This patch specifically implements the function of calculating image checksum 
and provides interface function that enables fsck to call to complete the 
calculation of image checksum.

Signed-off-by: Jiawei Wang <[email protected]>
---
 fsck/fssum.c | 513 +++++++++++++++++++++++++++++++++++++++++++++++++++
 fsck/fssum.h |  57 ++++++
 2 files changed, 570 insertions(+)
 create mode 100644 fsck/fssum.c
 create mode 100644 fsck/fssum.h

diff --git a/fsck/fssum.c b/fsck/fssum.c
new file mode 100644
index 0000000..9bcea1f
--- /dev/null
+++ b/fsck/fssum.c
@@ -0,0 +1,513 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sysmacros.h>
+#include <sys/xattr.h>
+#include "fssum.h"
+#include "erofs/print.h"
+#include "erofs/xattr.h"
+#include "erofs/list.h"
+#include "erofs/dir.h"
+
+static const void *erofs_fssum_MD5body(struct erofs_MD5_CTX *ctx, const void 
*data, unsigned long size)
+{
+       const unsigned char *ptr;
+       MD5_u32plus a, b, c, d;
+       MD5_u32plus saved_a, saved_b, saved_c, saved_d;
+
+       ptr = (const unsigned char *)data;
+
+       a = ctx->a;
+       b = ctx->b;
+       c = ctx->c;
+       d = ctx->d;
+
+       do {
+               saved_a = a;
+               saved_b = b;
+               saved_c = c;
+               saved_d = d;
+
+/* Round 1 */
+               STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7)
+               STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12)
+               STEP(F, c, d, a, b, SET(2), 0x242070db, 17)
+               STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22)
+               STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7)
+               STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12)
+               STEP(F, c, d, a, b, SET(6), 0xa8304613, 17)
+               STEP(F, b, c, d, a, SET(7), 0xfd469501, 22)
+               STEP(F, a, b, c, d, SET(8), 0x698098d8, 7)
+               STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12)
+               STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
+               STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
+               STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
+               STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
+               STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
+               STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)
+
+/* Round 2 */
+               STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5)
+               STEP(G, d, a, b, c, GET(6), 0xc040b340, 9)
+               STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
+               STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20)
+               STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5)
+               STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
+               STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
+               STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20)
+               STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5)
+               STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
+               STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14)
+               STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20)
+               STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
+               STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9)
+               STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14)
+               STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)
+
+/* Round 3 */
+               STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4)
+               STEP(H2, d, a, b, c, GET(8), 0x8771f681, 11)
+               STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16)
+               STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23)
+               STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4)
+               STEP(H2, d, a, b, c, GET(4), 0x4bdecfa9, 11)
+               STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16)
+               STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23)
+               STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4)
+               STEP(H2, d, a, b, c, GET(0), 0xeaa127fa, 11)
+               STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16)
+               STEP(H2, b, c, d, a, GET(6), 0x04881d05, 23)
+               STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4)
+               STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11)
+               STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16)
+               STEP(H2, b, c, d, a, GET(2), 0xc4ac5665, 23)
+
+/* Round 4 */
+               STEP(I, a, b, c, d, GET(0), 0xf4292244, 6)
+               STEP(I, d, a, b, c, GET(7), 0x432aff97, 10)
