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



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 getp-
       went(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 deallo-
       cated.

       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 pass-
       word 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 pro-
       vide a similar API.

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

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2010-02-25                                                GETSPNAM(3)