pwent.h

建立一个模拟数据库来存储你的登录用户名、密码

/* pwent.h - Password entry header file */

/* These routines write and read records from a password database,
   named "passdb" in the current directory.

   The 'mygetpwnam' routine takes as argument a username, and returns
   NULL on failure to find it in the database, or a pointer to static
   storage if found. This storage will be overwritten on the next
   call.

   The 'mysetpwent' routine takes a name, and a struct 'mypwent', and
   replaces the data pertaining to 'name' in the database with the
   supplied struct. It returns 0 on success, -1 on failure to replace
   the record.

   The database has free form records, the length of which must not
   exceed 79 characters, the fields are separated by ':', much like
   the passwd database. The fields are:
   name:uid:passwd:salt:no_of_failed_attempts:password_age respectively.

   Note the separate 'salt' field, to simplify some of non-obligatory
   assignments, it is of course entirely possible, not to use this
   field, but instead to include the salt in the password field, in
   similarity with the passwd database.  */

/* Usage: copy the files to your own working directory, and
   use; #include "pwent.h"   to include it. */

#ifndef PWENTH
#define PWENTH

/* Names of password files. */
#define MYPWENT_FILENAME     "passdb"
#define MYPWENT_TMP_FILENAME "passdb.tmp"

typedef struct {
   char *pwname;		/* Username */
   int  uid;			/* User id */
   char *passwd;		/* Password */
   char *passwd_salt;		/* Make dictionary attack harder */
   int  pwfailed;		/* No. of failed attempts */
   int  pwage;			/* Age of password in no of logins */
} mypwent;

mypwent *mygetpwnam(char *name);          /* Find entry matching username */
int mysetpwent(char *name, mypwent *pw);  /* Set entry based on uid */

#endif