+               STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
+               STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21)
+               STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
+               STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10)
+               STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
+               STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21)
+               STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6)
+               STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
+               STEP(I, c, d, a, b, GET(6), 0xa3014314, 15)
+               STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
+               STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6)
+               STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
+               STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15)
+               STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21)
+
+               a += saved_a;
+               b += saved_b;
+               c += saved_c;
+               d += saved_d;
+
+               ptr += 64;
+       } while (size -= 64);
+
+       ctx->a = a;
+       ctx->b = b;
+       ctx->c = c;
+       ctx->d = d;
+
+       return ptr;
+}
+
+void erofs_fssum_MD5Init(struct erofs_MD5_CTX *ctx)
+{
+       ctx->a = 0x67452301;
+       ctx->b = 0xefcdab89;
+       ctx->c = 0x98badcfe;
+       ctx->d = 0x10325476;
+
+       ctx->lo = 0;
+       ctx->hi = 0;
+}
+
+void erofs_fssum_MD5Update(struct erofs_MD5_CTX *ctx, const void *data, 
unsigned long size)
+{
+       MD5_u32plus saved_lo;
+       unsigned long used, available;
+
+       saved_lo = ctx->lo;
+       if ((ctx->lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
+               ctx->hi++;
+       ctx->hi += size >> 29;
+
+       used = saved_lo & 0x3f;
+
+       if (used) {
+               available = 64 - used;
+
+               if (size < available) {
+                       memcpy(&ctx->buffer[used], data, size);
+                       return;
+               }
+
+               memcpy(&ctx->buffer[used], data, available);
+               data = (const unsigned char *)data + available;
+               size -= available;
+               erofs_fssum_MD5body(ctx, ctx->buffer, 64);
+       }
+
+       if (size >= 64) {
+               data = erofs_fssum_MD5body(ctx, data, size & ~(unsigned 
long)0x3f);
+               size &= 0x3f;
+       }
+
+       memcpy(ctx->buffer, data, size);
+}
+
+void erofs_fssum_MD5Final(unsigned char *result, struct erofs_MD5_CTX *ctx)
+{
+       unsigned long used, available;
+
+       used = ctx->lo & 0x3f;
+
+       ctx->buffer[used++] = 0x80;
+
+       available = 64 - used;
+
+       if (available < 8) {
+               memset(&ctx->buffer[used], 0, available);
+               erofs_fssum_MD5body(ctx, ctx->buffer, 64);
+               used = 0;
+               available = 64;
+       }
+
+       memset(&ctx->buffer[used], 0, available - 8);
+
+       ctx->lo <<= 3;
+       OUT(&ctx->buffer[56], ctx->lo)
+       OUT(&ctx->buffer[60], ctx->hi)
+
+       erofs_fssum_MD5body(ctx, ctx->buffer, 64);
+
+       OUT(&result[0], ctx->a)
+       OUT(&result[4], ctx->b)
+       OUT(&result[8], ctx->c)
+       OUT(&result[12], ctx->d)
+
+       memset(ctx, 0, sizeof(*ctx));
+}
+
+void* erofs_fssum_alloc(size_t sz)
+{
+       void *p = malloc(sz);
+       
+       if (!p) {
+               erofs_err("malloc falied");
+               exit(-1);
+       }
+       
+       return p;
+}
+
+void erofs_fssum_init(struct erofs_sum_t *cs)
+{
+       erofs_fssum_MD5Init(&cs->md5);
+}
+
+void erofs_fssum_fini(struct erofs_sum_t *cs)
+{
+       erofs_fssum_MD5Final(cs->out, &cs->md5);
+}
+
+void erofs_fssum_add(struct erofs_sum_t *cs, void* buf, int size)
+{
+       erofs_fssum_MD5Update(&cs->md5, buf, size);
+}
+
+void erofs_fssum_addsum(struct erofs_sum_t *dst, struct erofs_sum_t *src)
+{
+       erofs_fssum_add(dst, src->out, sizeof(src->out));
+}
+
+void erofs_fssum_addu64(struct erofs_sum_t *dst, uint64_t val)
+{
+       uint64_t v = htobe64(val);
+       erofs_fssum_add(dst, &v, sizeof(v));
+}
+
+void erofs_fssum_addtime(struct erofs_sum_t *dst, time_t t)
+{
+       erofs_fssum_addu64(dst, t);
+}
+
+int erofs_fssum_addinode(struct erofs_sum_t *dst, struct erofs_inode vi)
+{
+        int err;
+       char buf[EROFS_MAX_BLOCK_SIZE];
+       erofs_off_t offset = 0;
+       
+       while (offset < vi.i_size) {
+               erofs_off_t maxsize = min_t(erofs_off_t,
+                                           vi.i_size - offset, 
erofs_blksiz(&g_sbi));
+
+               err = erofs_pread(&vi, buf, maxsize, offset);
+               if (err)
+                       return err;
+                       
