fdisk: introduce fdisk context

This is the first patch that adds the initial parts of the new fdisk internal
API. Two functions are created to both init and deinit the fdisk context. Only
the device's descriptor and path are added as a start and these are replaced
throughout fdisk.c and label specific code.

All logic that opens the file does it with fdisk_new_context_from_filename(),
and this enforces always opening the device with rw, then, if unsuccesfull,
with read-only. This changes the current logic that opens the device with
certain permissions depending on the user given options.  For example, -l opens
the device read-only.

This patch passed regression tests and local modifications for sgi/dos/sun disk
labels.

Signed-off-by: Davidlohr Bueso <dave@gnu.org>

1 files changed, 38 insertions, 44 deletions

diff --git a/fdisk/fdisk.c b/fdisk/fdisk.c
index 2589a166d..7f94523c0 100644
--- a/fdisk/fdisk.c
+++ b/fdisk/fdisk.c
@@ -55,6 +55,7 @@
 
 unsigned char *MBRbuffer;
 int MBRbuffer_changed;
+struct fdisk_context *cxt = NULL;
 
 #define hex_val(c)	({ \
 				char _c = (c); \
@@ -130,12 +131,10 @@ get_nr_sects(struct partition *p) {
 	return read4_little_endian(p->size4);
 }
 
-char	*disk_device,			/* must be specified */
-	*line_ptr,			/* interactive input */
+char	*line_ptr,			/* interactive input */
 	line_buffer[LINE_LENGTH];
 
-int	fd,				/* the disk */
-	nowarn = 0,			/* no warnings for fdisk -l/-s */
+int	nowarn = 0,			/* no warnings for fdisk -l/-s */
 	dos_compatible_flag = 0,	/* disabled by default */
 	dos_changed = 0,
 	partitions = 4;			/* maximum partition + 1 */
@@ -183,19 +182,19 @@ static void __attribute__ ((__noreturn__)) usage(FILE *out)
 
 void fatal(enum failure why)
 {
-	close(fd);
+	close(cxt->dev_fd);
 	switch (why) {
 		case unable_to_read:
-			err(EXIT_FAILURE, _("unable to read %s"), disk_device);
+			err(EXIT_FAILURE, _("unable to read %s"), cxt->dev_path);
 
 		case unable_to_seek:
-			err(EXIT_FAILURE, _("unable to seek on %s"), disk_device);
+			err(EXIT_FAILURE, _("unable to seek on %s"), cxt->dev_path);
 
 		case unable_to_write:
-			err(EXIT_FAILURE, _("unable to write %s"), disk_device);
+			err(EXIT_FAILURE, _("unable to write %s"), cxt->dev_path);
 
 		case ioctl_error:
-			err(EXIT_FAILURE, _("BLKGETSIZE ioctl failed on %s"), disk_device);
+			err(EXIT_FAILURE, _("BLKGETSIZE ioctl failed on %s"), cxt->dev_path);
 
 		default:
 			err(EXIT_FAILURE, _("fatal error"));
@@ -460,7 +459,7 @@ get_topology(int fd) {
 	blkid_probe pr;
 
 	pr = blkid_new_probe();
-	if (pr && blkid_probe_set_device(pr, fd, 0, 0) == 0) {
+	if (pr && blkid_probe_set_device(pr, cxt->dev_fd, 0, 0) == 0) {
 		blkid_topology tp = blkid_probe_get_topology(pr);
 
 		if (tp) {
@@ -494,7 +493,7 @@ get_topology(int fd) {
 		 */
 		phy_sector_size = sector_size;
 
-	else if (blkdev_get_sector_size(fd, &arg) == 0) {
+	else if (blkdev_get_sector_size(cxt->dev_fd, &arg) == 0) {
 		sector_size = arg;
 
 		if (!phy_sector_size)
@@ -664,24 +663,13 @@ static int get_boot(int try_only) {
 	disklabel = ANY_LABEL;
 	memset(MBRbuffer, 0, 512);
 
-	if (try_only && (fd = open(disk_device, O_RDONLY)) < 0)
-		err(EXIT_FAILURE, _("unable to open %s"), disk_device);
-	else {
-		if ((fd = open(disk_device, O_RDWR)) < 0) {
-			/* ok, can we read-only the device? */
-			if ((fd = open(disk_device, O_RDONLY)) < 0)
-				err(EXIT_FAILURE, _("unable to open %s"), disk_device);
-			printf(_("You will not be able to write the partition table.\n"));
-		}
-	}
-
-	if (512 != read(fd, MBRbuffer, 512)) {
+	if (512 != read(cxt->dev_fd, MBRbuffer, 512)) {
 		if (try_only)
 			return 1;
 		fatal(unable_to_read);
 	}
 
-	get_geometry(fd, NULL);
+	get_geometry(cxt->dev_fd, NULL);
 	update_units();
 
