disk: get_device_and_partition() "auto" partition and cleanup

Rework get_device_and_partition() to:
a) Implement a new partition ID of "auto", which requests that U-Boot
   search for the first "bootable" partition, and fall back to the first
   valid partition if none is found. This way, users don't need to
   specify an explicit partition in their commands.
b) Make use of get_device().
c) Add parameter to indicate whether returning a whole device is
   acceptable, or whether a partition is mandatory.
d) Make error-checking of the user's device-/partition-specification
   more complete. In particular, if strtoul() doesn't convert all
   characters, it's an error rather than just ignored.

The resultant device/partition returned by the function will be as
follows, based on whether the disk has a partition table (ptable) or not,
and whether the calling command allows the whole device to be returned
or not.

(D and P are integers, P >= 1)

D
D:
  No ptable:
    !allow_whole_dev: error
    allow_whole_dev: device D
  ptable:
    device D partition 1
D:0
  !allow_whole_dev: error
  allow_whole_dev: device D
D:P
  No ptable: error
  ptable: device D partition P
D:auto
  No ptable:
    !allow_whole_dev: error
    allow_whole_dev: device D
  ptable:
    first partition in device D with bootable flag set.
    If none, first valid paratition in device D.

Note: In order to review this patch, it's probably easiest to simply
look at the file contents post-application, rather than reading the
patch itself.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
[swarren: Rob implemented scanning for bootable partitions. I fixed a
couple of issues there, switched the syntax to ":auto", added the
error-checking rework, and ":0" syntax for the whole device]
Signed-off-by: Stephen Warren <swarren@nvidia.com>

1 files changed, 154 insertions, 43 deletions

diff --git a/disk/part.c b/disk/part.c
index ed6bbe2..0dd4b0f 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -24,6 +24,7 @@
 #include <common.h>
 #include <command.h>
 #include <ide.h>
+#include <malloc.h>
 #include <part.h>
 
 #undef	PART_DEBUG
@@ -465,66 +466,176 @@ int get_device(const char *ifname, const char *dev_str,
 	return dev;
 }
 
-int get_device_and_partition(const char *ifname, const char *dev_str,
+#define PART_UNSPECIFIED -2
+#define PART_AUTO -1
+#define MAX_SEARCH_PARTITIONS 16
+int get_device_and_partition(const char *ifname, const char *dev_part_str,
 			     block_dev_desc_t **dev_desc,
-			     disk_partition_t *info)
+			     disk_partition_t *info, int allow_whole_dev)
 {
-	int ret;
-	char *ep;
+	int ret = -1;
+	const char *part_str;
+	char *dup_str = NULL;
+	const char *dev_str;
 	int dev;
-	block_dev_desc_t *desc;
-	int part = 0;
-	char *part_str;
-
-	if (dev_str)
-		dev = simple_strtoul(dev_str, &ep, 16);
-
-	if (!dev_str || (dev_str == ep)) {
-		dev_str = getenv("bootdevice");
-		if (dev_str)
-			dev = simple_strtoul(dev_str, &ep, 16);
-		if (!dev_str || (dev_str == ep))
-			goto err;
+	char *ep;
+	int p;
+	int part;
+	disk_partition_t tmpinfo;
+
+	/* If no dev_part_str, use bootdevice environment variable */
+	if (!dev_part_str)
+		dev_part_str = getenv("bootdevice");
+
+	/* If still no dev_part_str, it's an error */
+	if (!dev_part_str) {
+		printf("** No device specified **\n");
+		goto cleanup;
+	}
+
+	/* Separate device and partition ID specification */
+	part_str = strchr(dev_part_str, ':');
+	if (part_str) {
+		dup_str = strdup(dev_part_str);
+		dup_str[part_str - dev_part_str] = 0;
+		dev_str = dup_str;
+		part_str++;
+	} else {
+		dev_str = dev_part_str;
 	}
 
