#include <pwd.h>

struct passwd *getpwuid(uid_t uid);

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


Partially implemented


IEEE Std 1003.1-2017


The getpwuid() function shall search the user database for an entry with a matching uid.

The getpwuid() function need not be thread-safe.

Applications wishing to check for error situations should set errno to 0 before calling getpwuid(). If getpwuid() returns a null pointer and errno is set to non-zero, an error occurred.

The getpwuid_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 contain an entry from the user database with a matching uid. Storage referenced by the structure is allocated from the memory provided with the buffer parameter, which is bufsize bytes in size. A call to sysconf(_SC_GETPW_R_SIZE_MAX) returns either -1 without changing errno or an initial value suggested for the size of this buffer. A null pointer shall be returned to the location pointed to by result on error or if the requested entry is not found.

Return value#

The getpwuid() function shall return a pointer to a struct passwd with the structure as defined in <pwd.h> with a matching entry if found. A null pointer shall be returned if the requested entry is not found, or an error occurs. If the requested entry was not found, errno shall not be changed. On error, errno shall be set to indicate the error.

The application shall not modify the structure to which the return value points, nor any storage areas pointed to by pointers within the structure. The returned pointer, and pointers within the structure, might be invalidated or the structure or the storage areas might be overwritten by a subsequent call to getpwent(), getpwnam(), or getpwuid(). The returned pointer, and pointers within the structure, might also be invalidated if the calling thread is terminated.

If successful, the getpwuid_r() function shall return zero, otherwise, an error number shall be returned to indicate the error.


These functions may fail if:

  • EIO - An I/O error has occurred.

  • EINTR - A signal was caught during getpwuid().

  • EMFILE - All file descriptors available to the process are currently open.

  • ENFILE - The maximum allowable number of files is currently open in the system.

The getpwuid_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.



Known bugs#


See Also#

  1. Standard library functions

  2. Table of Contents