fuzz: decompress_startswith() may return zero (#36490)

Also, disables fuzz-compress on oss-fuzz.
Fixes #36472.

src/fuzz/fuzz-compress.c

@@ -5,6 +5,7 @@
 #include "alloc-util.h"
 #include "compress.h"
 #include "fuzz.h"
+#include "tests.h"
 
 typedef struct header {
         uint32_t alg:2; /* We have only three compression algorithms so far, but we might add more in the
@@ -59,8 +60,6 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 
         size_t sw_len = MIN(data_len - 1, h->sw_len);
 
-        r = decompress_startswith(alg, buf, csize, &buf2, h->data, sw_len, h->data[sw_len]);
-        assert_se(r > 0);
-
+        ASSERT_OK(decompress_startswith(alg, buf, csize, &buf2, h->data, sw_len, h->data[sw_len]));
         return 0;
 }

src/fuzz/meson.build

@@ -5,7 +5,6 @@ simple_fuzzers += files(
         'fuzz-bus-label.c',
         'fuzz-calendarspec.c',
         'fuzz-catalog.c',
-        'fuzz-compress.c',
         'fuzz-env-file.c',
         'fuzz-hostname-setup.c',
         'fuzz-json.c',
@@ -14,3 +13,8 @@ simple_fuzzers += files(
         'fuzz-varlink.c',
         'fuzz-varlink-idl.c',
 )
+
+# The following fuzzers do not work on oss-fuzz. See #11018.
+if not want_ossfuzz
+        simple_fuzzers += files('fuzz-compress.c')
+endif

test/fuzz/.gitattributes

@@ -1,5 +1,6 @@
 /*/*                -whitespace
 /fuzz-bus-match/*   binary
+/fuzz-compress/*    binary
 /fuzz-dhcp*/*       binary
 /fuzz-dns-packet/*  binary
 /fuzz-fido-id-desc/ binary

test/fuzz/fuzz-compress/issue-36472

@@ -0,0 +1 @@
+ﾞ0000000000ﾞ000000000000000000000