1. preprocessor doesn't touch unchanged files anymore

2. doublechedk on whether file is up to date when making
3. changed the way preprocessor targets depend on the timestamp file
4. a bugfix in strip_suffix/strip_prefix

4 files changed, 82 insertions, 22 deletions

diff --git a/lib/component_factory.cc b/lib/component_factory.cc
index f8666dc..b8f5a16 100644
--- a/lib/component_factory.cc
+++ b/lib/component_factory.cc
@@ -1,325 +1,332 @@
 #ifdef USE_PCH
  #include "pch.h"
 #else
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <unistd.h>
  #include <sys/wait.h>
  #include <fcntl.h>
  #include <iostream>
  #include <fstream>
  #include <stdexcept>
  #include <vector>
  using namespace std;
  #include "sitecing/component_factory.h"
  #include "sitecing/sitecing_util.h"
  #include "sitecing/sitecing_parser.h"
  #include "sitecing/sitecing_exception.h"
 #endif
  
 namespace sitecing {
 
-    static const char *pp_targets[] = { ".cc", ".h", ".imports", ".classname", ".baseclassname", ".ancestors" };
+    static const char *pp_targets[] = { ".cc", ".h", ".imports", ".classname", ".baseclassname", ".ancestors", ".pp_stamp" };
     static const char *cc_targets[] = { ".o", ".d" };
 
     component_factory::component_factory(configuration& c)
         : config(c),
     root_source(normalize_path(c.root_source,strip_trailing_slash)+'/'),
     root_intermediate(normalize_path(c.root_intermediate,strip_trailing_slash)+'/'),
     root_so(normalize_path(c.root_so,strip_trailing_slash)+'/') {
     }
 
     void component_factory::get_dependencies(const string& dst,file_list_t& deps) {
         deps.clear();
         string dp = normalize_path(dst,strip_trailing_slash);
         // source documents
         try { // XXX: or just compare it off?
             string noro = strip_prefix(dp,root_source);
             return;
         }catch(utility_no_affix& una) {
         }
         // .so binaries
         try {
             string noso = strip_suffix(dp,".so");
             string noro = strip_prefix(noso,root_so);
             deps.push_back(root_intermediate+noro+".o");
             config_options *co_so_deps = config.lookup_config(noro,config_options::flag_so_deps);
             if(co_so_deps) {
                 for(list<string>::const_iterator i=co_so_deps->so_deps.begin();i!=co_so_deps->so_deps.end();++i)
                     deps.push_back(*i);
             }
             return;
         }catch(utility_no_prefix& unp) {
             throw konforka::exception(CODEPOINT,"component is outside of component root");
         }catch(utility_no_suffix& uns) {
         }
         // preprocessor targets
         for(int ppt=0;ppt<sizeof(pp_targets)/sizeof(*pp_targets);ppt++) {
             try {
                 string nos = strip_suffix(dp,pp_targets[ppt]);
                 string noro = strip_prefix(nos,root_intermediate);
                 deps.push_back(root_source+noro);
                 ifstream imports((root_intermediate+noro+".imports").c_str(),ios::in);
                 if(imports.good()) {
                     string str;
                     while(!imports.eof()) {
                         imports >> str;
                         if(!str.empty())
                             deps.push_back(root_intermediate+str+".classname");
                     }
                 }
                 ifstream ancestors((root_intermediate+noro+".ancestors").c_str(),ios::in);
                 if(ancestors.good()) {
                     string str;
                     while(!ancestors.eof()) {
                         ancestors >> str;
                         if(!str.empty())
                             deps.push_back(root_intermediate+str+".classname");
                     }
                 }
                 config_options *co_intermediate_deps = config.lookup_config(noro,config_options::flag_intermediate_deps);
                 if(co_intermediate_deps) {
                     for(list<string>::const_iterator i=co_intermediate_deps->intermediate_deps.begin();i!=co_intermediate_deps->intermediate_deps.end();++i)
                         deps.push_back(*i);
                 }
                 return;
             }catch(utility_no_affix& una) {
                 // do nothing. must be a cpp dependency.
             }
         }
         // compiler targets
         for(int cct=0;cct<sizeof(cc_targets)/sizeof(*cc_targets);cct++) {
             try {
                 string nos = strip_suffix(dp,cc_targets[cct]);
                 string noro = strip_prefix(nos,root_intermediate);
                 deps.push_back(root_intermediate+noro+".cc");
                 config_options *co_cpp_deps = config.lookup_config(noro,config_options::flag_cpp_deps);
                 if( (!co_cpp_deps) || co_cpp_deps->cpp_deps) {
                     ifstream df((root_intermediate+noro+".d").c_str(),ios::in);
                     if(df.good()) {
                         string str;
                         while(!df.eof()) {
                             df >> str;
                             if(str.find_first_of("\\:")==string::npos)
                                 deps.push_back(combine_path(config.root_source+noro,str));
                         }
                     }
                 }
                 // XXX: extra deps like IntermediateDeps?
             }catch(utility_no_affix& una) {
                 // do nothing.
             }
         }
     }
 
