diff --git a/include/map.h b/include/map.h
index ecbcee3..a795fa9 100644
--- a/include/map.h
+++ b/include/map.h
@@ -13,6 +13,7 @@ typedef enum mm_err {
 	MAP_ERR_UNMAP,
 	MAP_ERR_OPEN,
 	MAP_ERR_CLOSE,
+	MAP_ERR_STAT,
 } map_result_t;
 
 typedef union memory_map {
@@ -41,4 +42,27 @@ map_result_t map_file(const char* file, bool write, usize size, off_t offset, ma
 map_result_t map_anon(void* ptr, usize len, map_t *pOUT map);
 map_result_t map_free(map_t map);
 
+const char* map_error_str(map_result_t res);
+
+_mixin int _map_handle_err(const char* stmt, const char* file, int line, const char* func, map_result_t res)
+{
+	if(res == MAP_SUCCESS) return 1;
+	else {
+		const char* err = map_error_str(res);
+		ERROR("mapping failed at %s:%d->%s(): on stmt `%s`", file, line, func, stmt);
+		switch(res) {
+			// Non-errno errors
+			case MAP_ERR_UNKNOWN:
+			case MAP_SUCCESS:
+				fprintf(stderr, err);
+				if(0)
+			// errno errors
+			default:
+				perror(err);
+				return 0;
+		}
+	}
+}
+#define map_handle_err(stmt) _map_handle_err(#stmt, __FILE__, __LINE__, __func__, stmt)
+
 #endif /* _MAP_H */
diff --git a/src/main.c b/src/main.c
index 1df6c2f..40d4d8f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -12,6 +12,8 @@
 
 #include <tests.h>
 
+#include <map.h>
+
 void prog_info(FILE* out)
 {
 	fprintf(out, PROG_NAME " v%s - " PROG_DESCRIPTION
@@ -43,9 +45,15 @@ noreturn void usage_then_exit(int err, int argc, char** argv)
 
 int main(int argc, char** argv)
 {
-	TRACE("main start");
-	
-	usage_then_exit(0, argc, argv);
+	TRACE("main start with %d (pn: %s, a1: %s)", argc, argv[0], argv[1] ?: "<null>");
+
+	if(!argv[1] || !argv[2]) usage_then_exit(1, argc, argv);
+
+	map_t needle;
+	INFO("Mapping needle file `%s'", argv[1]);
+	if(!map_handle_err(map_file(argv[1], false, 0, 0, &needle))) return 2;
+
+	if(!map_handle_err(map_free(needle))) return 3;
 
 	TRACE("main end");
 
diff --git a/src/map.c b/src/map.c
index 3750c4c..74c9122 100644
--- a/src/map.c
+++ b/src/map.c
@@ -4,6 +4,7 @@
 #include <string.h>
 #include <fcntl.h>
 #include <sys/mman.h>
+#include <sys/stat.h>
 
 #include <macros.h>
 #include <map.h>
@@ -12,17 +13,21 @@
 static inline void _map_init(map_t *pOUT map)
 {
 	memset(map, 0xff, sizeof(map_t));
+	TRACE("blanked %p->%lu to 0xff", map, sizeof(map_t));
 }
 
 static inline bool _map_is_file(const map_t* map)
 {
+	TRACE("fd element of union is %x (%d)", map->file.fd, map->file.fd);
 	return map->file.fd > 0;
 }
 
 map_result_t map_fd(int fd, bool write, usize size, off_t offset, map_t *pOUT map)
 {
+	TRACE("mapping %lu bytes of fd %d (%s) from offset %lu to %p", size, fd, write ? "rw" : "ro", offset, map);
 	void* ptr = mmap(NULL, size, PROT_READ | (write ? PROT_WRITE : 0), MAP_SHARED, fd, offset);
 	if(ptr == MAP_FAILED) return MAP_ERR_MMAP;
+	TRACE("mapped %p->%lu", ptr, size);
 	map->file = (struct mm_file){
 		.origin = ptr,
 		.len = size,
@@ -34,16 +39,31 @@ map_result_t map_fd(int fd, bool write, usize size, off_t offset, map_t *pOUT ma
 
 map_result_t map_file(const char* file, bool write, usize size, off_t offset, map_t *pOUT map)
 {
+	TRACE("mapping %lu bytes of file `%s' (%s) from %lu to %p", size, file, write ? "rw" : "ro", offset, map);
+
 	int fd = open(file, write ? O_RDWR : O_RDONLY);
 	if(fd < 0) return MAP_ERR_OPEN;
+	TRACE("opened file %d", fd);
+
+	if(!size) {
+		TRACE("user asked for max-size map (size: 0), stating %d to find size...", fd);
+		struct stat st;
+		// Find size of file
+		if(fstat(fd, &st) != 0) return (close(fd), MAP_ERR_STAT);
+		TRACE("fstat() reports size is %lu", st.st_size);
+		size = st.st_size;
+	}
+	TRACE("passing fd %d, size %lu to `map_fd()`", fd, size);
 	return map_fd(fd, write, size, offset, map);
 }
 
 map_result_t map_anon(void* ptr, usize len, map_t *pOUT map)
 {
+	TRACE("mapping anon at %p (%s) of size %lu (map %p)", ptr, ptr ? "fixed" : "dynamic", len, map);
 	ptr = mmap(ptr, len, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | (ptr ? MAP_FIXED : 0), -1, 0);
 	if(ptr==MAP_FAILED) return MAP_ERR_MMAP;
 
+	TRACE("mapped ptr %p->%lu", ptr, len);
 	// Make sure .file.fd is -1, so we can tell this is anon in `map_free()`.
 	_map_init(map);
 	map->anon = (struct mm_anon) {
@@ -55,9 +75,30 @@ map_result_t map_anon(void* ptr, usize len, map_t *pOUT map)
 
 map_result_t map_free(map_t map)
 {
+	TRACE("unmapping %p->%lu", map.origin, map.len);
 	if( munmap(map.anon.origin, map.anon.len) != 0) return MAP_ERR_UNMAP;
 	if( _map_is_file(&map) ) {
+		TRACE("map is file, closing fd %d", map.file.fd);
 		if( close(map.file.fd) != 0 ) return MAP_ERR_CLOSE;
 	}
 	return MAP_SUCCESS;
 }
+
+const char* map_error_str(map_result_t res)
+{
+	switch(res)
+	{
+#define CASE(err, str) case err: return str
+		CASE(MAP_ERR_MMAP, "mmap() failed (creating a map)");
+		CASE(MAP_ERR_UNMAP, "munmap() failed (freeing a map)");
+		CASE(MAP_ERR_OPEN, "open() failed (mapping a filepath)");
+		CASE(MAP_ERR_CLOSE, "close() failed (freeing a file-map)");
+		CASE(MAP_ERR_STAT, "fstat() failed: (mapping a full filepath)");
+
+		CASE(MAP_SUCCESS, "success");
+#undef CASE
+		default: 
+			ERROR("unkown or invalid error code %d", (int)res);
+			return "unknown error";
+	}
+}