Backport to 2.4:

   *) Allow mod_dav_fs to tolerate race conditions between PROPFIND and an
      operation which removes a directory/file between apr_dir_read() and
      apr_stat(). Current behaviour is to abort the connection which seems
      inferior to tolerating (and logging) the error.
      trunk patch: http://svn.apache.org/r1910811
      2.4.x patch: https://svn.apache.org/repos/asf/httpd/httpd/patches/2.4.x/httpd-2.4-dav-tolerant.patch
      +1: minfrin, ylavic, jorton



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1913982 13f79535-47bb-0310-9956-ffa450edef68

CHANGES

@@ -1,6 +1,11 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.4.59
 
+  *) Allow mod_dav_fs to tolerate race conditions between PROPFIND and an
+     operation which removes a directory/file between apr_dir_read() and
+     apr_stat(). Current behaviour is to abort the connection which seems
+     inferior to tolerating (and logging) the error. [Joe Orton]
+
   *) mod_ldap: HTML-escape data in the ldap-status handler.
      [Eric Covener, Chamal De Silva]
 

STATUS

@@ -153,14 +153,6 @@ RELEASE SHOWSTOPPERS:
 PATCHES ACCEPTED TO BACKPORT FROM TRUNK:
   [ start all new proposals below, under PATCHES PROPOSED. ]
 
-   *) Allow mod_dav_fs to tolerate race conditions between PROPFIND and an
-      operation which removes a directory/file between apr_dir_read() and
-      apr_stat(). Current behaviour is to abort the connection which seems
-      inferior to tolerating (and logging) the error.
-      trunk patch: http://svn.apache.org/r1910811
-      2.4.x patch: https://svn.apache.org/repos/asf/httpd/httpd/patches/2.4.x/httpd-2.4-dav-tolerant.patch
-      +1: minfrin, ylavic, jorton
-
    *) core: Fix use after free warning with gcc -fanalyzer.
       trunk patch: http://svn.apache.org/r1892413
       2.4.x patch: https://svn.apache.org/repos/asf/httpd/httpd/patches/2.4.x/httpd-2.4-use-after-free.patch

include/ap_mmn.h

@@ -598,14 +598,15 @@
  * 20120211.128 (2.4.55-dev) Add AP_CTIME_OPTION_GMTOFF to util_time.h
  * 20120211.129 (2.4.58-dev) Add ap_get_pollfd_from_conn()
  * 20120211.130 (2.4.59-dev) Add ap_proxy_determine_address()
+ * 20120211.131 (2.4.59-dev) Add DAV_WALKTYPE_TOLERANT
  */
 
 #define MODULE_MAGIC_COOKIE 0x41503234UL /* "AP24" */
 
 #ifndef MODULE_MAGIC_NUMBER_MAJOR
 #define MODULE_MAGIC_NUMBER_MAJOR 20120211
 #endif
-#define MODULE_MAGIC_NUMBER_MINOR 130                 /* 0...n */
+#define MODULE_MAGIC_NUMBER_MINOR 131                 /* 0...n */
 
 /**
  * Determine if the server's current MODULE_MAGIC_NUMBER is at least a

modules/dav/fs/repos.c

@@ -35,6 +35,7 @@
 #include "mod_dav.h"
 #include "repos.h"
 
+APLOG_USE_MODULE(dav_fs);
 
 /* to assist in debugging mod_dav's GET handling */
 #define DEBUG_GET_HANDLER       0
@@ -1586,6 +1587,19 @@ static dav_error * dav_fs_walker(dav_fs_walker_context *fsctx, int depth)
         status = apr_stat(&fsctx->info1.finfo, fsctx->path1.buf,
                           DAV_FINFO_MASK, pool);
         if (status != APR_SUCCESS && status != APR_INCOMPLETE) {
+            dav_resource_private *ctx = params->root->info;
+
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, status, ctx->r,
+                          APLOGNO(10472) "could not access file (%s) during directory walk",
+                          fsctx->path1.buf);
+
+            /* If being tolerant, ignore failure due to losing a race
+             * with some other process deleting files out from under
+             * the directory walk. */
+            if ((params->walk_type & DAV_WALKTYPE_TOLERANT)
+                && APR_STATUS_IS_ENOENT(status)) {
+                continue;
+            }
             /* woah! where'd it go? */
             /* ### should have a better error here */
             err = dav_new_error(pool, HTTP_NOT_FOUND, 0, status, NULL);

modules/dav/main/mod_dav.c

@@ -2217,7 +2217,7 @@ static int dav_method_propfind(request_rec *r)
         return HTTP_BAD_REQUEST;
     }
 
-    ctx.w.walk_type = DAV_WALKTYPE_NORMAL | DAV_WALKTYPE_AUTH;
+    ctx.w.walk_type = DAV_WALKTYPE_NORMAL | DAV_WALKTYPE_AUTH | DAV_WALKTYPE_TOLERANT;
     ctx.w.func = dav_propfind_walker;
     ctx.w.walk_ctx = &ctx;
     ctx.w.pool = r->pool;

modules/dav/main/mod_dav.h

@@ -1823,6 +1823,7 @@ typedef struct
 #define DAV_WALKTYPE_AUTH       0x0001  /* limit to authorized files */
 #define DAV_WALKTYPE_NORMAL     0x0002  /* walk normal files */
 #define DAV_WALKTYPE_LOCKNULL   0x0004  /* walk locknull resources */
+#define DAV_WALKTYPE_TOLERANT   0x0008  /* tolerate non-fatal errors */
 
     /* callback function and a client context for the walk */
     dav_error * (*func)(dav_walk_resource *wres, int calltype);