Linux Certif

Toute la documentation sur la certification Linux LPI

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open, creat - ¥Õ¥¡¥¤¥ë¤Þ¤¿¤Ï¥Ç¥Ð¥¤¥¹¤Î¥ª¡¼¥×¥ó¡¢ºîÀ®¤ò¹Ô¤¦¡£

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#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>



int open(const char *pathname, int flags);

int open(const char *pathname, int flags, mode_t mode);

int creat(const char *pathname, mode_t mode);

ÀâÌÀ

¥Õ¥¡¥¤¥ë¤Î pathname ¤òÍ¿¤¨¤ë¤È¡¢ open() ¤Ï¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤òÊÖ¤¹¡£ ¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ï¡¢¤³¤Î¸å¤Ë³¤¯¥·¥¹¥Æ¥à¥³¡¼¥ë (read(2), write(2), lseek(2), fcntl(2) ¤Ê¤É) ¤Ç»ÈÍѤµ¤ì¤ë¾®¤µ¤ÊÈóÉé¤ÎÀ°¿ô¤Ç¤¢¤ë¡£ ¤³¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤¬À®¸ù¤·¤¿¾ì¹ç¤ËÊÖ¤µ¤ì¤ë¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ï ¤½¤Î¥×¥í¥»¥¹¤¬¤½¤Î»þÅÀ¤Ç¥ª¡¼¥×¥ó¤·¤Æ¤¤¤Ê¤¤¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Î ¤¦¤ÁºÇ¾®¤Î¿ô»ú¤Î¤â¤Î¤È¤Ê¤ë¡£

¿·¤·¤¤¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ï execve(2) ¤ò¼Â¹Ô¤·¤¿¸å¤â¥ª¡¼¥×¥ó¤µ¤ì¤¿¤Þ¤Þ¤È¤Ê¤ë (¤Ä¤Þ¤ê¡¢ fcntl(2) ¤ËÀâÌÀ¤¬¤¢¤ë FD_CLOEXEC ¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¡¦¥Õ¥é¥°¤ÏºÇ½é¤Ï̵¸ú¤Ç¤¢¤ë)¡£ ¥Õ¥¡¥¤¥ë¡¦¥ª¥Õ¥»¥Ã¥È (file offset) ¤Ï¥Õ¥¡¥¤¥ë¤ÎÀèƬ¤ËÀßÄꤵ¤ì¤ë (lseek(2) »²¾È)¡£

open() ¤ò¸Æ¤Ó½Ð¤¹¤È¡¢¡Ö¥ª¡¼¥×¥ó¥Õ¥¡¥¤¥ëµ­½Ò¡× (open file description) ¤¬ºîÀ®¤µ¤ì¤ë¡£¥Õ¥¡¥¤¥ëµ­½Ò¤È¤Ï¡¢¥·¥¹¥Æ¥àÁ´ÂΤΠ¥ª¡¼¥×¥óÃæ¤Î¥Õ¥¡¥¤¥ë¤Î¥Æ¡¼¥Ö¥ë¤Î¥¨¥ó¥È¥ê¤Ç¤¢¤ë¡£ ¤³¤Î¥¨¥ó¥È¥ê¤Ï¡¢¥Õ¥¡¥¤¥ë¡¦¥ª¥Õ¥»¥Ã¥È¤È¥Õ¥¡¥¤¥ë¾õÂ֥ե饰 (fcntl(2) F_SETFL Áàºî¤Ë¤è¤êÊѹ¹²Äǽ) ¤¬ÊÝ»ý¤¹¤ë¡£ ¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ï¤³¤ì¤é¤Î¥¨¥ó¥È¥ê¤Î°ì¤Ä¤Ø¤Î»²¾È¤Ç¤¢¤ë¡£ ¤³¤Î¸å¤Ç pathname ¤¬ºï½ü¤µ¤ì¤¿¤ê¡¢Â¾¤Î¥Õ¥¡¥¤¥ë¤ò»²¾È¤¹¤ë¤è¤¦¤ËÊѹ¹¤µ¤ì¤¿¤ê¤·¤Æ¤â¡¢ ¤³¤Î»²¾È¤Ï±Æ¶Á¤ò¼õ¤±¤Ê¤¤¡£ ¿·¤·¤¤¥ª¡¼¥×¥ó¥Õ¥¡¥¤¥ëµ­½Ò¤ÏºÇ½é¤Ï¾¤Î¤É¤Î¥×¥í¥»¥¹¤È¤â ¶¦Í­¤µ¤ì¤Æ¤¤¤Ê¤¤¤¬¡¢ fork(2) ¤Ç¶¦Í­¤¬µ¯¤³¤ë¾ì¹ç¤¬¤¢¤ë¡£