     bool component_factory::is_uptodate(const string& dst,file_list_t *deps) {
         string dp = normalize_path(dst,strip_trailing_slash);
         // XXX: or just compare it off, instead of throwing things around.
         try {
-            strip_prefix(dp,root_intermediate);
-            return file_factory::is_uptodate(dst,deps);
-        }catch(utility_no_prefix& unp) {
-        }
+            string noro = strip_prefix(dp,root_intermediate);
+            for(int ppt=0;(ppt+1)<sizeof(pp_targets)/sizeof(*pp_targets);ppt++) {
+                try {
+                    string nos = strip_suffix(noro,pp_targets[ppt]);
+                    return file_factory::is_uptodate(root_intermediate+nos+".pp_stamp",deps);
+                }catch(utility_no_suffix& uns) { }
+            }
+            bool rv =  file_factory::is_uptodate(dst,deps);
+            return rv;
+        }catch(utility_no_prefix& unp) { }
         try {
             strip_prefix(dp,root_so);
             return file_factory::is_uptodate(dst,deps);
-        }catch(utility_no_prefix& unp) {
-        }
+        }catch(utility_no_prefix& unp) { }
         return true;
     }
 
     void component_factory::build(const string& dst) {
         string dp = normalize_path(dst,strip_trailing_slash);
         // sources
         try {
             string noro = strip_prefix(dp,root_source);
             // building the sources is left up to developer
             return;
         }catch(utility_no_prefix& unp) {
         }
         // .so files
         try {
             string noso = strip_suffix(dp,".so");
             string noro = strip_prefix(noso,root_so);
             string o = root_intermediate+noro+".o";
             if(access(o.c_str(),R_OK))
                 throw konforka::exception(CODEPOINT,string("can't access compiled component code (")+o+")");
             make_path(dir_name(root_so+noro),0755);
             file_lock lock_cc(root_intermediate+noro+".o.lock");
             file_lock lock_so(root_so+noro+".so.lock");
             int stdO = open((root_intermediate+noro+".ld.stdout").c_str(),O_CREAT|O_TRUNC|O_WRONLY,0664);
             if(stdO<0)
                 throw konforka::exception(CODEPOINT,"failed to open/create linker stdout");
             int stdE = open((root_intermediate+noro+".ld.stderr").c_str(),O_CREAT|O_TRUNC|O_WRONLY,0664);
             if(stdE<0) {
                 close(stdO);
                 throw konforka::exception(CODEPOINT,"failed to open/create linker stderr");
             }
             list<string> args;
             config_options *co_ld_flags = config.lookup_config(noro,config_options::flag_ld_flags);
             if(co_ld_flags) {
                 args.insert(args.end(),co_ld_flags->ld_flags.begin(),co_ld_flags->ld_flags.end());
             }
             args.push_back("-shared");
             args.push_back(o);
             file_list_t ancestors;
             get_ancestors(noro,ancestors);
             for(file_list_t::const_iterator i=ancestors.begin();i!=ancestors.end();++i) {
                 string aso=root_so+*i+".so";
                 make(aso);
                 args.push_back(aso);
             }
             args.push_back("-o"); args.push_back(dp);
             // TODO: "g++" configurable
             int rv = execute("g++",args,stdO,stdE);
             if(! (WIFEXITED(rv) && !WEXITSTATUS(rv)) )
                 // TODO:TODO: linker_error
                 throw compile_error(CODEPOINT,"failed to link component",noro);
             return;
         }catch(utility_no_prefix& unp) {
             throw konforka::exception(CODEPOINT,"component is outside of component root");
         }catch(utility_no_suffix& uns) {
         }
         // compiler targets
         for(int cct=0;cct<sizeof(cc_targets)/sizeof(*cc_targets);cct++) {
             try {
                 string nos = strip_suffix(dp,cc_targets[cct]);
                 string noro = strip_prefix(nos,root_intermediate);
                 string cc = root_intermediate+noro+".cc";
                 string o = root_intermediate+noro+".o";
                 if(access(cc.c_str(),R_OK))
                     throw konforka::exception(CODEPOINT,string("can't access preprocessed component code (")+cc+")");
