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GCC 7: Allocate sufficient space for sprintf output.

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GCC 7.0.1 can determine if there is likely to be sufficient space in
the output buffer when using sprintf/snprintf, based on the format
string.

The errors were all either of this form:

bindtests.c:717:29: error: '%zu' directive output may be truncated writing between 1 and 19 bytes into a region of size 16 [-Werror=format-truncation=]
     snprintf (strs[i], 16, "%zu", i);
                             ^~~
bindtests.c:717:28: note: directive argument in the range [0, 2305843009213693951]
     snprintf (strs[i], 16, "%zu", i);
                             ^~~~~

or this form:

sync.c: In function 'fsync_devices':
sync.c:108:50: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size 251 [-Werror=format-truncation=]
       snprintf (dev_path, sizeof dev_path, "/dev/%s", d->d_name);
                                                  ^~

Fixed by converting these into dynamic allocation, or making the
output buffer larger, whichever was easier.

There is a gnulib macro we can use to make this simpler for integers.
It requires a new gnulib module (intprops), but it turns out that we
were already pulling that in through dependencies, so the change to
bootstrap is a no-op.  (thanks: Dan Berrange)
This commit is contained in:
Richard W.M. Jones
2017-02-14 14:52:53 +00:00
parent 0b3a5a0b00
commit a75076f271
7 changed files with 45 additions and 18 deletions
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10
daemon/9p.c
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@@ -71,9 +71,13 @@ do_list_9p (void)
if (d == NULL) break;
if (STRPREFIX (d->d_name, "virtio")) {
char mount_tag_path[256];
snprintf (mount_tag_path, sizeof mount_tag_path,
BUS_PATH "/%s/mount_tag", d->d_name);
CLEANUP_FREE char *mount_tag_path = NULL;
if (asprintf (&mount_tag_path, BUS_PATH "/%s/mount_tag",
d->d_name) == -1) {
reply_with_perror ("asprintf");
closedir (dir);
return NULL;
}
/* A bit unclear, but it looks like the virtio transport allows
* the mount tag length to be unlimited (or up to 65536 bytes).