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NAME

       getspnam,   getspnam_r,   getspent,   getspent_r,  setspent,  endspent,
       fgetspent,  fgetspent_r,  sgetspent,  sgetspent_r,  putspent,  lckpwdf,
       ulckpwdf - get shadow password file entry

SYNOPSIS

       /* 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

DESCRIPTION

       Long  ago  it  was  considered  safe to have encrypted passwords openly
       visible 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
       root.

       The  functions  described  below  resemble  those  for  the traditional
       password database (e.g., see getpwnam(3) and getpwent(3)).

       The getspnam() function returns a pointer to a structure containing the
       broken-out  fields  of  the record in the shadow password database that
       matches the username name.

       The getspent() function returns a pointer to  the  next  entry  in  the
       shadow  password  database.   The  position  in  the  input  stream  is
       initialized by setspent().  When done reading,  the  program  may  call
       endspent() so that resources can be deallocated.

       The fgetspent() function is similar to getspent() but uses the supplied
       stream instead of the one implicitly opened by setspent().

       The sgetspent() function parses the supplied string  s  into  a  struct
       spwd.

       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
       simultaneous  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
       similarly analogous to their nonreentrant counterparts.

       Some non-glibc systems also have functions with these names, often with
       different prototypes.

   Structure
       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 (measured
                                     in days since 1970-01-01 00:00:00 +0000 (UTC)) */
               unsigned long sp_flag;  /* Reserved */
           };

RETURN VALUE

       The functions that return a pointer return NULL if no more entries  are
       available or if an error occurs during processing.  The functions which
       have int as the return value return 0 for success and -1 for failure.

       For the nonreentrant functions, the return value may  point  to  static
       area, and may be overwritten by subsequent calls to these functions.

       The  reentrant  functions return zero on success.  In case of error, an
       error number is returned.

ERRORS

       ERANGE Supplied buffer is too small.

FILES

       /etc/shadow
              local shadow password database file

       /etc/.pwd.lock
              lock file

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

CONFORMING TO

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

SEE ALSO

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

COLOPHON

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