Jurko,
I must say that while it took me longer to understand builtin_normalize_path() than I hoped, actually making the changes went faster than I feared. The following patch is for engine/builtins.c that shipped with Boost 1.49.0; sorry it is not the latest. The only use case tested is where third party libraries live on a share specified with a UNC path.
Thanks,
Jim
$ diff -u builtins-1.49.0.c boost-build/engine/builtins.c
--- builtins-1.49.0.c 2011-06-06 13:36:22.000000000 -0700
+++ boost-build/engine/builtins.c 2012-08-30 14:35:20.000000000 -0700
@@ -1468,6 +1468,7 @@
/* Number of '..' elements seen and not processed yet. */
int dotdots = 0;
int rooted = 0;
+ int isUNC = 0;
char * result = 0;
/* Make a copy of input: we should not change it. Prepend a '/' before it as
@@ -1497,6 +1498,29 @@
if ( *current == '\\' )
*current = '/';
+# if defined( OS_NT ) || defined( OS_CYGWIN )
+ {
+ /* Detect UNC paths. At this point, a UNC path will have three leading
+ * forward slashes. A UNC path can only have two leading
+ * slashes, // or \\, as any other quantity will not work for Windows
+ * file operations. Note that even under cygwin, a leading double slash
+ * is treated as UNC, even if next token is "cygdrive", so we don't need to
+ * check for the cygdrive case. */
+ static regexp *re;
+ static int been_here = 0;
+
+ if(!been_here)
+ {
+ been_here = 1;
+ re = regcomp("^///[^/:]+/+[^/]");
+ }
+
+ if(in->size > 5 && regexec(re, in->value))
+ isUNC = 1;
+ }
+#endif
+
+
/* Now we remove any extra path elements by overwriting them with '\1'
* characters and cound how many more unused '..' path elements there are
* remaining. Note that each remaining path element with always starts with
@@ -1536,6 +1560,13 @@
string_new( out );
+# if defined( OS_NT ) || defined( OS_CYGWIN )
+ /* A UNC path would now have only a single / in front after processing above.
+ * Put a leading / in first, and we will end up with the double / needed. */
+ if(isUNC)
+ string_append( out, "/" );
+# endif
+
/* Now we know that we need to add exactly dotdots '..' path elements to the
* front and that our string is either empty or has a '/' as its first
* significant character. If we have any dotdots remaining then the passed