From b0623182beff3521929a732ec767d460d90d3afb Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Sun, 11 Jul 2021 20:06:19 +0100
Subject: [PATCH] Added rollback to unmap previous haystack maps on error in
 `map_haystacks()` before returning.
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Fortune for naka's current commit: Future blessing − 末吉
---
 include/macros.h |  7 +++++++
 src/main.c       | 12 ++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/macros.h b/include/macros.h
index ce3e17f..55223af 100644
--- a/include/macros.h
+++ b/include/macros.h
@@ -89,6 +89,13 @@ _mixin void _drain_val(void* x, ...) { IGNORE(x); } // This compiles to no-op on
 
 // Function macros
 
+//  debug-only statements
+#ifdef DEBUG
+#define DBG(x) x
+#else
+#define DBG(x) ((void)0)
+#endif
+
 //  Assertions
 
 #define assert_msg(expr, ...) ( (expr) ? 1 : FATAL(__VA_ARGS__))
diff --git a/src/main.c b/src/main.c
index 0f103a6..855153b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -48,14 +48,22 @@ noreturn void usage_then_exit(int err, int argc, char** argv)
 static int map_haystacks(const char* const * h, map_t maps[pOUT])
 {
 	const char* path;
+	usize d =0;
 	while( (path = *h++) )
 	{
 		map_t *pOUT c = maps++;
 		INFO("Mapping haystack file `%s' (to map addr %p)", path, c);
 		debug_assert(c);
-		if(!map_handle_err(map_file(path, false, 0, 0, c)))
-		//TODO: Handle unmapping previous haystacks before return
+		if(!map_handle_err(map_file(path, false, 0, 0, c))) {
+			//Handle unmapping previous haystacks before return
+			// Prep reset maps to before `c` for unwind
+			maps-=1;
+			ERROR("Failed to map file `%s', rolling back %lu maps. (erp: %p, prev: %p)", path, d, c, maps);
+			for(usize i=0;i<d;i++)
+				if(!map_handle_err(map_free(* (--maps)))) WARN("Failed to free map at %p (in %lu unwind)", maps, i);
 			return 0;
+		}
+		d+=1;
 	}
 	return 1;
 }