Messages in this thread Patch in this message | | | Date | Wed, 14 Jun 2006 20:19:28 -0700 | From | "Joshua Hudson" <> | Subject | patch for "bizarre read bug" in klibc dash |
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I had forked ash awhile back, patched up a few things to behave the way I wanted them. While I was at it, I fixed the "echo X | read X ; echo $X" bug that echoed a blank line. I tried awhile ago to raise who was responsible for the code and got nowhere.
I suppose you think the above code is a bizarre corner case. It is not. I use very complex shell expressions (think loops and subshells) in pipes, with read in the end to get the variable I was looking for. The work-around is particularly ugly.
I was quite surprised that this bug never got squashed in dash. So, I backported it.
Well, here's the patch.
--- usr/dash/eval.c.orig 2006-06-14 19:48:47.000000000 -0700 +++ usr/dash/eval.c 2006-06-14 20:07:58.000000000 -0700 @@ -539,7 +539,17 @@ sh_error("Pipe call failed"); } } - if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) { + if (!lp->next) { + extern void tempredir0(int prevfd); + /* Fix for "bizarre read bug" */ + if (prevfd > 0) { + tempredir0(prevfd); + close(prevfd); + } + evaltree(lp->n, 0); + if (prevfd > 0) + popredir(0); + } else if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) { INTON; if (pip[1] >= 0) { close(pip[0]); --- usr/dash/redir.c.orig 2006-06-14 19:59:21.000000000 -0700 +++ usr/dash/redir.c 2006-06-14 20:03:38.000000000 -0700 @@ -310,6 +310,21 @@ }
+void tempredir0(int fd) +{ + struct redirtab *sv = redirlist; + int i; + sv = ckmalloc(sizeof (struct redirtab)); + for (i = 0 ; i < 10 ; i++) + sv->renamed[i] = EMPTY; + sv->next = redirlist; + redirlist = sv; + INTOFF; + sv->renamed[0] = copyfd(0, 10); + close(0); + copyfd(fd, 0); + INTON; +}
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