Last minute tweaks to debug scripts

- Standardized littlefs debug statements to use hex prefixes and
  brackets for printing pairs.

- Removed the entry behavior for readtree and made -t the default.
  This is because 1. the CTZ skip-list parsing was broken, which is not
  surprising, and 2. the entry parsing was more complicated than useful.
  This functionality may be better implemented as a proper filesystem
  read script, complete with directory tree dumping.

- Changed test.py's --gdb argument to take [init, main, assert],
  this matches the names of the stages in C's startup.

- Added printing of tail to all mdir dumps in readtree/readmdir.

- Added a print for if any mdirs are corrupted in readtree.

- Added debug script side-effects to .gitignore.

3 files changed, 58 insertions, 126 deletions

diff --git a/scripts/readmdir.py b/scripts/readmdir.py
index 75f8b9a..b6c3dcc 100755
--- a/scripts/readmdir.py
+++ b/scripts/readmdir.py
@@ -233,8 +233,8 @@ class MetadataPair:
 
     def __lt__(self, other):
         # corrupt blocks don't count
-        if not self and other:
-            return True
+        if not self or not other:
+            return bool(other)
 
         # use sequence arithmetic to avoid overflow
         return not ((other.rev - self.rev) & 0x80000000)
@@ -318,14 +318,24 @@ def main(args):
 
     # find most recent pair
     mdir = MetadataPair(blocks)
-    print("mdir {%s} rev %d%s%s" % (
+
+    try:
+        mdir.tail = mdir[Tag('tail', 0, 0)]
+        if mdir.tail.size != 8 or mdir.tail.data == 8*b'\xff':
+            mdir.tail = None
+    except KeyError:
+        mdir.tail = None
+
+    print("mdir {%s} rev %d%s%s%s" % (
         ', '.join('%#x' % b
             for b in [args.block1, args.block2]
             if b is not None),
         mdir.rev,
         ' (was %s)' % ', '.join('%d' % m.rev for m in mdir.pair[1:])
         if len(mdir.pair) > 1 else '',
-        ' (corrupted)' if not mdir else ''))
+        ' (corrupted!)' if not mdir else '',
+        ' -> {%#x, %#x}' % struct.unpack('<II', mdir.tail.data)
+        if mdir.tail else ''))
     if args.all:
         mdir.dump_all(truncate=not args.no_truncate)
     elif args.log:
diff --git a/scripts/readtree.py b/scripts/readtree.py
index 3965a36..36135ab 100755
--- a/scripts/readtree.py
+++ b/scripts/readtree.py
@@ -7,97 +7,14 @@ import io
 import itertools as it
 from readmdir import Tag, MetadataPair
 