                 make_path(dir_name(cc),0755);
                 string pwd = dir_name(root_source+noro);
                 auto_chdir dir_changer(pwd);
                 file_lock lock_source(root_intermediate+noro+".lock");
                 file_lock lock_cc(root_intermediate+noro+".o.lock");
                 int stdO = open((root_intermediate+noro+".stdout").c_str(),O_CREAT|O_TRUNC|O_WRONLY,0664);
                 if(stdO<0)
                     throw konforka::exception(CODEPOINT,"failed to open/create compiler stdout");
                 int stdE = open((root_intermediate+noro+".stderr").c_str(),O_CREAT|O_TRUNC|O_WRONLY,0664);
                 if(stdE<0) {
                     close(stdO);
                     throw konforka::exception(CODEPOINT,"failed to open/create compiler's stderr");
                 }
                 list<string> args;
                 config_options *co_cpp_flags = config.lookup_config(noro,config_options::flag_cpp_flags);
                 if(co_cpp_flags) {
                     args.insert(args.end(),co_cpp_flags->cpp_flags.begin(),co_cpp_flags->cpp_flags.end());
                 }
                 // TODO: maybe move it to separare config option like CoreCPPFLags?
                 args.push_back("-I"+root_intermediate);
                 args.push_back("-I"+root_source);
                 args.push_back("-MD"); args.push_back("-MF"); args.push_back(root_intermediate+noro+".d");
                 args.push_back("-c");
                 args.push_back(cc);
                 args.push_back("-o"); args.push_back(o);
                 // TODO: "g++" configurable
                 int rv = execute("g++",args,stdO,stdE);
                 if(! (WIFEXITED(rv) && !WEXITSTATUS(rv)) )
                     throw compile_error(CODEPOINT,"failed to compile component",noro);
                 return;
             }catch(utility_no_affix& una) {
                 // do nothing, not a compiler target
             }
         }
         // preprocessor targets
         for(int ppt=0;ppt<sizeof(pp_targets)/sizeof(*pp_targets);ppt++) {
             try {
                 string nos = strip_suffix(dp,pp_targets[ppt]);
                 string noro = strip_prefix(nos,root_intermediate);
                 string src = root_source+noro;
                 if(access(src.c_str(),R_OK))
                     throw konforka::exception(CODEPOINT,string("can't access component source (")+src+")");
                 make_path(dir_name(root_intermediate+noro),0755);
                 file_lock lock(root_intermediate+noro+".lock");
                 sitecing_parser parser(*this);
                 config_options *co_skeleton = config.lookup_config(noro,config_options::flag_skeleton);
                 if(co_skeleton)
                     parser.skeleton = co_skeleton->skeleton;
                 static const char *id_chars = "abcdefghijklmnopqrstuvwxyz0123456789_ABCDEFGHIJKLMNOPQRSTUVWXYZ";
                 parser.class_name = normalize_path(noro,strip_leading_slash|strip_trailing_slash);
                 for(string::size_type illc = parser.class_name.find_first_not_of(id_chars);illc!=string::npos;illc=parser.class_name.find_first_not_of(id_chars,illc)) {
                     string::size_type lc = parser.class_name.find_first_of(id_chars,illc);
                     int n = ((lc==string::npos)?parser.class_name.length():lc)-illc;
                     parser.class_name.replace(illc,n,n,'_');
                 }
                 parser.class_name = "_SCC_"+parser.class_name;
                 parser.output_basename = nos;
                 parser.component_basename = noro;
                 try {
                     parser.preprocess(src);
+                    string sf = root_intermediate+noro+".pp_stamp";
+                    ofstream sfs(sf.c_str(),ios::trunc|ios::out); // touch .pp_stamp
                 }catch(preprocessor_error& pe) {
                     pe.component_name = noro;
                     pe.see(CODEPOINT);
                     throw;
                 }
                 return;
             }catch(utility_no_affix& una) {
                 // must be a crap from .d file
             }
         }
         cerr << "ignoring build request for " << dp << endl;
     }
 
