Merge patch series "Annotate switch/case fallthrough cases"

Andre Przywara <andre.przywara@arm.com> says:

C's implicit fallthrough behaviour in switch/case statements can lead to
subtle bugs. Quite some while ago many compilers introduced warnings in
those cases, requiring intentional fallthrough's to be annotated.

So far we were not enabling that compiler option, so many ambiguities
and some bugs in the code went unnoticed.

This series adds the required annotations in code paths that the first
stage of the U-Boot CI covers. There is a large number of cases left
in the libbz2 code. The usage of switch/case is borderline insane there,
labels are hidden in macros, and there are no breaks, but just goto's.
Upstream still uses very similar code, without any annotations. I still
am not 100% sure those are meant to fall through or not, and plan to do
further investigations, but didn't want to hold the rest of the patches
back. You can see for yourself by applying patch 18/18 and building for
sandbox64, for instance.

Because of this we cannot quite enable the warning in the Makefile yet,
but those fixes are worth regardless, and be it to increase readability.

Please note that those patches do not fix anything, really, they just add
those fallthrough annotations, so the series is not really critical.

Link: https://lore.kernel.org/r/20250327153313.2105227-1-andre.przywara@arm.com

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/zlib/inflate.c b/lib/zlib/inflate.c
index b4c72cc2c5c..2b7a464f74f 100644
--- a/lib/zlib/inflate.c
+++ b/lib/zlib/inflate.c
@@ -420,6 +420,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             if (state->flags & 0x0200) CRC2(state->check, hold);
             INITBITS();
             state->mode = TIME;
+            fallthrough;
         case TIME:
             NEEDBITS(32);
             if (state->head != Z_NULL)
@@ -427,6 +428,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             if (state->flags & 0x0200) CRC4(state->check, hold);
             INITBITS();
             state->mode = OS;
+            fallthrough;
         case OS:
             NEEDBITS(16);
             if (state->head != Z_NULL) {
@@ -436,6 +438,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             if (state->flags & 0x0200) CRC2(state->check, hold);
             INITBITS();
             state->mode = EXLEN;
+            fallthrough;
         case EXLEN:
             if (state->flags & 0x0400) {
                 NEEDBITS(16);
@@ -448,6 +451,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             else if (state->head != Z_NULL)
                 state->head->extra = Z_NULL;
             state->mode = EXTRA;
+            fallthrough;
         case EXTRA:
             if (state->flags & 0x0400) {
                 copy = state->length;
@@ -471,6 +475,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             state->length = 0;
             state->mode = NAME;
+            fallthrough;
         case NAME:
             if (state->flags & 0x0800) {
                 if (have == 0) goto inf_leave;
@@ -492,6 +497,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
                 state->head->name = Z_NULL;
             state->length = 0;
             state->mode = COMMENT;
+            fallthrough;
         case COMMENT:
             if (state->flags & 0x1000) {
                 if (have == 0) goto inf_leave;
@@ -512,6 +518,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             else if (state->head != Z_NULL)
                 state->head->comment = Z_NULL;
             state->mode = HCRC;
+            fallthrough;
         case HCRC:
             if (state->flags & 0x0200) {
                 NEEDBITS(16);
@@ -535,6 +542,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             strm->adler = state->check = REVERSE(hold);
             INITBITS();
             state->mode = DICT;
+            fallthrough;
         case DICT:
             if (state->havedict == 0) {
                 RESTORE();
@@ -542,9 +550,11 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             strm->adler = state->check = adler32(0L, Z_NULL, 0);
             state->mode = TYPE;
+            fallthrough;
         case TYPE:
 	    schedule();
             if (flush == Z_BLOCK) goto inf_leave;
+            fallthrough;
         case TYPEDO:
             if (state->last) {
                 BYTEBITS();
@@ -590,6 +600,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
                     state->length));
             INITBITS();
             state->mode = COPY;
+            fallthrough;
         case COPY:
             copy = state->length;
             if (copy) {
@@ -625,6 +636,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             Tracev((stderr, "inflate:       table sizes ok\n"));
             state->have = 0;
             state->mode = LENLENS;
+            fallthrough;
         case LENLENS:
             while (state->have < state->ncode) {
                 NEEDBITS(3);
@@ -646,6 +658,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             Tracev((stderr, "inflate:       code lengths ok\n"));
             state->have = 0;
             state->mode = CODELENS;
+            fallthrough;
         case CODELENS:
             while (state->have < state->nlen + state->ndist) {
                 for (;;) {
@@ -720,6 +733,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             Tracev((stderr, "inflate:       codes ok\n"));
             state->mode = LEN;
+            fallthrough;
         case LEN:
 	    schedule();
             if (have >= 6 && left >= 258) {
@@ -764,6 +778,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             state->extra = (unsigned)(this.op) & 15;
             state->mode = LENEXT;
+            fallthrough;
         case LENEXT:
             if (state->extra) {
                 NEEDBITS(state->extra);
@@ -772,6 +787,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             Tracevv((stderr, "inflate:         length %u\n", state->length));
             state->mode = DIST;
+            fallthrough;
         case DIST:
             for (;;) {
                 this = state->distcode[BITS(state->distbits)];
@@ -797,6 +813,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             state->offset = (unsigned)this.val;
             state->extra = (unsigned)(this.op) & 15;
             state->mode = DISTEXT;
+            fallthrough;
         case DISTEXT:
             if (state->extra) {
                 NEEDBITS(state->extra);
@@ -817,6 +834,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
             Tracevv((stderr, "inflate:         distance %u\n", state->offset));
             state->mode = MATCH;
+            fallthrough;
         case MATCH:
             if (left == 0) goto inf_leave;
             copy = out - left;
@@ -872,6 +890,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
 #ifdef GUNZIP
             state->mode = LENGTH;
+            fallthrough;
         case LENGTH:
             if (state->wrap && state->flags) {
                 NEEDBITS(32);
@@ -885,6 +904,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
             }
 #endif
             state->mode = DONE;
+            fallthrough;
         case DONE:
             ret = Z_STREAM_END;
             goto inf_leave;
@@ -894,6 +914,7 @@ __rcode int ZEXPORT inflate(z_streamp strm, int flush)
         case MEM:
             return Z_MEM_ERROR;
         case SYNC:
+            fallthrough;
         default:
             return Z_STREAM_ERROR;
         }