PGPRO-5646: remove compiler warning (gcc 11.2.0)

In function ‘ptrack_write_chunk’, inlined from ‘ptrackCheckpoint’ at engine.c:397:2: engine.c:78:13: warning: ‘write’ reading 8 bytes from a region of size 4 [-Wstringop-overread] 78 | if (write(fd, chunk, size) != size) | ^~~~~~~~~~~~~~~~~~~~~~ In file included from engine.c:47: engine.c: In function ‘ptrackCheckpoint’: engine.h:55:25: note: source object ‘magic’ of size 4 55 | char magic[PTRACK_MAGIC_SIZE]; | ^~~~~ In file included from engine.c:22: /usr/include/unistd.h:378:16: note: in a call to function ‘write’ declared with attribute ‘access (read_only, 2, 3)’ 378 | extern ssize_t write (int __fd, const void *__buf, size_t __n) __wur | ^~~~~ In C a pointer to the first field of a structure and a pointer to the structure itself are always equal.

Author: Marina Polyakova

engine.c

@@ -394,7 +394,7 @@ ptrackCheckpoint(void)
 *
 * Write both magic and varsion_num at once.
 */
-ptrack_write_chunk(ptrack_tmp_fd, &crc, (char *) &ptrack_map->magic,
+ptrack_write_chunk(ptrack_tmp_fd, &crc, (char *) ptrack_map,
 offsetof(PtrackMapHdr, init_lsn));
 
 init_lsn = pg_atomic_read_u64(&ptrack_map->init_lsn);