package/utils/busybox/patches/002-backport-ash-process-substitution.patch

   1 Stacy Harper reports that this script:
   2
   3    test() { . /tmp/bb_test; }
   4    echo "export TEST=foo" >/tmp/bb_test
   5    test 2>/dev/null
   6    echo "$TEST"
   7
   8 correctly prints 'foo' in BusyBox 1.33 but hangs in 1.34.
   9
  10 Bisection suggested the problem was caused by commit a1b0d3856 (ash: add
  11 process substitution in bash-compatibility mode).  Removing the call to
  12 unwindredir() in cmdloop() introduced in that commit makes the script
  13 work again.
  14
  15 Additionally, these examples of process substitution:
  16
  17    while true; do cat <(echo hi); done
  18    f() { while true; do cat <(echo hi); done }
  19    f
  20
  21 result in running out of file descriptors.  This is a regression from
  22 v5 of the process substitution patch caused by changes to evalcommand()
  23 not being transferred to v6.
  24
  25 function                                             old     new   delta
  26 static.pushredir                                       -      99     +99
  27 evalcommand                                         1729    1750     +21
  28 exitreset                                             69      86     +17
  29 cmdloop                                              372     365      -7
  30 unwindredir                                           28       -     -28
  31 pushredir                                            112       -    -112
  32 ------------------------------------------------------------------------------
  33 (add/remove: 1/2 grow/shrink: 2/1 up/down: 137/-147)          Total: -10 bytes
  34
  35 Signed-off-by: Ron Yorston <rmy at pobox.com>
  36 ---
  37  shell/ash.c | 10 +++++++---
  38  1 file changed, 7 insertions(+), 3 deletions(-)
  39
  40 diff --git a/shell/ash.c b/shell/ash.c
  41 index b5947147a..53c140930 100644
  42 --- a/shell/ash.c
  43 +++ b/shell/ash.c
  44 @@ -10278,6 +10278,9 @@ evalcommand(union node *cmd, int flags)
  45
  46         /* First expand the arguments. */
  47         TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
  48 +#if BASH_PROCESS_SUBST
  49 +       redir_stop = redirlist;
  50 +#endif
  51         file_stop = g_parsefile;
  52         back_exitstatus = 0;
  53
  54 @@ -10356,7 +10359,11 @@ evalcommand(union node *cmd, int flags)
  55                 lastarg = nargv[-1];
  56
  57         expredir(cmd->ncmd.redirect);
  58 +#if !BASH_PROCESS_SUBST
  59         redir_stop = pushredir(cmd->ncmd.redirect);
  60 +#else
  61 +       pushredir(cmd->ncmd.redirect);
  62 +#endif
  63         preverrout_fd = 2;
  64         if (BASH_XTRACEFD && xflag) {
  65                 /* NB: bash closes fd == $BASH_XTRACEFD when it is changed.
  66 @@ -13476,9 +13483,6 @@ cmdloop(int top)
  67  #if JOBS
  68                 if (doing_jobctl)
  69                         showjobs(SHOW_CHANGED|SHOW_STDERR);
  70 -#endif
  71 -#if BASH_PROCESS_SUBST
  72 -               unwindredir(NULL);
  73  #endif
  74                 inter = 0;
  75                 if (iflag && top) {
  76 --
  77 2.31.1