writeptr.c

UNIX编程高级环境（第二版）的网络套接字部分的程序源码

#include    "db.h"

/* Write a chain ptr field somewhere in the index file:
 * the free list, the hash table, or in an index record. */

void
_db_writeptr(DB *db, off_t offset, off_t ptrval)
{
    char    asciiptr[PTR_SZ + 1];

    if (ptrval < 0 || ptrval > PTR_MAX)
        err_quit("invalid ptr: %d", ptrval);
    sprintf(asciiptr, "%*d", PTR_SZ, ptrval);

    if (lseek(db->idxfd, offset, SEEK_SET) == -1)
        err_dump("lseek error to ptr field");
    if (write(db->idxfd, asciiptr, PTR_SZ) != PTR_SZ)
        err_dump("write error of ptr field");
}