Add gzip log writing to the ascii writer.

This feature can be enabled globally for all logs by setting
LogAscii::gzip_level to a value greater than 0.

This feature can be enabled on a per-log basis by setting gzip-level in
$confic to a value greater than 0.

src/logging/writers/ascii/Ascii.cc

@@ -24,6 +24,7 @@ Ascii::Ascii(WriterFrontend* frontend) : WriterBackend(frontend)
 	tsv = false;
 	use_json = false;
 	formatter = 0;
+	gzip_level = 0;
 
 	InitConfigOptions();
 	init_options = InitFilterOptions();
@@ -34,6 +35,7 @@ void Ascii::InitConfigOptions()
 	output_to_stdout = BifConst::LogAscii::output_to_stdout;
 	include_meta = BifConst::LogAscii::include_meta;
 	use_json = BifConst::LogAscii::use_json;
+	gzip_level = BifConst::LogAscii::gzip_level;
 
 	separator.assign(
 			(const char*) BifConst::LogAscii::separator->Bytes(),
@@ -89,6 +91,15 @@ bool Ascii::InitFilterOptions()
 				}
 			}
 
+		else if ( strcmp(i->first, "gzip_level" ) == 0 )
+			{
+			gzip_level = atoi(i->second);
+			if ( gzip_level < 0 || gzip_level > 9 )
+				{
+				Error("invalid value for 'gzip_level', must be a number between 0 and 9.");
+				return false;
+				}
+			}
 		else if ( strcmp(i->first, "use_json") == 0 )
 			{
 			if ( strcmp(i->second, "T") == 0 )
@@ -192,7 +203,7 @@ bool Ascii::WriteHeaderField(const string& key, const string& val)
 	{
 	string str = meta_prefix + key + separator + val + "\n";
 
-	return safe_write(fd, str.c_str(), str.length());
+	return InternalWrite(fd, str.c_str(), str.length());
 	}
 
 void Ascii::CloseFile(double t)
@@ -203,7 +214,7 @@ void Ascii::CloseFile(double t)
 	if ( include_meta && ! tsv )
 		WriteHeaderField("close", Timestamp(0));
 
-	safe_close(fd);
+	InternalClose(fd);
 	fd = 0;
 	}
 
@@ -219,7 +230,7 @@ bool Ascii::DoInit(const WriterInfo& info, int num_fields, const Field* const *
 	if ( output_to_stdout )
 		path = "/dev/stdout";
 
-	fname = IsSpecial(path) ? path : path + "." + LogExt();
+	fname = IsSpecial(path) ? path : path + "." + LogExt() + (( gzip_level > 0 ) ? ".gz" : "");
 
 	fd = open(fname.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0666);
 
@@ -231,6 +242,25 @@ bool Ascii::DoInit(const WriterInfo& info, int num_fields, const Field* const *
 		return false;
 		}
 
+	if ( gzip_level > 0 )
+		{
+		assert(gzip_level < 10);
+		char mode[4];
+		snprintf(mode, 3, "wb%d", gzip_level);
+		errno = 0; // errno will only be set under certain circumstances by gzdopen.
+		gzfile = gzdopen(fd, mode);
+		if ( gzfile == nullptr )
+			{
+			Error(Fmt("cannot gzip %s: %s", fname.c_str(), 
+			                                Strerror(errno)));
+			return false;
+			}
+		}
+	else
+		{
+		gzfile = 0;
+		}
+
 	if ( ! WriteHeader(path) )
 		{
 		Error(Fmt("error writing to %s: %s", fname.c_str(), Strerror(errno)));
@@ -264,7 +294,7 @@ bool Ascii::WriteHeader(const string& path)
 		{
 		// A single TSV-style line is all we need.
 		string str = names + "\n";
-		if ( ! safe_write(fd, str.c_str(), str.length()) )
+		if ( ! InternalWrite(fd, str.c_str(), str.length()) )
 			return false;
 
 		return true;
@@ -275,7 +305,7 @@ bool Ascii::WriteHeader(const string& path)
 		+ get_escaped_string(separator, false)
 		+ "\n";
 
-	if ( ! safe_write(fd, str.c_str(), str.length()) )
+	if ( ! InternalWrite(fd, str.c_str(), str.length()) )
 		return false;
 
 	if ( ! (WriteHeaderField("set_separator", get_escaped_string(set_separator, false)) &&
@@ -337,14 +367,14 @@ bool Ascii::DoWrite(int num_fields, const Field* const * fields,
 		char hex[4] = {'\\', 'x', '0', '0'};
 		bytetohex(bytes[0], hex + 2);
 
-		if ( ! safe_write(fd, hex, 4) )
+		if ( ! InternalWrite(fd, hex, 4) )
 			goto write_error;
 
 		++bytes;
 		--len;
 		}
 
-	if ( ! safe_write(fd, bytes, len) )
+	if ( ! InternalWrite(fd, bytes, len) )
 		goto write_error;
 
         if ( ! IsBuf() )
@@ -368,7 +398,7 @@ bool Ascii::DoRotate(const char* rotated_path, double open, double close, bool t
 
 	CloseFile(close);
 
-	string nname = string(rotated_path) + "." + LogExt();
+	string nname = string(rotated_path) + "." + LogExt() + (gzfile ? ".gz" : "");
 
 	if ( rename(fname.c_str(), nname.c_str()) != 0 )
 		{
@@ -434,4 +464,49 @@ string Ascii::Timestamp(double t)
 	return tmp;
 	}
 
+bool Ascii::InternalWrite(int fd, const char* data, int len)
+	{
+	if ( gzfile )
+		{
+		while ( len > 0 )
+			{
+			int n = gzwrite(gzfile, data, len);
+			
+			if ( n < 0 )
+				{
+				if ( n == Z_ERRNO )
+					Error(Fmt("Ascii::InternalWrite error: %s\n", Strerror(errno)));
+				else
+					Error(Fmt("Ascii::InternalWrite error: %s\n", gzerror(gzfile, &n)));
+
+				return false;
+				}
+
+			data += n;
+			len -= n;
+			}
+		}
+	else
+		return safe_write(fd, data, len);
+
+	return true;
+	}
+
+bool Ascii::InternalClose(int fd)
+	{
+	if ( gzfile )
+		{
+		if ( gzclose(gzfile) < 0 )
+			{
+			Error(Fmt("Ascii::InternalClose error: %s\n", Strerror(errno)));
+			return false;
+			}
+		}
+	else
+		{
+		safe_close(fd);
+		}
+
+	return true;
+	}