¥Ñ¥é¥á¡¼¥¿ flags ¤Ë¤Ï O_RDONLY, O_WRONLY, O_RDWR ¤Î¤É¤ì¤«¤Ò¤È¤Ä¤¬Æþ¤Ã¤Æ¤¤¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£ ¤³¤ì¤é¤Ï¤½¤ì¤¾¤ìÆɤ߹þ¤ßÀìÍÑ¡¢½ñ¤­¹þ¤ßÀìÍÑ¡¢Æɤ߽ñ¤­ÍÑ¤Ë ¥Õ¥¡¥¤¥ë¤ò¥ª¡¼¥×¥ó¤¹¤ë¤³¤È¤òÍ׵᤹¤ë¤â¤Î¤Ç¤¢¤ë¡£

¤µ¤é¤Ë¡¢ flags ¤Ë¤Ï¡¢¥Õ¥¡¥¤¥ëºîÀ®¥Õ¥é¥° (file creation flag) ¤È¥Õ¥¡¥¤¥ë¾õÂ֥ե饰 (file status flag) ¤ò 0 ¸Ä°Ê¾å¡Ö¥Ó¥Ã¥Èñ°Ì¤Î OR (bitwise-or)¡×¤Ç »ØÄꤹ¤ë¤³¤È¤¬¤Ç¤­¤ë¡£ ¥Õ¥¡¥¤¥ëºîÀ®¥Õ¥é¥° ¤Ï O_CREAT, O_EXCL, O_NOCTTY, and O_TRUNC ¤Ç¤¢¤ë¡£ ¥Õ¥¡¥¤¥ë¾õÂ֥ե饰 ¤Ï°Ê²¼¤Î¥ê¥¹¥È¤Î¤¦¤Á¾åµ­°Ê³°¤Î»Ä¤ê¤Î¤â¤Î¤Ç¤¢¤ë¡£ Æó¼ïÎà¤Î¥Õ¥é¥°¤Î°ã¤¤¤Ï¡¢¥Õ¥¡¥¤¥ë¾õÂ֥ե饰¤ÎÊý¤Ï fcntl(2) ¤ò»È¤Ã¤Æ¤½¤ÎÆâÍƤò¼èÆÀ¤·¤¿¤ê (¾ì¹ç¤Ë¤è¤Ã¤Æ¤Ï) Êѹ¹¤·¤¿¤ê¤Ç¤­¤ëÅÀ¤Ë¤¢¤ë¡£ ¥Õ¥¡¥¤¥ëºîÀ®¥Õ¥é¥°¤È¥Õ¥¡¥¤¥ë¾õÂ֥ե饰¤ÎÁ´¥ê¥¹¥È¤ò°Ê²¼¤Ë¼¨¤¹:

