Handle path slashes properly, when the binary is compiled in Windows and used in Linux and vice-versa

[deepak2427]

Summary

Hi,

The slashes in the paths are not currently handled properly, especially when the binary is compiled in Windows and used in Linux and vice-versa. This is also a problem for source file mapping. The patch introduces a new function to handle strncmp for paths independently.

[zturner]

I don't think this works. \ and / are only identical on Windows. On other
platforms \ is a character that can actually appear in a string.
Furthermore, this doesn't address the issue in FileSpec, which also has
issues dealing with Windows paths. Incidentally, I was already working on
a patch to address exactly this. I think the correct fix is to fix it in
FileSpec, and then update PathMappingList to use FileSpecs instead of
ConstStrings.

[deepak2427]

Yeah, updating the PathMappingList does seem more appropriate. We specifically had issues with interoperability handling paths between different operating systems. If your patch is ready, please put it up and we can test it out.

[zturner]

It's not ready yet, but I was hoping to have it ready by the end of the
day. I went down the wrong path yesterday so had to scrap it and start
over, but I think I'm on the right track now.

source/Target/PathMappingList.cpp

 using namespace lldb;
 using namespace lldb_private;
 
+// slash independent string compare which
+// considers '\\' to be the same as '/'
+static
+int strncmp_path( const char *a, const char *b, const int max )
+{
+    // loop until at max chars, end of line, or mismatch
+    for ( int i = 0; i < max; i++ )
+    {
+        // match slashes
+        bool skip = true;
+        skip &= ( a[i] == '\\' || a[i] == '/' );
+        skip &= ( b[i] == '\\' || b[i] == '/' );
+
+        // match character or skip
+        if ( (a[i] != b[i]) && !skip )
+            return i+1;
+
+        // break at end of line
+        if ( a[i] == '\0' )
+            break;
+    }
+
+    // success
+    return 0;
+}
+
 //----------------------------------------------------------------------
 // PathMappingList constructor
 //----------------------------------------------------------------------

 bool
 PathMappingList::RemapPath (const ConstString &path, ConstString &new_path) const
 {
+    // get the current path as a cstring
     const char *path_cstr = path.GetCString();
-    
     if (!path_cstr)
         return false;
     
+    // search through all items in the path mapping list
     const_iterator pos, end = m_pairs.end();
     for (pos = m_pairs.begin(); pos != end; ++pos)
     {
+        // get the length of the prefix
+        //
+        // prefix in this case is the partial string that we are to match
         const size_t prefixLen = pos->first.GetLength();
 
-        if (::strncmp (pos->first.GetCString(), path_cstr, prefixLen) == 0)
+        if ( strncmp_path(pos->first.GetCString(), path_cstr, prefixLen) == 0)
         {
             std::string new_path_str (pos->second.GetCString());
             new_path_str.append(path.GetCString() + prefixLen);
             new_path.SetCString(new_path_str.c_str());
             return true;
         }
+
+        // we can always match when our current path is empty and prefix is current directory
+        if ( path.GetLength() == 0 && strncmp_path( pos->first.GetCString(), ".", 1 ) == 0 )
+        {
+            new_path.SetCString( pos->second.GetCString( ) );
+            return true;
+        }
+
     }
+
+    // we cant make a match
     return false;
 }
 

     {
         const size_t prefix_len = pos->first.GetLength();
         
-        if (::strncmp (pos->first.GetCString(), path, prefix_len) == 0)
+        if ( strncmp_path(pos->first.GetCString(), path, prefix_len) == 0)
         {
             new_path = pos->second.GetCString();
             new_path.append(path + prefix_len);

                 
                 if (orig_path_len >= prefix_len)
                 {
-                    if (::strncmp (pos->first.GetCString(), orig_path, prefix_len) == 0)
+                    const char *precstr = pos->first.GetCString( );
+
+                    if ( strncmp_path(precstr, orig_path, prefix_len) == 0)
                     {
                         const size_t new_path_len = snprintf(new_path, sizeof(new_path), "%s/%s", pos->second.GetCString(), orig_path + prefix_len);
                         if (new_path_len < sizeof(new_path))

     return false;
 }
 
-
-
 uint32_t
 PathMappingList::FindIndexForPath (const ConstString &path) const
 {