getpwuid_r()

Get information about the user with a given ID

Synopsis:

#include <sys/types.h>
#include <pwd.h>

int getpwuid_r( uid_t uid,
                struct passwd* pwd, 
                char* buffer, 
                size_t bufsize, 
                struct passwd** result );

Arguments:

uid

The userid whose entry you want to find.

pwd

A pointer to a passwd structure where the function can store the entry.

buffer

A block of memory that the function can use to allocate storage referenced by the passwd structure. You can determine the maximum size needed for this buffer by calling sysconf() with an argument of _SC_GETPW_R_SIZE_MAX.

bufsize

The size of the block that buffer points to, in characters.

result

The address of a pointer to a passwd structure. If getpwnam_r() finds the entry, it stores a pointer to pwd in the location indicated by result; otherwise the function stores a NULL pointer there.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The getpwuid_r() function is a reentrant version of getpwuid(). It lets a process gain more knowledge about user with the given uid.

If _POSIX_THREAD_SAFE_FUNCTIONS is defined, the getpwuid_r() function updates the passwd structure pointed to by pwd and stores a pointer to that structure at the location pointed by result. The structure contains an entry from the user database with a matching uid.

The function stores a NULL pointer at the location pointed by result on error or if it can't find the requested entry.

Returns:

Zero for success, or an error number.

Errors:

ERANGE

Insufficient storage was supplied via buffer and bufsize to contain the resulting passwd structure.

The getpwuid_r() function uses the following functions, and as a result, errno can be set to an error for any of these calls:

• fclose()
• fgets()
• fopen()
• fseek()
• rewind()

Classification:

POSIX 1003.1 TSF

See also:

getlogin(), getpwent(), getpwent_r(), getpwnam(), getpwnam_r(), getpwuid()