O_APPEND

¥Õ¥¡¥¤¥ë¤òÄɲà (append) ¥â¡¼¥É¤Ç¥ª¡¼¥×¥ó¤¹¤ë¡£ Ëè²ó¤Î write(2) ¤ÎÁ°¤Ë lseek(2) ¤ò¹Ô¤Ã¤¿¤«¤Î¤è¤¦¤Ë¡¢¥Õ¥¡¥¤¥ë¡¦¥Ý¥¤¥ó¥¿¡¼¤ò¥Õ¥¡¥¤¥ë¤ÎºÇ¸å¤Ë°ÜÆ°¤¹¤ë¡£ NFS ¥Õ¥¡¥¤¥ë¡¦¥·¥¹¥Æ¥à¤Ç¡¢ O_APPEND ¤ò»ÈÍѤ¹¤ë¤È¡¢Ê£¿ô¤Î¥×¥í¥»¥¹¤¬¤Ò¤È¤Ä¤Î¥Õ¥¡¥¤¥ë¤ËƱ»þ¤Ë¥Ç¡¼¥¿¤òÄɲä·¤¿¾ì¹ç¡¢ ¥Õ¥¡¥¤¥ë¤¬²õ¤ì¤Æ¤·¤Þ¤¦¤³¤È¤¬¤¢¤ë¡£ ¤³¤ì¤Ï NFS ¤¬Äɲå⡼¥É¤ò¥µ¥Ý¡¼¥È¤·¤Æ¤¤¤Ê¤¤¤¿¤á¡¢ ¥¯¥é¥¤¥¢¥ó¥È¤Î¥«¡¼¥Í¥ë (kernel) ¤¬¤½¤ì¤ò¥·¥ß¥å¥ì¡¼¥È¤·¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¤Î¤À¤¬¡¢ ¶¥¹ç¾õÂÖ¤òÈò¤±¤ë¤³¤È¤Ï¤Ç¤­¤Ê¤¤¤«¤é¤Ç¤¢¤ë¡£

O_ASYNC

¥·¥°¥Ê¥ë¶îÆ° I/O (signal-driven I/O) ¤òÍ­¸ú¤Ë¤¹¤ë: ¤³¤Î¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ø¤Î ÆþÎϤޤ¿¤Ï½ÐÎϤ¬²Äǽ¤Ë¤Ê¤Ã¤¿¾ì¹ç¤Ë¡¢¥·¥°¥Ê¥ë¤òÀ¸À®¤¹¤ë (¥Ç¥Õ¥©¥ë¥È¤Ï SIGIO ¤Ç¤¢¤ë¤¬¡¢ fcntl(2) ¤Ë¤è¤Ã¤ÆÊѹ¹²Äǽ¤Ç¤¢¤ë)¡£ ¤³¤Îµ¡Ç½¤¬»ÈÍѲÄǽ¤Ê¤Î¤ÏüËö¡¢µ¿»÷üËö¡¢¥½¥±¥Ã¥È¤Î¤ß¤Ç¤¢¤ê¡¢ (Linux 2.6 °Ê¹ß¤Ç¤Ï) ¥Ñ¥¤¥×¤È FIFO ¤ËÂФ·¤Æ¤â»ÈÍѤǤ­¤ë¡£ ¤µ¤é¤Ë¾Ü¤·¤¤ÀâÌÀ¤Ï fcntl(2) ¤ò»²¾È¤¹¤ë¤³¤È¡£

O_CREAT

¥Õ¥¡¥¤¥ë¤¬Â¸ºß¤·¤Ê¤«¤Ã¤¿¾ì¹ç¤ÏºîÀ® (create) ¤¹¤ë¡£ ¥Õ¥¡¥¤¥ë¤Î½êÍ­¼Ô (¥æ¡¼¥¶¡¼ ID) ¤Ï¡¢¥×¥í¥»¥¹¤Î¼Â¸ú¥æ¡¼¥¶¡¼ ID ¤ËÀßÄꤵ¤ì¤ë¡£ ¥°¥ë¡¼¥×½êÍ­¸¢ (¥°¥ë¡¼¥× ID) ¤Ï¡¢¥×¥í¥»¥¹¤Î¼Â¸ú¥°¥ë¡¼¥× ID ¤Þ¤¿¤Ï¿Æ¥Ç¥£¥ì¥¯¥È¥ê¤Î¥°¥ë¡¼¥× ID ¤ËÀßÄꤵ¤ì¤ë (¤³¤ì¤Ï¡¢¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¥¿¥¤¥×¡¢¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó¡¢ ¿Æ¥Ç¥£¥ì¥¯¥È¥ê¤Î¥â¡¼¥É¤Ë°Í¸¤¹¤ë¡£ Î㤨¤Ð¡¢ mount(8) ¤ÇÀâÌÀ¤µ¤ì¤Æ¤¤¤ë ext2 ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Î¥Þ¥¦¥ó¥È¥ª¥×¥·¥ç¥ó bsdgroups ¤È sysvgroups ¤ò¸«¤è)¡£