     int component_factory::execute(const string& cmd, const list<string>& args,int stdo,int stde) {
         // XXX: is it right that we do stdio/stderr tricks outside of the function?
         cerr << "executing: " << cmd;
         vector<const char*> argv(args.size()+2);
         argv[0]=cmd.c_str();
         int an = 1;
         for(list<string>::const_iterator i=args.begin();i!=args.end();i++) {
             cerr << " " << *i ;
             argv[an++] = i->c_str();
         }
         cerr << endl;
         argv[an++]=NULL;
         pid_t pid = vfork();
         if(pid==-1) {
             close(stdo); close(stde);
             throw konforka::exception(CODEPOINT,"failed to vfork()");
         }
         if(!pid) {
             // child
             if(dup2(stdo,1)!=1)
                 _exit(-1);
             if(dup2(stde,2)!=2)
                 _exit(-1);
             close(0);
             execvp(cmd.c_str(),(char**)&argv.front());
             _exit(-1);
         }
         // parent
         close(stdo); close(stde);
         int rv;
         if(waitpid(pid,&rv,0)<0)
             throw konforka::exception(CODEPOINT,"failed to waitpid()");
         return rv;
     }
 
     string component_factory::get_classname(const string& component) {
         string cn = root_intermediate+normalize_path(component,strip_trailing_slash|strip_leading_slash)+".classname";
         make(cn);
         ifstream ifs(cn.c_str());
         if(!ifs.good())
             throw konforka::exception(CODEPOINT,"failed to access component .classname");
         ifs >> cn;
         return cn;
     }
 
     void component_factory::get_ancestors(const string& component,file_list_t& rv) {
         string cn = root_intermediate+normalize_path(component,strip_trailing_slash|strip_leading_slash)+".ancestors";
         make(cn);
         ifstream ifs(cn.c_str());
         if(!ifs.good())
             throw konforka::exception(CODEPOINT,"filed to access component .ancestors");
         rv.clear();
         while(!ifs.eof()) {
             string a;
             ifs >> a;
             if(!a.empty())
                 rv.push_back(a);
         }
     }
 
 }
diff --git a/lib/file_factory.cc b/lib/file_factory.cc
index c6b5748..7ca7b86 100644
--- a/lib/file_factory.cc
+++ b/lib/file_factory.cc
@@ -1,55 +1,56 @@
 #ifdef USE_PCH
  #include "pch.h"
 #else
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <unistd.h>
  #include <konforka/exception.h>
  using namespace std;
  #include "sitecing/file_factory.h"
 #endif
 
 namespace sitecing {
 
     bool file_factory::is_uptodate(const string& dst,file_list_t* deps) {
         file_list_t deplist;
         file_list_t *fl = deps?deps:&deplist;
         get_dependencies(dst,*fl);
         struct stat stdst;
         if(stat(dst.c_str(),&stdst))
             return false;
         for(file_list_t::const_iterator i=fl->begin();i!=fl->end();i++) {
             struct stat stdep;
             if(stat(i->c_str(),&stdep))
                 return false;
             if(stdst.st_mtime<stdep.st_mtime)
                 return false;
             if(!is_uptodate(*i))
                 return false;
         }
         return true;
     }
 
     void file_factory::make(const string& dst) {
         try {
             depth++;
             if(depth>25)
                 throw konforka::exception(CODEPOINT,"recursed too deeply.");
             file_list_t deps;
             if(!is_uptodate(dst,&deps)) {
                 for(file_list_t::const_iterator i=deps.begin();i!=deps.end();i++)
                     make(*i);
-                build(dst);
+                if(!is_uptodate(dst,&deps))
+                    build(dst);
             }
             depth--;
         }catch(konforka::exception& ke) {
             depth--;
             ke.see(CODEPOINT);
             throw;
         }catch(...) {
             depth--;
             throw;
         }
     }
 
