Rewrote test/blank.c to new API practice, inflated explanation comments

trunk/test/blank.c

@@ -1,63 +1,251 @@
 /* -*- indent-tabs-mode: t; tab-width: 8; c-basic-offset: 8; -*- */
 
+/** See this for the decisive API specs . libburn.h is The Original */
 #include <libburn/libburn.h>
 
+
+/*  test/blank.c , API illustration of blanking a used CD-RW
+    Copyright (C) ???? - 2006 Derek Foreman
+    Copyright (C) 2006 - 2006 Thomas Schmitt
+    This is provided under GPL only. Don't ask for anything else for now.
+    Read. Try. Think. Play. Write yourself some code. Be free of our copyright.
+*/
+
+
 #include <unistd.h>
 #include <stdio.h>
 #include <assert.h>
+#include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
 
+
+/* Some in-advance definitions to allow a more comprehensive ordering
+   of the functions and their explanations in here */
+int burn_app_aquire_by_adr(char *drive_adr);
+int burn_app_aquire_by_driveno(int drive_no);
+
+
+/** This is a rough example. For simplicity it uses global variables.
+    Drives are systemwide global, so we do not give away much of good style.
+*/
+
+/** This list will hold the drives known to libburn. This might be all CD
+    drives of the system and thus might impose severe impact on the system.
+*/
 static struct burn_drive_info *drives;
+
+/** If you start a long lasting operation with n_drives > 1 then you are not
+    friendly to the users of other drives on those systems. Beware. */
 static unsigned int n_drives;
 
-static void blank_disc(struct burn_drive *drive)
+
+/** You need to aquire a drive before burning. The API offers this as one
+    compact call and alternatively as application controllable gestures of
+    whitelisting, scanning for drives and finally grabbing one of them.
+
+    If you have a persistent address of the drive, then the compact call is
+    to prefer. See test/burniso.c for a more detailed explanation.
+*/
+int burn_app_aquire_drive(char *drive_adr, int driveno)
+{
+	int ret;
+
+	if(drive_adr != NULL && drive_adr[0] != 0)
+		ret = burn_app_aquire_by_adr(drive_adr);
+	else
+		ret = burn_app_aquire_by_driveno(driveno);
+	return ret;
+}
+
+/** If the persistent drive address is known, then this approach is much
+    more un-obtrusive to the systemwide livestock of drives. Only the
+    given drive device will be opened during this procedure.
+*/
+int burn_app_aquire_by_adr(char *drive_adr)
+{
+	int ret;
+	
+	printf("Aquiring drive '%s' ...\n",drive_adr);
+	ret = burn_drive_scan_and_grab(&drives,drive_adr,1);
+	if (ret <= 0)
+		printf("Failed\n");
+	else
+		printf("done\n");
+	return ret;
+}
+
+/** This method demonstrates how to use libburn without knowing a persistent
+    drive address in advance. It has to make sure that after assessing the
+    list of available drives, all drives get closed again. Only then it is
+    sysadmin-acceptable to aquire the desired drive for a prolonged time.
+    This drive closing is enforced here by shutting down libburn and
+    restarting it again with the much more un-obtrusive approach to use
+    a persistent address and thus to only touch the one desired drive.
+*/
+int burn_app_aquire_by_driveno(int driveno)
+{
+	char adr[BURN_DRIVE_ADR_LEN];
+	int ret;
+
+	printf("Scanning for devices ...\n");
+	while (!burn_drive_scan(&drives, &n_drives)) ;
+	if (n_drives <= 0) {
+		printf("Failed (no drives found)\n");
+		return 0;
+	}
+	printf("done\n");
+	if (n_drives <= driveno) {
+		fprintf(stderr,
+			"Found only %d drives. Number %d not available.\n",
+			n_drives,driveno);
+		return 0;
+	}
+
+
+	/* Interactive programs may choose the drive number at this moment.
+
+	   drive[0] to drive[n_drives-1] are struct burn_drive_info
+	   as defined in  libburn/libburn.h  . This structure is part of API
+	   and thus will strive for future compatibility on source level.
+	   Have a look at the info offered. Have a look at test/devices.c .
+	   Caution: do not take .location for drive address. Always use
+		    burn_drive_get_adr() or you might become incompatible
+		    in future.
+	   Note: bugs with struct burn_drive_info - if any - will not be
+		 easy to fix. Please report them but also strive for
+		 workarounds on application level.
+	*/
+
+
+	/* Now save yourself from sysadmins' revenge */
+
+	/* If n_drives == 1 this would be not really necessary, though.
+           You could now call burn_drive_grab() and avoid libburn restart.
+	   We don't try to be smart here and follow the API's strong urge. */
+
+	if (burn_drive_get_adr(&(drives[driveno]), adr) <=0) {
+		fprintf(stderr,
+		"Cannot inquire persistent drive address of drive number %d\n",
+			driveno);
+		return 0;
+	}
+	printf("Detected '%s' as persistent address of drive number %d\n",
+		adr,driveno);
+
+/* In cdrskin this causes a delayed sigsegv. I understand we risk only
+   a small memory leak by not doing:
+ 
+	burn_drive_info_free(drives);
+*/
+
+	burn_finish();
+	printf(
+	     "Re-Initializing library to release any unintended drives ...\n");
+	if (burn_initialize())
+		printf("done\n");
+	else {
+		printf("Failed\n");
+		fprintf(stderr,"\nFailed to re-initialize libburn.\n");
+		return 0;
+	}
+	ret = burn_app_aquire_by_adr(adr);
+	return ret;
+}
+
+/** Makes a previously used CD-RW ready for thorough re-usal.
+
+    To our knowledge it is hardly possible to abort an ongoing blank operation
+    because after start it is entirely handled by the drive.
+    So expect a blank run to survive the end of the blanking process and be
+    patient for the usual timespan of a normal blank run. Only after that
+    time has surely elapsed, only then you should start any rescue attempts
+    with the drive. If necessary at all.
+*/
+static void blank_disc(struct burn_drive *drive, int blank_fast)
 {
 	enum burn_disc_status s;
 	struct burn_progress p;
+	int do_blank = 0;
 
