Re: Z/OS Enhancement to gnu lib

[Bruno Haible]

Igor Todorovski wrote:
> This was the symptom we experienced with findutils (guarding the close in 
> gnulib fixed it):
> find . -name "test"
> The output is:
> find: '.': EDC5113I Bad file descriptor.
> 
> https://github.com/ZOSOpenTools/findutilsport/issues/4
> 
> We’ll do some more testing to see if there’s a better solution.

I'm sending you a testdir, generated through

  ./gnulib-tool --create-testdir --dir=/tmp/testdir --single-configure \
                areadlinkat areadlinkat-with-size faccessat fchmodat fchownat 
                fdopendir getcwd fstatat linkat mkdirat mkfifoat openat 
                readlinkat renameatu savedir symlinkat unlinkat utimensat

As part of your testing, please run it through
  ./configure && make && make check

(Sent via private mail, as it's too large for this mailing list.)

> __e2a_l is documented here: 
> https://www.ibm.com/docs/en/zos/2.2.0?topic=functions-e2a-l-convert-characters-from-ebcdic-ascii

Well, according to this documentation your patch was buggy: it did not
check the return value. Additionally, it ran a conversion on a buffer
full of uninitialized data (which is 1. slow and 2. triggers warnings
in tools like valgrind).  And when w_ioctl failed, your code was
accessing and returning unitialized data in dir[]. Ouch ouch ouch.

Fixing it like this:


2023-01-30  Bruno Haible  <bruno@clisp.org>

        at-internal: Fix support for z/OS.
        * lib/openat-proc.c (openat_proc_name) [z/OS]: Proper error handling.
        Convert only the relevant part of the dir[] buffer.

diff --git a/lib/openat-proc.c b/lib/openat-proc.c
index 6419a8cf5f..88f70be4f5 100644
--- a/lib/openat-proc.c
+++ b/lib/openat-proc.c
@@ -123,8 +123,16 @@ openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, 
char const *file)
 # endif
 # ifdef __MVS__
     char dir[_XOPEN_PATH_MAX];
-    if (w_ioctl (fd, _IOCC_GPN, sizeof dir, dir) == 0)
-      __e2a_l (dir, sizeof dir);
+    /* Documentation:
+       
https://www.ibm.com/docs/en/zos/2.2.0?topic=functions-w-ioctl-w-pioctl-control-devices
 */
+    if (w_ioctl (fd, _IOCC_GPN, sizeof dir, dir) < 0)
+      return NULL;
+    /* Documentation:
+       
https://www.ibm.com/docs/en/zos/2.2.0?topic=functions-e2a-l-convert-characters-from-ebcdic-ascii
 */
+    dirlen = __e2a_l (dir, strlen (dir));
+    if (dirlen < 0 || dirlen >= sizeof dir)
+      return NULL;
+    dir[dirlen] = '\0';
 # endif
 
     dirlen = strlen (dir);