O_DIRECT

¤³¤Î¥Õ¥¡¥¤¥ë¤ËÂФ¹¤ë I/O ¤Î¥­¥ã¥Ã¥·¥å¤Î¸ú²Ì¤òºÇ¾®²½¤·¤è¤¦¤È¤¹¤ë¡£ ¤³¤Î¥Õ¥é¥°¤ò»È¤¦¤È¡¢°ìÈÌŪ¤ËÀ­Ç½¤¬Äã²¼¤¹¤ë¡£ ¤·¤«¤·¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤¬Æȼ«¤Ë¥­¥ã¥Ã¥·¥ó¥°¤ò¹Ô¤Ã¤Æ¤¤¤ë¤è¤¦¤Ê ÆÃÊ̤ʾì¹ç¤Ë¤ÏÌò¤ËΩ¤Ä¡£ ¥Õ¥¡¥¤¥ë¤Î I/O ¤Ï¥æ¡¼¥¶¡¼¶õ´Ö¥Ð¥Ã¥Õ¥¡¤ËÂФ·¤ÆľÀܹԤï¤ì¤ë¡£ I/O ¤ÏƱ´ü¤Ç¹Ô¤ï¤ì¤ë¡£ ¤¹¤Ê¤ï¤Á read(2) ¤ª¤è¤Ó write(2) ¤¬´°Î»¤·¤¿»þÅÀ¤Ç¡¢¥Ç¡¼¥¿¤ÎžÁ÷¤¬´°Î»¤·¤¿¤³¤È¤¬Êݾڤµ¤ì¤ë¡£ Linux 2.4 ¤Ç¤Ï¡¢Å¾Á÷¥µ¥¤¥º¡¢ ¥æ¡¼¥¶¡¼¥Ð¥Ã¥Õ¥¡¤Î¥¢¥é¥¤¥ó¥á¥ó¥È¡¢¥Õ¥¡¥¤¥ë¥ª¥Õ¥»¥Ã¥È¤Ï¡¢ ¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ÎÏÀÍý¥Ö¥í¥Ã¥¯¥µ¥¤¥º¤ÎÇÜ¿ô¤Ç¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£ Linux 2.6 ¤Ç¤Ï¡¢512 ¥Ð¥¤¥È¤´¤È¤Î¶­³¦¤ËÇÛÃÖ¤µ¤ì¤Æ¤¤¤ì¤Ð½¼Ê¬¤Ç¤¢¤ë¡£

¥Ö¥í¥Ã¥¯¥Ç¥Ð¥¤¥¹¤ËÂФ¹¤ë»÷Ä̤ä¿°ÕÌ£¤Î¥¤¥ó¥¿¡¼¥Õ¥§¡¼¥¹¤¬ raw(8) ¤ÇÀâÌÀ¤µ¤ì¤Æ¤¤¤ë (⤷¡¢¤³¤Î¥¤¥ó¥¿¥Õ¥§¡¼¥¹¤ÏÈó¿ä¾©¤Ç¤¢¤ë)¡£

