filename_resolver.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2015-2020 Cirilo Bernardo <[email protected]>
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#include <fstream>
#include <mutex>
#include <sstream>
 
#include <wx/log.h>
#include <wx/uri.h>
#include <pgm_base.h>
#include <trace_helpers.h>
 
#include <common.h>
#include <embedded_files.h>
#include <env_vars.h>
#include <filename_resolver.h>
#include <confirm.h>
#include <wx_filename.h>
 
// configuration file version
#define CFGFILE_VERSION 1
 
// flag bits used to track different one-off messages to users
#define ERRFLG_ALIAS    (1)
#define ERRFLG_RELPATH  (2)
#define ERRFLG_ENVPATH  (4)
 
#define MASK_3D_RESOLVER "3D_RESOLVER"
 
static std::mutex mutex_resolver;
 
 
FILENAME_RESOLVER::FILENAME_RESOLVER() :
        m_pgm( nullptr ),
        m_project( nullptr )
{
    m_errflags = 0;
}
 
 
bool FILENAME_RESOLVER::Set3DConfigDir( const wxString& aConfigDir )
{
    if( aConfigDir.empty() )
        return false;
 
    wxFileName cfgdir( ExpandEnvVarSubstitutions( aConfigDir, m_project ), "" );
 
    cfgdir.Normalize( FN_NORMALIZE_FLAGS );
 
    if( !cfgdir.DirExists() )
        return false;
 
    m_configDir = cfgdir.GetPath();
    createPathList();
 
    return true;
}
 
 
bool FILENAME_RESOLVER::SetProject( const PROJECT* aProject, bool* flgChanged )
{
    m_project = aProject;
 
    if( !aProject )
        return false;
 
    wxFileName projdir( ExpandEnvVarSubstitutions( aProject->GetProjectPath(), aProject ), "" );
 
    projdir.Normalize( FN_NORMALIZE_FLAGS );
 
    if( !projdir.DirExists() )
        return false;
 
    m_curProjDir = projdir.GetPath();
 
    if( flgChanged )
        *flgChanged = false;
 
    if( m_paths.empty() )
    {
        SEARCH_PATH al;
        al.m_Alias = wxS( "${KIPRJMOD}" );
        al.m_Pathvar = wxS( "${KIPRJMOD}" );
        al.m_Pathexp = m_curProjDir;
        m_paths.push_back( al );
 
        if( flgChanged )
            *flgChanged = true;
    }
    else
    {
        if( m_paths.front().m_Pathexp != m_curProjDir )
        {
            m_paths.front().m_Pathexp = m_curProjDir;
 
            if( flgChanged )
                *flgChanged = true;
        }
        else
        {
            return true;
        }
    }
 
#ifdef DEBUG
    {
        std::ostringstream ostr;
        ostr << __FILE__ << ": " << __FUNCTION__ << ": " << __LINE__ << "\n";
        ostr << " * [INFO] changed project dir to ";
        ostr << m_paths.front().m_Pathexp.ToUTF8();
        wxLogTrace( MASK_3D_RESOLVER, "%s\n", ostr.str().c_str() );
    }
#endif
 
    return true;
}
 
 
wxString FILENAME_RESOLVER::GetProjectDir() const
{
    return m_curProjDir;
}
 
 
void FILENAME_RESOLVER::SetProgramBase( PGM_BASE* aBase )
{
    m_pgm = aBase;
 
    if( !m_pgm || m_paths.empty() )
        return;
 
    // recreate the path list
    m_paths.clear();
    createPathList();
}
 
 
bool FILENAME_RESOLVER::createPathList()
{
    if( !m_paths.empty() )
        return true;
 
    // add an entry for the default search path; at this point
    // we cannot set a sensible default so we use an empty string.
    // the user may change this later with a call to SetProjectDir()
 
