getgrgid

Synopsis

#include <grp.h>

struct group *getgrgid(gid_t gid);

int getgrgid_r(gid_t gid, struct group *grp, char *buffer,
               size_t bufsize, struct group **result);

Status

Implemented

Conformance

IEEE Std 1003.1-2017

Description

The getgrgid() function shall search the group database for an entry with a matching gid. The group database is the /etc/group file.

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

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

The getgrgid_r() function shall update the group structure pointed to by grp and store a pointer to that structure at the location pointed to by result. The structure shall contain an entry from the group database with a matching gid. Storage referenced by the group structure is allocated from the memory provided with the buffer parameter, which is bufsize bytes in size. A call to sysconf(_SC_GETGR_R_SIZE_MAX) returns either -1 without changing errno or an initial value suggested for the size of this buffer (2048). A null pointer shall be returned at the location pointed to by result on error or if the requested entry is not found.

Return value

The getgrgid() function shall return a pointer to a struct group with the structure defined in <grp.h> with a matching entry if one is found. The getgrgid() function shall return a null pointer if either the requested entry was not found, or an error occurred. 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 getgrent(), getgrgid(), or getgrnam(). The returned pointer, and pointers within the structure, might also be invalidated if the calling thread is terminated.

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

Errors

The getgrgid() and getgrgid_r() functions may fail if:

  • EIO - An I/O error has occurred.

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

  • 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 getgrgid_r() function may fail if:

  • ERANGE - Insufficient storage was supplied via buffer and bufsize to contain the data to be referenced by the resulting group structure.

POSIX deviations

No POSIX deviations discovered.