Fix fd_hist check occurring too early on decompress.

fsync after flushing buffer.
Remove unnecessary memset after anonymous mmap.
Do test malloc before compression backend to see how big a chunk can be passed.

main.c

@@ -291,12 +291,13 @@ static void decompress_file(void)
 
 		if (!NO_SET_PERMS)
 			preserve_perms(fd_in, fd_out);
-		if (fd_hist == -1)
-			fatal("Failed to open history file %s\n", control.outfile);
 	} else
 		fd_out = open_tmpoutfile();
 
 	fd_hist = open(control.outfile, O_RDONLY);
+	if (fd_hist == -1)
+		fatal("Failed to open history file %s\n", control.outfile);
+
 	read_magic(fd_in, &expected_size);
 	print_progress("Decompressing...");
 

rzip.c

@@ -583,8 +583,6 @@ static void rzip_chunk(struct rzip_state *st, int fd_in, int fd_out, i64 offset,
 			continue;
 		}
 		print_maxverbose("Preallocated %lld ram...\n", prealloc_size);
-		if (!memset(buf, 0, prealloc_size))
-			fatal("Failed to memset in rzip_chunk\n");
 		if (!STDIN) {
 			/* STDIN will use this already allocated ram */
 			if (munmap(buf, prealloc_size) != 0)

stream.c

@@ -600,6 +600,7 @@ void *open_stream_out(int f, int n, i64 limit)
 {
 	unsigned cwindow = control.window;
 	struct stream_info *sinfo;
+	uchar *testmalloc;
 	int i;
 
 	sinfo = malloc(sizeof(*sinfo));
@@ -642,6 +643,18 @@ void *open_stream_out(int f, int n, i64 limit)
 		return NULL;
 	}
 
+	/* Find the largest we can make the window based on ability to malloc
+	 * ram. We need enough for the 2 streams and for the compression
+	 * backend at most, being conservative. */
+retest_malloc:
+	testmalloc = malloc(sinfo->bufsize * (n + 1));
+	if (!testmalloc) {
+		sinfo->bufsize = sinfo->bufsize / 10 * 9;
+		goto retest_malloc;
+	}
+	free(testmalloc);
+	print_maxverbose("Succeeded to malloc for compression bufsize of %lld\n", sinfo->bufsize);
+
 	for (i = 0; i < n; i++) {
 		sinfo->s[i].buf = malloc(sinfo->bufsize);
 		if (!sinfo->s[i].buf)
@@ -783,6 +796,7 @@ static int flush_buffer(struct stream_info *sinfo, int stream)
 
 	if (write_buf(sinfo->fd, sinfo->s[stream].buf, c_len) != 0)
 		return -1;
+	fsync(sinfo->fd);
 	sinfo->cur_pos += c_len;
 
 	sinfo->s[stream].buflen = 0;