    SEARCH_PATH lpath;
    lpath.m_Alias = wxS( "${KIPRJMOD}" );
    lpath.m_Pathvar = wxS( "${KIPRJMOD}" );
    lpath.m_Pathexp = m_curProjDir;
    m_paths.push_back( lpath );
    wxFileName fndummy;
    wxUniChar psep = fndummy.GetPathSeparator();
    std::list< wxString > epaths;
 
    if( GetKicadPaths( epaths ) )
    {
        for( const wxString& currPath : epaths )
        {
            wxString currPathVarFormat = currPath;
            currPathVarFormat.Prepend( wxS( "${" ) );
            currPathVarFormat.Append( wxS( "}" ) );
 
            wxString pathVal = ExpandEnvVarSubstitutions( currPathVarFormat, m_project );
 
            if( pathVal.empty() )
            {
                lpath.m_Pathexp.clear();
            }
            else
            {
                fndummy.Assign( pathVal, "" );
                fndummy.Normalize( FN_NORMALIZE_FLAGS );
                lpath.m_Pathexp = fndummy.GetFullPath();
            }
 
            lpath.m_Alias = currPath;
            lpath.m_Pathvar = currPath;
 
            if( !lpath.m_Pathexp.empty() && psep == *lpath.m_Pathexp.rbegin() )
                lpath.m_Pathexp.erase( --lpath.m_Pathexp.end() );
 
            // we add it first with the alias set to the non-variable format
            m_paths.push_back( lpath );
 
            // now add it with the "new variable format ${VAR}"
            lpath.m_Alias = currPathVarFormat;
            m_paths.push_back( lpath );
        }
    }
 
    if( m_paths.empty() )
        return false;
 
#ifdef DEBUG
    wxLogTrace( MASK_3D_RESOLVER, wxS( " * [3D model] search paths:\n" ) );
    std::list< SEARCH_PATH >::const_iterator sPL = m_paths.begin();
 
    while( sPL != m_paths.end() )
    {
        wxLogTrace( MASK_3D_RESOLVER, wxS( "   + %s : '%s'\n" ), (*sPL).m_Alias.GetData(),
                    (*sPL).m_Pathexp.GetData() );
        ++sPL;
    }
#endif
 
    return true;
}
 
 
bool FILENAME_RESOLVER::UpdatePathList( const std::vector< SEARCH_PATH >& aPathList )
{
    wxUniChar envMarker( '$' );
 
    while( !m_paths.empty() && envMarker != *m_paths.back().m_Alias.rbegin() )
        m_paths.pop_back();
 
    for( const SEARCH_PATH& path : aPathList )
        addPath( path );
 
    return true;
}
 
 
wxString FILENAME_RESOLVER::ResolvePath( const wxString& aFileName, const wxString& aWorkingPath,
                                         std::vector<const EMBEDDED_FILES*> aEmbeddedFilesStack )
{
    std::lock_guard<std::mutex> lock( mutex_resolver );
 
    if( aFileName.empty() )
        return wxEmptyString;
 
    if( m_paths.empty() )
        createPathList();
 
    // first attempt to use the name as specified:
    wxString tname = aFileName;
 
    // Swap separators for non-Windows, in case a Windows path is being passed
#ifndef __WIN32__
    tname.Replace( "\\", "/" );
#endif
 
    // Note: variable expansion must preferably be performed via a threadsafe wrapper for the
    // getenv() system call. If we allow the wxFileName::Normalize() routine to perform expansion
    // then we will have a race condition since wxWidgets does not assure a threadsafe wrapper
    // for getenv().
    tname = ExpandEnvVarSubstitutions( tname, m_project );
 
    // Check to see if the file is a URI for an embedded file.
    if( tname.StartsWith( FILEEXT::KiCadUriPrefix + "://" ) )
    {
        if( aEmbeddedFilesStack.empty() )
        {
            wxLogTrace( wxT( "KICAD_EMBED" ),
                        wxT( "No EMBEDDED_FILES object provided for kicad_embed URI" ) );
            return wxEmptyString;
        }
 
        wxString path = tname.Mid( wxString( FILEEXT::KiCadUriPrefix + "://" ).length() );
 
        wxFileName temp_file = aEmbeddedFilesStack[0]->GetTemporaryFileName( path );
        int        ii = 1;
 
        while( !temp_file.IsOk() && ii < (int) aEmbeddedFilesStack.size() )
            temp_file = aEmbeddedFilesStack[ii++]->GetTemporaryFileName( path );
 
        if( !temp_file.IsOk() )
        {
            wxLogTrace( wxT( "KICAD_EMBED" ),
                        wxT( "Failed to get temp file '%s' for kicad_embed URI" ), path );
            return wxEmptyString;
        }
 
        wxLogTrace( wxT( "KICAD_EMBED" ), wxT( "Opening embedded file '%s' as '%s'" ),
                    tname, temp_file.GetFullPath() );
 
        return temp_file.GetFullPath();
    }
 
    wxFileName tmpFN( tname );
 
