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fgetpwent_r (3)
  • >> fgetpwent_r (3) ( Linux man: Библиотечные вызовы )
  •  

    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 prototype

    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)\tHOME %s\tSHELL %s\n", 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), putpwent(3), passwd(5)  

    COLOPHON

    This page is part of release 3.14 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    RETURN VALUE
    ERRORS
    CONFORMING TO
    NOTES
    EXAMPLE
    SEE ALSO
    COLOPHON


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