From 12577f3445df86023ba0cbe2462d55ea5dcafe20 Mon Sep 17 00:00:00 2001
From: Alejandro Sior <aho@sior.be>
Date: Fri, 17 Jun 2022 14:43:27 +0200
Subject: gptman: now can allocate partitions

---
 sector/README    |  7 +++++++
 sector/sector.ha | 45 +++++++++++++++++++++++++--------------------
 2 files changed, 32 insertions(+), 20 deletions(-)
 create mode 100644 sector/README

(limited to 'sector')

diff --git a/sector/README b/sector/README
new file mode 100644
index 0000000..c47a6f1
--- /dev/null
+++ b/sector/README
@@ -0,0 +1,7 @@
+The sector module provides a facility to read regions of
+sectors from a file and readily be able to keep them in sync
+with their original location.
+
+Normally, one would use mmap for this, however for ease of
+porting to other projects and due to the mmap offset alignment
+limitation, we proceed like this for now.
\ No newline at end of file
diff --git a/sector/sector.ha b/sector/sector.ha
index 50f417b..ae1133b 100644
--- a/sector/sector.ha
+++ b/sector/sector.ha
@@ -1,48 +1,53 @@
+use errors;
 use io;
 use types;
 
-use fmt;
-
-export const length: u64 = 512;
+export const sector_length: u64 = 512;
 
 export fn lba(no: u64) size = {
-	return no * length;
+	return no * sector_length;
 };
 
+// Type that represents a region of a file mapped to memory
+// which can be fetched or committed to.
 export type sector = struct {
 	buf: []u8,
 	fd: io::file,
-	lba_begin: u64,
-	lba_end: u64,
+	offs: u64,
+	length: u64,
 };
 
-export fn map(fd: io::file, lba_begin: u64, lba_end: u64) sector = {
+// Creates a sector based on a file and a region
+export fn map(fd: io::file, offs: u64, length: u64) sector = {
 	let self = sector {
-		buf = alloc([0...], (lba_end - lba_begin + 1)*length),
+		buf = alloc([0...], length * sector_length),
 		fd = fd,
-		lba_begin = lba_begin,
-		lba_end = lba_end
+		offs = offs,
+		length = length
 	};
 
 	return self;
 };
 
+// Finishes a sector and deallocates its related resources
 export fn finish(self: *sector) void = {
 	free(self.buf);
 };
 
-export fn fetch(self: *sector) void = {
-	// XXX proper error
-	io::seek(self.fd, (self.lba_begin * length): io::off, io::whence::SET)!;
-	io::read(self.fd, self.buf)!;
+// Fetches the content of a sector into the buffer
+export fn fetch(self: *sector) (void | io::error) = {
+	io::seek(self.fd, (self.offs * sector_length): io::off, io::whence::SET)?;
+	io::read(self.fd, self.buf)?;
 };
 
-export fn commit(self: *sector) void = {
-	io::seek(self.fd, (self.lba_begin * length): io::off, io::whence::SET)!;
-	io::write(self.fd, self.buf)!;
+// Commits the content of a sector into the file
+export fn commit(self: *sector) (void | io::error) = {
+	io::seek(self.fd, (self.offs * sector_length): io::off, io::whence::SET)?;
+	io::write(self.fd, self.buf)?;
 };
 
-export fn commit_at(self: *sector, fd: io::file, lba: u64) void = {
-	io::seek(fd, (lba * length): io::off, io::whence::SET)!;
-	io::write(fd, self.buf)!;
+// Commits the contents of a sector to another location in another file
+export fn commit_at(self: *sector, fd: io::file, lba: u64) (void | io::error) = {
+	io::seek(fd, (lba * sector_length): io::off, io::whence::SET)?;
+	io::write(fd, self.buf)?;
 };
-- 
cgit v1.2.3