 }
diff --git a/lib/sitecing_enflesher.ll b/lib/sitecing_enflesher.ll
index 5f631d7..46489c7 100644
--- a/lib/sitecing_enflesher.ll
+++ b/lib/sitecing_enflesher.ll
@@ -1,202 +1,254 @@
 %{
 #include <iostream>
 #include <fstream>
 #include <cassert>
 #include <stdexcept>
 using namespace std;
 #include "sitecing/sitecing_exception.h"
 using namespace sitecing;
 #define sitecing_enflesher_flexlexer_once
 #include "sitecing/sitecing_enflesher.h"
 #include "sitecing/sitecing_parser.h"
 #undef yyFlexLexer
 #define yyFlexLexer sitecing_enflesherFlexLexer
 %}
 %option 8bit c++ verbose noyywrap yyclass="sitecing_enflesher" yylineno prefix="sitecing_enflesher" stack debug
 
         ID[A-Za-z_][A-Za-z0-9_]*
 
 %%
 
         ^\%\%\#[^\n]+\n{
     string line = yytext;
     line.erase(0,3);
     line.erase(line.length()-1);
-    outs.flush();
-    outs.close();
-    outs.clear();
-    outs.open((parser.output_basename+line).c_str(),ios::trunc);
-    if(!outs.good())
-        throw preprocessor_error(CODEPOINT,"failed to write preprocessor output");
+    outs_open(parser.output_basename+line);
     anchor();
     anchoraged = true;
 }
         ^\%\%[^\n]+\n{
     string line = yytext;
     line.erase(0,2);
     line.erase(line.length()-1);
-    outs.flush();
-    outs.close();
-    outs.clear();
-    outs.open((parser.output_basename+line).c_str(),ios::trunc);
-    if(!outs.good())
-        throw preprocessor_error(CODEPOINT,"failed to write preprocessor output");
+    outs_open(parser.output_basename+line);
     anchoraged = false;
 }
 
         \<\%component_basename\%\>outs << parser.component_basename; anchor_time = true;
         \<\%impl\%\>            outs << parser.impl; anchor_time = true;
         \<\%member_functions:impl\%\>{
     for(sitecing_parser::member_functions_t::const_iterator i=parser.member_functions.begin();i!=parser.member_functions.end();i++) {
         outs << i->type << " " << parser.class_name << "::";
         if(i->name.empty()) {
             outs << parser.class_name << "()";
             bool first = true;
             for(sitecing_parser::member_variables_t::iterator i=parser.member_variables.begin();i!=parser.member_variables.end();i++) {
                 if(i->initializer.empty())
                     continue;
                 if(first) {
                     outs << ":";
                     first=false;
                 }else{
                     outs << ",";
                 }
                 if(i->bComponent) {
                     outs << i->name << "(NULL)";
                 }else {
                     outs << i->name << "(" << i->initializer << ")";
                 }
             }
         }else if(i->name == "~")
             outs << "~" << parser.class_name << "()";
         else
             outs << i->name << i->args;
         outs << "{\n" << i->body << "\n}\n";
     }
     anchor_time = true;
 }
         \<\%class_name\%\>      outs << parser.class_name; anchor_time = true;
         \<\%baseclass_header\%\>outs << parser.base_header; anchor_time = true;
         \<\%decl\%\>            outs << parser.decl; anchor_time = true;
         \<\%baseclass_name\%\>  outs << parser.base_class; anchor_time = true;
         \<\%member_variables:decl\%\>{
     for(sitecing_parser::member_variables_t::iterator i=parser.member_variables.begin();i!=parser.member_variables.end();i++) {
         if(i->bComponent) {
             if(i->type.empty()) {
                 i->type = parser.factory.get_classname(i->initializer);
             }
             if(i->bTypeOnly) {
                 outs << "typedef " << i->type << " " << i->name << ";\n";
             }else{
                 outs << "typedef " << i->type << " __type_" << i->name << ";\nsitecing::so_component __soc_" << i->name << ";\n__type_" << i->name << " *" << i->name << ";\n";
             }
         }else{
             outs << i->type << " " << i->name << ";\n";
         }
     }
     anchor_time = true;
 }
         \<\%member_functions:decl\%\>{
     for(sitecing_parser::member_functions_t::const_iterator i=parser.member_functions.begin();i!=parser.member_functions.end();i++) {
         (i->name.empty()?outs:outs << "virtual ")
             << i->type << " ";
         if(i->name.empty()) {
             outs << parser.class_name << "()";
         }else if(i->name == "~")
             outs << "~" << parser.class_name << "()";
         else
             outs << i->name << i->args;
         outs << ";\n";
     }
     anchor_time = true;
 }
         \<\%imports:list\%\>    {
     for(sitecing_parser::member_variables_t::const_iterator i=parser.member_variables.begin();i!=parser.member_variables.end();i++) {
         if(i->bComponent)
             outs << i->initializer << endl;
     }
     anchor_time = true;
 }
         \<\%imports:includes\%\>{
     for(sitecing_parser::member_variables_t::iterator i=parser.member_variables.begin();i!=parser.member_variables.end();i++) {
         if(i->bComponent)
             outs << "\n#include \"" << i->initializer << ".h\"\n";
     }
     anchor_time = true;
 }
         \<\%imports:import\%\>{
     for(sitecing_parser::member_variables_t::iterator i=parser.member_variables.begin();i!=parser.member_variables.end();i++) {
         if(!i->bComponent)
             continue;
         if(i->bTypeOnly)
             continue;
         outs << "__soc_" << i->name << "=__SCIF->ss->fetch(\"" << i->initializer << "\",__SCIF); " << i->name << "=static_cast<__type_" << i->name << "*>(__soc_" << i->name << ".ac->__the_most_derived_this());\n";
     }
     anchor_time = true;
 }
 
