Hi,
Updated patch attached.
[[[
Signal SVN_ERR_BAD_OLD_VALUE over DAV using a HTTP 412 status
code inside a 207 multi-status response.
* subversion/mod_dav_svn/util.c
(dav_svn__convert_err): Map SVN_ERR_BAD_OLD_VALUE to 412.
* subversion/libsvn_ra_neon/util.c
(multistatus_baton_t): New member contains_precondition_error.
(end_207_element): Check for HTTP 412 status code and create
a SVN_ERR_BAD_OLD_VALUE error if found.
* subversion/libsvn_ra_serf/ra_serf.h
(svn_ra_serf__server_error_t): New member
contains_precondition_error.
* subversion/libsvn_ra_serf/util.c
(parse_dav_status): New method.
(start_207): Parse DAV:status XML element.
(end_207): Parse DAV:status XML element. Use SVN_ERR_BAD_OLD_VALUE
error code if applicable.
(svn_ra_serf__handle_multistatus_only): Initialise new member.
Patch by: Jon Foster <jon.fos...@cabot.co.uk>
]]]
Daniel Shahaf wrote:
> > [[[
> > Signal SVN_ERR_BAD_OLD_VALUE over DAV using a HTTP 412 status
> > code inside a 207 multi-status response.
> >
> > * subversion/mod_dav_svn/util.c:
>
> No trailing colon here ----------^
Fixed.
[...]
> > Index: subversion/libsvn_ra_serf/util.c
> > ===================================================================
> > --- subversion/libsvn_ra_serf/util.c (revision 999102)
> > +++ subversion/libsvn_ra_serf/util.c (working copy)
> > @@ -836,6 +836,7 @@ svn_ra_serf__handle_discard_body(serf_request_t
*r
> > + server_err->contains_precondition_error = FALSE;
>
> (So, this is the error handler for a function that normally discards
> its response, and the meat of the patch is in
> svn_ra_serf__handle_multistatus_only().)
After reviewing this code again, I've dropped that chunk. I've
convinced
myself that the variable is never used in that code path.
> > @@ -945,6 +946,31 @@ svn_ra_serf__handle_status_only(serf_request_t
*re
> > return svn_error_return(err);
> > }
> >
> > +/* Given a string like "HTTP/1.1 500 (status)", parse out the
numeric status
> > + code. Ignores leading whitespace. This function will overwrite
and then
> > + clear the passed buf. */
>
> Sounds like a strange semantics. Couldn't you just take a
scratch_pool
> argument and duplicate the buffer, leaving the caller's copy
unchanged?
> Changing it in-place seems like a shoot-oneself-in-the-foot move...
Changed.
> > +static svn_error_t *
> > +parse_dav_status(svn_stringbuf_t *buf, int *status_code_out)
> > +{
> > + svn_error_t * err;
> > + const char * token;
> > + char * tok_status = 0;
>
> Style nit: no space after the * in the last three lines.
>
> Also, no need to initialize TOK_STATUS (says
svn_cstring_split_append()).
Both done.
> > +
> > + svn_stringbuf_strip_whitespace(buf);
> > + token = apr_strtok(buf->data, " \t\r\n", &tok_status);
> > + if (token)
> > + token = apr_strtok(NULL, " \t\r\n", &tok_status);
> > + if (!token)
> > + return svn_error_create(SVN_ERR_RA_DAV_MALFORMED_DATA, NULL,
> > + "Malformed DAV:status CDATA");
>
> Should the cdata be included in the error text? (using
svn_error_createf())
Can do, and in the new patch I have.
> > + err = svn_cstring_atoi(status_code_out, token);
> > + if (err)
> > + return svn_error_create(SVN_ERR_RA_DAV_MALFORMED_DATA, err,
> > + "Malformed DAV:status CDATA");
> > + svn_stringbuf_setempty(buf);
> > + return SVN_NO_ERROR;
> > +}
> > +
> > /*
> > * Expat callback invoked on a start element tag for a 207
response.
