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GETSPNAM(3)                Linux Programmer's Manual               GETSPNAM(3)



NAME
       getspnam,  getspnam_r,  getspent,  getspent_r, setspent, endspent, fgetspent, fget-
       spent_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 pass-
       word  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  ulckp-
       wdf()  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  analo-
       gous to their non-reentrant 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 1 Jan 1970) */
               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 1 Jan 1970) */
               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 non-reentrant 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
       This page is part of release 3.22 of the Linux man-pages project.  A description of
       the  project, and information about reporting bugs, can be found at http://www.ker-
       nel.org/doc/man-pages/.



GNU                               2008-07-09                       GETSPNAM(3)

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