From f8f5d9102eed6de69c05649ece6ac12e82769ed4 Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Fri, 9 Jul 2021 19:54:46 +0100
Subject: [PATCH] mmap() API facade.
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mmap() API anon test passes.

Fortune for naka's current commit: Future small blessing − 末小吉
---
 include/map.h   | 44 ++++++++++++++++++++++++++++++++++
 src/map.c       | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/tests/map.c | 19 +++++++++++++++
 3 files changed, 126 insertions(+)
 create mode 100644 include/map.h
 create mode 100644 src/map.c
 create mode 100644 src/tests/map.c

diff --git a/include/map.h b/include/map.h
new file mode 100644
index 0000000..ecbcee3
--- /dev/null
+++ b/include/map.h
@@ -0,0 +1,44 @@
+//! Memory mapping abstraction
+#ifndef _MAP_H
+#define _MAP_H
+
+#include <stdbool.h>
+#include "ints.h"
+
+typedef enum mm_err {
+	MAP_ERR_UNKNOWN = 0,
+	MAP_SUCCESS = 1,
+
+	MAP_ERR_MMAP,
+	MAP_ERR_UNMAP,
+	MAP_ERR_OPEN,
+	MAP_ERR_CLOSE,
+} map_result_t;
+
+typedef union memory_map {
+	// Common
+	struct {
+		void* origin;
+		usize len;
+	};
+	// Specific to anon / file
+	struct mm_file {	
+		void* origin;
+		usize len;
+
+		off_t fd_offset;
+		int fd;
+	} file;
+	struct mm_anon {
+		void* origin;
+		usize len;
+	} anon;
+
+} map_t;
+
+map_result_t map_fd(int fd, bool write, usize size, off_t offset, map_t *pOUT map);
+map_result_t map_file(const char* file, bool write, usize size, off_t offset, map_t *pOUT map);
+map_result_t map_anon(void* ptr, usize len, map_t *pOUT map);
+map_result_t map_free(map_t map);
+
+#endif /* _MAP_H */
diff --git a/src/map.c b/src/map.c
new file mode 100644
index 0000000..3750c4c
--- /dev/null
+++ b/src/map.c
@@ -0,0 +1,63 @@
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+
+#include <macros.h>
+#include <map.h>
+
+// Set all bytes to 0xff (ints i.e. fd will be -1)
+static inline void _map_init(map_t *pOUT map)
+{
+	memset(map, 0xff, sizeof(map_t));
+}
+
+static inline bool _map_is_file(const map_t* map)
+{
+	return map->file.fd > 0;
+}
+
+map_result_t map_fd(int fd, bool write, usize size, off_t offset, map_t *pOUT map)
+{
+	void* ptr = mmap(NULL, size, PROT_READ | (write ? PROT_WRITE : 0), MAP_SHARED, fd, offset);
+	if(ptr == MAP_FAILED) return MAP_ERR_MMAP;
+	map->file = (struct mm_file){
+		.origin = ptr,
+		.len = size,
+		.fd = fd,
+		.fd_offset = offset,
+	};
+	return MAP_SUCCESS;
+}
+
+map_result_t map_file(const char* file, bool write, usize size, off_t offset, map_t *pOUT map)
+{
+	int fd = open(file, write ? O_RDWR : O_RDONLY);
+	if(fd < 0) return MAP_ERR_OPEN;
+	return map_fd(fd, write, size, offset, map);
+}
+
+map_result_t map_anon(void* ptr, usize len, map_t *pOUT 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;
+
+	// Make sure .file.fd is -1, so we can tell this is anon in `map_free()`.
+	_map_init(map);
+	map->anon = (struct mm_anon) {
+		.origin = ptr,
+		.len = len,
+	};
+	return MAP_SUCCESS;
+}
+
+map_result_t map_free(map_t map)
+{
+	if( munmap(map.anon.origin, map.anon.len) != 0) return MAP_ERR_UNMAP;
+	if( _map_is_file(&map) ) {
+		if( close(map.file.fd) != 0 ) return MAP_ERR_CLOSE;
+	}
+	return MAP_SUCCESS;
+}
diff --git a/src/tests/map.c b/src/tests/map.c
new file mode 100644
index 0000000..f0038b7
--- /dev/null
+++ b/src/tests/map.c
@@ -0,0 +1,19 @@
+
+#include <string.h>
+
+#include <tests.h>
+#include <map.h>
+
+DEFTEST(map_anon)
+{
+	map_t map;
+	TEST_ASSERT(map_anon(NULL, 1024, &map) == MAP_SUCCESS);
+
+	memset(map.origin, 0xab, map.len);
+	TEST_ASSERT( ((u8*)map.origin)[10] == 0xab );
+
+	TEST_ASSERT(map_free(map) == MAP_SUCCESS);
+
+	return TEST_OK;
+}
+RUNTEST_DEBUG(map_anon)