    // this case covers full paths, leading expanded vars, and paths relative to the current
    // working directory (which is not necessarily the current project directory)
    if( tmpFN.FileExists() )
    {
        tmpFN.Normalize( FN_NORMALIZE_FLAGS );
        tname = tmpFN.GetFullPath();
 
        // special case: if a path begins with ${ENV_VAR} but is not in the resolver's path list
        // then add it.
        if( aFileName.StartsWith( wxS( "${" ) ) || aFileName.StartsWith( wxS( "$(" ) ) )
            checkEnvVarPath( aFileName );
 
        return tname;
    }
 
    // if a path begins with ${ENV_VAR}/$(ENV_VAR) and is not resolved then either the ENV_VAR is
    // not defined, or this is a user-defined alias that was incorrectly stored in ${} format by
    // older versions of KiCad. Try to match against user-defined aliases before giving up.
    if( aFileName.StartsWith( "${" ) || aFileName.StartsWith( "$(" ) )
    {
        // If expansion left the string unchanged, the variable was not found in the environment.
        // Try matching the variable name against user-defined (non-env-var) aliases in m_paths.
        if( tname == aFileName )
        {
            bool   useBrace = aFileName.StartsWith( "${" );
            size_t aliasEnd = aFileName.find( useBrace ? '}' : ')' );
 
            // Require a non-empty variable name (aliasEnd > 2) so ${} / $() fall through.
            if( aliasEnd != wxString::npos && aliasEnd > 2 )
            {
                wxString alias = aFileName.substr( 2, aliasEnd - 2 );
 
                // Skip the separator if present
                size_t relStart = aliasEnd + 1;
 
                if( relStart < aFileName.length()
                    && ( aFileName[relStart] == '/' || aFileName[relStart] == '\\' ) )
                {
                    relStart++;
                }
 
                wxString relpath;
 
                if( relStart < aFileName.length() )
                    relpath = aFileName.substr( relStart );
 
                for( const SEARCH_PATH& path : m_paths )
                {
                    if( path.m_Alias.StartsWith( wxS( "${" ) ) || path.m_Alias.StartsWith( wxS( "$(" ) ) )
                        continue;
 
                    if( path.m_Alias == alias && !path.m_Pathexp.empty() )
                    {
                        wxFileName fpath( wxFileName::DirName( path.m_Pathexp ) );
                        wxString   fullPath = fpath.GetPathWithSep() + relpath;
 
                        fullPath = ExpandEnvVarSubstitutions( fullPath, m_project );
 
                        if( wxFileName::FileExists( fullPath ) )
                        {
                            wxFileName tmp( fullPath );
 
                            if( tmp.Normalize( FN_NORMALIZE_FLAGS ) )
                                fullPath = tmp.GetFullPath();
 
                            return fullPath;
                        }
                    }
                }
            }
        }
 
        if( !( m_errflags & ERRFLG_ENVPATH ) )
        {
            m_errflags |= ERRFLG_ENVPATH;
            wxString errmsg = "[3D File Resolver] No such path; ensure the environment var is "
                              "defined";
            errmsg.append( "\n" );
            errmsg.append( tname );
            errmsg.append( "\n" );
            wxLogTrace( tracePathsAndFiles, errmsg );
        }
 
        return wxEmptyString;
    }
 
    // at this point aFileName is:
    // a. an aliased shortened name or
    // b. cannot be determined
 
    // check the path relative to the current project directory;
    // NB: this is not necessarily the same as the current working directory, which has already
    // been checked. This case accounts for partial paths which do not contain ${KIPRJMOD}.
    // This check is performed before checking the path relative to ${KICAD7_3DMODEL_DIR} so that
    // users can potentially override a model within ${KICAD7_3DMODEL_DIR}.
    if( !m_paths.begin()->m_Pathexp.empty() && !tname.StartsWith( ":" ) )
    {
        tmpFN.Assign( m_paths.begin()->m_Pathexp, "" );
        wxString fullPath = tmpFN.GetPathWithSep() + tname;
 
        fullPath = ExpandEnvVarSubstitutions( fullPath, m_project );
 
        if( wxFileName::FileExists( fullPath ) )
        {
            tmpFN.Assign( fullPath );
            tmpFN.Normalize( FN_NORMALIZE_FLAGS );
            tname = tmpFN.GetFullPath();
            return tname;
        }
 