> > */
> > @@ -968,6 +994,14 @@ start_207(svn_ra_serf__xml_parser_t *parser,
> > svn_stringbuf_setempty(ctx->cdata);
> > ctx->collect_cdata = TRUE;
> > }
> > + else if (ctx->in_error &&
> > + strcmp(name.namespace, "DAV:") == 0 &&
> > + strcmp(name.name, "status") == 0)
> > + {
> > + /* Start collecting cdata. */
> > + svn_stringbuf_setempty(ctx->cdata);
>
> Okay; D:responsedescription and D:status are siblings [1], so it's
> okay to reuse CTX->cdata.
>
> [1] http://paste.lisp.org/display/113346
>
> <paranoia on>
> Are you sure they will always be siblings? If we aren't sure that
yes,
> we could just use two stringbufs (instead of reusing ctx->cdata).
Even with the old code, if there are any elements with CDATA nested
inside <D:responsedescription>, Serf is going to go wrong. If we
collect CDATA into different variables, then it'll just go wrong in
a different way (e.g. the HTTP status line might be shown as part of
the message).
I think there's a whole package of work that could be done to make
Serf resilient against weird XML, but I think that's separate from
this work. (It's also quite hard to test).
> > + ctx->collect_cdata = TRUE;
[...]
> > + SVN_ERR(parse_dav_status(ctx->cdata, &status_code));
> Our convention is to have the output parameters first.
Changed.
Thanks for the thourough review!
Jon
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______________________________________________________________________Index: subversion/mod_dav_svn/util.c
===================================================================
--- subversion/mod_dav_svn/util.c (revision 999156)
+++ subversion/mod_dav_svn/util.c (working copy)
@@ -107,6 +107,9 @@ dav_svn__convert_err(svn_error_t *serr,
case SVN_ERR_FS_PATH_ALREADY_LOCKED:
status = HTTP_LOCKED;
break;
+ case SVN_ERR_BAD_OLD_VALUE:
+ status = HTTP_PRECONDITION_FAILED;
+ break;
/* add other mappings here */
}
Index: subversion/libsvn_ra_neon/util.c
===================================================================
--- subversion/libsvn_ra_neon/util.c (revision 999156)
+++ subversion/libsvn_ra_neon/util.c (working copy)
@@ -167,6 +167,7 @@ typedef struct
svn_ra_neon__request_t *req;
svn_stringbuf_t *description;
svn_boolean_t contains_error;
+ svn_boolean_t contains_precondition_error;
} multistatus_baton_t;
/* Implements svn_ra_neon__startelm_cb_t. */
@@ -231,6 +232,9 @@ end_207_element(void *baton, int state,
return svn_error_create(SVN_ERR_RA_DAV_REQUEST_FAILED, NULL,
_("The request response contained at least
"
"one error"));
+ else if (b->contains_precondition_error)
+ return svn_error_create(SVN_ERR_BAD_OLD_VALUE, NULL,
+ b->description->data);
else
return svn_error_create(SVN_ERR_RA_DAV_REQUEST_FAILED, NULL,
b->description->data);
@@ -260,6 +264,10 @@ end_207_element(void *baton, int state,
else
b->propstat_has_error = (status.klass != 2);
+ /* Handle "412 Precondition Failed" specially */
+ if (status.code == 412)
+ b->contains_precondition_error = TRUE;
+
free(status.reason_phrase);
}
else
Index: subversion/libsvn_ra_serf/util.c
===================================================================
