Re: /dev/fd/n bug in gawk 3.1.5

[Aharon Robbins]

Greetings. Re this:

> Date: Tue, 13 Jun 2006 17:49:58 -0700
> From: "John H. DuBois III" <address@hidden>
> Subject: /dev/fd/n bug in gawk 3.1.5
> To: address@hidden
>
> $ cat /dev/fd/4 /dev/fd/5 4<tm1 5<tm2
> Contents of tm1
> Contents of tm2
> $ gawk 1 /dev/fd/4 /dev/fd/5 4<tm1 5<tm2
> Contents of tm1
> Contents of tm1
>
>
> gawk: (FILENAME=/dev/fd/5 FNR=3) fatal: error reading input file `/dev/fd/4': 
> Bad file number

Thanks for this bug report. The following patch fixes the problem. It includes 
an
earlier patch to io.c as well.

The critical part of the patch is the change to the assignments to iop->flag.

Thanks,

Arnold
----------------- cut here -----------------------
--- ../gawk-3.1.5/io.c  2005-07-26 21:07:43.000000000 +0300
+++ io.c        2006-06-17 23:09:59.275743240 +0300
@@ -1440,7 +1440,7 @@
        iop->end = iop->buf + len;
        iop->dataend = iop->end;
        iop->fd = -1;
-       iop->flag = IOP_IS_INTERNAL | IOP_AT_START;
+       iop->flag = IOP_IS_INTERNAL | IOP_AT_START | IOP_NO_FREE;
 }
 
 /* specfdopen --- open an fd special file */
@@ -1454,15 +1454,12 @@
        fd = devopen(name, mode);
        if (fd == INVALID_HANDLE)
                return INVALID_HANDLE;
-       tp = iop_alloc(fd, name, NULL);
+       tp = iop_alloc(fd, name, iop);
        if (tp == NULL) {
                /* don't leak fd's */
                close(fd);
                return INVALID_HANDLE;
        }
-       *iop = *tp;
-       iop->flag |= IOP_NO_FREE;
-       free(tp);
        return 0;
 }
 
@@ -2480,9 +2477,12 @@
 {
        struct stat sbuf;
        struct open_hook *oh;
+       int iop_malloced = FALSE;
 
-       if (iop == NULL)
+       if (iop == NULL) {
                emalloc(iop, IOBUF *, sizeof(IOBUF), "iop_alloc");
+               iop_malloced = TRUE;
+       }
        memset(iop, '\0', sizeof(IOBUF));
        iop->flag = 0;
        iop->fd = fd;
@@ -2495,7 +2495,8 @@
        }
 
        if (iop->fd == INVALID_HANDLE) {
-               free(iop);
+               if (iop_malloced)
+                       free(iop);
                return NULL;
        }
        if (isatty(iop->fd))