+               erofs_fssum_add(dst, buf, maxsize);
+               offset += maxsize;
+       }
+       
+       return 0;
+}
+
+char* erofs_fssum_sum2string(struct erofs_sum_t *dst)
+{
+       int i;
+       char *s = erofs_fssum_alloc(CS_SIZE * 2 + 1);
+       
+       for (i = 0; i < CS_SIZE; ++i)
+               sprintf(s + i * 2, "%02x", dst->out[i]);
+               
+       return s;
+}
+
+int erofs_fssum_traverse_dirents(struct erofs_dir_context *ctx,
+                           void *dentry_blk, unsigned int lblk,
+                           unsigned int next_nameoff, unsigned int maxsize,
+                           struct erofs_sum_t *dircs, int level)
+{
+       struct erofs_sb_info *sbi = ctx->dir->sbi;
+       struct erofs_dirent *de = dentry_blk;
+       const struct erofs_dirent *end = dentry_blk + next_nameoff;
+       const char *prev_name = NULL;
+       const char *errmsg;
+       unsigned int prev_namelen = 0;
+       int ret = 0;
+       bool silent = false;
+
+       while (de < end) {
+               const char *de_name;
+               unsigned int de_namelen;
+               unsigned int nameoff;
+
+               nameoff = le16_to_cpu(de->nameoff);
+               de_name = (char *)dentry_blk + nameoff;
+
+               /* the last dirent check */
+               if (de + 1 >= end)
+                       de_namelen = strnlen(de_name, maxsize - nameoff);
+               else
+                       de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
+
+               ctx->de_nid = le64_to_cpu(de->nid);
+               erofs_dbg("traversed nid (%llu)", ctx->de_nid | 0ULL);
+
+               ret = -EFSCORRUPTED;
+               /* corrupted entry check */
+               if (nameoff != next_nameoff) {
+                       errmsg = "bogus dirent nameoff";
+                       break;
+               }
+
+               if (nameoff + de_namelen > maxsize || !de_namelen ||
+                               de_namelen > EROFS_NAME_LEN) {
+                       errmsg = "bogus dirent namelen";
+                       break;
+               }
+
+               ctx->dname = de_name;
+               ctx->de_namelen = de_namelen;
+               ctx->de_ftype = de->file_type;
+               ctx->dot_dotdot = is_dot_dotdot_len(de_name, de_namelen);
+               ret = erofs_fssum_sum(ctx, dircs, level);
+               if (ret) {
+                       silent = true;
+                       break;
+               }
+               prev_name = de_name;
+               prev_namelen = de_namelen;
+               next_nameoff += de_namelen;
+               ++de;
+       }
+out:
+       if (ret && !silent)
+               erofs_err("%s @ nid %llu, lblk %u, index %lu",
+                         errmsg, ctx->dir->nid | 0ULL, lblk,
+                         (de - (struct erofs_dirent *)dentry_blk) | 0UL);
+       return ret;
+}
+
+int erofs_fssum_iterate_dir(struct erofs_dir_context *ctx, struct erofs_sum_t 
*dircs, int level)
+{
+       struct erofs_inode *dir = ctx->dir;
+       struct erofs_sb_info *sbi = dir->sbi;
+       int err = 0;
+       erofs_off_t pos;
+       char buf[EROFS_MAX_BLOCK_SIZE];
+
+       if (!S_ISDIR(dir->i_mode))
+               return -ENOTDIR;
+
+       ctx->flags &= ~EROFS_READDIR_ALL_SPECIAL_FOUND;
+       pos = 0;
+       while (pos < dir->i_size) {
+               erofs_blk_t lblk = erofs_blknr(sbi, pos);
+               erofs_off_t maxsize = min_t(erofs_off_t,
+                                       dir->i_size - pos, erofs_blksiz(sbi));
+               const struct erofs_dirent *de = (const void *)buf;
+               unsigned int nameoff;
+
+               err = erofs_pread(dir, buf, maxsize, pos);
+               if (err) {
+                       erofs_err("I/O error occurred when reading dirents @ 
nid %llu, lblk %u: %d",
+                                 dir->nid | 0ULL, lblk, err);
+                       return err;
+               }
+
+               nameoff = le16_to_cpu(de->nameoff);
+               if (nameoff < sizeof(struct erofs_dirent) ||
+                   nameoff >= erofs_blksiz(sbi)) {
+                       erofs_err("invalid de[0].nameoff %u @ nid %llu, lblk 
%u",
+                                 nameoff, dir->nid | 0ULL, lblk);
+                       return -EFSCORRUPTED;
+               }
+               err = erofs_fssum_traverse_dirents(ctx, buf, lblk, nameoff, 
maxsize, dircs, level);
+               if (err)
+                       break;
+               pos += maxsize;
+       }
+       
+       return err;
+}
+
+int erofs_fssum_sum(struct erofs_dir_context *ctx, struct erofs_sum_t *dircs, 
int level)
+{
+       int err;
+       struct erofs_sum_t meta;
+       struct erofs_sum_t cs;
+       struct erofs_inode vi = { .sbi = &g_sbi, .nid = ctx->de_nid };
+       
+       
+       if (ctx->dot_dotdot)
