Hello, I'm coming back to the ZSH_XTRACEFD feature again :) About closing file descriptors or not: I don't understand what it means to "leak a FILE". I'm not sure to understand the past comments either: we only use fdopen when the value of ZSH_XTRACEFD is > 2. For 0, 1 and 2, we re-use the existing file descriptors stdin, stdout and stderr. Anyway, I added the patch in an attachment. Also, here's the link to the commit on my fork: https://github.com/pawamoy/zsh/commit/b9b37333fcf02a463f6f742976b37b45ab08742d In this patch, I never close any file descriptor. There's one last thing that looks weird to me: single instructions like ZSH_XTRACEFD=5 are not properly logged in the xtrace output. It seems they are truncated up to the end of the variable assignment: - with a=0 ZSH_XTRACEFD=5, nothing appear in the output either - with ZXH_XTRACEFD=5 a=0, only a=0 appears in the output (but no +(eval):18 prefix or similar) Any idea about this? Cheers, Timothée On Wed, May 6, 2020 at 12:20 AM Bart Schaefer wrote: > (Peter, for some reason Gmail is classifying all email from > ntlworld.com as spam, with the notation that it "can't guarantee that > this message came from ntlworld.com") > > On Tue, May 5, 2020 at 9:48 AM Peter Stephenson > wrote: > > > > > > The problem is if we fopen() the file descriptor to use stdio as output, > we can either > > leak the entire FILE, not opened by the user, or we can close the entire > FILE. > > In that case we should be doing the fopen() on a dup() of the > descriptor, and fclose()ing the FILE. > > If it is important that fileno(xtrerr) == $ZSH_XTRACEFD, then we should > 1) dup() the descriptor to save a copy > 2) fopen() the original > 3) after fclose(), dup2() the copy back to the original > 4) close() the copy > > However, I'm not sure it's necessary to be that convoluted. >