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           - get shadow password file entry


           /* General shadow password file API */
           #include <shadow.h>
           struct spwd *getspnam(const char *name);
           struct spwd *getspent(void);
           void setspent(void);
           void endspent(void);
           struct spwd *fgetspent(FILE *fp);
           struct spwd *sgetspent(const char *s);
           int putspent(struct spwd *p, FILE *fp);
           int lckpwdf(void);
           int ulckpwdf(void);
           /* GNU extension */
           #include <shadow.h>
           int getspent_r(struct spwd *spbuf,
                   char *buf, size_t buflen, struct spwd **spbufp);
           int getspnam_r(const char *name, struct spwd *spbuf,
                   char *buf, size_t buflen, struct spwd **spbufp);
           int fgetspent_r(FILE *fp, struct spwd *spbuf,
                   char *buf, size_t buflen, struct spwd **spbufp);
           int sgetspent_r(const char *s, struct spwd *spbuf,
                   char *buf, size_t buflen, struct spwd **spbufp);
       Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
           getspent_r(), getspnam_r(), fgetspent_r(), sgetspent_r():
               _BSD_SOURCE || _SVID_SOURCE


           Long ago it was considered safe to have encrypted passwords openly vis-
           ible in the password file.  When computers got faster  and  people  got
           more  security-conscious,  this  was  no  longer  acceptable.  Julianne
           Frances Haugh implemented the shadow  password  suite  that  keeps  the
           encrypted  passwords  in  the shadow password database (e.g., the local
           shadow password file /etc/shadow, NIS,  and  LDAP),  readable  only  by
           stream instead of the one implicitly opened by setspent().
           The sgetspent() function parses the supplied string  s  into  a  struct
           The putspent() function writes the contents of the supplied struct spwd
           *p as a text line in the shadow password file format to the stream  fp.
           String  entries with value NULL and numerical entries with value -1 are
           written as an empty string.
           The lckpwdf() function is intended to protect against multiple simulta-
           neous  accesses of the shadow password database.  It tries to acquire a
           lock, and returns 0 on success, or -1 on  failure  (lock  not  obtained
           within  15  seconds).  The ulckpwdf() function releases the lock again.
           Note that there is no protection against direct access  of  the  shadow
           password  file.  Only programs that use lckpwdf() will notice the lock.
           These were the functions that formed the original shadow API.  They are
           widely available.
       Reentrant versions
           Analogous  to  the reentrant functions for the password database, glibc
           also has reentrant functions for the  shadow  password  database.   The
           getspnam_r()  function  is  like  getspnam()  but  stores the retrieved
           shadow password structure in the  space  pointed  to  by  spbuf.   This
           shadow  password  structure  contains  pointers  to  strings, and these
           strings are stored in the buffer buf of size buflen.  A pointer to  the
           result  (in  case of success) or NULL (in case no entry was found or an
           error occurred) is stored in *spbufp.
           The functions getspent_r(), fgetspent_r(), and sgetspent_r() are  simi-
           larly analogous to their nonreentrant counterparts.
           Some non-glibc systems also have functions with these names, often with
           different prototypes.
           The shadow password structure is defined in <shadow.h> as follows:
               struct spwd {
                   char *sp_namp;     /* Login name */
                   char *sp_pwdp;     /* Encrypted password */
                   long  sp_lstchg;   /* Date of last change
                                         (measured in days since
                                         1970-01-01 00:00:00 +0000 (UTC)) */
                   long  sp_min;      /* Min # of days between changes */
                   long  sp_max;      /* Max # of days between changes */
                   long  sp_warn;     /* # of days before password expires
                                         to warn user to change it */
                   long  sp_inact;    /* # of days after password expires
                                         until account is disabled */
                   long  sp_expire;   /* Date when account expires
           The reentrant functions return zero on success.  In case of  error,  an
           error number is returned.


           EACCES The  caller  does not have permission to access the shadow pass-
                  word file.
           ERANGE Supplied buffer is too small.


                  local shadow password database file
                  lock file
           The include file <paths.h> defines the  constant  _PATH_SHADOW  to  the
           pathname of the shadow password file.


           The  shadow  password database and its associated API are not specified
           in POSIX.1-2001.  However, many other systems provide a similar API.


           getgrnam(3), getpwnam(3), getpwnam_r(3), shadow(5)

    GNU 2013-04-19 GETSPNAM(3)


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