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 <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 2d24825..818ce53 100644 (file)
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -434,19 +434,21 @@ static int list_blocks_proc(ext2_filsys fs EXT2FS_ATTR((unused)),
 
 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]);
 }