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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  comput-
       ers  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  pass-
       word  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  pass-
       word  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 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 subse-
       quent 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 informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                               2008-07-09                       GETSPNAM(3)