Advanced UNIX Programming

Related Re-entrant Functions

A number of functions covered in this chapter so far have re-entrant counterparts on some platforms. For example, the function synopsis for getgrnam_r(3C) under IRIX 6.5 is as follows:

#include <stdio.h>
#include <grp.h>
#include <sys/types.h>

int getgrnam_r(const char *name,  /* Group name to search */
    struct group *grent,          /* Used for storage */
    char *buffer,                 /* Used for storage */
    int bufsize,                  /* Size of buffer in bytes */
    struct group **grp);          /* Pointer to return pointer */

To be re-entrant, the caller must supply the function with all of its needs. In the case of getgrnam_r(3C) shown, argument grent and buffer are two storage areas that are provided to the function for its own internal use. The buffer points ...