{"id":1241,"date":"2012-02-11T06:18:50","date_gmt":"2012-02-10T12:18:50","guid":{"rendered":"http:\/\/peta.okechan.net\/blog\/?p=1241"},"modified":"2013-02-01T15:00:52","modified_gmt":"2013-02-01T06:00:52","slug":"xv6%e3%82%bd%e3%83%bc%e3%82%b9%e3%82%b3%e3%83%bc%e3%83%89%e3%83%aa%e3%83%bc%e3%83%87%e3%82%a3%e3%83%b3%e3%82%b0-%e3%81%9d%e3%81%ae5","status":"publish","type":"post","link":"https:\/\/peta.okechan.net\/blog\/archives\/1241","title":{"rendered":"[xv6 #5] Chapter 0 – Operating system interfaces – Code: File system"},"content":{"rendered":"

\u30c6\u30ad\u30b9\u30c8\u306e14\u301c15\u30da\u30fc\u30b8<\/p>\n

\u672c\u6587<\/h3>\n

xv6\u306f\u3001\u30c7\u30fc\u30bf\u30d5\u30a1\u30a4\u30eb\uff08\u89e3\u91c8\u3055\u308c\u3066\u3044\u306a\u3044\u751f\u306e\u30d0\u30a4\u30c8\u5217\uff09\u3068\u3001\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\uff08\u4ed6\u306e\u30c7\u30fc\u30bf\u30d5\u30a1\u30a4\u30eb\u3084\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u542b\u3080\uff09\u3092\u63d0\u4f9b\u3059\u308b\u3002
\nxv6\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u3001\u7279\u5225\u306a\u7a2e\u985e\u306e\u30d5\u30a1\u30a4\u30eb\u3068\u3057\u3066\u5b9f\u88c5\u3057\u3066\u3044\u308b\u3002
\n\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u3001root\u3068\u547c\u3070\u308c\u308b\u7279\u6b8a\u306a\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u304b\u3089\u59cb\u307e\u308b\u30c4\u30ea\u30fc\u306e\u4e2d\u306b\u914d\u7f6e\u3055\u308c\u308b\u3002
\n\/a\/b\/c \u306e\u3088\u3046\u306a\u30d1\u30b9\u306f\u3001\u30eb\u30fc\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea”\/”\u306e\u4e2d\u306b\u3042\u308ba\u3068\u3044\u3046\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306e\u4e2d\u306b\u3042\u308bb\u3068\u3044\u3046\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306e\u4e2d\u306b\u3042\u308bc\u3068\u540d\u4ed8\u3051\u3089\u308c\u305f\u30d5\u30a1\u30a4\u30eb\uff08\u3082\u3057\u304f\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\uff09\u3092\u6307\u3057\u793a\u3059\u3002
\n“\/”\u304b\u3089\u59cb\u307e\u3063\u3066\u306a\u3044\u30d1\u30b9\u306f\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea(current directory)\u3092\u8d77\u70b9\u306b\u76f8\u5bfe\u7684\u306b\u8a55\u4fa1\u3055\u308c\u308b\u3002
\n\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u3001chdir\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3067\u5909\u66f4\u51fa\u6765\u308b\u3002
\n\u4ee5\u4e0b\u306e2\u3064\u306e\u30b3\u30fc\u30c9\u306f\u540c\u3058\u30d5\u30a1\u30a4\u30eb\u3092\u958b\u304f\u3002<\/p>\n

chdir("\/a");\r\nchdir("b");\r\nopen("c", O_RDONLY);<\/pre>\n
open("\/a\/b\/c", O_RDONLY);<\/pre>\n
\u6700\u521d\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092”\/a\/b”\u306b\u5909\u66f4\u3059\u308b\u3002
\n2\u3064\u3081\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u5909\u66f4\u3057\u306a\u3044\u3002<\/p>\n
\u65b0\u3057\u3044\u30d5\u30a1\u30a4\u30eb\u3084\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u4f5c\u308b\u305f\u3081\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u304c\u3044\u304f\u3064\u304b\u3042\u308b\u3002
\nmkdir\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u4f5c\u6210\u3059\u308b\u3002
\nopen\u3092O_CREATE\u30d5\u30e9\u30b0\u3067\u547c\u3076\u3068\u65b0\u3057\u3044\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3059\u308b\u3002
\nmknod\u3067\u65b0\u3057\u3044\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3059\u308b\u3002
\n\u4ee5\u4e0a3\u3064\u5168\u3066\u306b\u3064\u3044\u3066\u6b21\u3067\u4f8b\u793a\u3059\u308b\u3002<\/p>\n
mkdir("\/dir");\r\nfd = open("\/dir\/file", O_CREATE|O_WRONLY);\r\nclose(fd);\r\nmknod("\/console", 1, 1);<\/pre>\n
mknod\u306f\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u306e\u4e2d\u306b\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u308b\u304c\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u306f\u4e2d\u8eab\u3092\u6301\u305f\u306a\u3044\u3002
\n\u3057\u304b\u3057\u306a\u304c\u3089\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u306b\u306f\u305d\u308c\u304c\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3067\u3042\u308b\u3068\u3044\u3046\u60c5\u5831\u304c\u30de\u30fc\u30af\u3055\u308c\u3001\u30ab\u30fc\u30cd\u30eb\u30c7\u30d0\u30a4\u30b9\u3092\u4e00\u610f\u306b\u8b58\u5225\u3059\u308b\u305f\u3081\u306e\u30e1\u30b8\u30e3\u30fc\u305d\u3057\u3066\u30de\u30a4\u30ca\u30fc\u30c7\u30d0\u30a4\u30b9\u756a\u53f7\uff08mknod\u306e\u5f15\u6570\u306e\u5f8c\u308d\u4e8c\u3064\u306b\u5bfe\u5fdc\uff09\u304c\u8a18\u9332\u3055\u308c\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u304c\u5f8c\u3067\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u958b\u3044\u305f\u3068\u304d\u3001\u30ab\u30fc\u30cd\u30eb\u306fread\u3084write\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u3001\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u3078read\u3057\u305f\u308awrite\u3057\u305f\u308a\u3059\u308b\u4ee3\u308f\u308a\u306b\u3001\u30ab\u30fc\u30cd\u30eb\u30c7\u30d0\u30a4\u30b9\u306e\u5b9f\u88c5\u3078\u3059\u308a\u66ff\u3048\u308b\u3002<\/p>\n
fstat\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u6307\u3057\u793a\u3057\u3066\u3044\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u3064\u3044\u3066\u306e\u60c5\u5831\u3092\u53d6\u308a\u51fa\u3059\u3002
\nstat.h\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308bstat\u69cb\u9020\u4f53\u3067\u7d50\u679c\u304c\u8fd4\u3063\u3066\u304f\u308b\u3002
\n\uff08\u3061\u306a\u307f\u306b\u4ee5\u4e0b\u306fstat.h\u306e\u4e00\u90e8\u3067\u306f\u306a\u304f\u5168\u3066\u3067\u3059\uff09<\/p>\n
#define T_DIR  1   \/\/ Directory\r\n#define T_FILE 2   \/\/ File\r\n#define T_DEV  3   \/\/ Special device\r\n\r\nstruct stat {\r\n  short type;  \/\/ Type of file\r\n  int dev;     \/\/ Device number\r\n  uint ino;    \/\/ Inode number on device\r\n  short nlink; \/\/ Number of links to file\r\n  uint size;   \/\/ Size of file in bytes\r\n};<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u540d\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u81ea\u4f53\u3068\u306f\u5225\u306b\u306a\u3063\u3066\u3044\u308b\u3002\uff08stat\u69cb\u9020\u4f53\u306b\u306fname\u306a\u3093\u3066\u30e1\u30f3\u30d0\u306f\u306a\u3044\uff09
\n1\u3064\u306e\u30d5\u30a1\u30a4\u30eb\uff08inode\uff09\u306f\u8907\u6570\u306e\u540d\u524d\uff08link\uff09\u3092\u6301\u3064\u3053\u3068\u304c\u51fa\u6765\u308b\u3002
\nlink\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306f\u3001\u65e2\u5b58\u306e\u30d5\u30a1\u30a4\u30eb\u306a\u3069\u3068\u540c\u3058inode\u3092\u6307\u3057\u793a\u3059\u3088\u3046\u306a\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u4e0a\u306e\u5225\u540d\u3092\u4f5c\u6210\u3059\u308b\u3002
\n\u6b21\u306e\u30b3\u30fc\u30c9\u306f\u3001a\u3068\u3044\u3046\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3057\u3001b\u3068\u3044\u3046\u5225\u540d\u3092\u3064\u3051\u308b\u3002<\/p>\n
open("a", O_CREATE|O_WRONLY);\r\nlink("a", "b");<\/pre>\n
a\u306b\u5bfe\u3059\u308b\u8aad\u307f\u66f8\u304d\u306f\u3001b\u306b\u5bfe\u3059\u308b\u8aad\u307f\u66f8\u304d\u3068\u540c\u3058\u3067\u3042\u308b\u3002
\n\u3069\u306einode\u3082\u4e00\u610f\u306einode\u756a\u53f7\u3067\u8b58\u5225\u3055\u308c\u308b\u3002
\n\u4e0a\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u305f\u3042\u3068\u3001fstat\u306e\u7d50\u679c\u3092\u8abf\u3079\u308b\u3068a\u3068b\u304c\u540c\u3058\u5185\u5bb9\u3092\u53c2\u7167\u3057\u3066\u308b\u3068\u3044\u3046\u3053\u3068\u304c\u5206\u304b\u308b\u3002
\n\u3064\u307e\u308a\u4e21\u65b9\u3068\u3082\u540c\u3058inode\u756a\u53f7\uff08ino\uff09\u304c\u8fd4\u3063\u3066\u304f\u308b\u306f\u305a\u3067\u3042\u308b\u3002
\n\u305d\u3057\u3066nlink\u306b\u306f2\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u306f\u305a\u3067\u3042\u308b\u3002<\/p>\n
unlink\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306f\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u304b\u3089\u540d\u524d\u3092\u53d6\u308a\u9664\u304f\u3002
\n\u30d5\u30a1\u30a4\u30eb\u306einode\u3068\u30c7\u30a3\u30b9\u30af\u30b9\u30da\u30fc\u30b9\u304c\u89e3\u653e\u3055\u308c\u308b\u306e\u306f\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3078\u306e\u30ea\u30f3\u30af\u6570\u304c\u30bc\u30ed\u306b\u306a\u3063\u305f\u3068\u304d\u3001\u304b\u3064\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u53c2\u7167\u3059\u308b\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u306a\u3044\u3068\u304d\u3060\u3051\u3067\u3042\u308b\u3002
\n\u306a\u306e\u3067\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u306e\u6700\u5f8c\u306b<\/p>\n
unlink("a");<\/pre>\n