O_DIRECTORY

pathname ¤¬¥Ç¥£¥ì¥¯¥È¥ê¤Ç¤Ê¤±¤ì¤Ð¥ª¡¼¥×¥ó¤Ï¼ºÇÔ¤¹¤ë¡£ ¤³¤Î¥Õ¥é¥°¤Ï Linux ÆÃÍ­¤Ç¤¢¤ê¡¢ opendir(3) ¤¬ FIFO ¤ä¥Æ¡¼¥×¥Ç¥Ð¥¤¥¹¤ËÂФ·¤Æ¥³¡¼¥ë¤µ¤ì¤¿¾ì¹ç¤Î ¥µ¡¼¥Ó¥¹ÉÔǽ (denial-of-service) ¹¶·â¤òÈò¤±¤ë¤¿¤á¤Ë ¥«¡¼¥Í¥ë 2.1.126 ¤ÇÄɲ䵤줿¡£ ¤·¤«¤·¤³¤ì¤Ï opendir(3) ¤Î¼ÂÁõ°Ê³°¤Ç¤Ï»ÈÍѤ¹¤ë¤Ù¤­¤Ç¤Ï¤Ê¤¤¡£

O_EXCL

O_CREAT ¤È°ì½ï¤Ë»ÈÍѤµ¤ì¤¿¾ì¹ç¡¢ ¥Õ¥¡¥¤¥ë¤¬´û¤Ë¸ºß¤·¤¿¾ì¹ç¤Ï¥¨¥é¡¼¤È¤Ê¤ê¡¢ open() ¤Ï¼ºÇÔ¤¹¤ë¡£ ¤³¤Î¾ì¹ç¡¢¥·¥ó¥Ü¥ê¥Ã¥¯¥ê¥ó¥¯¤Ç¤¢¤Ã¤Æ¤â¸ºß¤¹¤ë¤¦¤Á¤ËÆþ¤ê¡¢ ¤½¤ì¤¬¤É¤³¤ò»Ø¤·¤Æ¤¤¤ë¤«¤Ë¤Ï¤è¤é¤Ê¤¤¡£ O_EXCL ¤Ï NFS ¥Õ¥¡¥¤¥ë¡¦¥·¥¹¥Æ¥à¤Ç¤Ïµ¡Ç½¤·¤Ê¤¤¡¢ ¤³¤Î¥Õ¥é¥°¤Ç¥í¥Ã¥¯ (lock) µ¡Ç½¤ò¼Â¸½¤¹¤ë¥×¥í¥°¥é¥à¤Ï¡¢ ¶¥¹ç¾ò·ï¤ò´Þ¤à¤À¤í¤¦¡£ ¥í¥Ã¥¯¥Õ¥¡¥¤¥ë¤ò»ÈÍѤ·¤¿Ê¬²òÉÔǽ (atomic) ¤Î¥í¥Ã¥¯µ¡Ç½¤Î²ò·è¤Ë¤Ï Ʊ¤¸¥Õ¥¡¥¤¥ë¡¦¥·¥¹¥Æ¥à¤Ë¾¤È̾Á°¤Î½Å¤Ê¤é¤Ê¤¤¥Õ¥¡¥¤¥ë (Î㤨¤Ð¥Û¥¹¥È̾¤È pid ¤ÎÁȤ߹ç¤ï¤») ¤òºîÀ®¤·¡¢ link(2) ¤ò»ÈÍѤ·¤Æ¤½¤Î¥í¥Ã¥¯¥Õ¥¡¥¤¥ë¤Ø¤Î¥ê¥ó¥¯¤òºîÀ®¤¹¤ë¡£ link(2) ¥³¡¼¥ë¤ÎÊÖ¤êÃͤ¬ 0 ¤Ê¤é¤Ð¥í¥Ã¥¯¤ËÀ®¸ù¤·¤Æ¤¤¤ë¡£ ¤¢¤ë¤¤¤Ï¡¢¤½¤Î¥Õ¥¡¥¤¥ë¤Ë stat(2) ¤ò»ÈÍѤ·¤Æ¥ê¥ó¥¯¿ô (link count) ¤¬ 2 ¤Ë¤Ê¤Ã¤Æ¤¤¤ë¤«¤ò¥Á¥§¥Ã¥¯¤¹¤ë¡£ ¤½¤¦¤Ê¤Ã¤Æ¤¤¤ì¤Ð¡¢Æ±¤¸¤¯¥í¥Ã¥¯¤ËÀ®¸ù¤·¤Æ¤¤¤ë¤È¤¤¤¦¤³¤È¤Ç¤¢¤ë¡£

