GETPWENT_R(3) Linux Programmer s Manual GETPWENT_R(3)

NAME getpwent_r, fgetpwent_r - get passwd file entry reentrantly

SYNOPSIS #include <pwd.h>

int getpwent_r(struct passwd *pwbuf, char *buf, size_t buflen, struct passwd **pwbufp);

int fgetpwent_r(FILE *fp, struct passwd *pwbuf, char *buf, size_t buflen, struct passwd **pwbufp);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getpwent_r(), _BSD_SOURCE || _SVID_SOURCE fgetpwent_r(): _SVID_SOURCE

DESCRIPTION The functions getpwent_r() and fgetpwent_r() are the reentrant versions of getpwent(3) and fgetpwent(3). The former reads the next passwd entry from the stream initialized by setpwent(3). The latter reads the next passwd entry from the stream fp.

The passwd structure is defined in <pwd.h> as follows:

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; /* real name */ char *pw_dir; /* home directory */ char *pw_shell; /* shell program */ };

The non-reentrant 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 pwbuf that can hold a struct passwd. And next the buffer buf of size buflen that can hold additional strings. The result of these functions, the struct passwd read from the stream, is stored in the provided buffer *pwbuf, and a pointer to this struct passwd is returned in *pwbufp.

RETURN VALUE On success, these functions return 0 and *pwbufp is a pointer to the struct passwd. On error, these functions return an error value and *pwbufp is NULL.

ERRORS ENOENT No more entries.

ERANGE Insufficient buffer space supplied. Try again with larger buffer.

CONFORMING TO These functions are GNU extensions, done in a style resembling the POSIX version of functions like getpwnam_r(3). Other systems use pro- totype

struct passwd * getpwent_r(struct passwd *pwd, char *buf, int buflen);

or, better,

int getpwent_r(struct passwd *pwd, char *buf, int buflen, FILE **pw_fp);

NOTES The function getpwent_r() is not really reentrant since it shares the reading position in the stream with all other threads.

EXAMPLE #define _GNU_SOURCE #include <pwd.h> #include <stdio.h> #define BUFLEN 4096

int main(void) { struct passwd pw, *pwp; char buf[BUFLEN]; int i;

setpwent(); while (1) { i = getpwent_r(&pw, buf, BUFLEN, &pwp); if (i) break; printf("%s (%d)HOME %sSHELL %s0, pwp->pw_name, pwp->pw_uid, pwp->pw_dir, pwp->pw_shell); } endpwent(); exit(EXIT_SUCCESS); }

SEE ALSO fgetpwent(3), getpw(3), getpwent(3), getpwnam(3), getpwuid(3), putp- went(3), passwd(5)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

GNU 2007-07-26 GETPWENT_R(3)