case the last component is a symlnk, the name of the symlnk is > saved internally if the path had not been specified w/ a trailing > slash. Otherwise the name of the target is saved internally. Correction: A symlnk is always followed if the pathname ends w/ a trailing slash; if not, it depends on what the system call specified when it invoked "path resolution" (path_conv::check() ). If the system call specified "do not follow", "path resolution" does not follow the symlnk (again, if path does NOT end w/ a trailing /). > In short, there is a basic difference between specifying a path > w/ a trailing slash or not ... Correct! Look at how the response is different between stat final and stat final/ in case of a symlnk. (stat(1) basically calls lstat(2), which directs path resolution NOT to follow a symlnk; however that directive is ignored by path resolution if the pathname ends w/ a slash) mkdir(2) and rmdir(2) are exceptions, in that these syscalls must strip trailing slashes; they must also specify "do not follow". The reason is, that these syscalls must not accept a symlnk as an argument. Henri ===== -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple