[PATCH] get part of callout return string

Try this patch if you like, to get special parts of the callout output.
This beast works now:
CALLOUT, BUS="scsi", PROGRAM="/bin/echo -n node link1 link2", ID="node *", NAME="%1c", SYMLINK="%2c %3c"

The callout returned string is separated by spaces and is
addressed by the "len" value of the 'c' format char.
Since we support symlinks, this my be useful for other uses of callout too.

  introduce 'len number' for format chars
  the first use is 'c'-the callout return to select a part of the output string like:
  CALLOUT, BUS="scsi", PROGRAM="/bin/echo -n node link1 link2", ID="node *", NAME="%1c", SYMLINK="%2c %3c"
  (note: first part is requested by len=1, len=0 will return the whole string)
  add a test to udev-test.pl

2 files changed, 45 insertions, 5 deletions

diff --git a/namedev.c b/namedev.c
index 74a411799b..212d6bb68d 100644
--- a/namedev.c
+++ b/namedev.c
@@ -200,15 +200,30 @@ static void build_kernel_number(struct sysfs_class_device *class_dev, struct ude
 static void apply_format(struct udevice *udev, unsigned char *string)
 {
 	char name[NAME_SIZE];
+	char temp[NAME_SIZE];
+	char *tail;
 	char *pos;
+	char *pos2;
+	char *pos3;
+	int num;
 
 	while (1) {
+		num = 0;
 		pos = strchr(string, '%');
 
 		if (pos) {
-			strfieldcpy(name, pos+2);
-			*pos = 0x00;
-			switch (pos[1]) {
+			*pos = '\0';
+			tail = pos+1;
+			if (isdigit(tail[0])) {
+				num = (int) strtoul(&pos[1], &tail, 10);
+				if (tail == NULL) {
+					dbg("format parsing error '%s'", pos+1);
+					break;
+				}
+			}
+			strfieldcpy(name, tail+1);
+
+			switch (tail[0]) {
 			case 'b':
 				if (strlen(udev->bus_id) == 0)
 					break;
@@ -241,8 +256,24 @@ static void apply_format(struct udevice *udev, unsigned char *string)
 			case 'c':
 				if (strlen(udev->callout_value) == 0)
 					break;
-				strcat(pos, udev->callout_value);
-				dbg("substitute callout output '%s'", udev->callout_value);
+				if (num) {
+					/* get part of return string */
+					strncpy(temp, udev->callout_value, sizeof(temp));
+					pos2 = temp;
+					while (num) {
+						num--;
+						pos3 = strsep(&pos2, " ");
+						if (pos3 == NULL) {
+							dbg("requested part of callout string not found");
+							break;
+						}
+					}
+					strcat(pos, pos3);
+					dbg("substitute partial callout output '%s'", pos3);
+				} else {
+					strcat(pos, udev->callout_value);
+					dbg("substitute callout output '%s'", udev->callout_value);
+				}
 				break;
 			default:
 				dbg("unknown substitution type '%%%c'", pos[1]);
diff --git a/test/udev-test.pl b/test/udev-test.pl
index 3dfbaa2530..1a35e3da82 100644
--- a/test/udev-test.pl
+++ b/test/udev-test.pl
@@ -153,6 +153,15 @@ CALLOUT, BUS="scsi", PROGRAM="/bin/echo -n test-%b", ID="test-*", NAME="%c"
 EOF
 	},
 	{
+		desc     => "callout program substitution (numbered part of)",
+		subsys   => "block",
+		devpath  => "block/sda/sda3",
+		expected => "link1" ,
+		conf     => <<EOF
+CALLOUT, BUS="scsi", PROGRAM="/bin/echo -n node link1 link2", ID="node *", NAME="%1c", SYMLINK="%2c %3c"
+EOF
+	},
+	{
 		desc     => "devfs disk naming substitution",
 		subsys   => "block",
 		devpath  => "block/sda",