    }
 
    // check path relative to search path
    if( !aWorkingPath.IsEmpty() && !tname.StartsWith( ":" ) )
    {
        wxString tmp = aWorkingPath;
        tmp.Append( tmpFN.GetPathSeparator() );
        tmp.Append( tname );
        tmpFN.Assign( tmp );
 
        if( tmpFN.MakeAbsolute() && tmpFN.FileExists() )
        {
            tname = tmpFN.GetFullPath();
            return tname;
        }
    }
 
    // check the partial path relative to ${KICAD7_3DMODEL_DIR} (legacy behavior)
    if( !tname.StartsWith( wxS( ":" ) ) )
    {
        wxFileName fpath;
        wxString fullPath( wxString::Format( wxS( "${%s}" ),
                                       ENV_VAR::GetVersionedEnvVarName( wxS( "3DMODEL_DIR" ) ) ) );
        fullPath.Append( fpath.GetPathSeparator() );
        fullPath.Append( tname );
        fullPath = ExpandEnvVarSubstitutions( fullPath, m_project );
        fpath.Assign( fullPath );
 
        if( fpath.Normalize( FN_NORMALIZE_FLAGS ) && fpath.FileExists() )
        {
            tname = fpath.GetFullPath();
            return tname;
        }
 
    }
 
    // at this point the filename must contain an alias or else it is invalid
    wxString alias;         // the alias portion of the short filename
    wxString relpath;       // the path relative to the alias
 
    if( !SplitAlias( tname, alias, relpath ) )
    {
        if( !( m_errflags & ERRFLG_RELPATH ) )
        {
            // this can happen if the file was intended to be relative to ${KICAD7_3DMODEL_DIR}
            // but ${KICAD7_3DMODEL_DIR} is not set or is incorrect.
            m_errflags |= ERRFLG_RELPATH;
            wxString errmsg = "[3D File Resolver] No such path";
            errmsg.append( wxS( "\n" ) );
            errmsg.append( tname );
            errmsg.append( wxS( "\n" ) );
            wxLogTrace( tracePathsAndFiles, errmsg );
        }
 
        return wxEmptyString;
    }
 
    for( const SEARCH_PATH& path : m_paths )
    {
        // ${ENV_VAR} paths have already been checked; skip them
        if( path.m_Alias.StartsWith( wxS( "${" ) ) || path.m_Alias.StartsWith( wxS( "$(" ) ) )
            continue;
 
        if( path.m_Alias == alias && !path.m_Pathexp.empty() )
        {
            wxFileName fpath( wxFileName::DirName( path.m_Pathexp ) );
            wxString fullPath = fpath.GetPathWithSep() + relpath;
 
            fullPath = ExpandEnvVarSubstitutions( fullPath, m_project );
 
            if( wxFileName::FileExists( fullPath ) )
            {
                tname = fullPath;
 
                wxFileName tmp( fullPath );
 
                if( tmp.Normalize( FN_NORMALIZE_FLAGS ) )
                    tname = tmp.GetFullPath();
 
                return tname;
            }
        }
    }
 
    if( !( m_errflags & ERRFLG_ALIAS ) )
    {
        m_errflags |= ERRFLG_ALIAS;
        wxString errmsg = "[3D File Resolver] No such path; ensure the path alias is defined";
        errmsg.append( "\n" );
        errmsg.append( tname.substr( 1 ) );
        errmsg.append( "\n" );
        wxLogTrace( tracePathsAndFiles, errmsg );
    }
 
    return wxEmptyString;
}
 
 
bool FILENAME_RESOLVER::addPath( const SEARCH_PATH& aPath )
{
    if( aPath.m_Alias.empty() || aPath.m_Pathvar.empty() )
        return false;
 
    std::lock_guard<std::mutex> lock( mutex_resolver );
 
    SEARCH_PATH tpath = aPath;
 
