print "mostly-printable" xattr strings in debugfs

Taking a cue from getfattr... if a string is "mostly" printable characters, go ahead & print as a string, and escape what's left over.

so we get:

Extended attributes stored in inode body:
selinux = "system_u:object_r:root_t:s0\000" (28)

instead of:

Extended attributes stored in inode body:
selinux = "73 79 73 74 65 6d 5f 75 3a 6f 62 6a 65 63 74 5f 72 3a 72 6f 6f 74 5f 74 3a 73 30 00 " (28)

(selinux includes the trailing null in "len" so it never prints as a string today)

Signed-off-by Eric Sandeen <[email protected]>

---

Index: e2fsprogs-1.40.5/debugfs/debugfs.c
===================================================================

debugfs/debugfs.c +9 -8

@@ -434,19 +434,21 @@ static int list_blocks_proc(ext2_filsys 
 
 static void dump_xattr_string(FILE *out, const char *str, int len)
 {
-	int printable = 1;
+	int printable = 0;
 	int i;
 
-	/* check is string printable? */
+	/* check: is string "printable enough?" */
 	for (i = 0; i < len; i++)
-		if (!isprint(str[i])) {
-			printable = 0;
-			break;
-		}
+		if (isprint(str[i]))
+			printable++;
+
+	if (printable <= len*7/8)
+		printable = 0;
 
 	for (i = 0; i < len; i++)
 		if (printable)
-			fprintf(out, "%c", (unsigned char)str[i]);
+			fprintf(out, isprint(str[i]) ? "%c" : "\\%03o",
+				(unsigned char)str[i]);
 		else
 			fprintf(out, "%02x ", (unsigned char)str[i]);
 }
 
-

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Quoted 3 lines · Eric Sandeen

Taking a cue from getfattr... if a string is "mostly" printable characters, go ahead & print as a string, and escape what's left over.

Ted, ping on this? Since we use selinux a lot, it'd be nice to have something readable in debugfs output.