When the input filter finishes, check whether we returned data during the last read and if not, delegate to the remaining filter chain.

Without that, ProcessPartial for the request body breaks forwarding
of uploaded files using mod_proxy_ajp and mod_wl.

See issue #2091.

Author: rainerjung

apache2/apache2_io.c

@@ -36,6 +36,7 @@ apr_status_t input_filter(ap_filter_t *f, apr_bucket_brigade *bb_out,
     msc_data_chunk *chunk = NULL;
     apr_bucket *bucket;
     apr_status_t rc;
+    int no_data = 1;
     char *my_error_msg = NULL;
 
     if (msr == NULL) {
@@ -110,6 +111,7 @@ apr_status_t input_filter(ap_filter_t *f, apr_bucket_brigade *bb_out,
 
             if (bucket == NULL) return APR_EGENERAL;
             APR_BRIGADE_INSERT_TAIL(bb_out, bucket);
+            no_data = 0;
 
             if (msr->txcfg->debuglog_level >= 4) {
                 msr_log(msr, 4, "Input filter: Forwarded %" APR_SIZE_T_FMT " bytes.", chunk->length);
@@ -130,6 +132,7 @@ apr_status_t input_filter(ap_filter_t *f, apr_bucket_brigade *bb_out,
 
             if (bucket == NULL) return APR_EGENERAL;
             APR_BRIGADE_INSERT_TAIL(bb_out, bucket);
+            no_data = 0;
 
             if (msr->txcfg->debuglog_level >= 4) {
                 msr_log(msr, 4, "Input stream filter: Forwarded %" APR_SIZE_T_FMT " bytes.", msr->stream_input_length);
@@ -145,6 +148,7 @@ apr_status_t input_filter(ap_filter_t *f, apr_bucket_brigade *bb_out,
             bucket = apr_bucket_eos_create(f->r->connection->bucket_alloc);
             if (bucket == NULL) return APR_EGENERAL;
             APR_BRIGADE_INSERT_TAIL(bb_out, bucket);
+            no_data = 0;
 
             if (msr->txcfg->debuglog_level >= 4) {
                 msr_log(msr, 4, "Input filter: Sent EOS.");
@@ -158,6 +162,10 @@ apr_status_t input_filter(ap_filter_t *f, apr_bucket_brigade *bb_out,
         if (msr->txcfg->debuglog_level >= 4) {
             msr_log(msr, 4, "Input filter: Input forwarding complete.");
         }
+
+        if (no_data) {
+            return ap_get_brigade(f->next, bb_out, mode, block, nbytes);
+        }
     }
 
     return APR_SUCCESS;