From 3ddbfeafde93d1aab16a710498d86eef4e787406 Mon Sep 17 00:00:00 2001
From: Michael Krelin <hacker@klever.net>
Date: Wed, 30 Mar 2005 15:50:28 +0000
Subject: 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
---
diff --git a/include/sitecing/sitecing_enflesher.h b/include/sitecing/sitecing_enflesher.h
index 512a358..8bc43a0 100644
--- a/include/sitecing/sitecing_enflesher.h
+++ b/include/sitecing/sitecing_enflesher.h
@@ -42,6 +42,11 @@ class sitecing_enflesher : public sitecing_enflesherFlexLexer {
 	 * The output stream.
 	 */
 	ofstream outs;
+	/**
+	 * the outs stream destination file.
+	 * @see outs
+	 */
+	string outs_filename;
 
 	/**
 	 * @param p The parser object containing preparsed data.
@@ -61,6 +66,14 @@ class sitecing_enflesher : public sitecing_enflesherFlexLexer {
 	 * Put a #line anchor into output.
 	 */
 	void anchor();
+
+	/**
+	 * Close previously opened output stream, rename to the 'correct'
+	 * destination filename, if needed, and open new file.
+	 * @see outs
+	 * @see outs_filename
+	 */
+	void outs_open(const string& nfile);
 };
 
 #endif /* __SITECING_SITECING_ENFLESHER_H */
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
@@ -19,7 +19,7 @@
  
 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)
@@ -116,15 +116,20 @@ namespace sitecing {
 	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;
     }
 
@@ -249,6 +254,8 @@ namespace sitecing {
 		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);
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
@@ -39,7 +39,8 @@ namespace sitecing {
 	    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) {
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
@@ -22,12 +22,7 @@ ID	[A-Za-z_][A-Za-z0-9_]*
     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;
 }
@@ -35,12 +30,7 @@ ID	[A-Za-z_][A-Za-z0-9_]*
     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;
 }
 
@@ -197,6 +187,68 @@ void sitecing_enflesher::anchor() {
     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
@@ -56,13 +56,13 @@ namespace sitecing {
     }
 
     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());
     }
--
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