PostgreSQL用户密码如何通过md5加密存储，是否加了salt

CreateRole：
  shadow_pass = encrypt_password(Password_encryption, stmt->role,password);
  |--  pg_md5_encrypt(password, role, strlen(role),encrypted_password);
  |  |--  memcpy(crypt_buf, passwd, passwd_len);
  |  |  memcpy(crypt_buf + passwd_len, role, strlen(role));
  |  |  strcpy(buf, "md5");
  |--  |--  pg_md5_hash(crypt_buf, passwd_len + salt_len, buf + 3);
  new_record[Anum_pg_authid_rolpassword - 1] =CStringGetTextDatum(shadow_pass);

postgres=# create user yzs with password '123456';

Breakpoint 1, encrypt_password (target_type=PASSWORD_TYPE_MD5, role=0x99c3b3c "yzs", password=0x99c3b4c "123456") at crypt.c:111
111    PasswordType guessed_type = get_password_type(password);
(gdb) bt
#0  encrypt_password (target_type=PASSWORD_TYPE_MD5, role=0x99c3b3c "yzs", password=0x99c3b4c "123456") at crypt.c:111
#1  0x0827b7a2 in CreateRole (pstate=0x9a0d804, stmt=0x99c3bbc) at user.c:412
#2  0x0840fc18 in standard_ProcessUtility (pstmt=0x99c3c14, queryString=0x99c31dc "create user yzs with password '123456';", context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0, 
    dest=0x99c3d74, completionTag=0xbf9119e6 "") at utility.c:722
#3  0x0840f42a in ProcessUtility (pstmt=0x99c3c14, queryString=0x99c31dc "create user yzs with password '123456';", context=PROCESS_UTILITY_TOPLEVEL, params=0x0, queryEnv=0x0, 
    dest=0x99c3d74, completionTag=0xbf9119e6 "") at utility.c:357
#4  0x0840e6ea in PortalRunUtility (portal=0x9a20634, pstmt=0x99c3c14, isTopLevel=1 '\001', setHoldSnapshot=0 '\000', dest=0x99c3d74, completionTag=0xbf9119e6 "") at pquery.c:1178
#5  0x0840e8b7 in PortalRunMulti (portal=0x9a20634, isTopLevel=1 '\001', setHoldSnapshot=0 '\000', dest=0x99c3d74, altdest=0x99c3d74, completionTag=0xbf9119e6 "") at pquery.c:1324
#6  0x0840ded2 in PortalRun (portal=0x9a20634, count=2147483647, isTopLevel=1 '\001', run_once=1 '\001', dest=0x99c3d74, altdest=0x99c3d74, completionTag=0xbf9119e6 "") at pquery.c:799
#7  0x08408692 in exec_simple_query (query_string=0x99c31dc "create user yzs with password '123456';") at postgres.c:1099
#8  0x0840c5d4 in PostgresMain (argc=1, argv=0x997edc4, dbname=0x997ecf4 "postgres", username=0x99558cc "postgres") at postgres.c:4088
#9  0x083864e6 in BackendRun (port=0x9978038) at postmaster.c:4409
#10 0x08385c5d in BackendStartup (port=0x9978038) at postmaster.c:4081
#11 0x083822d9 in ServerLoop () at postmaster.c:1755
#12 0x083819d6 in PostmasterMain (argc=3, argv=0x9953810) at postmaster.c:1363
#13 0x082dfb60 in main (argc=3, argv=0x9953810) at main.c:228
(gdb) n
114    if (guessed_type != PASSWORD_TYPE_PLAINTEXT)
(gdb) 
123    switch (target_type)
(gdb) 
126        encrypted_password = palloc(MD5_PASSWD_LEN + 1);
(gdb) 
128        if (!pg_md5_encrypt(password, role, strlen(role),
(gdb) s
pg_md5_encrypt (passwd=0x99c3b4c "123456", salt=0x99c3b3c "yzs", salt_len=3, buf=0x9a0d984 "") at md5.c:326
326    size_t    passwd_len = strlen(passwd);
(gdb) n
329    char     *crypt_buf = malloc(passwd_len + salt_len + 1);
(gdb) 
332    if (!crypt_buf)
(gdb) 
339    memcpy(crypt_buf, passwd, passwd_len);
(gdb) 
340    memcpy(crypt_buf + passwd_len, salt, salt_len);
(gdb) p crypt_buf
$1 = 0x9979e68 "123456A"
(gdb) n
342    strcpy(buf, "md5");
(gdb) p crypt_buf
$2 = 0x9979e68 "123456yzsנ\tQ"
(gdb) n
343    ret = pg_md5_hash(crypt_buf, passwd_len + salt_len, buf + 3);
(gdb) p crypt_buf
$3 = 0x9979e68 "123456yzsנ\tQ"
(gdb) n
345    free(crypt_buf);
(gdb) p crypt_buf
$4 = 0x9979e68 "123456yzsנ\tQ"
(gdb) n
347    return ret;
(gdb) 
348  }
(gdb) p ret
$5 = 1 '\001'
(gdb) n
encrypt_password (target_type=PASSWORD_TYPE_MD5, role=0x99c3b3c "yzs", password=0x99c3b4c "123456") at crypt.c:131
131        return encrypted_password;
(gdb) 
146  }
(gdb) 
CreateRole (pstate=0x9a0d804, stmt=0x99c3bbc) at user.c:415
415          CStringGetTextDatum(shadow_pass);
(gdb) p shadow_pass
$6 = 0x9a0d984 "md5aed8080c314507e15542d5e9519723a8"

postgres=# select *from pg_authid where rolname='yzs';
 rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolbypassrls | rolconnlimit |             rolpassword             | rolvaliduntil 
---------+----------+------------+---------------+-------------+-------------+----------------+--------------+--------------+-------------------------------------+---------------
 yzs     | f        | t          | f             | f           | t           | f              | f            |           -1 | md5aed8080c314507e15542d5e9519723a8 | 
(1 row)