O_LARGEFILE

(LFS) off_t ¤Ç¤Ï¥µ¥¤¥º¤òɽ¤»¤Ê¤¤ (¤À¤À¤· off64_t ¤Ç¤Ï¥µ¥¤¥º¤òɽ¤»¤ë) ¥Õ¥¡¥¤¥ë¤ò¥ª¡¼¥×¥ó²Äǽ¤Ë¤¹¤ë¡£ ¤³¤ÎÄêµÁ¤òÍ­¸ú¤Ë¤¹¤ë¤¿¤á¤Ë¤Ï¡¢ _LARGEFILE64_SOURCE ¥Þ¥¯¥í¤òÄêµÁ¤·¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£ 32¥Ó¥Ã¥È¥·¥¹¥Æ¥à¤Ë¤ª¤¤¤ÆÂ礭¤Ê¥Õ¥¡¥¤¥ë¤Ë¥¢¥¯¥»¥¹¤¹¤ëÊýË¡¤òÆÀ¤¿¤¤¾ì¹ç¡¢ (O_LARGEFILE ¤ò»È¤¦¤è¤ê¤â) _FILE_OFFSET_BITS µ¡Ç½¸¡ºº¥Þ¥¯¥í¤ò¥»¥Ã¥È¤¹¤ëÊý¤¬Ë¾¤Þ¤·¤¤ÊýË¡¤Ç¤¢¤ë (feature_test_macros(7) ¤ò»²¾È)¡£

O_NOATIME

(Linux 2.6.8 °Ê¹ß) ¥Õ¥¡¥¤¥ë¤ËÂФ·¤Æ read(2) ¤¬¼Â¹Ô¤µ¤ì¤¿¤È¤­¤Ë¡¢ºÇ½ª¥¢¥¯¥»¥¹»þ¹ï (inode ¤Î st_atime) ¤ò¹¹¿·¤·¤Ê¤¤¡£ ¤³¤Î¥Õ¥é¥°¤Ï¥¤¥ó¥Ç¥Ã¥¯¥¹ºîÀ®¤ä¥Ð¥Ã¥¯¥¢¥Ã¥×¥×¥í¥°¥é¥à¤Ç»È¤¦¤³¤È¤ò°Õ¿Þ¤·¤Æ¤¤¤ë¡£ ¤³¤ì¤ò»È¤¦¤È¥Ç¥£¥¹¥¯¤ËÂФ¹¤ëÁàºî¤òÂçÉý¤Ë¸º¤é¤¹¤³¤È¤¬¤Ç¤­¤ë¡£ ¤³¤Î¥Õ¥é¥°¤ÏÁ´¤Æ¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤ËÂФ·¤ÆÍ­¸ú¤Ç¤¢¤ë¤ï¤±¤Ç¤Ï¤Ê¤¤¡£ ¤½¤Î°ìÎ㤬 NFS ¤Ç¤¢¤ê¡¢¥µ¡¼¥Ð¤¬¥¢¥¯¥»¥¹»þ¹ï¤ò´ÉÍý¤·¤Æ¤¤¤ë¡£

O_NOCTTY

pathname ¤¬Ã¼Ëö (terminal) ¥Ç¥Ð¥¤¥¹ --- tty(4) »²¾È --- ¤ò»Ø¤·¤Æ¤¤¤ë¾ì¹ç¤Ë¡¢¤¿¤È¤¨¤½¤Î¥×¥í¥»¥¹¤¬À©¸æüËö¤ò»ý¤Ã¤Æ¤¤¤Ê¤¯¤Æ¤â¡¢ ¥ª¡¼¥×¥ó¤·¤¿¥Õ¥¡¥¤¥ë¤ÏÀ©¸æüËö¤Ë¤Ï¤Ê¤é¤Ê¤¤¡£

