1GETSPNAM(3)                Linux Programmer's Manual               GETSPNAM(3)
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NAME

6       getspnam,  getspnam_r,  getspent, getspent_r, setspent, endspent, fget‐
7       spent, fgetspent_r, sgetspent, sgetspent_r, putspent, lckpwdf, ulckpwdf
8       - get shadow password file entry
9

SYNOPSIS

11       /* General shadow password file API */
12       #include <shadow.h>
13
14       struct spwd *getspnam(const char *name);
15
16       struct spwd *getspent(void);
17
18       void setspent(void);
19
20       void endspent(void);
21
22       struct spwd *fgetspent(FILE *fp);
23
24       struct spwd *sgetspent(const char *s);
25
26       int putspent(struct spwd *p, FILE *fp);
27
28       int lckpwdf(void);
29
30       int ulckpwdf(void);
31
32       /* GNU extension */
33       #include <shadow.h>
34
35       int getspent_r(struct spwd *spbuf,
36               char *buf, size_t buflen, struct spwd **spbufp);
37
38       int getspnam_r(const char *name, struct spwd *spbuf,
39               char *buf, size_t buflen, struct spwd **spbufp);
40
41       int fgetspent_r(FILE *fp, struct spwd *spbuf,
42               char *buf, size_t buflen, struct spwd **spbufp);
43
44       int sgetspent_r(const char *s, struct spwd *spbuf,
45               char *buf, size_t buflen, struct spwd **spbufp);
46
47   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
48
49       getspent_r(), getspnam_r(), fgetspent_r(), sgetspent_r(): _BSD_SOURCE
50       || _SVID_SOURCE
51

DESCRIPTION

53       Long ago it was considered safe to have encrypted passwords openly vis‐
54       ible  in  the  password file.  When computers got faster and people got
55       more security-conscious,  this  was  no  longer  acceptable.   Julianne
56       Frances  Haugh  implemented  the  shadow  password suite that keeps the
57       encrypted passwords in the shadow password database  (e.g.,  the  local
58       shadow  password  file  /etc/shadow,  NIS,  and LDAP), readable only by
59       root.
60
61       The functions described below resemble those for the traditional  pass‐
62       word database (e.g., see getpwnam(3) and getpwent(3)).
63
64       The getspnam() function returns a pointer to a structure containing the
65       broken-out fields of the record in the shadow  password  database  that
66       matches the username name.
67
68       The  getspent()  function  returns  a  pointer to the next entry in the
69       shadow password database.  The position in the input stream is initial‐
70       ized by setspent().  When done reading, the program may call endspent()
71       so that resources can be deallocated.
72
73       The fgetspent() function is similar to getspent() but uses the supplied
74       stream instead of the one implicitly opened by setspent().
75
76       The  sgetspent()  function  parses  the supplied string s into a struct
77       spwd.
78
79       The putspent() function writes the contents of the supplied struct spwd
80       *p  as a text line in the shadow password file format to the stream fp.
81       String entries with value NULL and numerical entries with value -1  are
82       written as an empty string.
83
84       The lckpwdf() function is intended to protect against multiple simulta‐
85       neous accesses of the shadow password database.  It tries to acquire  a
86       lock,  and  returns  0  on success, or -1 on failure (lock not obtained
87       within 15 seconds).  The ulckpwdf() function releases the  lock  again.
88       Note  that  there  is no protection against direct access of the shadow
89       password file.  Only programs that use lckpwdf() will notice the lock.
90
91       These were the functions that formed the original shadow API.  They are
92       widely available.
93
94   Reentrant versions
95       Analogous  to  the reentrant functions for the password database, glibc
96       also has reentrant functions for the  shadow  password  database.   The
97       getspnam_r()  function  is  like  getspnam()  but  stores the retrieved
98       shadow password structure in the  space  pointed  to  by  spbuf.   This
99       shadow  password  structure  contains  pointers  to  strings, and these
100       strings are stored in the buffer buf of size buflen.  A pointer to  the
101       result  (in  case of success) or NULL (in case no entry was found or an
102       error occurred) is stored in *spbufp.
103
104       The functions getspent_r(), fgetspent_r(), and sgetspent_r() are  simi‐
105       larly analogous to their non-reentrant counterparts.
106
107       Some non-glibc systems also have functions with these names, often with
108       different prototypes.
109
110   Structure
111       The shadow password structure is defined in <shadow.h> as follows:
112
113           struct spwd {
114               char *sp_namp;     /* Login name */
115               char *sp_pwdp;     /* Encrypted password */
116               long  sp_lstchg;   /* Date of last change (measured
117                                     in days since 1 Jan 1970) */
118               long  sp_min;      /* Min # of days between changes */
119               long  sp_max;      /* Max # of days between changes */
120               long  sp_warn;     /* # of days before password expires
121                                     to warn user to change it */
122               long  sp_inact;    /* # of days after password expires
123                                     until account is disabled */
124               long  sp_expire;   /* Date when account expires (measured
125                                     in days since 1 Jan 1970) */
126               unsigned long sp_flag;  /* Reserved */
127           };
128

RETURN VALUE

130       The functions that return a pointer return NULL if no more entries  are
131       available or if an error occurs during processing.  The functions which
132       have int as the return value return 0 for success and -1 for failure.
133
134       For the non-reentrant functions, the return value may point  to  static
135       area, and may be overwritten by subsequent calls to these functions.
136
137       The  reentrant  functions return zero on success.  In case of error, an
138       error number is returned.
139

ERRORS

141       ERANGE Supplied buffer is too small.
142

FILES

144       /etc/shadow
145              local shadow password database file
146
147       /etc/.pwd.lock
148              lock file
149
150       The include file <paths.h> defines the  constant  _PATH_SHADOW  to  the
151       pathname of the shadow password file.
152

CONFORMING TO

154       The  shadow  password database and its associated API are not specified
155       in POSIX.1-2001.  However, many other systems provide a similar API.
156

SEE ALSO

158       getgrnam(3), getpwnam(3), getpwnam_r(3), shadow(5)
159

COLOPHON

161       This page is part of release 3.22 of the Linux  man-pages  project.   A
162       description  of  the project, and information about reporting bugs, can
163       be found at http://www.kernel.org/doc/man-pages/.
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167GNU                               2008-07-09                       GETSPNAM(3)
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