GETPWNAM(P) GETPWNAM(P)
NAME
getpwnam, getpwnam_r - search user database for a name
SYNOPSIS
#include
struct passwd *getpwnam(const char *name);
int getpwnam_r(const char *name, struct passwd *pwd, char *buffer,
size_t bufsize, struct passwd **result);
DESCRIPTION
The getpwnam() function shall search the user database for an entry with a matching name.
The getpwnam() function need not be reentrant. A function that is not required to be reen-
trant is not required to be thread-safe.
Applications wishing to check for error situations should set errno to 0 before calling
getpwnam(). If getpwnam() returns a null pointer and errno is non-zero, an error occurred.
The getpwnam_r() function shall update the passwd structure pointed to by pwd and store a
pointer to that structure at the location pointed to by result. The structure shall con-
tain an entry from the user database with a matching name. Storage referenced by the
structure is allocated from the memory provided with the buffer parameter, which is buf-
size bytes in size. The maximum size needed for this buffer can be determined with the
{_SC_GETPW_R_SIZE_MAX} sysconf() parameter. A NULL pointer shall be returned at the loca-
tion pointed to by result on error or if the requested entry is not found.
RETURN VALUE
The getpwnam() function shall return a pointer to a struct passwd with the structure as
defined in with a matching entry if found. A null pointer shall be returned if the
requested entry is not found, or an error occurs. On error, errno shall be set to indicate
the error.
The return value may point to a static area which is overwritten by a subsequent call to
getpwent(), getpwnam(), or getpwuid().
If successful, the getpwnam_r() function shall return zero; otherwise, an error number
shall be returned to indicate the error.
ERRORS
The getpwnam() and getpwnam_r() functions may fail if:
EIO An I/O error has occurred.
EINTR A signal was caught during getpwnam().
EMFILE {OPEN_MAX} file descriptors are currently open in the calling process.
ENFILE The maximum allowable number of files is currently open in the system.
The getpwnam_r() function may fail if:
ERANGE Insufficient storage was supplied via buffer and bufsize to contain the data to be
referenced by the resulting passwd structure.
The following sections are informative.
EXAMPLES
Getting an Entry for the Login Name
The following example uses the getlogin() function to return the name of the user who
logged in; this information is passed to the getpwnam() function to get the user database
entry for that user.
#include
#include
#include
#include
#include
...
char *lgn;
struct passwd *pw;
...
if ((lgn = getlogin()) == NULL || (pw = getpwnam(lgn)) == NULL) {
fprintf(stderr, "Get of user information failed.\n"); exit(1);
}
...
APPLICATION USAGE
Three names associated with the current process can be determined: getpwuid( geteuid())
returns the name associated with the effective user ID of the process; getlogin() returns
the name associated with the current login activity; and getpwuid( getuid()) returns the
name associated with the real user ID of the process.
The getpwnam_r() function is thread-safe and returns values in a user-supplied buffer
instead of possibly using a static data area that may be overwritten by each call.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
getpwuid() , the Base Definitions volume of IEEE Std 1003.1-2001, , ,
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
POSIX 2003 GETPWNAM(P)
|