    #ifdef _WIN32
    while( tpath.m_Pathvar.EndsWith( wxT( "\\" ) ) )
        tpath.m_Pathvar.erase( tpath.m_Pathvar.length() - 1 );
    #else
    while( tpath.m_Pathvar.EndsWith( wxT( "/" ) ) && tpath.m_Pathvar.length() > 1 )
        tpath.m_Pathvar.erase( tpath.m_Pathvar.length() - 1 );
    #endif
 
    wxFileName path( ExpandEnvVarSubstitutions( tpath.m_Pathvar, m_project ), "" );
 
    path.Normalize( FN_NORMALIZE_FLAGS );
 
    if( !path.DirExists() )
    {
        wxString versionedPath = wxString::Format( wxS( "${%s}" ),
                                       ENV_VAR::GetVersionedEnvVarName( wxS( "3DMODEL_DIR" ) ) );
 
        if( aPath.m_Pathvar == versionedPath
          || aPath.m_Pathvar == wxS( "${KIPRJMOD}" ) || aPath.m_Pathvar == wxS( "$(KIPRJMOD)" )
          || aPath.m_Pathvar == wxS( "${KISYS3DMOD}" )
          || aPath.m_Pathvar == wxS( "$(KISYS3DMOD)" ) )
        {
            // suppress the message if the missing pathvar is a system variable
        }
        else
        {
            wxString msg = _( "The given path does not exist" );
            msg.append( wxT( "\n" ) );
            msg.append( tpath.m_Pathvar );
            DisplayErrorMessage( nullptr, msg );
        }
 
        tpath.m_Pathexp.clear();
    }
    else
    {
        tpath.m_Pathexp = path.GetFullPath();
 
#ifdef _WIN32
        while( tpath.m_Pathexp.EndsWith( wxT( "\\" ) ) )
            tpath.m_Pathexp.erase( tpath.m_Pathexp.length() - 1 );
#else
        while( tpath.m_Pathexp.EndsWith( wxT( "/" ) ) && tpath.m_Pathexp.length() > 1 )
            tpath.m_Pathexp.erase( tpath.m_Pathexp.length() - 1 );
#endif
    }
 
    std::list< SEARCH_PATH >::iterator sPL = m_paths.begin();
    std::list< SEARCH_PATH >::iterator ePL = m_paths.end();
 
    while( sPL != ePL )
    {
        if( tpath.m_Alias == sPL->m_Alias )
        {
            wxString msg = _( "Alias: " );
            msg.append( tpath.m_Alias );
            msg.append( wxT( "\n" ) );
            msg.append( _( "This path:" ) + wxS( " " ) );
            msg.append( tpath.m_Pathvar );
            msg.append( wxT( "\n" ) );
            msg.append( _( "Existing path:" ) + wxS( " " ) );
            msg.append( sPL->m_Pathvar );
            DisplayErrorMessage( nullptr, _( "Bad alias (duplicate name)" ), msg );
            return false;
        }
 
        ++sPL;
    }
 
    m_paths.push_back( tpath );
    return true;
}
 
 
void FILENAME_RESOLVER::checkEnvVarPath( const wxString& aPath )
{
    bool useParen = false;
 
    if( aPath.StartsWith( wxS( "$(" ) ) )
        useParen = true;
    else if( !aPath.StartsWith( wxS( "${" ) ) )
        return;
 
    size_t pEnd;
 
    if( useParen )
        pEnd = aPath.find( wxS( ")" ) );
    else
        pEnd = aPath.find( wxS( "}" ) );
 
    if( pEnd == wxString::npos )
        return;
 
    wxString envar = aPath.substr( 0, pEnd + 1 );
 
    // check if the alias exists; if not then add it to the end of the
    // env var section of the path list
    auto sPL = m_paths.begin();
    auto ePL = m_paths.end();
 
    while( sPL != ePL )
    {
        if( sPL->m_Alias == envar )
            return;
 
        if( !sPL->m_Alias.StartsWith( wxS( "${" ) ) )
            break;
 
        ++sPL;
    }
 
    SEARCH_PATH lpath;
    lpath.m_Alias = envar;
    lpath.m_Pathvar = lpath.m_Alias;
    wxFileName tmpFN( ExpandEnvVarSubstitutions( lpath.m_Alias, m_project ), "" );
 
    wxUniChar psep = tmpFN.GetPathSeparator();
    tmpFN.Normalize( FN_NORMALIZE_FLAGS );
 
    if( !tmpFN.DirExists() )
        return;
 
    lpath.m_Pathexp = tmpFN.GetFullPath();
 
    if( !lpath.m_Pathexp.empty() && psep == *lpath.m_Pathexp.rbegin() )
        lpath.m_Pathexp.erase( --lpath.m_Pathexp.end() );
 
