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getspnam(3c)
Standard C Library Functions getspnam(3C)
NAME
getspnam, getspnam_r, getspent, getspent_r, setspent, endspent, fget‐
spent, fgetspent_r - get password entry
SYNOPSIS
#include <shadow.h>
struct spwd *getspnam(const char *name);
struct spwd *getspnam_r(const char *name, struct spwd *result,
char *buffer, int buflen);
struct spwd *getspent(void);
struct spwd *getspent_r(struct spwd *result, char *buffer,
int buflen);
void setspent(void);
void endspent(void);
struct spwd *fgetspent(FILE *fp);
struct spwd *fgetspent_r(FILE *fp, struct spwd *result,
char *buffer, int buflen);
DESCRIPTION
These functions are used to obtain shadow password entries. An entry
may come from any of the sources for shadow specified in the /etc/nss‐
witch.conf file (see nsswitch.conf(5)).
The getspnam() function searches for a shadow password entry with the
login name specified by the character string argument name.
The setspent(), getspent(), and endspent() functions are used to enu‐
merate shadow password entries from the database.
The setspent() function sets (or resets) the enumeration to the begin‐
ning of the set of shadow password entries. This function should be
called before the first call to getspent(). Calls to getspnam() leave
the enumeration position in an indeterminate state.
Successive calls to getspent() return either successive entries or
NULL, indicating the end of the enumeration.
The endspent() function may be called to indicate that the caller
expects to do no further shadow password retrieval operations; the sys‐
tem may then close the shadow password file, deallocate resources it
was using, and so forth. It is still allowed, but possibly less effi‐
cient, for the process to call more shadow password functions after
calling endspent().
The fgetspent() function, unlike the other functions above, does not
use nsswitch.conf; it reads and parses the next line from the stream
fp, which is assumed to have the format of the shadow file (see
shadow(5)).
Reentrant Interfaces
The getspnam(), getspent(), and fgetspent() functions use thread-spe‐
cific data storage that is reused in each call to one of these func‐
tions by the same thread, making them safe to use but not recommended
for multithreaded applications.
The getspnam_r(), getspent_r(), and fgetspent_r() functions provide
reentrant interfaces for these operations.
Each reentrant interface performs the same operation as its non-reen‐
trant counterpart, named by removing the _r suffix. The reentrant
interfaces, however, use buffers supplied by the caller to store
returned results, and are safe for use in both single-threaded and mul‐
tithreaded applications.
Each reentrant interface takes the same argument as its non-reentrant
counterpart, as well as the following additional arguments. The result
argument must be a pointer to a struct spwd structure allocated by the
caller. On successful completion, the function returns the shadow pass‐
word entry in this structure. The buffer argument must be a pointer to
a buffer supplied by the caller. This buffer is used as storage space
for the shadow password data. All of the pointers within the returned
struct spwd result point to data stored within this buffer (see RETURN
VALUES). The buffer must be large enough to hold all of the data asso‐
ciated with the shadow password entry. The buflen argument should give
the size in bytes of the buffer indicated by buffer.
For enumeration in multithreaded applications, the position within the
enumeration is a process-wide property shared by all threads. The set‐
spent() function may be used in a multithreaded application but resets
the enumeration position for all threads. If multiple threads inter‐
leave calls to getspent_r(), the threads will enumerate disjoint sub‐
sets of the shadow password database.
Like its non-reentrant counterpart, getspnam_r() leaves the enumeration
position in an indeterminate state.
RETURN VALUES
Password entries are represented by the struct spwd structure defined
in <shadow.h>:
struct spwd{
char *sp_namp; /* login name */
char *sp_pwdp; /* encrypted passwd */
int sp_lstchg; /* date of last change */
int sp_min; /* min days to passwd change */
int sp_max; /* max days to passwd change*/
int sp_warn; /* warning period */
int sp_inact; /* max days inactive */
int sp_expire; /* account expiry date */
unsigned int sp_flag; /* not used */
};
See shadow(5) for more information on the interpretation of this data.
The getspnam()and getspnam_r() functions each return a pointer to a
struct spwd if they successfully locate the requested entry; otherwise
they return NULL.
The getspent(), getspent_r(), fgetspent(), and fgetspent() functions
each return a pointer to a struct spwd if they successfully enumerate
an entry; otherwise they return NULL, indicating the end of the enumer‐
ation.
The getspnam(), getspent(), and fgetspent() functions use thread-spe‐
cific data storage, so returned data must be copied before a subsequent
call to any of these functions if the data is to be saved.
When the pointer returned by the reentrant functions getspnam_r(), get‐
spent_r(), and fgetspent_r() is non-null, it is always equal to the
result pointer that was supplied by the caller.
ERRORS
The reentrant functions getspnam_r(), getspent_r(), and fgetspent_r()
will return NULL and set errno to ERANGE if the length of the buffer
supplied by caller is not large enough to store the result. See
Intro(2) for the proper usage and interpretation of errno in multi‐
threaded applications.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ MT-LevelT{ See "Reentrant Interfaces" in DESCRIPTION.
T}
SEE ALSO
passwd(1), yppasswd(1), getpwnam(3C), getlogin(3C), nsswitch.conf(5),
passwd(5), shadow(5), attributes(7)
WARNINGS
The reentrant interfaces getspnam_r(), getspent_r(), and fgetspent_r()
are included in this release on an uncommitted basis only, and are sub‐
ject to change or removal in future minor releases.
NOTES
Use of the enumeration interfaces getspent() and getspent_r() is not
recommended; enumeration is supported for the shadow file and NIS, but
in general is not efficient and may not be supported for all database
sources. The semantics of enumeration are discussed further in nss‐
witch.conf(5).
Access to shadow password information may be restricted in a manner
depending on the database source being used. Access to the /etc/shadow
file is generally restricted to processes running with the effective
uid of the file owner or the {PRIV_FILE_DAC_READ} privilege. Other
database sources may impose stronger or less stringent restrictions.
Empty fields in the database source return -1 values for all fields
except sp_pwdp and sp_flag, where the value returned is 0.
When NIS is used as the database source, the information for the shadow
password entries is obtained from the passwd.byname map. This map
stores only the information for the sp_namp and sp_pwdp fields of the
struct spwd structure. Shadow password entries obtained from NIS will
contain the value -1 in the remainder of the fields.
Oracle Solaris 11.4 19 May 2014 getspnam(3C)