O_NOFOLLOW

pathname ¤¬¥·¥ó¥Ü¥ê¥Ã¥¯¡¦¥ê¥ó¥¯¤À¤Ã¤¿¾ì¹ç¡¢¥ª¡¼¥×¥ó¤Ï¼ºÇÔ¤¹¤ë¡£ ¤³¤ì¤Ï FreeBSD ¤Î³ÈÄ¥¤Ç¡¢Linux ¤Ë¤Ï 2.1.126 ¤è¤êÄɲ䵤줿¡£ pathname ¤ÎÁ°¤Î¥³¥ó¥Ý¡¼¥Í¥ó¥È (earlier component; ÌõÃð: ºÇ¸å¤Î¥Ç¥£¥ì¥¯¥È¥ê¥»¥Ñ¥ì¡¼¥¿¤è¤êÁ°¤ÎÉôʬ) ¤¬ ¥·¥ó¥Ü¥ê¥Ã¥¯¡¦¥ê¥ó¥¯¤Ç¤¢¤ë¾ì¹ç¤Ë¤Ï¡¢¤½¤ì¤¬»Ø¤¹À褬»²¾È¤µ¤ì¤ë¡£

O_NONBLOCK ¤Þ¤¿¤Ï O_NDELAY

²Äǽ¤Ê¤é¤Ð¡¢¥Õ¥¡¥¤¥ë¤ÏÈóÄä»ß (non-blocking) ¥â¡¼¥É¤Ç¥ª¡¼¥×¥ó¤µ¤ì¤ë¡£ open() ¤â¡¢ÊÖ¤·¤¿¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤ËÂФ¹¤ë°Ê¸å¤Î¤¹¤Ù¤Æ¤ÎÁàºî¤â ¸Æ¤Ó½Ð¤·¤¿¥×¥í¥»¥¹¤òÂÔ¤¿¤»¤ë¤³¤È¤Ï¤Ê¤¤¡£ FIFO (¥Í¡¼¥à¥É¡¦¥Ñ¥¤¥×) ¤ò°·¤¦¾ì¹ç¤Ë¤Ï fifo(7) ¤â»²¾È¤¹¤ë¤³¤È¡£ ¶¯À©¥Õ¥¡¥¤¥ë¥í¥Ã¥¯ (mandatory file lock) ¤ä¥Õ¥¡¥¤¥ë¥ê¡¼¥¹ (file lease) ¤ÈÁȤ߹ç¤ï¤»¤¿¾ì¹ç¤Î¡¢ O_NONBLOCK ¤Î¸ú²Ì¤Ë¤Ä¤¤¤Æ¤ÎµÄÏÀ¤Ï¡¢ fcntl(2) ¤ò»²¾È¤¹¤ë¤³¤È¡£

O_SYNC

¥Õ¥¡¥¤¥ë¤ÏƱ´ü (synchronous) I/O ¥â¡¼¥É¤Ç¥ª¡¼¥×¥ó¤µ¤ì¤ë¡£ open() ¤¬ÊÖ¤·¤¿¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤ËÂФ·¤Æ write(2) ¤ò¹Ô¤¦¤È¡¢É¬¤º¸Æ¤Ó½Ð¤·¤¿¥×¥í¥»¥¹¤ò¥Ö¥í¥Ã¥¯¤·¡¢ ³ºÅö¥Ï¡¼¥É¥¦¥§¥¢¤ËʪÍýŪ¤Ë½ñ¤­¹þ¤Þ¤ì¤ë¤Þ¤ÇÊÖ¤é¤Ê¤¤¡£ °Ê²¼¤Î¡ÖÃí°Õ¡×¤Î¾Ï¤â»²¾È¡£

