Re: [Qemu-devel] Hacks for building on gcc 7 / Fedora 26

[Philippe Mathieu-Daudé]

Hi Dave,

On 04/07/2017 11:38 AM, Dr. David Alan Gilbert wrote:
> Hi,
>    Fedora 26 has gcc 7.0.1 which has the normal compliment
> of new fussy warnings; so far I've posted :
>
> tests/check-qdict: Fix missing brackets
> slirp/smb: Replace constant strings by glib string
>
> that fix one actual mistake and work around something it's being
> fussy over.
>
> But I've also got a pile of hacks, attached below that I'm
> not too sure what I'll do with them yet, but they're attached
> for anyone else trying to build.  Note they're smoke-only-tested.
>
> I also have gcc bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80346
> filed for what I reckon is a couple of overly pessimistic warnings.
>
> Enjoy,
>
> Dave
>
> From 15353ce59e35e1d85927138982241491ea65cee2 Mon Sep 17 00:00:00 2001
> From: "Dr. David Alan Gilbert" <address@hidden>
> Date: Thu, 6 Apr 2017 15:44:50 +0100
> Subject: [HACK!] Hacks for f26 build
>
> ---
>  block/blkdebug.c         | 4 ++--
>  block/blkverify.c        | 4 ++--
>  hw/usb/bus.c             | 5 +++--
>  include/qemu/iov.h       | 4 ++--
>  tests/bios-tables-test.c | 2 +-
>  5 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/block/blkdebug.c b/block/blkdebug.c
> index 67e8024e36..34c645d095 100644
> --- a/block/blkdebug.c
> +++ b/block/blkdebug.c
> @@ -689,9 +689,9 @@ static void blkdebug_refresh_filename(BlockDriverState *bs, 
> QDict *options)
>      }
>
>      if (!force_json && bs->file->bs->exact_filename[0]) {
> -        snprintf(bs->exact_filename, sizeof(bs->exact_filename),
> +        g_assert_cmpint(snprintf(bs->exact_filename, 
> sizeof(bs->exact_filename),
>                   "blkdebug:%s:%s", s->config_file ?: "",
> -                 bs->file->bs->exact_filename);
> +                 bs->file->bs->exact_filename), <, sizeof(bs->exact_filename));

I'm not sure this works as expected if you compile with CPPFLAGS 
+=-DG_DISABLE_ASSERT.

I added in me docker TODO "also build with -DG_DISABLE_ASSERT".

>      }
>
>      opts = qdict_new();
> diff --git a/block/blkverify.c b/block/blkverify.c
> index 9a1e21c6ad..d038947a5a 100644
> --- a/block/blkverify.c
> +++ b/block/blkverify.c
> @@ -305,10 +305,10 @@ static void blkverify_refresh_filename(BlockDriverState 
> *bs, QDict *options)
>      if (bs->file->bs->exact_filename[0]
>          && s->test_file->bs->exact_filename[0])
>      {
> -        snprintf(bs->exact_filename, sizeof(bs->exact_filename),
> +        g_assert_cmpint(snprintf(bs->exact_filename, 
> sizeof(bs->exact_filename),
>                   "blkverify:%s:%s",
>                   bs->file->bs->exact_filename,
> -                 s->test_file->bs->exact_filename);
> +                 s->test_file->bs->exact_filename), <, 
> sizeof(bs->exact_filename));
>      }
>  }
>
> diff --git a/hw/usb/bus.c b/hw/usb/bus.c
> index 24f1608b4b..6023f3b419 100644
> --- a/hw/usb/bus.c
> +++ b/hw/usb/bus.c
> @@ -8,6 +8,7 @@
>  #include "monitor/monitor.h"
>  #include "trace.h"
>  #include "qemu/cutils.h"
> +#include <glib.h>
>
>  static void usb_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
>
> @@ -407,8 +408,8 @@ void usb_register_companion(const char *masterbus, USBPort 
> *ports[],
>  void usb_port_location(USBPort *downstream, USBPort *upstream, int portnr)
>  {
>      if (upstream) {
> -        snprintf(downstream->path, sizeof(downstream->path), "%s.%d",
> -                 upstream->path, portnr);
> +        g_assert_cmpint(snprintf(downstream->path, sizeof(downstream->path), 
> "%s.%d",
> +                 upstream->path, portnr), <, sizeof(downstream->path));
>          downstream->hubcount = upstream->hubcount + 1;
>      } else {
>          snprintf(downstream->path, sizeof(downstream->path), "%d", portnr);
> diff --git a/include/qemu/iov.h b/include/qemu/iov.h
> index bd9fd55b0a..ebb0221140 100644
> --- a/include/qemu/iov.h
> +++ b/include/qemu/iov.h
> @@ -46,7 +46,7 @@ static inline size_t
>  iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
>               size_t offset, const void *buf, size_t bytes)
>  {
> -    if (__builtin_constant_p(bytes) && iov_cnt &&
> +    if (__builtin_constant_p(bytes) && iov_cnt && bytes <= INT_MAX &&
>          offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
>          memcpy(iov[0].iov_base + offset, buf, bytes);
>          return bytes;
> @@ -59,7 +59,7 @@ static inline size_t
>  iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
>             size_t offset, void *buf, size_t bytes)
>  {
> -    if (__builtin_constant_p(bytes) && iov_cnt &&
> +    if (__builtin_constant_p(bytes) && iov_cnt && bytes <= INT_MAX &&
>          offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
>          memcpy(buf, iov[0].iov_base + offset, bytes);
>          return bytes;
> diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c
> index 88dbf97853..c55de4f65b 100644
> --- a/tests/bios-tables-test.c
> +++ b/tests/bios-tables-test.c
> @@ -98,7 +98,7 @@ static void test_acpi_rsdt_table(test_data *data)
>      AcpiRsdtDescriptorRev1 *rsdt_table = &data->rsdt_table;
>      uint32_t addr = data->rsdp_table.rsdt_physical_address;
>      uint32_t *tables;
> -    int tables_nr;
> +    unsigned int tables_nr;

Personally I prefer size_t here.

>      uint8_t checksum;
>
>      /* read the header */

regards,
Phil.