- Use datasize-max instead of all available physical memory for
 determining the decompression window.

- Fix for CVE-2018-5786

Index: lrzip.c
--- lrzip.c.orig
+++ lrzip.c
@@ -90,6 +90,32 @@ i64 get_ram(rzip_control *control)
 
 	return ramsize;
 }
+#elif defined(__OpenBSD__)
+# include <sys/resource.h>
+i64 get_ram(rzip_control *control)
+{
+	struct rlimit rl;
+	i64 ramsize = (i64)sysconf(_SC_PHYS_PAGES) * PAGE_SIZE;
+
+	/* Raise limits all the way to the max */
+
+	if (getrlimit(RLIMIT_DATA, &rl) == -1)
+		fatal_return(("Failed to get limits in get_ram\n"), -1);
+
+	rl.rlim_cur = rl.rlim_max;
+	if (setrlimit(RLIMIT_DATA, &rl) == -1)
+		fatal_return(("Failed to set limits in get_ram\n"), -1);
+
+	/* Declare detected RAM to be either the max RAM available from
+	physical memory or the max RAM allowed by RLIMIT_DATA, whatever
+	is smaller, to prevent the heuristics from selecting
+	compression windows which cause lrzip to go into deep swap */
+
+	if (rl.rlim_max < ramsize)
+		return rl.rlim_max;
+
+	return ramsize;
+}
 #else /* __APPLE__ */
 i64 get_ram(rzip_control *control)
 {
@@ -1093,7 +1119,7 @@ next_chunk:
 		do {
 			i64 head_off;
 
-			if (unlikely(last_head && last_head < second_last))
+			if (unlikely(last_head && last_head <= second_last))
 				failure_goto(("Invalid earlier last_head position, corrupt archive.\n"), error);
 			second_last = last_head;
 			if (unlikely(last_head + ofs > infile_size))