Re: [xslt] xsltproc error during parallel docbook building

[Alexander Shigin <shigin rambler-co ru>]

В Пнд, 07/12/2009 в 18:56 -0800, C Y пишет:
> Hi!  BRL-CAD is attempting to use xsltproc to build our docbook
> documentation, and we're getting an intermittent error when doing
> parallel building (e.g. firing off a lot of xsltproc commands at
> once):
> 
> xsltApplyStylesheet: saving to lessons/en/mged11_refining_mug.html may
> not be possible
> 
> it's not specific to that one file and appears to occur randomly when
> a lot of xsltproc instances are running.  Restarting the make process
> usually immediately succeeds. Is this a known limitation of xsltproc?

Can you specify the full command line? But it seems there is race
condition in xsltCheckWritePath: the two processes can try to make the
directory at the same time.

The attached patch can solve the problem, but may cause some security
risk.

diff --git a/libxslt/security.c b/libxslt/security.c
index b766cf7..76033aa 100644
--- a/libxslt/security.c
+++ b/libxslt/security.c
@@ -10,6 +10,7 @@
 #include "libxslt.h"
 
 #include <string.h>
+#include <errno.h>
 
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
@@ -342,8 +343,19 @@ xsltCheckWritePath(xsltSecurityPrefsPtr sec,
 		}
 	    }
 	    ret = xsltCheckWritePath(sec, ctxt, directory);
-	    if (ret == 1)
+	    if (ret == 1) {
 		ret = mkdir(directory, 0755);
+                /* The another process can create the same directory.
+                 * I'm not sure it's a good check: it can be wise to check
+                 * owner of the directory before continue */
+                if (ret == -1 && errno == EEXIST) {
+                    struct stat buf;
+                    ret = stat(path, &buf);
+                    if (ret == 0) {
+                        ret = S_ISDIR(buf.st_mode) ? 0 : -1;
+                    }
+                }
+            }
 	}
 	xmlFree(directory);
 	if (ret < 0)