writeptr.c

来自「用Ｃ语言编的邮件系统（毕业论文）」· C语言 代码 · 共 21 行

#include	"mail.h"

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

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