    if( lpath.m_Pathexp.empty() )
        return;
 
    m_paths.insert( sPL, lpath );
}
 
 
wxString FILENAME_RESOLVER::ShortenPath( const wxString& aFullPathName )
{
    wxString fname = aFullPathName;
 
    if( m_paths.empty() )
        createPathList();
 
    std::lock_guard<std::mutex> lock( mutex_resolver );
 
    std::list< SEARCH_PATH >::const_iterator sL = m_paths.begin();
    size_t idx;
 
    while( sL != m_paths.end() )
    {
        // undefined paths do not participate in the
        // file name shortening procedure
        if( sL->m_Pathexp.empty() )
        {
            ++sL;
            continue;
        }
 
        wxFileName fpath;
 
        // in the case of aliases, ensure that we use the most recent definition
        if( sL->m_Alias.StartsWith( wxS( "${" ) ) || sL->m_Alias.StartsWith( wxS( "$(" ) ) )
        {
            wxString tpath = ExpandEnvVarSubstitutions( sL->m_Alias, m_project );
 
            if( tpath.empty() )
            {
                ++sL;
                continue;
            }
 
            fpath.Assign( tpath, wxT( "" ) );
        }
        else
        {
            fpath.Assign( sL->m_Pathexp, wxT( "" ) );
        }
 
        wxString fps = fpath.GetPathWithSep();
        wxString tname;
 
        idx = fname.find( fps );
 
        if( idx == 0 )
        {
            fname = fname.substr( fps.size() );
 
            #ifdef _WIN32
            // ensure only the '/' separator is used in the internal name
            fname.Replace( wxT( "\\" ), wxT( "/" ) );
            #endif
 
            if( sL->m_Alias.StartsWith( wxS( "${" ) ) || sL->m_Alias.StartsWith( wxS( "$(" ) ) )
            {
                // old style ENV_VAR
                tname = sL->m_Alias;
                tname.Append( wxS( "/" ) );
                tname.append( fname );
            }
            else
            {
                // user-defined alias: use ${alias}/path format
                tname = wxS( "${" );
                tname.append( sL->m_Alias );
                tname.append( wxS( "}/" ) );
                tname.append( fname );
            }
 
            return tname;
        }
 
        ++sL;
    }
 
#ifdef _WIN32
    // it is strange to convert an MSWin full path to use the
    // UNIX separator but this is done for consistency and can
    // be helpful even when transferring project files from
    // MSWin to *NIX.
    fname.Replace( wxT( "\\" ), wxT( "/" ) );
#endif
 
    return fname;
}
 
 
const std::list< SEARCH_PATH >* FILENAME_RESOLVER::GetPaths() const
{
    return &m_paths;
}
 
 
bool FILENAME_RESOLVER::SplitAlias( const wxString& aFileName,
    wxString& anAlias, wxString& aRelPath ) const
{
    anAlias.clear();
    aRelPath.clear();
 
    size_t searchStart = 0;
 
    if( aFileName.StartsWith( wxT( ":" ) ) )
        searchStart = 1;
 
    size_t tagpos = aFileName.find( wxT( ":" ), searchStart );
 
    if( tagpos == wxString::npos || tagpos == searchStart )
        return false;
 
    if( tagpos + 1 >= aFileName.length() )
        return false;
 
    anAlias = aFileName.substr( searchStart, tagpos - searchStart );
    aRelPath = aFileName.substr( tagpos + 1 );
 
    return true;
}
 
 
bool FILENAME_RESOLVER::ValidateFileName( const wxString& aFileName, bool& hasAlias ) const
{
    // Rules:
    // 1. The generic form of an aliased 3D relative path is:
    //    ALIAS:relative/path
    // 2. ALIAS is a UTF string excluding wxT( "{}[]()%~<>\"='`;:.,&?/\\|$" )
    // 3. The relative path must be a valid relative path for the platform
    // 4. We allow a URI for embedded files, but only if it has a name
 
    hasAlias = false;
 
    if( aFileName.empty() )
        return false;
 
    if( aFileName.StartsWith( wxT( "file://" ) )
        || aFileName.StartsWith( FILEEXT::KiCadUriPrefix + "://" ) )
    {
        size_t prefixLength = aFileName.StartsWith( wxT( "file://" ) ) ? 7 : 14;
        if( aFileName.length() > prefixLength && aFileName[prefixLength] != '/' )
            return true;
        else
            return false;
    }
 
    wxString filename = aFileName;
    wxString lpath;
    size_t aliasStart = aFileName.StartsWith( ':' ) ? 1 : 0;
    size_t aliasEnd = aFileName.find( ':', aliasStart );
 
