Write log messages to kernel log

This makes them accessible after boot and it provides time stamps that
can be useful for rudimentary profiling. Note that the kernel log is
also echoed on the console during early boot, so the only thing we lose
is the coloring of the log messages.

The syslog priority markers could be computed, but not without runtime
overhead or very nasty build-time hacks, so I decided to hardcode them.

I also tweaked the messages themselves a bit.

Author: mthuurne

debug.h

@@ -1,9 +1,10 @@
-
 #ifndef DEBUG_H
 #define DEBUG_H
 
 #include <stdio.h>
 
+// Compile time log filter:
+
 #define NODEBUG_L 0
 #define ERROR_L 1
 #define WARNING_L 2
@@ -16,64 +17,34 @@
 
 // -------------
 
-#ifndef COLOR_DEBUG
-#define COLOR_DEBUG   "\e[0;34m"
-#endif
-#ifndef COLOR_WARNING
-#define COLOR_WARNING "\e[01;33m"
-#endif
-#ifndef COLOR_ERROR
-#define COLOR_ERROR   "\e[01;31m"
-#endif
+extern FILE *logfile;
 
-#define COLOR_END "\e[0m"
+#define OUTPUT_LOG_MSG(LEVEL, ...) do { \
+	fprintf(logfile, LEVEL "mininit: " __VA_ARGS__); \
+	} while (0)
 
-#if (LOG_LEVEL >= DEBUG_L)
-# ifdef COLOR_DEBUG
-#  define DEBUG(str, ...) \
-    fprintf(stdout, COLOR_DEBUG "DEBUG: " str COLOR_END, ##__VA_ARGS__)
-# else
-#  define DEBUG(...) \
-    fprintf(stdout, "DEBUG: " __VA_ARGS__)
-# endif
+#if LOG_LEVEL >= DEBUG_L
+#define DEBUG(...) OUTPUT_LOG_MSG("<15>", __VA_ARGS__)
 #else
 #define DEBUG(...)
 #endif
 
-#if (LOG_LEVEL >= INFO_L)
-# ifdef COLOR_INFO
-#  define INFO(str, ...) \
-    fprintf(stdout, COLOR_INFO str COLOR_END, ##__VA_ARGS__)
-# else
-#  define INFO(...) \
-    fprintf(stdout, __VA_ARGS__)
-# endif
+#if LOG_LEVEL >= INFO_L
+#define INFO(...) OUTPUT_LOG_MSG("<14>", __VA_ARGS__)
 #else
 #define INFO(...)
 #endif
 
-#if (LOG_LEVEL >= WARNING_L)
-# ifdef COLOR_WARNING
-#  define WARNING(str, ...) \
-    fprintf(stderr, COLOR_WARNING "WARNING: " str COLOR_END, ##__VA_ARGS__)
-# else
-#  define WARNING(...) \
-    fprintf(stderr, "WARNING: " __VA_ARGS__)
-# endif
+#if LOG_LEVEL >= WARNING_L
+#define WARNING(...) OUTPUT_LOG_MSG("<12>", "WARNING: " __VA_ARGS__)
 #else
 #define WARNING(...)
 #endif
 
-#if (LOG_LEVEL >= ERROR_L)
-# ifdef COLOR_ERROR
-#  define ERROR(str, ...) \
-    fprintf(stderr, COLOR_ERROR "ERROR: " str COLOR_END, ##__VA_ARGS__)
-# else
-#  define ERROR(...) \
-    fprintf(stderr, "ERROR: " __VA_ARGS__)
-# endif
+#if LOG_LEVEL >= ERROR_L
+#define ERROR(...) OUTPUT_LOG_MSG("<11>", "ERROR: " __VA_ARGS__)
 #else
 #define ERROR(...)
 #endif
 
-#endif
+#endif // DEBUG_H

mininit.c

@@ -83,21 +83,30 @@ void perform_updates(bool is_backup)
 }
 
 
+FILE *logfile;
+
 int main(int argc, char **argv, char **envp)
 {
-	INFO("OpenDingux mininit 1.1.0 "
-			"by Ignacio Garcia Perez <[email protected]>, "
-			"Paul Cercueil <[email protected]> and "
-			"Maarten ter Huurne <[email protected]>\n");
+	logfile = stderr;
 
 	/* Mount devtmpfs to get a full set of device nodes. */
-	DEBUG("Mounting /dev\n");
 	if (mount("devtmpfs", "/dev", "devtmpfs", 0, NULL)) {
 		INFO("Couldn't mount devtmpfs on /dev: %d\n", errno);
 		/* If there are sufficient static device nodes in the fs containing
 		 * mininit, we can boot without devtmpfs, so don't give up yet. */
 	}
 
+	/* Write our log messages to the kernel log. */
+	FILE *kmsg = fopen("/dev/kmsg", "w");
+	if (kmsg) {
+		setlinebuf(kmsg);
+		logfile = kmsg;
+	}
+	INFO("OpenDingux mininit 1.1.0\n");
+	if (!kmsg) {
+		WARNING("Failed to open '/dev/kmsg': %d\n", errno);
+	}
+
 	/* Look for "rootfs_bak" parameter. */
 	bool is_backup = false;
 	for (int i = 1; i < argc; i++) {
@@ -137,10 +146,12 @@ int main(int argc, char **argv, char **envp)
 	losetup(loop_dev, rootfs_img);
 
 	/* Mount the loop device that was just set up. */
+	DEBUG("Loop-mounting '%s' on '/root'\n", rootfs_img);
 	if (mount(loop_dev, "/root", ROOTFS_TYPE, MS_RDONLY, NULL)) {
 		ERROR("Failed to mount the rootfs image: %d\n", errno);
 		return -1;
 	}
+	INFO("%s mounted on /root\n", rootfs_img);
 
 	/* Make the freshly mounted rootfs image the working directory. */
 	if (chdir("/root")) {
@@ -190,6 +201,8 @@ int main(int argc, char **argv, char **envp)
 		return -1;
 	}
 
+	INFO("root switch done\n");
+
 	/* Clean up the initramfs and then release it. */
 	if (fd >= 0) {
 		DEBUG("Removing initramfs contents\n");
@@ -228,15 +241,21 @@ int main(int argc, char **argv, char **envp)
 			ERROR("Unable to find the 'init' executable\n");
 			return -1;
 		}
+		DEBUG("Checking for 'init' executable: %s\n", inits[i]);
 		if (!access(inits[i], X_OK)) {
-			DEBUG("Found 'init' executable: %s\n", inits[i]);
 			argv[0] = (char *)inits[i];
 			break;
 		}
 	}
+	INFO("starting %s\n", argv[0]);
+
+	if (kmsg) {
+		logfile = stderr;
+		fclose(kmsg);
+	}
 
 	/* Execute the 'init' executable */
 	execvpe(argv[0], argv, envp);
 	ERROR("Exec of 'init' failed: %d\n", errno);
-	return 0;
+	return -1;
 }

splashkill.c

@@ -47,8 +47,12 @@ static int waitForEnter()
 	return 0;
 }
 
+FILE *logfile;
+
 int main(int argc, char **argv)
 {
+	logfile = stderr;
+
 	signal(SIGINT,  &quit_hdl);
 	signal(SIGSEGV, &quit_hdl);
 	signal(SIGTERM, &quit_hdl);