-	desc = get_dev(ifname, dev);
-	if (!desc || (desc->type == DEV_TYPE_UNKNOWN))
-		goto err;
+	/* Look up the device */
+	dev = get_device(ifname, dev_str, dev_desc);
+	if (dev < 0)
+		goto cleanup;
+
+	/* Convert partition ID string to number */
+	if (!part_str || !*part_str) {
+		part = PART_UNSPECIFIED;
+	} else if (!strcmp(part_str, "auto")) {
+		part = PART_AUTO;
+	} else {
+		/* Something specified -> use exactly that */
+		part = (int)simple_strtoul(part_str, &ep, 16);
+		/*
+		 * Less than whole string converted,
+		 * or request for whole device, but caller requires partition.
+		 */
+		if (*ep || (part == 0 && !allow_whole_dev)) {
+			printf("** Bad partition specification %s %s **\n",
+			    ifname, dev_part_str);
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * No partition table on device,
+	 * or user requested partition 0 (entire device).
+	 */
+	if (((*dev_desc)->part_type == PART_TYPE_UNKNOWN) ||
+	    (part == 0)) {
+		if (!(*dev_desc)->lba) {
+			printf("** Bad device size - %s %s **\n", ifname,
+			       dev_str);
+			goto cleanup;
+		}
 
-	if (desc->part_type == PART_TYPE_UNKNOWN) {
-		/* disk doesn't use partition table */
-		if (!desc->lba) {
-			printf("**Bad disk size - %s %d:0 **\n", ifname, dev);
-			return -1;
+		/*
+		 * If user specified a partition ID other than 0,
+		 * or the calling command only accepts partitions,
+		 * it's an error.
+		 */
+		if ((part > 0) || (!allow_whole_dev)) {
+			printf("** No partition table - %s %s **\n", ifname,
+			       dev_str);
+			goto cleanup;
 		}
+
 		info->start = 0;
-		info->size = desc->lba;
-		info->blksz = desc->blksz;
+		info->size = (*dev_desc)->lba;
+		info->blksz = (*dev_desc)->blksz;
+		info->bootable = 0;
+#ifdef CONFIG_PARTITION_UUIDS
+		info->uuid[0] = 0;
+#endif
 
-		*dev_desc = desc;
-		return 0;
+		ret = 0;
+		goto cleanup;
 	}
 
-	part_str = strchr(dev_str, ':');
-	if (part_str)
-		part = (int)simple_strtoul(++part_str, NULL, 16);
-
-	ret = get_partition_info(desc, part, info);
-	if (ret) {
-		printf("** Invalid partition %d, use `dev[:part]' **\n", part);
-		return -1;
+	/*
+	 * Now there's known to be a partition table,
+	 * not specifying a partition means to pick partition 1.
+	 */
+	if (part == PART_UNSPECIFIED)
+		part = 1;
+
+	/*
+	 * If user didn't specify a partition number, or did specify something
+	 * other than "auto", use that partition number directly.
+	 */
+	if (part != PART_AUTO) {
+		ret = get_partition_info(*dev_desc, part, info);
+		if (ret) {
+			printf("** Invalid partition %d **\n", part);
+			goto cleanup;
+		}
+	} else {
+		/*
+		 * Find the first bootable partition.
+		 * If none are bootable, fall back to the first valid partition.
+		 */
+		part = 0;
+		for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) {
+			ret = get_partition_info(*dev_desc, p, info);
+			if (ret)
+				continue;
+
+			/*
+			 * First valid partition, or new better partition?
+			 * If so, save partition ID.
+			 */
+			if (!part || info->bootable)
+				part = p;
+
+			/* Best possible partition? Stop searching. */
+			if (info->bootable)
+				break;
+
+			/*
+			 * We now need to search further for best possible.
+			 * If we what we just queried was the best so far,
+			 * save the info since we over-write it next loop.
+			 */
+			if (part == p)
+				tmpinfo = *info;
+		}
+		/* If we found any acceptable partition */
+		if (part) {
+			/*
+			 * If we searched all possible partition IDs,
+			 * return the first valid partition we found.
+			 */
+			if (p == MAX_SEARCH_PARTITIONS + 1)
+				*info = tmpinfo;
+			ret = 0;
+		} else {
+			printf("** No valid partitions found **\n");
+			goto cleanup;
+		}
 	}
 	if (strncmp((char *)info->type, BOOT_PART_TYPE, sizeof(info->type)) != 0) {
 		printf("** Invalid partition type \"%.32s\""
 			" (expect \"" BOOT_PART_TYPE "\")\n",
 			info->type);
-		return -1;
+		ret  = -1;
+		goto cleanup;
 	}
 
-	*dev_desc = desc;
-	return part;
+	ret = part;
+	goto cleanup;
 
-err:
-	puts("** Invalid boot device, use `dev[:part]' **\n");
-	return -1;
+cleanup:
+	free(dup_str);
+	return ret;
 }