lib/log: Cleanup log API

Rather than exposing log internals (through always_flush and
set_stream), do all logging init through pb_log_init(). If pb_log_init()
hasn't been called, pb_log will drop messages.

Also, add a pb_debug() function, specifically for debugging information.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

6 files changed, 65 insertions, 51 deletions

diff --git a/discover/pb-discover.c b/discover/pb-discover.c
index 6d62e14..c16d690 100644
--- a/discover/pb-discover.c
+++ b/discover/pb-discover.c
@@ -123,6 +123,7 @@ int main(int argc, char *argv[])
 	struct opts opts;
 	struct pb_udev *udev;
 	struct user_event *uev;
+	FILE *log;
 
 	if (opts_parse(&opts, argc, argv)) {
 		print_usage();
@@ -139,17 +140,17 @@ int main(int argc, char *argv[])
 		return EXIT_SUCCESS;
 	}
 
+	log = stderr;
 	if (strcmp(opts.log_file, "-")) {
-		FILE *log = fopen(opts.log_file, "a");
-
-		assert(log);
-		pb_log_set_stream(log);
-	} else
-		pb_log_set_stream(stderr);
+		log = fopen(opts.log_file, "a");
+		if (!log) {
+			fprintf(stderr, "can't open log file %s, logging to "
+					"stderr\n", opts.log_file);
+			log = stderr;
+		}
+	}
+	pb_log_init(log);
 
-#if defined(DEBUG)
-	pb_log_always_flush(1);
-#endif
 	pb_log("--- pb-discover ---\n");
 
 	/* we look for closed sockets when we write, so ignore SIGPIPE */
diff --git a/lib/log/log.c b/lib/log/log.c
index ecbd714..b250a9e 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -1,38 +1,54 @@
 
+#include <assert.h>
 #include <stdarg.h>
 
 #include "log.h"
 
 static FILE *logf;
-static int always_flush;
+static bool debug;
+
+static void __log(const char *fmt, va_list ap)
+{
+	if (!logf)
+		return;
+	vfprintf(logf, fmt, ap);
+	if (debug)
+		fflush(logf);
+}
 
 void pb_log(const char *fmt, ...)
 {
 	va_list ap;
-	FILE *stream;
-
-	stream = logf ? logf : stderr;
-
 	va_start(ap, fmt);
-	vfprintf(stream, fmt, ap);
+	__log(fmt, ap);
 	va_end(ap);
-
-	if (always_flush)
-		fflush(stream);
 }
 
-void pb_log_set_stream(FILE *stream)
+void pb_debug(const char *fmt, ...)
 {
-	fflush(logf ? logf : stderr);
-	logf = stream;
+	va_list ap;
+	if (!debug)
+		return;
+	va_start(ap, fmt);
+	__log(fmt, ap);
+	va_end(ap);
 }
 
-FILE * pb_log_get_stream(void)
+void __pb_log_init(FILE *fp, bool _debug)
 {
-	return logf ? logf : stderr;
+	if (logf)
+		fflush(logf);
+	logf = fp;
+	debug = _debug;
 }
 
-void pb_log_always_flush(int state)
+FILE *pb_log_get_stream(void)
 {
-	always_flush = state;
+	static FILE *null_stream;
+	if (!logf) {
+		if (!null_stream)
+			null_stream = fopen("/dev/null", "a");
+		return null_stream;
+	}
+	return logf;
 }
diff --git a/lib/log/log.h b/lib/log/log.h
index 6f44bea..e34de33 100644
--- a/lib/log/log.h
+++ b/lib/log/log.h
@@ -1,11 +1,20 @@
 #ifndef _LOG_H
 #define _LOG_H
 
+#include <stdbool.h>
 #include <stdio.h>
 
 void __attribute__ ((format (printf, 1, 2))) pb_log(const char *fmt, ...);
-void pb_log_set_stream(FILE *stream);
-FILE * pb_log_get_stream(void);
-void pb_log_always_flush(int state);
+void __attribute__ ((format (printf, 1, 2))) pb_debug(const char *fmt, ...);
+
+void __pb_log_init(FILE *stream, bool debug);
+
+#ifdef DEBUG
+#define pb_log_init(s) __pb_log_init(s, true)
+#else
+#define pb_log_init(s) __pb_log_init(s, false)
+#endif
+
+FILE *pb_log_get_stream(void);
 
 #endif /* _LOG_H */
diff --git a/test/urls/parse-url.c b/test/urls/parse-url.c
index cfa6762..1688eab 100644
--- a/test/urls/parse-url.c
+++ b/test/urls/parse-url.c
@@ -8,17 +8,12 @@
 int main(int argc, char **argv)
 {
 	struct pb_url *url;
-	FILE *null;
 
 	if (argc != 2 && argc != 3) {
 		fprintf(stderr, "Usage: %s <URL> [update]\n", argv[0]);
 		return EXIT_FAILURE;
 	}
 
-	/* discard log output */
-	null = fopen("/dev/null", "w");
-	pb_log_set_stream(null);
-
 	url = pb_url_parse(NULL, argv[1]);
 	if (!url)
 		return EXIT_FAILURE;
diff --git a/ui/ncurses/generic-main.c b/ui/ncurses/generic-main.c
index cafd23a..9236a80 100644
--- a/ui/ncurses/generic-main.c
+++ b/ui/ncurses/generic-main.c
@@ -206,6 +206,7 @@ int main(int argc, char *argv[])
 	int result;
 	int cui_result;
 	struct opts opts;
+	FILE *log;
 
 	result = opts_parse(&opts, argc, argv);
 
@@ -224,20 +225,15 @@ int main(int argc, char *argv[])
 		return EXIT_SUCCESS;
 	}
 
+	log = stderr;
 	if (strcmp(opts.log_file, "-")) {
-		FILE *log = fopen(opts.log_file, "a");
+		log = fopen(opts.log_file, "a");
 
 		if (!log)
 			log = fopen("/dev/null", "a");
+	}
 
-		assert(log);
-		pb_log_set_stream(log);
-	} else
-		pb_log_set_stream(stderr);
-
-#if defined(DEBUG)
-	pb_log_always_flush(1);
-#endif
+	pb_log_init(log);
 
 	pb_log("--- petitboot-nc ---\n");
 
diff --git a/ui/twin/main-generic.c b/ui/twin/main-generic.c
index 99520d0..649ad00 100644
--- a/ui/twin/main-generic.c
+++ b/ui/twin/main-generic.c
@@ -268,6 +268,7 @@ int main(int argc, char *argv[])
 	int result;
 	int ui_result;
 	struct pbt_client *client;
+	FILE *log;
 
 	result = pbt_opts_parse(&opts, argc, argv);
 
@@ -286,17 +287,13 @@ int main(int argc, char *argv[])
 		return EXIT_SUCCESS;
 	}
 
+	log = stderr;
 	if (strcmp(opts.log_file, "-")) {
 		FILE *log = fopen(opts.log_file, "a");
-
-		assert(log);
-		pb_log_set_stream(log);
-	} else
-		pb_log_set_stream(stderr);
-
-#if defined(DEBUG)
-	pb_log_always_flush(1);
-#endif
+		if (!log)
+			log = stderr;
+	}
+	pb_log_init(log);
 
 	pb_log("--- petitboot-twin ---\n");