    // ensure that the file separators suit the current platform
#ifdef __WINDOWS__
    filename.Replace( wxT( "/" ), wxT( "\\" ) );
 
    // if we see the :\ pattern then it must be a drive designator
    if( aliasEnd != wxString::npos )
    {
        size_t pos1 = filename.find( wxT( ":\\" ) );
 
        if( pos1 != wxString::npos && ( pos1 != aliasEnd || pos1 != 1 ) )
            return false;
 
        // if we have a drive designator then we have no alias
        if( pos1 != wxString::npos )
            aliasEnd = wxString::npos;
    }
#else
    filename.Replace( wxT( "\\" ), wxT( "/" ) );
#endif
 
    // names may not end with ':'
    if( aliasEnd == aFileName.length() -1 )
        return false;
 
    if( aliasEnd != wxString::npos )
    {
        // ensure the alias component is not empty
        if( aliasEnd == aliasStart )
            return false;
 
        lpath = filename.substr( aliasStart, aliasEnd );
 
        // check the alias for restricted characters
        if( wxString::npos != lpath.find_first_of( wxT( "{}[]()%~<>\"='`;:.,&?/\\|$" ) ) )
            return false;
 
        hasAlias = true;
        lpath = aFileName.substr( aliasEnd + 1 );
    }
    else
    {
        lpath = aFileName;
 
        // in the case of ${ENV_VAR}|$(ENV_VAR)/path, strip the
        // environment string before testing
        aliasEnd = wxString::npos;
 
        if( aFileName.StartsWith( wxS( "${" ) ) )
            aliasEnd = aFileName.find( '}' );
        else if( aFileName.StartsWith( wxS( "$(" ) ) )
            aliasEnd = aFileName.find( ')' );
 
        if( aliasEnd != wxString::npos )
            lpath = aFileName.substr( aliasEnd + 1 );
 
    }
 
    // Test for forbidden chars in filenames. Should be wxFileName::GetForbiddenChars()
    // On MSW, the list returned by wxFileName::GetForbiddenChars() contains separators
    // '\'and '/' used here because lpath can be a full path.
    // So remove separators
    wxString lpath_no_sep = lpath;
 
#ifdef __WINDOWS__
    lpath_no_sep.Replace( "/", " " );
    lpath_no_sep.Replace( "\\", " " );
 
    // A disk identifier is allowed, and therefore remove its separator
    if( lpath_no_sep.Length() > 1 && lpath_no_sep[1] == ':' )
        lpath_no_sep[1] = ' ';
#endif
 
    if( wxString::npos != lpath_no_sep.find_first_of( wxFileName::GetForbiddenChars() ) )
        return false;
 
    return true;
}
 
 
bool FILENAME_RESOLVER::GetKicadPaths( std::list< wxString >& paths ) const
{
    paths.clear();
 
    if( !m_pgm )
        return false;
 
    bool hasKisys3D = false;
 
 
    // iterate over the list of internally defined ENV VARs
    // and add them to the paths list
    ENV_VAR_MAP_CITER mS = m_pgm->GetLocalEnvVariables().begin();
    ENV_VAR_MAP_CITER mE = m_pgm->GetLocalEnvVariables().end();
 
    while( mS != mE )
    {
        // filter out URLs, template directories, and known system paths
        if( mS->first == wxS( "KICAD_PTEMPLATES" )
            || mS->first.Matches( wxS( "KICAD*_FOOTPRINT_DIR") ) )
        {
            ++mS;
            continue;
        }
 
        if( wxString::npos != mS->second.GetValue().find( wxS( "://" ) ) )
        {
            ++mS;
            continue;
        }
 
        //also add the path without the ${} to act as legacy alias support for older files
        paths.push_back( mS->first );
 
        if( mS->first.Matches( wxS("KICAD*_3DMODEL_DIR") ) )
            hasKisys3D = true;
 
        ++mS;
    }
 
    if( !hasKisys3D )
        paths.emplace_back( ENV_VAR::GetVersionedEnvVarName( wxS( "3DMODEL_DIR" ) ) );
 
    return true;
}