compression: add separate pre-processor definitions

Follow-up for cd3c6322db

journal-def.h should be self-contained too, as it represents the journal object ABI.
Duplicate the enums, as they also need to be in config.h for it to be self-contained,
and enums are not available to the preprocessor. Use an assert to ensure they don't
diverge.

meson.build

@@ -1470,11 +1470,14 @@ elif compression == 'lz4' and not have_lz4
 elif compression == 'xz' and not have_xz
         error('default-compression=xz requires xz')
 endif
-conf.set('OBJECT_COMPRESSED_NONE', 0)
+# These values are defined here so that config.h is self-contained, but they are also
-conf.set('OBJECT_COMPRESSED_XZ', 1)
+# re-defined (with different names to avoid conflits) in src/libsystemd/sd-journal/journal-def.h
-conf.set('OBJECT_COMPRESSED_LZ4', 2)
+# as that source file represents the journal object ABI, and we want that to be self-contained too.
-conf.set('OBJECT_COMPRESSED_ZSTD', 4)
+conf.set('COMPRESSION_NONE', 0)
-conf.set('DEFAULT_COMPRESSION', 'OBJECT_COMPRESSED_@0@'.format(compression.to_upper()))
+conf.set('COMPRESSION_XZ', 1)
+conf.set('COMPRESSION_LZ4', 2)
+conf.set('COMPRESSION_ZSTD', 4)
+conf.set('DEFAULT_COMPRESSION', 'COMPRESSION_@0@'.format(compression.to_upper()))
 
 want_xkbcommon = get_option('xkbcommon')
 if want_xkbcommon != 'false' and not skip_deps

src/libsystemd/sd-journal/compress.h

@@ -18,18 +18,18 @@ int compress_blob_zstd(const void *src, uint64_t src_size,
 static inline int compress_blob(const void *src, uint64_t src_size,
                                 void *dst, size_t dst_alloc_size, size_t *dst_size) {
         int r;
-#if DEFAULT_COMPRESSION == OBJECT_COMPRESSED_ZSTD
+#if DEFAULT_COMPRESSION == COMPRESSION_ZSTD
         r = compress_blob_zstd(src, src_size, dst, dst_alloc_size, dst_size);
         if (r == 0)
-                return OBJECT_COMPRESSED_ZSTD;
+                return COMPRESSION_ZSTD;
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_LZ4
+#elif DEFAULT_COMPRESSION == COMPRESSION_LZ4
         r = compress_blob_lz4(src, src_size, dst, dst_alloc_size, dst_size);
         if (r == 0)
-                return OBJECT_COMPRESSED_LZ4;
+                return COMPRESSION_LZ4;
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_XZ
+#elif DEFAULT_COMPRESSION == COMPRESSION_XZ
         r = compress_blob_xz(src, src_size, dst, dst_alloc_size, dst_size);
         if (r == 0)
-                return OBJECT_COMPRESSED_XZ;
+                return COMPRESSION_XZ;
 #else
         r = -EOPNOTSUPP;
 #endif
@@ -72,13 +72,13 @@ int decompress_stream_xz(int fdf, int fdt, uint64_t max_size);
 int decompress_stream_lz4(int fdf, int fdt, uint64_t max_size);
 int decompress_stream_zstd(int fdf, int fdt, uint64_t max_size);
 
-#if DEFAULT_COMPRESSION == OBJECT_COMPRESSED_ZSTD
+#if DEFAULT_COMPRESSION == COMPRESSION_ZSTD
 #  define compress_stream compress_stream_zstd
 #  define COMPRESSED_EXT ".zst"
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_LZ4
+#elif DEFAULT_COMPRESSION == COMPRESSION_LZ4
 #  define compress_stream compress_stream_lz4
 #  define COMPRESSED_EXT ".lz4"
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_XZ
+#elif DEFAULT_COMPRESSION == COMPRESSION_XZ
 #  define compress_stream compress_stream_xz
 #  define COMPRESSED_EXT ".xz"
 #else

src/libsystemd/sd-journal/journal-def.h

@@ -43,12 +43,21 @@ typedef enum ObjectType {
 } ObjectType;
 
 /* Object flags
- * The per-compression enums are defined in meson.build so that config.h is self-contained */
+ * The per-compression enums are also redefined in meson.build so that config.h is self-contained */
 enum {
+        OBJECT_COMPRESSED_XZ   = 1 << 0,
+        OBJECT_COMPRESSED_LZ4  = 1 << 1,
+        OBJECT_COMPRESSED_ZSTD = 1 << 2,
         OBJECT_COMPRESSION_MASK = (OBJECT_COMPRESSED_XZ | OBJECT_COMPRESSED_LZ4 | OBJECT_COMPRESSED_ZSTD),
         _OBJECT_COMPRESSED_MAX = OBJECT_COMPRESSION_MASK,
 };
 
+#ifdef COMPRESSION_XZ
+assert_cc(OBJECT_COMPRESSED_XZ == COMPRESSION_XZ);
+assert_cc(OBJECT_COMPRESSED_LZ4 == COMPRESSION_LZ4);
+assert_cc(OBJECT_COMPRESSED_ZSTD == COMPRESSION_ZSTD);
+#endif
+
 struct ObjectHeader {
         uint8_t type;
         uint8_t flags;

src/libsystemd/sd-journal/journal-file.c

@@ -3359,11 +3359,11 @@ int journal_file_open(
                 .open_flags = open_flags,
                 .writable = (open_flags & O_ACCMODE) != O_RDONLY,
 
-#if DEFAULT_COMPRESSION == OBJECT_COMPRESSED_ZSTD
+#if DEFAULT_COMPRESSION == COMPRESSION_ZSTD
                 .compress_zstd = FLAGS_SET(file_flags, JOURNAL_COMPRESS),
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_LZ4
+#elif DEFAULT_COMPRESSION == COMPRESSION_LZ4
                 .compress_lz4 = FLAGS_SET(file_flags, JOURNAL_COMPRESS),
-#elif DEFAULT_COMPRESSION == OBJECT_COMPRESSED_XZ
+#elif DEFAULT_COMPRESSION == COMPRESSION_XZ
                 .compress_xz = FLAGS_SET(file_flags, JOURNAL_COMPRESS),
 #endif
                 .compress_threshold_bytes = compress_threshold_bytes == UINT64_MAX ?