'\" t
.\"     Title: shadow
.\"    Author: Julianne Frances Haugh
.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
.\"      Date: 2012-05-25
.\"    Manual: 库函数调用
.\"    Source: shadow-utils 4.1.5.1
.\"  Language: Chinese Simplified
.\"
.TH "SHADOW" "3" "2012-05-25" "shadow\-utils 4\&.1\&.5\&.1" "库函数调用"
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.SH "名称"
shadow, getspnam \- 加密密码文件工具函数
.SH "SYNTAX"
.PP

\fI#include <shadow\&.h>\fR
.PP

\fIstruct spwd *getspent();\fR
.PP

\fIstruct spwd *getspnam(char\fR
\fI*name\fR\fI);\fR
.PP

\fIvoid setspent();\fR
.PP

\fIvoid endspent();\fR
.PP

\fIstruct spwd *fgetspent(FILE\fR
\fI*fp\fR\fI);\fR
.PP

\fIstruct spwd *sgetspent(char\fR
\fI*cp\fR\fI);\fR
.PP

\fIint putspent(struct spwd\fR
\fI*p,\fR
\fIFILE\fR
\fI*fp\fR\fI);\fR
.PP

\fIint lckpwdf();\fR
.PP

\fIint ulckpwdf();\fR
.SH "描述"
.PP
\fIshadow\fR
处理 shadow 密码文件
/etc/shadow
的内容。\fI#include\fR
文件中的结构是：
.sp
.if n \{\
.RS 4
.\}
.nf
struct spwd {
      char		*sp_namp; /* user login name */
      char		*sp_pwdp; /* encrypted password */
      long int		sp_lstchg; /* last password change */
      long int		sp_min; /* days until change allowed\&. */
      long int		sp_max; /* days before change required */
      long int		sp_warn; /* days warning for expiration */
      long int		sp_inact; /* days before account inactive */
      long int		sp_expire; /* date when account expires */
      unsigned long int	sp_flag; /* reserved for future use */
}
    
.fi
.if n \{\
.RE
.\}
.PP
每个字段的含义是：
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_namp \- 指向以 null 结束的用户名的指针
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_pwdp \- 指向 null 结束的密码的指针
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_lstchg \- 最近更改密码的日期(日期计算方法是从1970年1月1日开始的天数)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_min \- days before which password may not be changed
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_max \- days after which password must be changed
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_warn \- days before password is to expire that user is warned of pending password expiration
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_inact \- days after password expires that account is considered inactive and disabled
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_expire \- days since Jan 1, 1970 when account will be disabled
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
sp_flag \- reserved for future use
.RE
.SH "描述"
.PP

\fIgetspent\fR,
\fIgetspname\fR,
\fIfgetspent\fR, and
\fIsgetspent\fR
each return a pointer to a
\fIstruct spwd\fR\&.
\fIgetspent\fR
returns the next entry from the file, and
\fIfgetspent\fR
returns the next entry from the given stream, which is assumed to be a file of the proper format\&.
\fIsgetspent\fR
returns a pointer to a
\fIstruct spwd\fR
using the provided string as input\&.
\fIgetspnam\fR
searches from the current position in the file for an entry matching
\fIname\fR\&.
.PP
\fIsetspent\fR
和
\fIendspent\fR
分别用来开始和结束对影子密码文件的访问。
.PP
需要使用
\fIlckpwdf\fR
和
\fIulckpwdf\fR
函数来确保对
/etc/shadow
文件的互斥访问。\fIlckpwdf\fR
使用
\fIpw_lock\fR
来获取一个最长为 15 秒的锁，然后继续使用
\fIspw_lock\fR
来获取长度为开始的 15 秒时间的剩余量的第二把锁。总计 15 秒之后，无论哪个失败，\fIlckpwdf\fR
都返回 \-1。两把锁都获取成功时，返回 0。
.SH "DIAGNOSTICS"
.PP
如果没有更多条目了或者处理时出错，此函数返回 NULL。使用
\fIint\fR
类型返回值的函数返回 0 表示成功，\-1 表示失败。
.SH "CAVEATS"
.PP
这些函数只能由超级用户使用，因为对影子密码文件的访问是受限的。
.SH "文件"
.PP
/etc/shadow
.RS 4
安全用户账户信息。
.RE
.SH "参见"
.PP
\fBgetpwent\fR(3),
\fBshadow\fR(5)\&.