getspnam(3) - Linux manual page (original) (raw)
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getspnam(3) Library Functions Manual getspnam(3)
NAME top
getspnam, getspnam_r, getspent, getspent_r, setspent, endspent,
fgetspent, fgetspent_r, sgetspent, sgetspent_r, putspent, lckpwdf,
ulckpwdf - get shadow password file entryLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
/* 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_**[.**_size_**], size_t** _size_**, struct spwd** _spbufp_**);**
**int getspnam_r(const char ***_name_**, struct spwd ***_spbuf_**,**
**char** _buf_**[.**_size_**], size_t** _size_**, struct spwd** _spbufp_**);**
**int fgetspent_r(FILE ***_stream_**, struct spwd ***_spbuf_**,**
**char** _buf_**[.**_size_**], size_t** _size_**, struct spwd** _spbufp_**);**
**int sgetspent_r(const char ***_s_**, struct spwd ***_spbuf_**,**
**char** _buf_**[.**_size_**], size_t** _size_**, 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:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCEDESCRIPTION top
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)](../man3/getpwnam.3.html) and [getpwent(3)](../man3/getpwent.3.html)).
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 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 buffer buf of size size. 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 top
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](../man3/errno.3.html)_ set to indicate 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 top
**EACCES** The caller does not have permission to access the shadow
password file.
**ERANGE** Supplied buffer is too small.FILES top
_/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.ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌───────────────┬───────────────┬────────────────────────────────┐
│ **Interface** │ **Attribute** │ **Value** │
├───────────────┼───────────────┼────────────────────────────────┤
│ **getspnam**() │ Thread safety │ MT-Unsafe race:getspnam locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ **getspent**() │ Thread safety │ MT-Unsafe race:getspent │
│ │ │ race:spentbuf locale │
├───────────────┼───────────────┼────────────────────────────────┤
│ **setspent**(), │ Thread safety │ MT-Unsafe race:getspent locale │
│ **endspent**(), │ │ │
│ **getspent_r**() │ │ │
├───────────────┼───────────────┼────────────────────────────────┤
│ **fgetspent**() │ Thread safety │ MT-Unsafe race:fgetspent │
├───────────────┼───────────────┼────────────────────────────────┤
│ **sgetspent**() │ Thread safety │ MT-Unsafe race:sgetspent │
├───────────────┼───────────────┼────────────────────────────────┤
│ **putspent**(), │ Thread safety │ MT-Safe locale │
│ **getspnam_r**(), │ │ │
│ **sgetspent_r**() │ │ │
├───────────────┼───────────────┼────────────────────────────────┤
│ **lckpwdf**(), │ Thread safety │ MT-Safe │
│ **ulckpwdf**(), │ │ │
│ **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.VERSIONS top
Many other systems provide a similar API.STANDARDS top
None.SEE ALSO top
[getgrnam(3)](../man3/getgrnam.3.html), [getpwnam(3)](../man3/getpwnam.3.html), [getpwnam_r(3)](../man3/getpwnam%5Fr.3.html), [shadow(5)](../man5/shadow.5.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-12-24 getspnam(3)
Pages that refer to this page:getent(1), getpwnam(3), setaliasent(3), nsswitch.conf(5), nscd(8)