-def popc(x):
-    return bin(x).count('1')
-
-def ctz(x):
-    return len(bin(x)) - len(bin(x).rstrip('0'))
-
-def dumpentries(args, mdir, f):
-    for k, id_ in enumerate(mdir.ids):
-        name = mdir[Tag('name', id_, 0)]
-        struct_ = mdir[Tag('struct', id_, 0)]
-
-        desc = "id %d %s %s" % (
-            id_, name.typerepr(),
-            json.dumps(name.data.decode('utf8')))
-        if struct_.is_('dirstruct'):
-            desc += " dir {%#x, %#x}" % struct.unpack(
-                '<II', struct_.data[:8].ljust(8, b'\xff'))
-        if struct_.is_('ctzstruct'):
-            desc += " ctz {%#x} size %d" % struct.unpack(
-                '<II', struct_.data[:8].ljust(8, b'\xff'))
-        if struct_.is_('inlinestruct'):
-            desc += " inline size %d" % struct_.size
-
-        data = None
-        if struct_.is_('inlinestruct'):
-            data = struct_.data
-        elif struct_.is_('ctzstruct'):
-            block, size = struct.unpack(
-                '<II', struct_.data[:8].ljust(8, b'\xff'))
-            data = []
-            i = 0 if size == 0 else (size-1) // (args.block_size - 8)
-            if i != 0:
-                i = ((size-1) - 4*popc(i-1)+2) // (args.block_size - 8)
-            with open(args.disk, 'rb') as f2:
-                while i >= 0:
-                    f2.seek(block * args.block_size)
-                    dat = f2.read(args.block_size)
-                    data.append(dat[4*(ctz(i)+1) if i != 0 else 0:])
-                    block, = struct.unpack('<I', dat[:4].ljust(4, b'\xff'))
-                    i -= 1
-            data = bytes(it.islice(
-                it.chain.from_iterable(reversed(data)), size))
-
-        f.write("%-45s%s\n" % (desc,
-            "%-23s  %-8s" % (
-                ' '.join('%02x' % c for c in data[:8]),
-                ''.join(c if c >= ' ' and c <= '~' else '.'
-                    for c in map(chr, data[:8])))
-            if not args.no_truncate and len(desc) < 45
-                and data is not None else ""))
-
-        if name.is_('superblock') and struct_.is_('inlinestruct'):
-            f.write(
-                "  block_size %d\n"
-                "  block_count %d\n"
-                "  name_max %d\n"
-                "  file_max %d\n"
-                "  attr_max %d\n" % struct.unpack(
-                    '<IIIII', struct_.data[4:4+20].ljust(20, b'\xff')))
-
-        for tag in mdir.tags:
-            if tag.id==id_ and tag.is_('userattr'):
-                desc = "%s size %d" % (tag.typerepr(), tag.size)
-                f.write("  %-43s%s\n" % (desc,
-                    "%-23s  %-8s" % (
-                        ' '.join('%02x' % c for c in tag.data[:8]),
-                        ''.join(c if c >= ' ' and c <= '~' else '.'
-                            for c in map(chr, tag.data[:8])))
-                    if not args.no_truncate and len(desc) < 43 else ""))
-
-                if args.no_truncate:
-                    for i in range(0, len(tag.data), 16):
-                        f.write("    %08x: %-47s  %-16s\n" % (
-                            i, ' '.join('%02x' % c for c in tag.data[i:i+16]),
-                            ''.join(c if c >= ' ' and c <= '~' else '.'
-                                for c in map(chr, tag.data[i:i+16]))))
-
-        if args.no_truncate and data is not None:
-            for i in range(0, len(data), 16):
-                f.write("  %08x: %-47s  %-16s\n" % (
-                    i, ' '.join('%02x' % c for c in data[i:i+16]),
-                    ''.join(c if c >= ' ' and c <= '~' else '.'
-                        for c in map(chr, data[i:i+16]))))
-
 def main(args):
+    superblock = None
+    gstate = b'\0\0\0\0\0\0\0\0\0\0\0\0'
+    dirs = []
+    mdirs = []
+    corrupted = []
+    cycle = False
     with open(args.disk, 'rb') as f:
-        dirs = []
-        superblock = None
-        gstate = b''
-        mdirs = []
-        cycle = False
         tail = (args.block1, args.block2)
         hard = False
         while True:
@@ -144,6 +61,10 @@ def main(args):
             except KeyError:
                 pass
 
+            # corrupted?
+            if not mdir:
+                corrupted.append(mdir)
+
             # add to directories
             mdirs.append(mdir)
             if mdir.tail is None or not mdir.tail.is_('hardtail'):
@@ -178,7 +99,7 @@ def main(args):
 
         dir[0].path = path.replace('//', '/')
 
-    # dump tree
+    # print littlefs + version info
     version = ('?', '?')
     if superblock:
         version = tuple(reversed(
@@ -187,53 +108,56 @@ def main(args):
         "data (truncated, if it fits)"
         if not any([args.no_truncate, args.tags, args.log, args.all]) else ""))
 
-    if gstate:
-        print("gstate 0x%s" % ''.join('%02x' % c for c in gstate))
-        tag = Tag(struct.unpack('<I', gstate[0:4].ljust(4, b'\xff'))[0])
-        blocks = struct.unpack('<II', gstate[4:4+8].ljust(8, b'\xff'))
-        if tag.size or not tag.isvalid:
-            print("  orphans >=%d" % max(tag.size, 1))
-        if tag.type:
-            print("  move dir {%#x, %#x} id %d" % (
-                blocks[0], blocks[1], tag.id))
-
+    # print gstate
+    print("gstate 0x%s" % ''.join('%02x' % c for c in gstate))
+    tag = Tag(struct.unpack('<I', gstate[0:4].ljust(4, b'\xff'))[0])
+    blocks = struct.unpack('<II', gstate[4:4+8].ljust(8, b'\xff'))
+    if tag.size or not tag.isvalid:
+        print("  orphans >=%d" % max(tag.size, 1))
+    if tag.type:
+        print("  move dir {%#x, %#x} id %d" % (
+            blocks[0], blocks[1], tag.id))
+
+    # print mdir info
     for i, dir in enumerate(dirs):
         print("dir %s" % (json.dumps(dir[0].path)
             if hasattr(dir[0], 'path') else '(orphan)'))
 
