NAME

getspent, getspnam, setspent, endspent, fgetspent, lckpwdf, ulckpwdf − manipulate shadow password file entry

SYNOPSIS

#include <shadow.h>

struct spwd ∗getspent (void);

struct spwd ∗getspnam (const char ∗name);

int lckpwdf (void);

int ulckpwdf (void);

void setspent (void);

void endspent (void);

struct spwd ∗fgetspent (FILE ∗fp);

DESCRIPTION

The getspent and getspnam routines each return a pointer to an object with the following structure containing the broken-out fields of a line in the /etc/shadow file.  Each line in the file contains a “shadow password” structure, declared in the shadow.h header file:

struct spwd{
char∗sp_namp;
char∗sp_pwdp;
longsp_lstchg;
longsp_min;
longsp_max;
longsp_warn;
longsp_inact;
longsp_expire;
unsigned longsp_flag;
};

The getspent routine when first called returns a pointer to the first spwd structure in the file; thereafter, it returns a pointer to the next spwd structure in the file; so successive calls can be used to search the entire file.  The getspnam routine searches from the beginning of the file until a login name matching name is found, and returns a pointer to the particular structure in which it was found.  The getspent and getspnam routines populate the sp_min, sp_max, sp_lstchg, sp_warn, sp_inact, sp_expire, or sp_flag field with −1 if the corresponding field in /etc/shadow is empty.  If an end-of-file or an error is encountered on reading, or there is a format error in the file, these functions return a null pointer and set errno to EINVAL. 

/etc/.pwd.lock is the lock file.  It is used to coordinate modification access to the password files /etc/passwd and /etc/shadow.  lckpwdf and ulckpwdf are routines that are used to gain modification access to the password files, through the lock file.  A process first uses lckpwdf to lock the lock file, thereby gaining exclusive rights to modify the /etc/passwd or /etc/shadow password file.  Upon completing modifications, a process should release the lock on the lock file via ulckpwdf.  This mechanism prevents simultaneous modification of the password files. 

lckpwdf attempts to lock the file /etc/.pwd.lock within 15 seconds.  If unsuccessful, for example, /etc/.pwd.lock is already locked, it returns −1.  If successful, a return code other than −1 is returned. 

ulckpwdf attempts to unlock the file /etc/.pwd.lock.  If unsuccessful, for example, /etc/.pwd.lock is already unlocked, it returns −1.  If successful, it returns 0. 

A call to the setspent routine has the effect of rewinding the shadow password file to allow repeated searches.  The endspent routine may be called to close the shadow password file when processing is complete. 

The fgetspent routine returns a pointer to the next spwd structure in the stream fp, which matches the format of /etc/shadow. 

FILES

/etc/shadow
/etc/passwd
/etc/.pwd.lock

SEE ALSO

getpwent(3C), putpwent(3C), putspent(3C)

DIAGNOSTICS

getspent, getspnam, lckpwdf, ulckpwdf, and fgetspent return a null pointer on EOF or error. 

NOTES

This routine is for internal use only; compatibility is not guaranteed. 

All information is contained in a static area, so it must be copied if it is to be saved.