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(const 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  data‐
       base.   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 proto‐
       types.

   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, with errno set to indicate the cause of the error.

       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
       EACCES The caller does not have permission to access the shadow password file.

       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 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2014-05-28                                GETSPNAM(3)