[Qemu-devel] rawhide gcc failures [was: Proposal for deprecating unsupported host OSes & architecutures]

[Eric Blake <eblake@redhat.com>]

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On 03/16/2017 10:23 AM, Peter Maydell wrote:
> OK, here's a concrete proposal for deprecating/dropping out of
> date host OS and architecture support.
> 
> We'll put this in the ChangeLog 'Future incompatible changes'
> section:
> -----
> * Removal of support for untested host OS and architectures:

Tangentially-related: do we officially support bleeding-edge OS builds?
For example, current rawhide has a new-enough gcc that gives some
(possibly-useful) new warnings (-Werror=format-truncation) that fire
when formatting what can be easily proven to be larger than a
fixed-width buffer will hold.  If rawhide is not a current target, then
I don't need to spend any time on this (yet); but if rawhide builds ARE
supported, then we want this patched before 2.9:


  CC      block/blkdebug.o
block/blkdebug.c: In function ‘blkdebug_refresh_filename’:
block/blkdebug.c:693:31: error: ‘%s’ directive output may be truncated
writing up to 4095 bytes into a region of size 4086
[-Werror=format-truncation=]
                  "blkdebug:%s:%s", s->config_file ?: "",
                               ^~
block/blkdebug.c:692:9: note: ‘snprintf’ output 11 or more bytes
(assuming 4106) into a destination of size 4096
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  "blkdebug:%s:%s", s->config_file ?: "",
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  bs->file->bs->exact_filename);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/home/dummy/qemu/rules.mak:69: block/blkdebug.o] Error 1
  CC      block/blkverify.o
block/blkverify.c: In function ‘blkverify_refresh_filename’:
block/blkverify.c:309:29: error: ‘%s’ directive output may be truncated
writing up to 4095 bytes into a region of size 4086
[-Werror=format-truncation=]
                  "blkverify:%s:%s",
                             ^~
block/blkverify.c:308:9: note: ‘snprintf’ output between 12 and 8202
bytes into a destination of size 4096
         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  "blkverify:%s:%s",
                  ~~~~~~~~~~~~~~~~~~
                  bs->file->bs->exact_filename,
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  s->test_file->bs->exact_filename);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/home/dummy/qemu/rules.mak:69: block/blkverify.o] Error 1
  CC      hw/usb/bus.o
hw/usb/bus.c: In function ‘usb_port_location’:
hw/usb/bus.c:410:66: error: ‘%d’ directive output may be truncated
writing between 1 and 11 bytes into a region of size between 0 and 15
[-Werror=format-truncation=]
         snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
                                                                  ^~
hw/usb/bus.c:410:9: note: ‘snprintf’ output between 3 and 28 bytes into
a destination of size 16
         snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  upstream->path, portnr);
                  ~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/home/dummy/qemu/rules.mak:69: hw/usb/bus.o] Error 1
  CC      net/slirp.o
net/slirp.c: In function ‘slirp_smb_cleanup’:
net/slirp.c:565:44: error: ‘%s’ directive output may be truncated
writing up to 127 bytes into a region of size 121
[-Werror=format-truncation=]
         snprintf(cmd, sizeof(cmd), "rm -rf %s", s->smb_dir);
                                            ^~
net/slirp.c:565:9: note: ‘snprintf’ output between 8 and 135 bytes into
a destination of size 128
         snprintf(cmd, sizeof(cmd), "rm -rf %s", s->smb_dir);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/slirp.c: In function ‘slirp_smb’:
net/slirp.c:609:46: error: ‘%s’ directive output may be truncated
writing 8 bytes into a region of size between 0 and 127
[-Werror=format-truncation=]
     snprintf(smb_conf, sizeof(smb_conf), "%s/%s", s->smb_dir, "smb.conf");
                                              ^~               ~~~~~~~~~~
net/slirp.c:609:5: note: ‘snprintf’ output between 10 and 137 bytes into
a destination of size 128
     snprintf(smb_conf, sizeof(smb_conf), "%s/%s", s->smb_dir, "smb.conf");
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/slirp.c:654:55: error: ‘%s’ directive output may be truncated
writing up to 127 bytes into a region of size 110
[-Werror=format-truncation=]
     snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -l %s -s %s",
                                                       ^~
net/slirp.c:654:5: note: ‘snprintf’ output 23 or more bytes (assuming
150) into a destination of size 128
     snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -l %s -s %s",
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
              CONFIG_SMBD_COMMAND, s->smb_dir, smb_conf);
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [/home/dummy/qemu/rules.mak:69: net/slirp.o] Error 1
make: Target 'all' not remade because of errors.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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