[Bug 1892338] Re: zip --symlink is incompatible with piped output

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: zip (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1892338

Title:
  zip --symlink is incompatible with piped output

Status in zip package in Ubuntu:
  Confirmed

Bug description:
  Hi folks,

  As in the summary, if you use --symlink (-y) with the output piped to
  a process, it stops building the zip on the first symlink it
  encounters with an unhelpful error (as the user is not using -0
  intentionally).

  Here's the simplest test case I can build:

  root at test123:~/test# mkdir asdf
  root at test123:~/test# ln -s asdf test
  root at test123:~/test# date > hello.txt
  root at test123:~/test# ls -l
  total 2
  drwxr-xr-x 2 root root  4 Aug 20 09:10 asdf
  -rw-r--r-- 1 root root 29 Aug 20 08:50 hello.txt
  lrwxrwxrwx 1 root root  4 Aug 20 08:24 test -> asdf
  root at test123:~/test# zip -1ryv - . | cat > ../test.zip
    adding: test

  zip error: Invalid command arguments (zip -0 not supported for I/O on pipes or devices)
  66.0 B 0:00:00 [93.4KiB/s] [<=>                                                ]

  I believe the issue is around line 575 of zipup.c... my understanding
  of the code is tenuous at best, but I think q is not reset when m is
  set to STORE:

      l = issymlnk(a);
      if (l) {
        ifile = fbad;
        m = STORE;
      }
      else if (isdir) { /* directory */
        ifile = fbad;
        m = STORE;
        q = 0;
      }

  If I build with q = 0; in the if (l) block too, it appears to work (it
  complains that the file size changed while zipping, but zip does not
  error out, the zip file is created correctly), but I don't know what
  other problems this would introduce.

  Not sure if anyone's maintaining this package so I don't want to put
  too much effort into it, I'll have a go at attaching a patch which I
  think fixes the issue, but again I'm not sure if it causes any new
  issues (and one probably wants to fix the warning about the file size
  changing at the very least).

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