Allow varnishncsa logformat to be read from a file. Adds supports to

varnishncsa for specifying the logging format by reading the log
format from a file using the option "-f". Since -f means prefer
X-Forwarded-For over client.ip in Varnish 3, maybe we should use
another option letter.

bin/varnishncsa/varnishncsa.c

@@ -933,6 +933,28 @@ sighup(void)
 	return (1);
 }
 
+static char *
+read_format(const char *formatfile)
+{
+        FILE *fmtfile;
+        size_t len = 0;
+        char *fmt = NULL;
+
+        fmtfile = fopen(formatfile, "r");
+        if (fmtfile == NULL)
+                VUT_Error(1, "Can't open format file (%s)", strerror(errno));
+        if (getline(&fmt, &len, fmtfile) == -1) {
+                free(fmt);
+                if (feof(fmtfile))
+                        VUT_Error(1, "Empty format file");
+                else
+                        VUT_Error(1, "Can't read format from file (%s)",
+			    strerror(errno));
+        }
+        fclose(fmtfile);
+        return (fmt);
+}
+
 int
 main(int argc, char * const *argv)
 {
@@ -962,6 +984,13 @@ main(int argc, char * const *argv)
 			format = strdup(optarg);
 			AN(format);
 			break;
+		case 'f':
+			/* Format string from file */
+			if (format != NULL)
+				free(format);
+			format = read_format(optarg);
+			AN(format);
+			break;
 		case 'h':
 			/* Usage help */
 			usage(0);

bin/varnishncsa/varnishncsa_options.h

@@ -40,6 +40,14 @@
 	    "Set the output log format string."				\
 	)
 
+#define NCSA_OPT_f                                                      \
+        VOPT("f:", "[-f formatfile]", "Read output format from file",   \
+            "Read output format from a file. Will read a single line"   \
+            " from the specified file, and use that line as the"	\
+	    " format."							\
+	)
+
+
 #define NCSA_OPT_g							\
 	VOPT("g:", "[-g <request|vxid>]", "Grouping mode (default: vxid)", \
 	    "The grouping of the log records. The default is to group"	\
@@ -60,6 +68,7 @@ VSL_OPT_C
 VUT_OPT_d
 VUT_OPT_D
 NCSA_OPT_F
+NCSA_OPT_f
 NCSA_OPT_g
 VUT_OPT_h
 VUT_OPT_n