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libvduse: Avoid warning about dangerous use of strncpy()

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GCC 8 added a -Wstringop-truncation warning:

  The -Wstringop-truncation warning added in GCC 8.0 via r254630 for
  bug 81117 is specifically intended to highlight likely unintended
  uses of the strncpy function that truncate the terminating NUL
  character from the source string.

Here the next line indeed unconditionally zeroes the last byte, but
1/ the buffer has been calloc'd, so we don't need to add an extra
byte, and 2/ we called vduse_name_is_invalid() which checked the
string length, so we can simply call strcpy().

This fixes when using gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0:

  [42/666] Compiling C object subprojects/libvduse/libvduse.a.p/libvduse.c.o
  FAILED: subprojects/libvduse/libvduse.a.p/libvduse.c.o
  cc -m64 -mcx16 -Isubprojects/libvduse/libvduse.a.p -Isubprojects/libvduse -I../../subprojects/libvduse [...] -o subprojects/libvduse/libvduse.a.p/libvduse.c.o -c ../../subprojects/libvduse/libvduse.c
  In file included from /usr/include/string.h:495,
                   from ../../subprojects/libvduse/libvduse.c:24:
  In function ‘strncpy’,
      inlined from ‘vduse_dev_create’ at ../../subprojects/libvduse/libvduse.c:1312:5:
  /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 256 equals destination size [-Werror=stringop-truncation]
    106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
        |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors
  ninja: build stopped: cannot make progress due to previous errors.

Fixes: d9cf16c0be ("libvduse: Replace strcpy() with strncpy()")
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Bin Meng <bmeng@tinylab.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20221111124550.35753-1-philmd@linaro.org>
This commit is contained in:
Philippe Mathieu-Daudé 2022-11-11 13:45:50 +01:00 committed by Stefan Hajnoczi
parent 6a4cff8e1a
commit 57bc6e40e8
1 changed files with 2 additions and 2 deletions
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subprojects/libvduse/libvduse.c
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@ -1309,8 +1309,8 @@ VduseDev *vduse_dev_create(const char *name, uint32_t device_id,
goto err_dev; goto err_dev;
} }
strncpy(dev_config->name, name, VDUSE_NAME_MAX); assert(!vduse_name_is_invalid(name));
dev_config->name[VDUSE_NAME_MAX - 1] = '\0'; strcpy(dev_config->name, name);
dev_config->device_id = device_id; dev_config->device_id = device_id;
dev_config->vendor_id = vendor_id; dev_config->vendor_id = vendor_id;
dev_config->features = features; dev_config->features = features;