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Dropped switch-case from lfs3_rbyd_appendrattr_

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Now that lfs3_mtree_traverse_ uses a sort of state matrix,
lfs3_rbyd_appendrattr_ is the only function still relying on a big
switch-case statement. Replacing it with a series of if-else statements
leaves the codebase switch-case free (ignoring test/bench runners, etc).

Switch-case statements are extremely error prone in C, with the shared
scope, implicit fallthrough, etc. And, with today's compilers, the
result still ends up the same, so switch-case statements offer no
benefit except maybe a more enjoyable syntax for masochists.

Avoiding switch-case statements in code where we care about correctness
is probably a good idea.

No code changes
This commit is contained in:
Christopher Haster
2025-11-08 22:13:49 -06:00
parent e9f2944573
commit 8bb43ac4b2
1 changed files with 12 additions and 24 deletions
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36
lfs3.c
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@ -3551,30 +3551,26 @@ static int lfs3_rbyd_appendrattr_(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
} u;
} ctx;
switch (rattr.from) {
// direct buffer?
case LFS3_FROM_BUF:;
if (rattr.from == LFS3_FROM_BUF) {
ctx.u.data = LFS3_DATA_BUF(rattr.u.buffer, rattr.count);
datas = &ctx.u.data;
data_count = 1;
break;
// indirect concatenated data?
case LFS3_FROM_DATA:;
} else if (rattr.from == LFS3_FROM_DATA) {
datas = rattr.u.datas;
data_count = rattr.count;
break;
// le32?
case LFS3_FROM_LE32:;
} else if (rattr.from == LFS3_FROM_LE32) {
ctx.u.le32.data = lfs3_data_fromle32(rattr.u.le32,
ctx.u.le32.buf);
datas = &ctx.u.le32.data;
data_count = 1;
break;
// leb128?
case LFS3_FROM_LEB128:;
} else if (rattr.from == LFS3_FROM_LEB128) {
// leb128s should not exceed 31-bits
LFS3_ASSERT(rattr.u.leb128 <= 0x7fffffff);
// little-leb128s should not exceed 28-bits
@ -3584,43 +3580,38 @@ static int lfs3_rbyd_appendrattr_(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
ctx.u.leb128.buf);
datas = &ctx.u.leb128.data;
data_count = 1;
break;
// name?
case LFS3_FROM_NAME:;
} else if (rattr.from == LFS3_FROM_NAME) {
const lfs3_name_t *name = rattr.u.etc;
ctx.u.name.datas[0] = lfs3_data_fromleb128(name->did, ctx.u.name.buf);
ctx.u.name.datas[1] = LFS3_DATA_BUF(name->name, name->name_len);
datas = ctx.u.name.datas;
data_count = 2;
break;
// bptr?
case LFS3_FROM_BPTR:;
} else if (rattr.from == LFS3_FROM_BPTR) {
ctx.u.bptr.data = lfs3_data_frombptr(rattr.u.etc,
ctx.u.bptr.buf);
datas = &ctx.u.bptr.data;
data_count = 1;
break;
// ecksum?
case LFS3_FROM_ECKSUM:;
} else if (rattr.from == LFS3_FROM_ECKSUM) {
ctx.u.ecksum.data = lfs3_data_fromecksum(rattr.u.etc,
ctx.u.ecksum.buf);
datas = &ctx.u.ecksum.data;
data_count = 1;
break;
// btree?
case LFS3_FROM_BTREE:;
} else if (rattr.from == LFS3_FROM_BTREE) {
ctx.u.btree.data = lfs3_data_frombtree(rattr.u.etc,
ctx.u.btree.buf);
datas = &ctx.u.btree.data;
data_count = 1;
break;
// shrub trunk?
case LFS3_FROM_SHRUB:;
} else if (rattr.from == LFS3_FROM_SHRUB) {
// note unlike the other lazy tags, we _need_ to lazily encode
// shrub trunks, since they change underneath us during mdir
// compactions, relocations, etc
@ -3628,25 +3619,22 @@ static int lfs3_rbyd_appendrattr_(lfs3_t *lfs3, lfs3_rbyd_t *rbyd,
ctx.u.shrub.buf);
datas = &ctx.u.shrub.data;
data_count = 1;
break;
// mptr?
case LFS3_FROM_MPTR:;
} else if (rattr.from == LFS3_FROM_MPTR) {
ctx.u.mptr.data = lfs3_data_frommptr(rattr.u.etc,
ctx.u.mptr.buf);
datas = &ctx.u.mptr.data;
data_count = 1;
break;
// geometry?
case LFS3_FROM_GEOMETRY:;
} else if (rattr.from == LFS3_FROM_GEOMETRY) {
ctx.u.geometry.data = lfs3_data_fromgeometry(rattr.u.etc,
ctx.u.geometry.buf);
datas = &ctx.u.geometry.data;
data_count = 1;
break;
default:;
} else {
LFS3_UNREACHABLE();
}