         \<\%base_component\%\>  {
     // TODO:
     anchor_time = true;
 }
 
         \<\%ancestors:includes\%\>{
     for(sitecing_parser::ancestor_classes_t::const_iterator i=parser.ancestor_classes.begin();i!=parser.ancestor_classes.end();++i) {
         outs << "#include \"" << i->path << ".h\"\n";
     }
     anchor_time = true;
 }
         \<\%ancestors:component_list\%\>{
     for(sitecing_parser::ancestor_classes_t::const_iterator i=parser.ancestor_classes.begin();i!=parser.ancestor_classes.end();++i) {
         outs << i->path << "\n";
     }
     anchor_time = true;
 }
         \<\%ancestors:base_clause_part\%\>{
     for(sitecing_parser::ancestor_classes_t::const_iterator i=parser.ancestor_classes.begin();i!=parser.ancestor_classes.end();++i) {
         outs << ", virtual public " << parser.factory.get_classname(i->path);
     }
 }
         \<\%ancestors:typedefs\%\>      {
     for(sitecing_parser::ancestor_classes_t::const_iterator i=parser.ancestor_classes.begin();i!=parser.ancestor_classes.end();++i) {
         outs << "typedef class " << parser.factory.get_classname(i->path) << " " << i->name << ";\n";
     }
     anchor_time = true;
 }
         \<\%ancestors:import\%\>        {
     for(sitecing_parser::ancestor_classes_t::const_iterator i=parser.ancestor_classes.begin();i!=parser.ancestor_classes.end();++i) {
         outs << i->name << "::__do_imports();\n";
     }
     anchor_time = true;
 }
 
         \n                      {
     if(anchor_time)
         anchor();
     ECHO;
 }
         .                       ECHO;
 
 %%
 
 void sitecing_enflesher::LexerOutput(const char *buf,int size) {
     outs.write(buf,size);
 }
 
 void sitecing_enflesher::enflesh() {
     ifstream ifs(parser.skeleton.c_str());
     if(!ifs.good())
         throw preprocessor_error(CODEPOINT,"failed to open skeleton file");
     switch_streams(&ifs,NULL);
     yylex();
 }
 
