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https://issues.apache.org/jira/browse/ZOOKEEPER-311?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Darroch updated ZOOKEEPER-311:
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Release Note: The zoo_create() function is revised to take path_buffer and
path_buffer_len arguments. The path_buffer will be filled with as much of the
actual path of the new node fits into the buffer, including a null terminator.
Unlike 3.x behaviour, if path_buffer_len (formerly max_realpath_len) is 1, the
buffer will be filled with a single null terminator.
Hadoop Flags: [Incompatible change]
Status: Patch Available (was: Open)
> handle small path lengths in zoo_create()
> -----------------------------------------
>
> Key: ZOOKEEPER-311
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-311
> Project: Zookeeper
> Issue Type: Improvement
> Components: c client
> Affects Versions: 3.1.0, 3.0.1, 3.0.0
> Reporter: Chris Darroch
> Priority: Minor
> Fix For: 4.0.0
>
> Attachments: ZOOKEEPER-311.patch, ZOOKEEPER-311.patch
>
>
> The synchronous completion for zoo_create() contains the following code:
> if (sc->u.str.str_len > strlen(res.path)) {
> len = strlen(res.path);
> } else {
> len = sc->u.str.str_len-1;
> }
> if (len > 0) {
> memcpy(sc->u.str.str, res.path, len);
> sc->u.str.str[len] = '\0';
> }
> In the case where the max_realpath_len argument to zoo_create() is 0, none of
> this code executes, which is OK. In the case where max_realpath_len is 1, a
> user might expect their buffer to be filled with a null terminator, but
> again, nothing will happen (even if strlen(res.path) is 0, which is unlikely
> since new node's will have paths longer than "/").
> The name of the argument to zoo_create() is also a little misleading, as is
> its description ("the maximum length of real path you would want") in
> zookeeper.h, and the example usage in the Programmer's Guide:
> int rc = zoo_create(zh,"/xyz","value", 5, &CREATE_ONLY, ZOO_EPHEMERAL,
> buffer, sizeof(buffer)-1);
> In fact this value should be the actual length of the buffer, including space
> for the null terminator. If the user supplies a max_realpath_len of 10 and a
> buffer of 11 bytes, and strlen(res.path) is 10, the code will truncate the
> returned value to 9 bytes and put the null terminator in the second-last
> byte, leaving the final byte of the buffer unused.
> It would be better, I think, to rename the realpath and max_realpath_len
> arguments to something like path_buffer and path_buffer_len, akin to
> zoo_set(). The path_buffer_len would be treated as the full length of the
> buffer (as the code does now, in fact, but the docs suggest otherwise).
> The code in the synchronous completion could then be changed as per the
> attached patch.
> Since this would change, slightly, the behaviour or "contract" of the API, I
> would be inclined to suggest waiting until 4.0.0 to implement this change.
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