+               return 0;
+       
+       err = erofs_read_inode_from_disk(&vi);
+       if (err) {
+               erofs_err("failed to read file inode from disk");
+               return err;
+       }
+
+       erofs_fssum_init(&meta);
+       erofs_fssum_init(&cs);
+       
+       erofs_fssum_addu64(&meta, level);
+       erofs_fssum_add(&meta, ctx->dname, ctx->de_namelen);
+       if (!S_ISDIR(vi.i_mode))
+               erofs_fssum_addu64(&meta, vi.i_nlink);
+       erofs_fssum_addu64(&meta, vi.i_uid);
+       erofs_fssum_addu64(&meta, vi.i_gid);
+       erofs_fssum_addu64(&meta, vi.i_mode);
+       erofs_fssum_addtime(&meta, vi.i_mtime);
+
+       if (S_ISDIR(vi.i_mode) || S_ISREG(vi.i_mode)) {
+               ssize_t kllen;
+               ssize_t ret;
+               char *keylst, *key;
+               
+               kllen = erofs_listxattr(&vi, NULL, 0);
+               if (kllen < 0)
+                       return kllen;
+               
+               keylst = malloc(kllen);
+               if(!keylst)
+                       return -ENOMEM;
+                       
+               ret = erofs_listxattr(&vi, keylst, kllen);
+               if (ret < 0) {
+                       free(keylst);
+                       return err;
+               }
+               
+               for (key = keylst; key < keylst + kllen; key += strlen(key) + 
1) {
+                       char *value;
+                       ssize_t size;
+                               
+                       ret = erofs_getxattr(&vi, key, NULL, 0);
+                       if (ret < 0)
+                               return ret;
+                               
+                       erofs_fssum_add(&meta, key, strlen(key));
+                       if (ret == 0)
+                               continue;
+                       if (ret) {
+                               size = ret;
+                               value = malloc(size);
+                               if (!value)
+                                       return -ENOMEM;
+                               ret = erofs_getxattr(&vi, key, value, size);
+                               if (ret < 0){
+                                       free(value);
+                                       free(keylst);
+                                       return ret;
+                               }
+                               erofs_fssum_add(&meta, value, size);
+                               printf("key:%s val:%s\n", key, value);
+                       }    
+               }
+               free(keylst);
+       }
+       
+       if (S_ISDIR(vi.i_mode)) {
+               struct erofs_dir_context nctx = {
+                       .flags = ctx->dir ? EROFS_READDIR_VALID_PNID : 0,
+                       .pnid = ctx->dir ? ctx->dir->nid : 0,
+                       .dir = &vi,
+               };
+               
+               err = erofs_fssum_iterate_dir(&nctx, &cs, level + 1);
+               if (err)
+                       return err;
+       } else {
+               if (S_ISREG(vi.i_mode)) {
+                       erofs_fssum_addu64(&meta, vi.i_size);
+                       err = erofs_fssum_addinode(&cs, vi); 
+                       if (err)
+                               return err;
+               } else if (S_ISLNK(vi.i_mode)) {
+                       err = erofs_fssum_addinode(&cs, vi);
+                       if (err)
+                               return err;
+               } else if (S_ISCHR(vi.i_mode) || S_ISBLK(vi.i_mode)) {
+                       erofs_fssum_addu64(&cs, major(vi.u.i_rdev));
+                       erofs_fssum_addu64(&cs, minor(vi.u.i_rdev));
+               }
+       }
+       
+       erofs_fssum_fini(&cs);
+       erofs_fssum_fini(&meta);
+       erofs_fssum_addsum(dircs, &cs);
+       erofs_fssum_addsum(dircs, &meta);
+       
+       return 0;
+}
+
+int erofs_fssum_calculate(struct erofs_dir_context *ctx)
+{
+       struct erofs_sum_t ans_cs;
+       struct erofs_inode vi = { .sbi = &g_sbi, .nid = ctx->de_nid };
+       struct erofs_dir_context nctx = {
+                       .flags = ctx->dir ? EROFS_READDIR_VALID_PNID : 0,
+                       .pnid = ctx->dir ? ctx->dir->nid : 0,
+                       .dir = &vi,
+               };
+       int ret = 0;
+       
+       ret = erofs_read_inode_from_disk(&vi);
+       if (ret) {
+               erofs_err("failed to read file inode from disk");
+               return ret;
+       }
+       erofs_fssum_init(&ans_cs);
+       ret = erofs_fssum_iterate_dir(&nctx, &ans_cs, 1);
+       erofs_fssum_fini(&ans_cs);
+       fprintf(stdout, "%s\n", erofs_fssum_sum2string(&ans_cs));
+       
+       return ret;
+}
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
-- 
2.34.1

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