 void sitecing_enflesher::anchor() {
     if(!anchoraged)
         return;
     outs << "\n#line " << lineno() << " \"" << parser.skeleton << "\"\n";
     anchor_time = false;
 }
+
+void sitecing_enflesher::outs_open(const string& nfile) {
+    if(!outs_filename.empty()) {
+        outs.flush();
+        outs.close();
+        outs.clear();
+        /*
+         * compare source and destination files.
+         *
+         * one can also keep a hash for the old one and compute one for the
+         * output while writing, but I'm not sure if it's any better. Surely a
+         * bit less accurate, unless we're going to compare it in case of
+         * difference, anyway.
+         */
+        bool overwrite = false;
+        struct stat st_s, st_d;
+        string fn_s = outs_filename+".new";
+        string fn_d = outs_filename;
+        if(stat(fn_d.c_str(),&st_d)) {
+            overwrite = true;
+        }else{
+            if(stat(fn_s.c_str(),&st_s))
+                throw preprocessor_error(CODEPOINT,"failed to stat() supposedly created file");
+            if(st_s.st_size!=st_d.st_size) {
+                overwrite = true;
+            }else{
+                ifstream i_s(fn_s.c_str(),ios::in);
+                if(!i_s)
+                    throw preprocessor_error(CODEPOINT,"failed to open supposedly created file");
+                ifstream i_d(fn_d.c_str(),ios::in);
+                if(!i_d)
+                    throw preprocessor_error(CODEPOINT,"failed to open the old preprocessed source");
+                off_t remaining = st_s.st_size;
+                char t1[2048];
+                char t2[sizeof(t1)];
+                while(remaining) {
+                    int rb = remaining;
+                    if(rb>sizeof(t1))
+                        rb = sizeof(t1);
+                    if(i_s.read(t1,rb).gcount()!=rb)
+                        throw preprocessor_error(CODEPOINT,"error reading just created file");
+                    if(i_d.read(t2,rb).gcount()!=rb)
+                        throw preprocessor_error(CODEPOINT,"error reading the old preprocessed source");
+                    if(memcmp(t1,t2,rb)) {
+                        overwrite = true;
+                        break;
+                    }
+                    remaining -= rb;
+                }
+            }
+        }
+        if(overwrite) {
+            cerr << "renaming '" << fn_s << "'" << endl;
+            if(rename(fn_s.c_str(),fn_d.c_str()))
+                throw preprocessor_error(CODEPOINT,"failed to rename() generated output");
+        }
+    }
+    outs_filename = nfile;
+    outs.open((nfile+".new").c_str(),ios::trunc);
+    if(!outs.good())
+        throw preprocessor_error(CODEPOINT,"failed to write preprocessor output");
+}
 /*
  * vim:set ft=lex:
  */
diff --git a/lib/sitecing_util.cc b/lib/sitecing_util.cc
index 5466b28..f892a60 100644
--- a/lib/sitecing_util.cc
+++ b/lib/sitecing_util.cc
@@ -1,161 +1,161 @@
 #ifdef USE_PCH
  #include "pch.h"
 #else
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <sys/ipc.h>
  #include <sys/sem.h>
  #include <errno.h>
  #include <iostream>
  #include <fstream>
  #include <cassert>
  #include "sitecing/sitecing_util.h"
 #endif
 
 namespace sitecing {
 
     /*
      * XXX: all of these utilities could be sheerly optimized.
      */
 
     string normalize_path(const string& path,int opts) {
         const char *s = path.c_str();
         string rv;
         string::size_type notslash = 0;
         if( (*s)=='.' && s[1]=='/' )
             s+=2;
         if(opts&strip_leading_slash)
             for(;(*s) && (*s)=='/';s++);
         for(;*s;s++) {
             if( (*s)=='/' ) {
                 if(s[1]=='/')
                     continue;
                 if(s[1]=='.' && s[2]=='/') {
                     s+=2;
                     continue;
                 }
             }
             if(opts&restrict_dotdot) {
                 if(
                                 ( rv.empty() && s[0]=='.' && s[1]=='.' && s[2]=='/' )// "^../"
                         || ( s[0]=='/' && s[1]=='.' && s[2]=='.' && (s[3]==0 || s[3]=='/') ) // "/..(/|$)"
                   )
                     throw utility_restricted_sequence(CODEPOINT,"restricted updir sequence encountered");
             }
             rv += *s;
             if( (*s) != '/' )
                 notslash=rv.length();
         }
         if(!(opts&strip_trailing_slash))
             notslash++;
         if(notslash<rv.length())
             rv.erase(notslash); // XXX: check the logic of stripping/not strippling trailing slash
         return rv;
     }
 
