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LSEEK
Section: System calls (2)Updated: January 17, 1998
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lseek - ¥Õ¥¡¥¤¥ë¤ÎÆɤ߽ñ¤¥ª¥Õ¥»¥Ã¥È¤Î°ÌÃÖ¤òÊѤ¨¤ë½ñ¼°
#include <sys/types.h>#include <unistd.h>
off_t lseek(int fildes, off_t offset, int whence);
ÀâÌÀ
lseek ´Ø¿ô¤Ï¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥¿¡¼(descriptor) fildes ¤Î¥ª¥Õ¥»¥Ã¥È¤ò whence ¤Ë½¾¤Ã¤Æ offset °ú¤¿ô¤Î°ÌÃ֤ذʲ¼¤Î¤è¤¦¤ËÊѹ¹¤¹¤ë:- SEEK_SET
- ¥ª¥Õ¥»¥Ã¥È¤Ï offset ¥Ð¥¤¥È¤ËÀßÄꤵ¤ì¤ë¡£
- SEEK_CUR
- ¥ª¥Õ¥»¥Ã¥È¤Ï¸½ºß°ÌÃÖ¤Ë offset ¥Ð¥¤¥È¤ò¤·¤¿Ãͤˤʤ롣
- SEEK_END
- ¥ª¥Õ¥»¥Ã¥È¤Ï¥Õ¥¡¥¤¥ë¤Î¥µ¥¤¥º¤Ë offset ¥Ð¥¤¥È¤ò¤·¤¿Ãͤˤʤ롣
lseek ´Ø¿ô¤Ï¥ª¥Õ¥»¥Ã¥È¤ò¸ºß¤¹¤ë¥Õ¥¡¥¤¥ë¤Î¥Õ¥¡¥¤¥ë¤ÎºÇ¸å(end-of-file)¤ò Ķ¤¨¤¿¾ì½ê¤ËÀßÄꤹ¤ë¤³¤È¤¬¤Ç¤¤ë¡£¤â¤·¥Ç¡¼¥¿¤¬¤³¤Î»þÅÀ¤è¤ê¸å¤Ë½ñ¤¹þ¤Þ¤ì¤¿ ¤Ê¤é¤Ð¡¢´Ö¤Î¶õ·ä¤ÎÉôʬ¤òÆɤ߹þ¤ó¤À¾ì¹ç¤Ï(¼ÂºÝ¤Ë¤½¤³¤Ë¥Ç¡¼¥¿¤ò½ñ¤¹þ¤à¤Þ¤Ç¤Ï )¥¼¥í¤Î¥Ð¥¤¥ÈÎó¤¬ÊÖ¤µ¤ì¤ë¡£
ÊÖ¤êÃÍ
À®¸ù¤·¤¿¾ì¹ç¤Ï lseek ¤Ï·ë²Ì¤Î¥Õ¥¡¥¤¥ë°ÌÃÖ¤ò¥Õ¥¡¥¤¥ë¤ÎÀèƬ¤«¤é¤Î¥Ð¥¤¥È¿ô¤ÇÊÖ¤¹¡£¤½¤¦¤Ç¤Ê¤ì¤Ð ÃͤȤ·¤Æ (off_t)-1 ¤òÊÖ¤·¡¢ errno ¤Ë¥¨¥é¡¼¤¬»Ø¼¨¤µ¤ì¤ë¡£¥¨¥é¡¼
- EBADF
- fildes ¤¬¥ª¡¼¥×¥ó¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¼¤Ç¤Ê¤¤¡£
- ESPIPE
- fildes ¤¬¥Ñ¥¤¥×(pipe), ¥½¥±¥Ã¥È(socket), FIFO ¤ò»²¾È¤·¤Æ¤¤¤ë¡£
- EINVAL
-
whence
¤¬Àµ¤·¤¤ÃͤǤʤ¤¡£
½àµò
SVr4, POSIX, BSD 4.3À©¸Â
¤¤¤¯¤Ä¤«¤Î¥Ç¥Ð¥¤¥¹¤Ç¤Ï seek ¤¬¤Ç¤¤Ê¤¤¡£POSIX ¤Ç¤Ï¤½¤Î¤è¤¦¤Ê ¥Ç¥Ð¥¤¥¹¤Î¥µ¥Ý¡¼¥È¤òÍ׵ᤷ¤Æ¤¤¤Ê¤¤¡£Linux ÆÃͤÎÀ©¸Â¤È¤·¤Æ: tty ¥Ç¥Ð¥¤¥¹¤Ë lseek ¤ò»ÈÍѤ¹¤ë¤È¡¢ ESPIPE ¤òÊÖ¤¹¡£Â¾¤Î¥·¥¹¥Æ¥à¤Ç¤Ï½ñ¤¹þ¤Þ¤ì¤¿Ê¸»ú¤Î¿ô¤òÊÖ¤·¡¢ SEEK_SET ¤Ç¤½¤Î¥«¥¦¥ó¥¿¡¼¤òÀßÄê¤Ç¤¤ë¡£¤¤¤¯¤Ä¤«¤Î¥Ç¥Ð¥¤¥¹¡¢Î㤨¤Ð /dev/null ¤Ï ESPIPE ¥¨¥é¡¼¤òµ¯¤³¤µ¤Ê¤¤¤¬¡¢ÊÖ¤µ¤ì¤ë ¥Ý¥¤¥ó¥¿¡¼¤Ï̤ÄêµÁ¤Ç¤¢¤ë¡£
Ãí°Õ
¤³¤Îʸ¾Ï¤Ç»ÈÍѤ·¤¿ whence ¤Ï±Ñ¸ì¤È¤·¤ÆÀµ¤·¤¯¤Ê¤¤¤¬¡¢ Îò»ËŪÍýͳ¤Ë¤è¤ê°Ý»ý¤µ¤ì¤Æ¤¤¤ë¡£¸Å¤¤¥³¡¼¥É¤òÊÑ´¹¤¹¤ë»þ¤Ï whence ¤ÎÃͤò°Ê²¼¤Î¥Þ¥¯¥í¤ËÃÖ¤´¹¤¨¤ë¤³¤È:
| old | new |
| 0 | SEEK_SET |
| 1 | SEEK_CUR |
| 2 | SEEK_END |
| L_SET | SEEK_SET |
| L_INCR | SEEK_CUR |
| L_XTND | SEEK_END |
SVR1-3 ¤Ç¤Ï off_t ¤ÎÂå¤ê¤Ë long ¤òÊÖ¤·¡¢ BSD ¤Ç¤Ï int ¤òÊÖ¤¹¡£
´ØÏ¢¹àÌÜ
dup(2), open(2), fseek(3)