[PATCH 1/4] erofs-utils: tests: add fssum option for fsck

[Jiawei Wang]

This patch introduces a fssum option to the erofs-utils fsck tool, 
enabling checksum calculation for erofs image files.

Signed-off-by: Jiawei Wang <kyr1ewang at qq.com>
---
 fsck/fssum.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fsck/main.c  | 30 +++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 fsck/fssum.h

diff --git a/fsck/fssum.h b/fsck/fssum.h
new file mode 100644
index 0000000..0203169
--- /dev/null
+++ b/fsck/fssum.h
@@ -0,0 +1,57 @@
+#ifndef EROFS_FSSUM_H
+#define EROFS_FSSUM_H
+#include "erofs/dir.h"
+
+#define CS_SIZE 16
+#define CHUNKS 128
+
+#define F(x, y, z)			((z) ^ ((x) & ((y) ^ (z))))
+#define G(x, y, z)			((y) ^ ((z) & ((x) ^ (y))))
+#define H(x, y, z)			(((x) ^ (y)) ^ (z))
+#define H2(x, y, z)			((x) ^ ((y) ^ (z)))
+#define I(x, y, z)			((y) ^ ((x) | ~(z)))
+
+#define STEP(f, a, b, c, d, x, t, s) \
+	(a) += f((b), (c), (d)) + (x) + (t); \
+	(a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
+	(a) += (b);
+	
+#define OUT(dst, src) \
+	(dst)[0] = (unsigned char)(src); \
+	(dst)[1] = (unsigned char)((src) >> 8); \
+	(dst)[2] = (unsigned char)((src) >> 16); \
+	(dst)[3] = (unsigned char)((src) >> 24);
+
+#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
+#define SET(n) \
+	(*(MD5_u32plus *)&ptr[(n) * 4])
+#define GET(n) \
+	SET(n)
+#else
+#define SET(n) \
+	(ctx->block[(n)] = \
+	(MD5_u32plus)ptr[(n) * 4] | \
+	((MD5_u32plus)ptr[(n) * 4 + 1] << 8) | \
+	((MD5_u32plus)ptr[(n) * 4 + 2] << 16) | \
+	((MD5_u32plus)ptr[(n) * 4 + 3] << 24))
+#define GET(n) \
+	(ctx->block[(n)])
+#endif
+
+typedef unsigned int MD5_u32plus;
+
+struct erofs_MD5_CTX {
+	MD5_u32plus lo, hi;
+	MD5_u32plus a, b, c, d;
+	unsigned char buffer[64];
+	MD5_u32plus block[16];
+};
+
+struct erofs_sum_t {
+	struct erofs_MD5_CTX md5;
+	unsigned char out[16];
+};
+
+int erofs_fssum_calculate(struct erofs_dir_context *ctx);
+
+#endif
diff --git a/fsck/main.c b/fsck/main.c
index 28f1e7e..051b74f 100644
--- a/fsck/main.c
+++ b/fsck/main.c
@@ -13,6 +13,7 @@
 #include "erofs/compress.h"
 #include "erofs/decompress.h"
 #include "erofs/dir.h"
+#include "fssum.h"
 #include "../lib/compressor.h"
 
 static int erofsfsck_check_inode(erofs_nid_t pnid, erofs_nid_t nid);
@@ -31,6 +32,7 @@ struct erofsfsck_cfg {
 	bool overwrite;
 	bool preserve_owner;
 	bool preserve_perms;
+	bool checksum;
 };
 static struct erofsfsck_cfg fsckcfg;
 
@@ -48,6 +50,7 @@ static struct option long_options[] = {
 	{"no-preserve-owner", no_argument, 0, 10},
 	{"no-preserve-perms", no_argument, 0, 11},
 	{"offset", required_argument, 0, 12},
+	{"fssum", no_argument, 0, 13},
 	{0, 0, 0, 0},
 };
 
@@ -98,6 +101,7 @@ static void usage(int argc, char **argv)
 		" --extract[=X]          check if all files are well encoded, optionally\n"
 		"                        extract to X\n"
 		" --offset=#             skip # bytes at the beginning of IMAGE\n"
+		" --fssum           	calculate the checksum of iamge\n"
 		"\n"
 		" -a, -A, -y             no-op, for compatibility with fsck of other filesystems\n"
 		"\n"
@@ -225,6 +229,9 @@ static int erofsfsck_parse_options_cfg(int argc, char **argv)
 				return -EINVAL;
 			}
 			break;
+		case 13:
+			fsckcfg.checksum = true;
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -932,6 +939,23 @@ out:
 	return ret;
 }
 
+static int erofsfsck_sum_image(struct erofs_sb_info *sbi)
+{
+	int ret = 0;
+	struct erofs_dir_context ctx = {
+		.flags = 0,
+		.pnid = 0,
+		.dir = NULL,
+		.de_nid = sbi->root_nid,
+		.dname = "",
+		.de_namelen = 0,
+	};
+	
+	ret = erofs_fssum_calculate(&ctx);
+	
+	return ret;
+}
+
 #ifdef FUZZING
 int erofsfsck_fuzz_one(int argc, char *argv[])
 #else
@@ -953,6 +977,7 @@ int main(int argc, char *argv[])
 	fsckcfg.check_decomp = false;
 	fsckcfg.force = false;
 	fsckcfg.overwrite = false;
+	fsckcfg.checksum = false;
 	fsckcfg.preserve_owner = fsckcfg.superuser;
 	fsckcfg.preserve_perms = fsckcfg.superuser;
 
@@ -1017,6 +1042,11 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if (fsckcfg.checksum) {
+		err = erofsfsck_sum_image(&g_sbi);
+		if (err)
+			erofs_err("fssum calculation for image falied");
+	}
 exit_hardlink:
 	if (fsckcfg.extract_path)
 		erofsfsck_hardlink_exit();
-- 
2.34.1