         for j, mdir in enumerate(dir):
-            print("mdir {%#x, %#x} rev %d%s" % (
-                mdir.blocks[0], mdir.blocks[1], mdir.rev,
-                ' (corrupted)' if not mdir else ''))
+            print("mdir {%#x, %#x} rev %d (was %d)%s%s" % (
+                mdir.blocks[0], mdir.blocks[1], mdir.rev, mdir.pair[1].rev,
+                ' (corrupted!)' if not mdir else '',
+                ' -> {%#x, %#x}' % struct.unpack('<II', mdir.tail.data)
+                if mdir.tail else ''))
 
             f = io.StringIO()
-            if args.tags:
-                mdir.dump_tags(f, truncate=not args.no_truncate)
-            elif args.log:
+            if args.log:
                 mdir.dump_log(f, truncate=not args.no_truncate)
             elif args.all:
                 mdir.dump_all(f, truncate=not args.no_truncate)
             else:
-                dumpentries(args, mdir, f)
+                mdir.dump_tags(f, truncate=not args.no_truncate)
 
             lines = list(filter(None, f.getvalue().split('\n')))
             for k, line in enumerate(lines):
                 print("%s %s" % (
-                    ' ' if i == len(dirs)-1 and j == len(dir)-1 else
+                    ' ' if j == len(dir)-1 else
                     'v' if k == len(lines)-1 else
-                    '.' if j == len(dir)-1 else
                     '|',
                     line))
 
-    if cycle:
-        print("*** cycle detected! -> {%#x, %#x} ***" % (cycle[0], cycle[1]))
+    errcode = 0
+    for mdir in corrupted:
+        errcode = errcode or 1
+        print("*** corrupted mdir {%#x, %#x}! ***" % (
+            mdir.blocks[0], mdir.blocks[1]))
 
     if cycle:
-        return 2
-    elif not all(mdir for dir in dirs for mdir in dir):
-        return 1
-    else:
-        return 0;
+        errcode = errcode or 2
+        print("*** cycle detected {%#x, %#x}! ***" % (
+            cycle[0], cycle[1]))
+
+    return errcode
 
 if __name__ == "__main__":
     import argparse
@@ -246,12 +170,10 @@ if __name__ == "__main__":
         help="Size of a block in bytes.")
     parser.add_argument('block1', nargs='?', default=0,
         type=lambda x: int(x, 0),
-        help="Optional first block address for finding the root.")
+        help="Optional first block address for finding the superblock.")
     parser.add_argument('block2', nargs='?', default=1,
         type=lambda x: int(x, 0),
-        help="Optional second block address for finding the root.")
-    parser.add_argument('-t', '--tags', action='store_true',
-        help="Show metadata tags instead of reconstructing entries.")
+        help="Optional second block address for finding the superblock.")
     parser.add_argument('-l', '--log', action='store_true',
         help="Show tags in log.")
     parser.add_argument('-a', '--all', action='store_true',
diff --git a/scripts/test.py b/scripts/test.py
index 6187028..e5869c2 100755
--- a/scripts/test.py
+++ b/scripts/test.py
@@ -231,7 +231,7 @@ class TestCase:
                 ncmd.extend(['-ex', 'r'])
                 if failure.assert_:
                     ncmd.extend(['-ex', 'up 2'])
-            elif gdb == 'start':
+            elif gdb == 'main':
                 ncmd.extend([
                     '-ex', 'b %s:%d' % (self.suite.path, self.code_lineno),
                     '-ex', 'r'])
@@ -760,7 +760,7 @@ if __name__ == "__main__":
         help="Store disk image in a file.")
     parser.add_argument('-b', '--build', action='store_true',
         help="Only build the tests, do not execute.")
-    parser.add_argument('-g', '--gdb', choices=['init', 'start', 'assert'],
+    parser.add_argument('-g', '--gdb', choices=['init', 'main', 'assert'],
         nargs='?', const='assert',
         help="Drop into gdb on test failure.")
     parser.add_argument('--no-internal', action='store_true',