1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
|
'\" t
.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl)
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.TH getpwent_r 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
getpwent_r, fgetpwent_r \- get passwd file entry reentrantly
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <pwd.h>
.PP
.BI "int getpwent_r(struct passwd *restrict " pwbuf ,
.BI " char " buf "[restrict ." buflen "], size_t " buflen ,
.BI " struct passwd **restrict " pwbufp );
.BI "int fgetpwent_r(FILE *restrict " stream \
", struct passwd *restrict " pwbuf ,
.BI " char " buf "[restrict ." buflen "], size_t " buflen ,
.BI " struct passwd **restrict " pwbufp );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR getpwent_r (),
.nf
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE || _SVID_SOURCE
.fi
.PP
.BR fgetpwent_r ():
.nf
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_SVID_SOURCE
.fi
.SH DESCRIPTION
The functions
.BR getpwent_r ()
and
.BR fgetpwent_r ()
are the reentrant versions of
.BR getpwent (3)
and
.BR fgetpwent (3).
The former reads the next passwd entry from the stream initialized by
.BR setpwent (3).
The latter reads the next passwd entry from
.IR stream .
.PP
The \fIpasswd\fP structure is defined in
.I <pwd.h>
as follows:
.PP
.in +4n
.EX
struct passwd {
char *pw_name; /* username */
char *pw_passwd; /* user password */
uid_t pw_uid; /* user ID */
gid_t pw_gid; /* group ID */
char *pw_gecos; /* user information */
char *pw_dir; /* home directory */
char *pw_shell; /* shell program */
};
.EE
.in
.PP
For more information about the fields of this structure, see
.BR passwd (5).
.PP
The nonreentrant functions return a pointer to static storage,
where this static storage contains further pointers to user
name, password, gecos field, home directory and shell.
The reentrant functions described here return all of that in
caller-provided buffers.
First of all there is the buffer
.I pwbuf
that can hold a \fIstruct passwd\fP.
And next the buffer
.I buf
of size
.I buflen
that can hold additional strings.
The result of these functions, the \fIstruct passwd\fP read from the stream,
is stored in the provided buffer
.IR *pwbuf ,
and a pointer to this \fIstruct passwd\fP is returned in
.IR *pwbufp .
.SH RETURN VALUE
On success, these functions return 0 and
.I *pwbufp
is a pointer to the \fIstruct passwd\fP.
On error, these functions return an error value and
.I *pwbufp
is NULL.
.SH ERRORS
.TP
.B ENOENT
No more entries.
.TP
.B ERANGE
Insufficient buffer space supplied.
Try again with larger buffer.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lb lb lbx
l l l.
Interface Attribute Value
T{
.BR getpwent_r ()
T} Thread safety T{
MT-Unsafe race:pwent locale
T}
T{
.BR fgetpwent_r ()
T} Thread safety MT-Safe
.TE
.hy
.ad
.sp 1
In the above table,
.I pwent
in
.I race:pwent
signifies that if any of the functions
.BR setpwent (),
.BR getpwent (),
.BR endpwent (),
or
.BR getpwent_r ()
are used in parallel in different threads of a program,
then data races could occur.
.SH VERSIONS
Other systems use the prototype
.PP
.in +4n
.EX
struct passwd *
getpwent_r(struct passwd *pwd, char *buf, int buflen);
.EE
.in
.PP
or, better,
.PP
.in +4n
.EX
int
getpwent_r(struct passwd *pwd, char *buf, int buflen,
FILE **pw_fp);
.EE
.in
.SH STANDARDS
None.
.SH HISTORY
These functions are done in a style resembling
the POSIX version of functions like
.BR getpwnam_r (3).
.SH NOTES
The function
.BR getpwent_r ()
is not really reentrant since it shares the reading position
in the stream with all other threads.
.SH EXAMPLES
.\" SRC BEGIN (getpwent_r.c)
.EX
#define _GNU_SOURCE
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#define BUFLEN 4096
int
main(void)
{
struct passwd pw;
struct passwd *pwp;
char buf[BUFLEN];
int i;
setpwent();
while (1) {
i = getpwent_r(&pw, buf, sizeof(buf), &pwp);
if (i)
break;
printf("%s (%jd)\etHOME %s\etSHELL %s\en", pwp\->pw_name,
(intmax_t) pwp\->pw_uid, pwp\->pw_dir, pwp\->pw_shell);
}
endpwent();
exit(EXIT_SUCCESS);
}
.EE
.\" perhaps add error checking - should use strerror_r
.\" #include <errno.h>
.\" #include <stdlib.h>
.\" if (i) {
.\" if (i == ENOENT)
.\" break;
.\" printf("getpwent_r: %s", strerror(i));
.\" exit(EXIT_SUCCESS);
.\" }
.\" SRC END
.SH SEE ALSO
.BR fgetpwent (3),
.BR getpw (3),
.BR getpwent (3),
.BR getpwnam (3),
.BR getpwuid (3),
.BR putpwent (3),
.BR passwd (5)
|
