Re: [Qemu-devel] [PATCH v3 00/10] curl: fix curl read

["Richard W.M. Jones" <rjones@redhat.com>]

On Mon, May 20, 2013 at 09:41:06AM +0100, Richard W.M. Jones wrote:
> On Mon, May 20, 2013 at 03:03:34PM +0800, Fam Zheng wrote:
> > CURL library API has changed, the current curl driver is not working.
> > This patch rewrites the use of API as well as the structure of internal
> > states. 
> 
> I tried this, but it segfaults:
> 
> Program terminated with signal 11, Segmentation fault.

That stack trace was wrong.  I was testing against the version of
libcurl in Fedora which is known to be broken.

Here is the stack trace, this time really running against
curl-7_30_0-147-gae26ee3:

Program terminated with signal 11, Segmentation fault.
#0  curl_read_cb (ptr=<optimized out>, size=<optimized out>, 
    nmemb=<optimized out>, opaque=0x7f63d48ba340) at block/curl.c:240
240         size_t aio_base = acb->sector_num * SECTOR_SIZE;
Missing separate debuginfos, use: debuginfo-install SDL-1.2.15-3.fc18.x86_64 bluez-libs-4.101-6.fc18.x86_64 brlapi-0.5.6-12.fc18.x86_64 celt051-0.5.1.3-5.fc18.x86_64 ceph-devel-0.56.3-1.fc18.x86_64 ceph-libs-0.56.3-1.fc18.x86_64 cryptopp-5.6.2-2.fc18.x86_64 cyrus-sasl-lib-2.1.25-2.fc18.x86_64 leveldb-1.7.0-4.fc18.x86_64 libfdt-1.3.0-5.fc18.x86_64 libseccomp-1.0.1-0.fc18.x86_64 libselinux-2.1.12-7.3.fc18.x86_64 libusbx-1.0.14-1.fc18.x86_64 nss-mdns-0.10-11.fc18.x86_64 snappy-1.0.5-2.fc18.x86_64 spice-server-0.12.2-3.fc18.x86_64 usbredir-0.6-1.fc18.x86_64 xen-libs-4.2.2-3.fc18.x86_64
(gdb) bt
#0  curl_read_cb (ptr=<optimized out>, size=<optimized out>, 
    nmemb=<optimized out>, opaque=0x7f63d48ba340) at block/curl.c:240
#1  0x00007f63cef51cc8 in Curl_client_write ()
   from /home/rjones/d/curl/lib/.libs/libcurl.so.4
#2  0x00007f63cef697ef in Curl_readwrite ()
   from /home/rjones/d/curl/lib/.libs/libcurl.so.4
#3  0x00007f63cef710b0 in multi_runsingle ()
   from /home/rjones/d/curl/lib/.libs/libcurl.so.4
#4  0x00007f63cef720f7 in multi_socket ()
   from /home/rjones/d/curl/lib/.libs/libcurl.so.4
#5  0x00007f63cef721df in curl_multi_socket_action ()
   from /home/rjones/d/curl/lib/.libs/libcurl.so.4
#6  0x00007f63d27d9043 in curl_fd_handler (arg=0x7f63d48e16c0)
    at block/curl.c:265
#7  0x00007f63d27bcbbb in aio_dispatch (ctx=0x7f63d48b33f0, ctx=0x7f63d48b33f0)
    at aio-posix.c:149
#8  0x00007f63d27bd0b1 in aio_poll (ctx=0x7f63d48b33f0, 
    blocking=blocking@entry=true) at aio-posix.c:248
#9  0x00007f63d29019c9 in qemu_aio_wait () at main-loop.c:484
#10 0x00007f63d27d2b65 in bdrv_rwv_co (bs=bs@entry=0x7f63d48b96e0, 
    sector_num=sector_num@entry=0, qiov=qiov@entry=0x7fff2c127e10, 
    is_write=is_write@entry=false) at block.c:2215
#11 0x00007f63d27d2c90 in bdrv_rw_co (is_write=false, 
    nb_sectors=<optimized out>, buf=<optimized out>, sector_num=0, bs=
    0x7f63d48b96e0) at block.c:2234
#12 bdrv_read (bs=bs@entry=0x7f63d48b96e0, sector_num=sector_num@entry=0, 
    buf=buf@entry=0x7fff2c128100 "3\300\216м", nb_sectors=nb_sectors@entry=4)
    at block.c:2241
#13 0x00007f63d27d2d82 in bdrv_pread (bs=0x7f63d48b96e0, offset=offset@entry=
    0, buf=buf@entry=0x7fff2c128100, count1=count1@entry=2048) at block.c:2303
#14 0x00007f63d27d3460 in find_image_format (pdrv=<synthetic pointer>, 
    filename=0x7f63d48b6b40 "http://192.168.0.249/scratch/winxp.img", 
    bs=<optimized out>) at block.c:533
#15 bdrv_open (bs=0x7f63d48b6cc0, filename=filename@entry=
    0x7f63d48b6b40 "http://192.168.0.249/scratch/winxp.img", options=
    0x7f63d48b76a0, options@entry=0x7f63d48b5980, flags=8258, drv=drv@entry=
    0x0) at block.c:1047
#16 0x00007f63d2806093 in drive_init (all_opts=0x7f63d48b2420, 
    block_default_type=IF_NONE) at blockdev.c:698
#17 0x00007f63d297054b in drive_init_func (opts=<optimized out>, 
    opaque=<optimized out>) at vl.c:1117
#18 0x00007f63d2a9a6f3 in qemu_opts_foreach (list=<optimized out>, 
    func=func@entry=0x7f63d2970530 <drive_init_func>, opaque=opaque@entry=
    0x7f63d2e938f0 <pc_i440fx_machine_v1_5+48>, 
    abort_on_failure=abort_on_failure@entry=1) at util/qemu-option.c:1162
#19 0x00007f63d27b7b89 in main (argc=<optimized out>, argv=<optimized out>, 
    envp=<optimized out>) at vl.c:4201

---

For completeness:

(1) qemu from git (without your patches) works.

(2) I'm testing using the following command:

$ LD_LIBRARY_PATH=~/d/curl/lib/.libs \
  LIBGUESTFS_BACKEND=direct \
  LIBGUESTFS_QEMU=~/d/qemu/qemu.wrapper \
  ./run ./fish/guestfish -a http://192.168.0.249/scratch/winxp.img -i -v

where:

(a) ~/d/libguestfs contains libguestfs from git
(b) ~/d/curl contains curl-7_30_0-147-gae26ee3
(c) http://192.168.0.249/scratch/winxp.img is a Windows XP image
(d) qemu.wrapper is:

----------------------------------------------------------------------
#!/bin/sh -
qemudir=/home/rjones/d/qemu
exec $qemudir/x86_64-softmmu/qemu-system-x86_64 -L $qemudir/pc-bios "$@"
----------------------------------------------------------------------

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Fedora Windows cross-compiler. Compile Windows programs, test, and
build Windows installers. Over 100 libraries supported.
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