     string strip_prefix(const string& str,const string& prefix) {
-        if(str.compare(0,prefix.length(),prefix))
+        if( (str.length()<prefix.length()) || str.compare(0,prefix.length(),prefix))
             throw utility_no_prefix(CODEPOINT,"no such prefix");
         return str.substr(prefix.length());
     }
 
     string strip_suffix(const string& str,const string& suffix) {
-        if(str.compare(str.length()-suffix.length(),suffix.length(),suffix))
+        if( (str.length()<suffix.length()) || str.compare(str.length()-suffix.length(),suffix.length(),suffix))
             throw utility_no_suffix(CODEPOINT,"no such suffix");
         return str.substr(0,str.length()-suffix.length());
     }
 
     string dir_name(const string& filename) {
         string::size_type sl = filename.find_last_of('/');
         if(sl==string::npos)
             return ""; // no slashes -- no dir.
         string::size_type nosl = filename.find_last_not_of('/',sl);
         if(nosl==string::npos)
             return ""; // only slashes -- no dir. XXX: only slashes after the last slash... does it mean no dir?
         return filename.substr(0,nosl+1);
     }
 
     void make_path(const string& path,mode_t mode) {
         struct stat st;
         for(string::size_type sl=0;sl!=string::npos;sl=path.find('/',sl+1)) {
             if(!sl)
                 continue;
             string p = path.substr(0,sl);
             if(stat(p.c_str(),&st) || !S_ISDIR(st.st_mode)) {
                 if(mkdir(p.c_str(),mode))
                     throw konforka::exception(CODEPOINT,"failed to mkdir()");
             }
         }
         if(stat(path.c_str(),&st) || !S_ISDIR(st.st_mode)) {
             if(mkdir(path.c_str(),mode))
                 throw konforka::exception(CODEPOINT,"failed to mkdir()");
         }
     }
 
     void file_lock::lock(const string& f) {
         unlock();
         fd = open(f.c_str(),O_CREAT|O_RDWR,S_IRUSR|S_IWUSR);
         if(fd<0)
             throw konforka::exception(CODEPOINT,"failed to open/create lockfile");
         try {
             lock();
         }catch(konforka::exception& ke) {
             ke.see(CODEPOINT);
             close(fd); fd=-1;
             throw;
         }catch(...) {
             close(fd); fd=-1;
             throw;
         }
     }
     void file_lock::lock() {
         assert(fd>=0);
         struct flock fl;
         fl.l_type = F_WRLCK;
         fl.l_whence=SEEK_SET;
         fl.l_start=fl.l_len=0;
         for(int tries=3;tries;tries--) {
             if(!fcntl(fd,F_SETLK,&fl))
                 return;
             sleep(8);
         }
         throw konforka::exception(CODEPOINT,"failed to obtain file lock");
     }
     void file_lock::unlock() {
         if(fd<0)
             return;
         struct flock fl;
         fl.l_type = F_UNLCK;
         fl.l_whence=SEEK_SET;
         fl.l_start=fl.l_len=0;
         int rv = fcntl(fd,F_SETLK,&fl);
         close(fd);
         fd=-1;
         if(rv)
             throw konforka::exception(CODEPOINT,"failed to release file lock");
     }
 
     void pid_file::set(const string& f,bool u) {
         ofstream of(f.c_str(),ios::trunc);
         if(!of)
             throw konforka::exception(CODEPOINT,"failed to open file for writing pid");
         of << getpid() << endl;
         of.close();
         file_name = f;
         unlink_pid = u;
     }
     void pid_file::unlink() {
         if(!unlink_pid)
             return;
         ::unlink(file_name.c_str());
     }
 
     void semaphore::init() {
         deinit();
         semid = semget(IPC_PRIVATE,1,IPC_CREAT|0600);
         if(semid<0)
             throw konforka::exception(CODEPOINT,"failed to semget()");
         if(semctl(semid,0,SETVAL,1))
             throw konforka::exception(CODEPOINT,"failed to semctl()");