 	if (!check_dos_label())
@@ -1232,11 +1220,11 @@ list_disk_geometry(void) {
 
 	if (megabytes < 10000)
 		printf(_("\nDisk %s: %ld MB, %lld bytes\n"),
-		       disk_device, megabytes, bytes);
+		       cxt->dev_path, megabytes, bytes);
 	else {
 		long hectomega = (megabytes + 50) / 100;
 		printf(_("\nDisk %s: %ld.%ld GB, %llu bytes\n"),
-		       disk_device, hectomega / 10, hectomega % 10, bytes);
+		       cxt->dev_path, hectomega / 10, hectomega % 10, bytes);
 	}
 	printf(_("%d heads, %llu sectors/track, %d cylinders"),
 	       heads, sectors, cylinders);
@@ -1424,8 +1412,8 @@ list_table(int xtra) {
 	/* Heuristic: we list partition 3 of /dev/foo as /dev/foo3,
 	   but if the device name ends in a digit, say /dev/foo1,
 	   then the partition is called /dev/foo1p3. */
-	w = strlen(disk_device);
-	if (w && isdigit(disk_device[w-1]))
+	w = strlen(cxt->dev_path);
+	if (w && isdigit(cxt->dev_path[w-1]))
 		w++;
 	if (w < 5)
 		w = 5;
@@ -1450,7 +1438,7 @@ list_table(int xtra) {
 				pblocks *= (sector_size / 1024);
                         printf(
 			    "%s  %c %11lu %11lu %11lu%c  %2x  %s\n",
-			partname(disk_device, i+1, w+2),
+			partname(cxt->dev_path, i+1, w+2),
 /* boot flag */		!p->boot_ind ? ' ' : p->boot_ind == ACTIVE_FLAG
 			? '*' : '?',
 /* start */		(unsigned long) cround(get_partition_start(pe)),
@@ -1480,7 +1468,7 @@ x_list_table(int extend) {
 	int i;
 
 	printf(_("\nDisk %s: %d heads, %llu sectors, %d cylinders\n\n"),
-		disk_device, heads, sectors, cylinders);
+		cxt->dev_path, heads, sectors, cylinders);
         printf(_("Nr AF  Hd Sec  Cyl  Hd Sec  Cyl     Start      Size ID\n"));
 	for (i = 0 ; i < partitions; i++) {
 		pe = &ptes[i];
@@ -1695,12 +1683,12 @@ reread_partition_table(int leave) {
 	int i;
 	struct stat statbuf;
 
-	i = fstat(fd, &statbuf);
+	i = fstat(cxt->dev_fd, &statbuf);
 	if (i == 0 && S_ISBLK(statbuf.st_mode)) {
 		sync();
 #ifdef BLKRRPART
 		printf(_("Calling ioctl() to re-read partition table.\n"));
-		i = ioctl(fd, BLKRRPART);
+		i = ioctl(cxt->dev_fd, BLKRRPART);
 #else
 		errno = ENOSYS;
 		i = 1;
@@ -1721,7 +1709,7 @@ reread_partition_table(int leave) {
 		"information.\n"));
 
 	if (leave) {
-		if (fsync(fd) || close(fd)) {
+		if (fsync(cxt->dev_fd) || close(cxt->dev_fd)) {
 			fprintf(stderr, _("\nError closing file\n"));
 			exit(1);
 		}
@@ -1755,7 +1743,7 @@ static void
 print_raw(void) {
 	int i;
 
-	printf(_("Device: %s\n"), disk_device);
+	printf(_("Device: %s\n"), cxt->dev_path);
 	if (disklabel == SUN_LABEL || disklabel == SGI_LABEL)
 		print_buffer(MBRbuffer);
 	else for (i = 3; i < partitions; i++)
@@ -1811,9 +1799,9 @@ move_begin(int i) {
 	}
 }
 
-static void __attribute__ ((__noreturn__)) handle_quit(void)
+static void __attribute__ ((__noreturn__)) handle_quit(struct fdisk_context *cxt)
 {
-	close(fd);
+	fdisk_free_context(cxt);
 	printf("\n");
 	exit(EXIT_SUCCESS);
 }
@@ -1883,7 +1871,7 @@ expert_command_prompt(void)
 				x_list_table(0);
 			break;
 		case 'q':
-			handle_quit();
+			handle_quit(cxt);
 		case 'r':
 			return;
 		case 's':
@@ -1939,7 +1927,10 @@ print_partition_table_from_option(char *device)
 {
 	int gb;
 
-	disk_device = device;
+	cxt = fdisk_new_context_from_filename(device);
+	if (!cxt)
+		err(EXIT_FAILURE, _("unable to open %s"), device);
+
 	gpt_warning(device);
 	gb = get_boot(1);
 	if (gb < 0) { /* no DOS signature */
@@ -1949,7 +1940,7 @@ print_partition_table_from_option(char *device)
 	}
 	else if (!gb)
 		list_table(0);
-	close(fd);
+	fdisk_free_context(cxt);
 }
 
 /*
@@ -2001,7 +1992,7 @@ static void command_prompt(void)
 		/* OSF label, and no DOS label */
 		printf(_("Detected an OSF/1 disklabel on %s, entering "
 			 "disklabel mode.\n"),
-		       disk_device);
+		       cxt->dev_path);
 		bsd_command_prompt();
 		/* If we return we may want to make an empty DOS label? */
 		disklabel = DOS_LABEL;
@@ -2070,7 +2061,7 @@ static void command_prompt(void)
 			list_table(0);
 			break;
 		case 'q':
-			handle_quit();
+			handle_quit(cxt);
 		case 's':
 			create_sunlabel();
 			break;
@@ -2209,8 +2200,11 @@ int main(int argc, char **argv)
 		exit(EXIT_SUCCESS);
 	}
 
-	if (argc-optind == 1)
-		disk_device = argv[optind];
+	if (argc-optind == 1) {
+		cxt = fdisk_new_context_from_filename(argv[optind]);
+		if (!cxt)
+			err(EXIT_FAILURE, _("unable to open %s"), argv[optind]);
+	}
 	else
 		usage(stderr);
 
@@ -2218,7 +2212,7 @@ int main(int argc, char **argv)
 		"Changes will remain in memory only, until you decide to write them.\n"
 		"Be careful before using the write command.\n\n"), PACKAGE_STRING);
 
-	gpt_warning(disk_device);
+	gpt_warning(cxt->dev_path);
 	get_boot(0);
 
 	command_prompt();