Fix incorrect read size assignment in HashFile()

* Also remove part of the output validation for the "Max Path size" test since
  ARM and x86 QEMU tests produce different console width sizes, and we cannot
  validate the part that is console-width dependent (but we still can validate
  that the tests does produce the expected "[1 failed]" error).
* Also flesh out README and allow for release binaries.

.github/workflows/Linux.yml

@@ -70,3 +70,10 @@ jobs:
       with:
         name: ${{ matrix.TARGET_TYPE }}
         path: ./*.efi
+
+    - name: Create release
+      uses: softprops/action-gh-release@v1
+      if: startsWith(github.ref, 'refs/tags/')
+      with:
+        token: ${{ secrets.GITHUB_TOKEN }}
+        files: ./*.efi

README.md

@@ -7,8 +7,59 @@
 uefi-md5sum - MD5 checksum validation for UEFI
 ==============================================
 
-uefi-md5sum is a UEFI bootloader designed to perform MD5 checksum verification
-from media containing an `md5sum.txt` list of hashes.
+## Description
+
+uefi-md5sum is a UEFI bootloader designed to perform MD5 hash verification of a
+media containing an `md5sum.txt` list of hashes.
+
+This is primarily aimed at being used with [Rufus](https://rufus.ie) for the
+creation of USB bootable media (such as Linux or Windows installation drives)
+that can perform self-verification on each boot.
+
+The reasoning with wanting to perform validation on boot rather than on media
+creation is based on the fact that flash based media, and especially cheap USB
+flash drives or SD cards, are exceedingly prone to failures **after** the media
+was written.
+
+As such, we assert that, only validating the content at write-time (like
+balenaEtcher and, in part, Microsoft's Media Creation Tool do) is not enough to
+help users ensure that their installation media hasn't become compromised.
+
+This boot time validation can also prove itself useful if the boot process or
+installation process produces errors, in which case, the first thing a user
+may want to do, is reboot and let uefi-md5sum perform its check, to highlight
+or rule out data corruption.
+
+## Usage
+
+uefi-md5sum is intended to replace, and then chain load, the original UEFI
+bootloader.
+
+To accomplish this, the original `/efi/boot/boot###.efi` should be renamed to
+`/efi/boot/boot###_original.efi` with uefi-md5sum bootloader then installed as
+`/efi/boot/boot###.efi`.
+
+## md5sum.txt extensions
+
+If `md5sum.txt` sets an `md5sum_totalbytes` variable, in the form of a comment
+similar to:
+```
+# md5sum_totalbytes = 0x1234abcd
+```
+Then uefi-md5sum interprets this value to be sum of all the file sizes of the
+files referenced in `md5sum.txt`, and uses it for more accurate progress
+reporting. Otherwise, progress is only incremented after each file has been
+processed, regardless of its actual size.
+
+Thus, the provision of `md5sum_totalbytes` allows for accurate progress report,
+as well the avoidance of apparent progress "freezeouts" when very large files
+are being hashed (such as large squashfs or install.wim images).
+
+It should be noted however that, currently, uefi-md5sum supports only the
+provision of an `md5sum_totalbytes` value in **lowercase** hexadecimal (no
+uppercase hex, no decimal). On the other hand, there is no restriction to where,
+in `md5sum.txt`, `md5sum_totalbytes` needs to be specified (i.e. it does not
+necessarily mean to appear at the beginning of the file).
 
 ## Prerequisites
 

src/hash.c

@@ -338,7 +338,7 @@ EFI_STATUS HashFile(
 	// Compute the MD5 Hash
 	Md5Init(&Context);
 	for (ReadBytes = 0; ; ReadBytes += ReadSize) {
-		ReadSize = sizeof(Buffer);
+		ReadSize = READ_BUFFERSIZE;
 		Status = File->Read(File, &ReadSize, Buffer);
 		if (EFI_ERROR(Status))
 			goto out;

tests/test_list.txt

@@ -69,7 +69,6 @@ Mixed case hash: [14] Not Found
 # Max Path size
 > filename=$(cat /dev/zero | tr '\0' 'a' | head -c 512)
 > echo -n "00112233445566778899aabbccddeeff $filename" > image/md5sum.txt
-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...: [2] Invalid Parameter
 1/1 file processed [1 failed]
 
 # Comment preceded by whitespaces