getspnam(3)                                           Library Functions Manual                                          getspnam(3)

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

       Standard C library (libc, -lc)

       /* 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 *stream);
       struct spwd *sgetspent(const char *s);

       int putspent(const struct spwd *p, FILE *stream);

       int lckpwdf(void);
       int ulckpwdf(void);

       /* GNU extension */
       #include <shadow.h>

       int getspent_r(struct spwd *spbuf,
                      char buf[.buflen], size_t buflen, struct spwd **spbufp);
       int getspnam_r(const char *name, struct spwd *spbuf,
                      char buf[.buflen], size_t buflen, struct spwd **spbufp);

       int fgetspent_r(FILE *stream, struct spwd *spbuf,
                      char buf[.buflen], size_t buflen, struct spwd **spbufp);
       int sgetspent_r(const char *s, struct spwd *spbuf,
                      char buf[.buflen], 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():
           Since glibc 2.19:
           glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

       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 pass‐
       word 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‐

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

       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 stream.  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 buf‐
       fer buf of size buflen.  A pointer to the result (in case of success) or NULL (in case no entry was found or  an  error  oc‐
       curred) 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.

       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 */

       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 er‐

       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.

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

       ERANGE Supplied buffer is too small.

              local shadow password database file

              lock file

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

       For an explanation of the terms used in this section, see attributes(7).

       │Interface                 │ Attribute     │ Value                                                                          │
       │getspnam()                │ Thread safety │ MT-Unsafe race:getspnam locale                                                 │
       │getspent()                │ Thread safety │ MT-Unsafe race:getspent race:spentbuf locale                                   │
       │setspent(), endspent(),   │ Thread safety │ MT-Unsafe race:getspent locale                                                 │
       │getspent_r()              │               │                                                                                │
       │fgetspent()               │ Thread safety │ MT-Unsafe race:fgetspent                                                       │
       │sgetspent()               │ Thread safety │ MT-Unsafe race:sgetspent                                                       │
       │putspent(), getspnam_r(), │ Thread safety │ MT-Safe locale                                                                 │
       │sgetspent_r()             │               │                                                                                │
       │lckpwdf(), ulckpwdf(),    │ Thread safety │ MT-Safe                                                                        │
       │fgetspent_r()             │               │                                                                                │
       In  the  above table, getspent in race:getspent signifies that if any of the functions setspent(), getspent(), getspent_r(),
       or endspent() are used in parallel in different threads of a program, then data races could occur.

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

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

Linux man-pages 6.03                                         2023-02-05                                                 getspnam(3)