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Diffstat (limited to 'man/man3/getpwent_r.3')
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diff --git a/man/man3/getpwent_r.3 b/man/man3/getpwent_r.3 new file mode 100644 index 0000000..60f1414 --- /dev/null +++ b/man/man3/getpwent_r.3 @@ -0,0 +1,227 @@ +'\" t +.\" Copyright (c) 2003 Andries Brouwer (aeb@cwi.nl) +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH getpwent_r 3 2024-05-02 "Linux man-pages (unreleased)" +.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> +.P +.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 +.P +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR getpwent_r (), +.nf + Since glibc 2.19: + _DEFAULT_SOURCE + glibc 2.19 and earlier: + _BSD_SOURCE || _SVID_SOURCE +.fi +.P +.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 . +.P +The \fIpasswd\fP structure is defined in +.I <pwd.h> +as follows: +.P +.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 +.P +For more information about the fields of this structure, see +.BR passwd (5). +.P +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). +.TS +allbox; +lb lb lbx +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR getpwent_r () +T} Thread safety T{ +.na +.nh +MT-Unsafe race:pwent locale +T} +T{ +.na +.nh +.BR fgetpwent_r () +T} Thread safety MT-Safe +.TE +.P +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 +.P +.in +4n +.EX +struct passwd * +getpwent_r(struct passwd *pwd, char *buf, int buflen); +.EE +.in +.P +or, better, +.P +.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) |