O_TRUNC

¥Õ¥¡¥¤¥ë¤¬´û¤Ë¸ºß¤·¡¢Ä̾ï¥Õ¥¡¥¤¥ë¤Ç¤¢¤ê¡¢ ½ñ¤­¹þ¤ß²Ä¥â¡¼¥É¤Ç¥ª¡¼¥×¥ó¤µ¤ì¤Æ¤¤¤ë (¤Ä¤Þ¤ê¡¢O_RDWR ¤Þ¤¿¤Ï O_WRONLY ¤Î) ¾ì¹ç¡¢ Ťµ 0 ¤ËÀÚ¤êµÍ¤á (truncate) ¤é¤ì¤ë¡£ ¥Õ¥¡¥¤¥ë¤¬ FIFO ¤Þ¤¿¤ÏüËö¥Ç¥Ð¥¤¥¹¥Õ¥¡¥¤¥ë¤Î¾ì¹ç¡¢ O_TRUNC ¥Õ¥é¥°¤Ï̵»ë¤µ¤ì¤ë¡£ ¤½¤ì°Ê³°¤Î¾ì¹ç¡¢O_TRUNC ¤Î¸ú²Ì¤Ï̤ÄêµÁ¤Ç¤¢¤ë¡£

¤³¤ì¤é¤ÎÁªÂò¥Õ¥é¥°¤Î¤¤¤¯¤Ä¤«¤Ï¥Õ¥¡¥¤¥ë¤ò¥ª¡¼¥×¥ó¤·¤¿¸å¤Ç¤â fcntl(2) ¤ò»ÈÍѤ·¤ÆÊѹ¹¤¹¤ë¤³¤È¤¬¤Ç¤­¤ë¡£

°ú¤­¿ô mode ¤Ï¿·¤·¤¤¥Õ¥¡¥¤¥ë¤òºîÀ®¤¹¤ë¾ì¹ç¤Ë»ÈÍѤ¹¤ë¥¢¥¯¥»¥¹µö²Ä (permission) ¤ò»ØÄꤹ¤ë¡£ ¤½¤ì¤Ï¥×¥í¥»¥¹¤Î umask ¤ÇÄ̾ïÄ̤꽤Àµ¤µ¤ì¡¢ºîÀ®¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¤Îµö²Ä¤Ï (mode & ~umask) ¤È¤Ê¤ë¡£ ¤³¤Î¥â¡¼¥É¤Ï¿·¤·¤¯ºîÀ®¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¤Î ¾­Íè¤Î¥¢¥¯¥»¥¹¤Ë¤Î¤ßŬÍѤµ¤ì¤ëÅÀ¤ËÃí°Õ¤¹¤ë¤³¤È¡£ Æɤ߼è¤êÀìÍѤΥե¡¥¤¥ë¤òºîÀ®¤¹¤ë open() ¥³¡¼¥ë¤Ç¤¢¤Ã¤Æ¤â¡¢ Æɤ߽ñ¤­²Äǽ¤Ê¥Õ¥¡¥¤¥ë¡¦¥Ç¥£¥¹¥¯¥ê¥×¥¿¤òÊÖ¤¹¤³¤È¤¬¤¢¤ê¤¦¤ë¡£

mode ¤Î¤¿¤á¤Ë°Ê²¼¤Î¥·¥ó¥Ü¥ëÄê¿ô¤¬Ä󶡤µ¤ì¤Æ¤¤¤ë :

S_IRWXU

00700 ¥æ¡¼¥¶¡¼ (¥Õ¥¡¥¤¥ë¤Î½êÍ­¼Ô) ¤ËÆɤ߹þ¤ß¡¢½ñ¤­¹þ¤ß¡¢ ¼Â¹Ô¤Îµö²Ä¤¬¤¢¤ë¡£

S_IRUSR

00400 ¥æ¡¼¥¶¡¼¤ËÆɤ߹þ¤ß¤Îµö²Ä¤¬¤¢¤ë¡£

S_IWUSR

00200 ¥æ¡¼¥¶¡¼¤Ë½ñ¤­¹þ¤ß¤Îµö²Ä¤¬¤¢¤ë¡£

S_IXUSR

00100 ¥æ¡¼¥¶¡¼¤Ë¼Â¹Ô¤Îµö²Ä¤¬¤¢¤ë¡£

S_IRWXG

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