Originální popis anglicky:
getpwnam, getpwnam_r, getpwuid, getpwuid_r - get password file entry
Návod, kniha: Linux Programmer's Manual
#include <sys/types.h>
#include <pwd.h>
struct passwd *getpwnam(const char *name);
struct passwd *getpwuid(uid_t uid);
int getpwnam_r(const char *name, struct passwd *pwbuf,
char *buf, size_t buflen, struct passwd **pwbufp);
int getpwuid_r(uid_t uid, struct passwd *pwbuf,
char *buf, size_t buflen, struct passwd **pwbufp);
The
getpwnam() function returns a pointer to a structure containing the
broken out fields of a line from
/etc/passwd for the entry that matches
the user name
name.
The
getpwuid() function returns a pointer to a structure containing the
broken out fields of a line from
/etc/passwd for the entry that matches
the user uid
uid.
The
getpwnam_r() and
getpwuid_r() functions find the same
information, but store the retrieved passwd structure in the space pointed to
by
pwbuf. This passwd structure contains pointers to strings, and these
strings are stored in the buffer
buf of size
buflen. A pointer
to the result (in case of success) or NULL (in case no entry was found or an
error occurred) is stored in *
pwbufp.
The
passwd structure is defined in
<pwd.h> as follows:
struct passwd {
char *pw_name; /* user name */
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 maximum needed size for
buf can be found using
sysconf(3) with
the _SC_GETPW_R_SIZE_MAX parameter.
The
getpwnam() and
getpwuid() functions return a pointer to the
passwd structure, or NULL if the matching entry is not found or an error
occurs. If an error occurs,
errno is set appropriately. If one wants to
check
errno after the call, it should be set to zero before the call.
The return value may point to static area, and may be overwritten by subsequent
calls to
getpwent(),
getpwnam(), or
getpwuid().
The
getpwnam_r() and
getpwuid_r() functions return zero on
success. In case of error, an error value is returned.
- 0 or ENOENT or ESRCH or EBADF
or EPERM or ...
- The given name or uid was not found.
- EINTR
- A signal was caught.
- EIO
- I/O error.
- EMFILE
- The maximum number (OPEN_MAX) of files was open already in
the calling process.
- ENFILE
- The maximum number of files was open already in the
system.
- ENOMEM
- Insufficient memory to allocate passwd structure.
- ERANGE
- Insufficient buffer space supplied.
- /etc/passwd
- password database file
SVID 3, BSD 4.3, POSIX 1003.1-2003
The formulation given above under "RETURN VALUE" is from POSIX
1003.1-2001. It does not call "not found" an error, hence does not
specify what value
errno might have in this situation. But that makes
it impossible to recognize errors. One might argue that according to POSIX
errno should be left unchanged if an entry is not found. Experiments on
various Unix-like systems shows that lots of different values occur in this
situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.
endpwent(3),
fgetpwent(3),
getgrnam(3),
getpw(3),
getpwent(3),
putpwent(3),
setpwent(3),
passwd(5)
