2017-05-17 17:09 GMT+02:00 William Roberts [off-list ref]:

On Wed, May 17, 2017 at 7:59 AM, Sebastien Buisson
[off-list ref] wrote:

quoted

2017-05-16 22:40 GMT+02:00 Stephen Smalley [off-list ref]:

quoted

quoted

+     strcpy(*brief, policydb.policybrief);
+     /* *len is the length of the output string */
+     *len = policybrief_len - 1;

Is there a particular reason to not just return policybrief_len here as
well, for consistency in the interface?  How do you intend to use this
value in the caller?

As called in the other patch to expose policy brief via selinuxfs
(sel_read_policybrief), the intent is to provide the caller with the
length of the string returned.
Or should I set *len to policy brief_len here, and just make the
caller aware that the returned length is in fact the length of the
buffer (i.e. including terminating NUL byte)?

What is the caller supposed to do with length? This interface seemed kind of
odd. If it's guaranteed NUL byte terminated, do they even need length?

The length is useful as an input parameter in case the caller provides
its own buffer (instead of letting the function allocate one), and as
an output parameter in case the buffer given in input is not large
enough.
In any case, it can spare the caller the effort of recomputing the
length. As an example, sel_read_policybrief() in the 2/2 patch needs
to know the length of the string to put in the user buffer.
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