From b63237555b88502e45ff151f5f726ca3650dfdab Mon Sep 17 00:00:00 2001
From: Christopher Haster <geky@geky.net>
Date: Mon, 1 Dec 2025 15:21:37 -0600
Subject: [PATCH] rattrs: Brought back LFS3_FROM_LLEB128

This was originally dropped because it's not strictly necessary,
little-leb128s (28-bits) can always be encoded with the default leb128
encoder (31-bits). But it is useful if only for the assert.

Note this matches lfs3_data_readlleb128, which was never dropped, and is
useful for decreasing decoder DSIZEs.

Maybe it makes sense to drop both of these in the future, especially if
we start running into from-field pressure. But for now, this assert is
useful for ensuring disk compatibility with little 4-byte leb128s.

---

Surprisingly no code cost, at least by default (code alignment?). Though
it did add 4 bytes to the gbmap build (so yes, probably code alignment):

                 code          stack          ctx
  before:       35316           2176          660
  after:        35316 (+0.0%)   2176 (+0.0%)  660 (+0.0%)

                 code          stack          ctx
  gbmap before: 38168           2192          772
  gbmap after:  38172 (+0.0%)   2192 (+0.0%)  772 (+0.0%)
---
 lfs3.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/lfs3.c b/lfs3.c
index 63111ee8..d54eaa5f 100644
--- a/lfs3.c
+++ b/lfs3.c
@@ -1894,16 +1894,17 @@ enum lfs3_from {
 
     LFS3_FROM_LE32      = 4,
     LFS3_FROM_LEB128    = 5,
-    LFS3_FROM_NAME      = 6,
+    LFS3_FROM_LLEB128   = 6,
+    LFS3_FROM_NAME      = 7,
 
-    LFS3_FROM_ECKSUM    = 7,
-    LFS3_FROM_BRANCH    = 8,
+    LFS3_FROM_ECKSUM    = 8,
+    LFS3_FROM_BRANCH    = 9,
 
-    LFS3_FROM_BPTR      = 9,
-    LFS3_FROM_BTREE     = 10,
-    LFS3_FROM_SHRUB     = 11,
-    LFS3_FROM_MPTR      = 12,
-    LFS3_FROM_GEOMETRY  = 13,
+    LFS3_FROM_BPTR      = 10,
+    LFS3_FROM_BTREE     = 11,
+    LFS3_FROM_SHRUB     = 12,
+    LFS3_FROM_MPTR      = 13,
+    LFS3_FROM_GEOMETRY  = 14,
 };
 
 typedef uint8_t lfs3_from_t;
@@ -3295,6 +3296,10 @@ static int lfs3_rbyd_appendrattr_(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
                 lfs3_data_t data;
                 uint8_t buf[LFS3_LEB128_DSIZE];
             } leb128;
+            struct {
+                lfs3_data_t data;
+                uint8_t buf[LFS3_LLEB128_DSIZE];
+            } lleb128;
             struct {
                 lfs3_data_t datas[2];
                 uint8_t buf[LFS3_LEB128_DSIZE];
@@ -3373,10 +3378,13 @@ static int lfs3_rbyd_appendrattr_(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
         datas = &ctx.u.le32.data;
         data_count = 1;
 
-    // leb128?
-    } else if (from == LFS3_FROM_LEB128) {
+    // leb128? little-leb128?
+    } else if (from == LFS3_FROM_LEB128
+            || from == LFS3_FROM_LLEB128) {
         // leb128s should not exceed 31-bits
         LFS3_ASSERT(args[0] <= 0x7fffffff);
+        // little-leb128s should not exceed 28-bits
+        LFS3_ASSERT(from != LFS3_FROM_LLEB128 || args[0] <= 0x0fffffff);
         ctx.u.leb128.data = lfs3_data_fromleb128(args[0],
                 ctx.u.leb128.buf);
         datas = &ctx.u.leb128.data;
@@ -15897,7 +15905,7 @@ static int lfs3_formatinited(lfs3_t *lfs3) {
         *r++ = LFS3_RATTR_ARG(lfs3_wcompat(lfs3));
         *r++ = LFS3_RATTR(2, LFS3_TAG_GEOMETRY, 0, LFS3_FROM_GEOMETRY);
         *r++ = LFS3_RATTR_ARG(&geometry);
-        *r++ = LFS3_RATTR(2, LFS3_TAG_NAMELIMIT, 0, LFS3_FROM_LEB128);
+        *r++ = LFS3_RATTR(2, LFS3_TAG_NAMELIMIT, 0, LFS3_FROM_LLEB128);
         *r++ = LFS3_RATTR_ARG(lfs3->name_limit);
         *r++ = LFS3_RATTR(2, LFS3_TAG_FILELIMIT, 0, LFS3_FROM_LEB128);
         *r++ = LFS3_RATTR_ARG(lfs3->file_limit);