--- subversion/libsvn_ra_serf/util.c (revision 999156)
+++ subversion/libsvn_ra_serf/util.c (working copy)
@@ -945,6 +945,34 @@ svn_ra_serf__handle_status_only(serf_request_t *re
return svn_error_return(err);
}
+/* Given a string like "HTTP/1.1 500 (status)", parse out the numeric status
+ code. Ignores leading whitespace. */
+static svn_error_t *
+parse_dav_status(int *status_code_out, svn_stringbuf_t *buf,
+ apr_pool_t *scratch_pool)
+{
+ svn_error_t *err;
+ const char *token;
+ char *tok_status;
+ svn_stringbuf_t *temp_buf = svn_stringbuf_create(buf->data, scratch_pool);
+
+ svn_stringbuf_strip_whitespace(temp_buf);
+ token = apr_strtok(temp_buf->data, " \t\r\n", &tok_status);
+ if (token)
+ token = apr_strtok(NULL, " \t\r\n", &tok_status);
+ if (!token)
+ return svn_error_createf(SVN_ERR_RA_DAV_MALFORMED_DATA, NULL,
+ "Malformed DAV:status CDATA '%s'",
+ buf->data);
+ err = svn_cstring_atoi(status_code_out, token);
+ if (err)
+ return svn_error_createf(SVN_ERR_RA_DAV_MALFORMED_DATA, err,
+ "Malformed DAV:status CDATA '%s'",
+ buf->data);
+
+ return SVN_NO_ERROR;
+}
+
/*
* Expat callback invoked on a start element tag for a 207 response.
*/
@@ -968,6 +996,14 @@ start_207(svn_ra_serf__xml_parser_t *parser,
svn_stringbuf_setempty(ctx->cdata);
ctx->collect_cdata = TRUE;
}
+ else if (ctx->in_error &&
+ strcmp(name.namespace, "DAV:") == 0 &&
+ strcmp(name.name, "status") == 0)
+ {
+ /* Start collecting cdata. */
+ svn_stringbuf_setempty(ctx->cdata);
+ ctx->collect_cdata = TRUE;
+ }
return SVN_NO_ERROR;
}
@@ -993,9 +1029,24 @@ end_207(svn_ra_serf__xml_parser_t *parser,
ctx->collect_cdata = FALSE;
ctx->error->message = apr_pstrmemdup(ctx->error->pool, ctx->cdata->data,
ctx->cdata->len);
- ctx->error->apr_err = SVN_ERR_RA_DAV_REQUEST_FAILED;
+ if (ctx->contains_precondition_error)
+ ctx->error->apr_err = SVN_ERR_BAD_OLD_VALUE;
+ else
+ ctx->error->apr_err = SVN_ERR_RA_DAV_REQUEST_FAILED;
}
+ else if (ctx->in_error &&
+ strcmp(name.namespace, "DAV:") == 0 &&
+ strcmp(name.name, "status") == 0)
+ {
+ int status_code;
+ ctx->collect_cdata = FALSE;
+
+ SVN_ERR(parse_dav_status(&status_code, ctx->cdata, parser->pool));
+ if (status_code == 412)
+ ctx->contains_precondition_error = TRUE;
+ }
+
return SVN_NO_ERROR;
}
@@ -1044,6 +1095,7 @@ svn_ra_serf__handle_multistatus_only(serf_request_
{
server_err->error = svn_error_create(APR_SUCCESS, NULL, NULL);
server_err->has_xml_response = TRUE;
+ server_err->contains_precondition_error = FALSE;
server_err->cdata = svn_stringbuf_create("", pool);
server_err->collect_cdata = FALSE;
server_err->parser.pool = server_err->error->pool;
Index: subversion/libsvn_ra_serf/ra_serf.h
===================================================================
--- subversion/libsvn_ra_serf/ra_serf.h (revision 999156)
+++ subversion/libsvn_ra_serf/ra_serf.h (working copy)
@@ -673,6 +673,9 @@ typedef struct svn_ra_serf__server_error_t {
/* Have we seen an error tag? */
svn_boolean_t in_error;
+ /* Have we seen a HTTP "412 Precondition Failed" error? */
+ svn_boolean_t contains_precondition_error;
+
/* Should we be collecting the XML cdata? */
svn_boolean_t collect_cdata;