+#ifdef Blank_late_grab_obsoletion_revoke_and_faiL
+        /* This is obsoleted now by the burn_app_aquire* functions.
+           There is no real benefit in grabbing late.
+           Beneficial is to scan only one drive.
+        */ 
 	if (!burn_drive_grab(drive, 1)) {
 		fprintf(stderr, "Unable to open the drive!\n");
 		return;
 	}
+#endif /* Blank_late_grab_obsoletion_revoke_and_faiL */
 
-	while (burn_drive_get_status(drive, NULL)) {
+	while (burn_drive_get_status(drive, NULL))
 		usleep(1000);
-	}
 
 	while ((s = burn_disc_get_status(drive)) == BURN_DISC_UNREADY)
 		usleep(1000);
-	printf("%d\n", s);
+	printf(
-	if (s != BURN_DISC_FULL) {
+	  "Drive media status:  %d  (see libburn/libburn.h BURN_DISC_*)\n", s);
+	do_blank = 0;
+	if (s == BURN_DISC_BLANK) {
+		fprintf(stderr,
+		  "IDLE: Blank CD media detected. Will leave it untouched\n");
+	} else if (s == BURN_DISC_FULL || s == BURN_DISC_APPENDABLE) {
+		do_blank = 1;
+	} else if (s == BURN_DISC_EMPTY) {
+		fprintf(stderr,"FATAL: No media detected in drive\n");
+	} else {
+		fprintf(stderr,
+			"FATAL: Cannot recognize drive and media state\n");
+	}
+	if(do_blank && !burn_disc_erasable(drive)) {
+		fprintf(stderr,
+		       "FATAL : Media is not of erasable type\n");
+		do_blank = 0;
+	}
+	if (!do_blank) {
 		burn_drive_release(drive, 0);
-		fprintf(stderr, "No disc found!\n");
 		return;
 	}
 
-	fprintf(stderr, "Blanking disc...");
+	printf(
-	burn_disc_erase(drive, 1);
+	    "Beginning to %s-blank CD media. Will display sector numbers.\n",
-
+		(blank_fast?"fast":"full"));
+	burn_disc_erase(drive, blank_fast);
 	while (burn_drive_get_status(drive, &p)) {
 		printf("%d\n", p.sector);
 		sleep(2);
 	}
-	fprintf(stderr, "Done\n");
+	printf("Done\n");
 
 	burn_drive_release(drive, 0);
 }
 
-void parse_args(int argc, char **argv, int *drive)
+void parse_args(int argc, char **argv, char **drive_adr, int *driveno,
+		int *blank_fast)
 {
 	int i;
 	int help = 0;
+	static char no_drive_adr[]= {""};
 
+	*drive_adr = no_drive_adr;
 	for (i = 1; i < argc; ++i) {
-		if (!strcmp(argv[i], "--drive")) {
+		if (!strcmp(argv[i], "--blank_fast")) {
+			*blank_fast= 1;
+
+		} else if (!strcmp(argv[i], "--blank_full")) {
+			*blank_fast= 0;
+
+		} else if (!strcmp(argv[i], "--drive")) {
 			++i;
-			if (i >= argc)
+			if (i >= argc) {
 				printf("--drive requires an argument\n");
-			else
+				exit(3);
-				*drive = atoi(argv[i]);
+			} else if (isdigit(argv[i][0])) {
+				*drive_adr = no_drive_adr;
+				*driveno = atoi(argv[i]);
+			} else
+				*drive_adr = argv[i];
 		} else if (!strcmp(argv[i], "--verbose")) {
 			++i;
 			if (i >= argc)
@@ -69,31 +257,37 @@ void parse_args(int argc, char **argv, int *drive)
 		}
 	}
 	if (help) {
-		printf("Usage: %s [--drive <num>] [--verbose <level>]\n",
+		printf("Usage: %s\n", argv[0]);
-		       argv[0]);
+		printf("       [--blank_fast|--blank_full] [--drive <address>|<num>]\n");
-		exit(EXIT_FAILURE);
+		printf("       [--verbose <level>]\n");
+		exit(3);
 	}
 }
 
 int main(int argc, char **argv)
 {
-	int drive = 0;
+	int driveno = 0, blank_fast= 1;
+	char *drive_adr= NULL;
 
-	parse_args(argc, argv, &drive);
 
-	fprintf(stderr, "Initializing library...");
+	parse_args(argc, argv, &drive_adr, &driveno, &blank_fast);
+
+	printf("Initializing library ...\n");
 	if (burn_initialize())
-		fprintf(stderr, "Success\n");
+		printf("done\n");
 	else {
 		printf("Failed\n");
+		fprintf(stderr,"\nFATAL: Failed to initialize libburn.\n");
 		return 1;
 	}
 
-	fprintf(stderr, "Scanning for devices...");
+	if (burn_app_aquire_drive(drive_adr,driveno)<=0) {
-	while (!burn_drive_scan(&drives, &n_drives)) ;
+		fprintf(stderr,"\nFATAL: Failed to aquire drive.\n");
-	fprintf(stderr, "Done\n");
+		return 2;
+	}
+
+	blank_disc(drives[driveno].drive, blank_fast);
 
-	blank_disc(drives[drive].drive);
 	burn_drive_info_free(drives);
 	burn_finish();
 	return 0;