See comment for explanation and https://listman.redhat.com/archives/libguestfs/2023-August/032468.html --- tests/Makefile.am | 2 + plugins/sh/call.c | 33 +++++++----- tests/test-sh-pwrite-ignore-stdin.sh | 77 ++++++++++++++++++++++++++++ 3 files changed, 100 insertions(+), 12 deletions(-) diff --git a/tests/Makefile.am b/tests/Makefile.am index d57eb01b8..e69893e0d 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -1325,11 +1325,13 @@ test-shell.img: TESTS += \ test-sh-errors.sh \ test-sh-extents.sh \ + test-sh-pwrite-ignore-stdin.sh \ test-sh-tmpdir-leak.sh \ $(NULL) EXTRA_DIST += \ test-sh-errors.sh \ test-sh-extents.sh \ + test-sh-pwrite-ignore-stdin.sh \ test-sh-tmpdir-leak.sh \ $(NULL) diff --git a/plugins/sh/call.c b/plugins/sh/call.c index 888c6459a..621465252 100644 --- a/plugins/sh/call.c +++ b/plugins/sh/call.c @@ -275,22 +275,31 @@ call3 (const char *wbuf, size_t wbuflen, /* sent to stdin (can be NULL) */ r = write (pfds[0].fd, wbuf, wbuflen); if (r == -1) { if (errno == EPIPE) { - /* We tried to write to the script but it didn't consume - * the data. Probably the script exited without reading - * from stdin. This is an error in the script. + /* In nbdkit <= 1.35.11 we gave an error here, arguing that + * scripts must always consume or discard their full input + * when 'pwrite' is called. Previously we had many cases + * where scripts forgot to discard the data on a path out of + * pwrite (such as an error or where the script is not + * interested in the data being written), resulting in + * intermittent test failures. + * + * It is valid for a script to ignore the written data + * (plenty of non-sh plugins do this), or for a script to be + * gradually processing the data, encounter an error and + * wish to exit immediately. Therefore ignore this error. */ - nbdkit_error ("%s: write to script failed because of a broken pipe: " - "this can happen if the script exits without " - "consuming stdin, which usually indicates a bug " - "in the script", - argv0); + nbdkit_debug ("%s: write: %m (ignored)", argv0); + wbuflen = 0; /* discard the rest */ } - else + else { nbdkit_error ("%s: write: %m", argv0); - goto error; + goto error; + } + } + else { + wbuf += r; + wbuflen -= r; } - wbuf += r; - wbuflen -= r; /* After writing all the data we close the pipe so that * the reader on the other end doesn't wait for more. */ diff --git a/tests/test-sh-pwrite-ignore-stdin.sh b/tests/test-sh-pwrite-ignore-stdin.sh new file mode 100755 index 000000000..3448eca17 --- /dev/null +++ b/tests/test-sh-pwrite-ignore-stdin.sh @@ -0,0 +1,77 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright Red Hat +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +# Test that pwrite is allowed to ignore stdin (in nbdkit >= 1.36). + +source ./functions.sh +set -e +set -x + +requires_plugin sh +requires_nbdsh_uri + +sock=$(mktemp -u /tmp/nbdkit-test-sock.XXXXXX) +pid=sh-pwrite-ignore-stdin.pid +files="$sock $pid" +rm -f $files +cleanup_fn rm -f $files + +start_nbdkit -P $pid -U $sock sh - <<'EOF' +case "$1" in + can_write) echo 0 ;; + pwrite) + # Always ignore the input. If the offset >= 32M return an error. + if [ $4 -ge 33554432 ]; then + echo 'ENOSPC Out of space' >&2 + exit 1 + fi + ;; + get_size) + echo 64M + ;; + pread) + ;; + *) exit 2 ;; +esac +EOF + +nbdsh -u "nbd+unix://?socket=$sock" -c ' +buf = bytearray(16*1024*1024) +h.pwrite(buf, 0) + +try: + h.pwrite(buf, 32*1024*1024) + assert False +except nbd.Error: + # Expect an error here. + pass +' -- 2.41.0