\u3092\u8ffd\u52a0\u3057\u3066\u3082\u3001b\u3068\u3057\u3066\u30a2\u30af\u30bb\u30b9\u53ef\u80fd\u306ainode\u3068\u305d\u306e\u5185\u5bb9\u306f\u6d88\u3048\u306a\u3044\u3002<\/p>\n
fd = open("\/tmp\/xyz", O_CREATE|O_RDWR);\r\nunlink("\/tmp\/xyz");<\/pre>\n
\u3053\u306e\u30b3\u30fc\u30c9\u306f\u3001\u4e00\u6642\u7684\u306ainode\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306b\u7406\u306b\u304b\u306a\u3063\u305f\u65b9\u6cd5\u3067\u3042\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u304cfd\u3092close\u3057\u305f\u3068\u304d\u3001\u3082\u3057\u304f\u306f\u30d7\u30ed\u30bb\u30b9\u304c\u7d42\u4e86\u3057\u305f\u3068\u304d\u306b\u3001\u81ea\u52d5\u7684\u306b\u4e00\u6642\u30d5\u30a1\u30a4\u30eb\u304c\u6d88\u53bb\u3055\u308c\u308b\u3002<\/p>\n
\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u3092\u64cd\u4f5c\u3059\u308bxv6\u306e\u30b3\u30de\u30f3\u30c9\u306f\u3001mkdir, ln, rm\u7b49\u306e\u3088\u3046\u306b\u30e6\u30fc\u30b6\u30ec\u30d9\u30eb\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308b\u3002
\n\u3053\u306e\u30c7\u30b6\u30a4\u30f3\u306b\u3088\u3063\u3066\u3001\u65b0\u3057\u3044\u30e6\u30fc\u30b6\u30fc\u30b3\u30de\u30f3\u30c9\u306b\u3088\u3063\u3066\u30b7\u30a7\u30eb\u3092\u62e1\u5f35\u3059\u308b\u4e8b\u304c\u53ef\u80fd\u3068\u306a\u308b\u3002
\n\u4eca\u3068\u306a\u3063\u3066\u306f\u3001\u3053\u306e\u8a2d\u8a08\u306e\u5229\u70b9\u306f\u660e\u3089\u304b\u3060\u304c\u3001Unix\u304c\u751f\u307e\u308c\u305f\u6642\u4ee3\u306b\u8a2d\u8a08\u3055\u308c\u305f\u4ed6\u306e\u30b7\u30b9\u30c6\u30e0\u306f\u3001\u3057\u3070\u3057\u3070\u305d\u306e\u3088\u3046\u306a\u30b3\u30de\u30f3\u30c9\u3092\u30b7\u30a7\u30eb\u306e\u4e2d\u306b\u7d44\u307f\u8fbc\u3093\u3067\u3042\u308b\u3002\uff08\u305d\u3057\u3066\u30b7\u30a7\u30eb\u81ea\u4f53\u3082\u30e6\u30fc\u30b6\u7a7a\u9593\u3067\u306f\u306a\u304f\u30ab\u30fc\u30cd\u30eb\u7a7a\u9593\u3067\u5b9f\u884c\u3055\u308c\u308b\u3088\u3046\u306b\u306a\u3063\u3066\u305f\u308a\u3059\u308b\u3002\uff09<\/p>\n
1\u3064\u306e\u4f8b\u5916\u304ccd\u3067\u3001\u30b7\u30a7\u30eb\u306e\u4e2d\u306b\u7d44\u307f\u8fbc\u307e\u308c\u3066\u3044\u308b\u3002
\n\uff08sh.c\u306emain\u95a2\u6570\u3002\u4e8c\u3064\u76ee\u306ewhile\u6587\u306e\u4e2d\u306e\u6700\u521d\u306eif\u6587\u306b\u6ce8\u76ee\uff09<\/p>\n
int\r\nmain(void)\r\n{\r\n  static char buf[100];\r\n  int fd;\r\n  \r\n  \/\/ Assumes three file descriptors open.\r\n  while((fd = open("console", O_RDWR)) >= 0){\r\n    if(fd >= 3){\r\n      close(fd);\r\n      break;\r\n    }\r\n  }\r\n  \r\n  \/\/ Read and run input commands.\r\n  while(getcmd(buf, sizeof(buf)) >= 0){\r\n    if(buf[0] == 'c' && buf[1] == 'd' && buf[2] == ' '){\r\n      \/\/ Clumsy but will have to do for now.\r\n      \/\/ Chdir has no effect on the parent if run in the child.\r\n      buf[strlen(buf)-1] = 0;  \/\/ chop \\n\r\n      if(chdir(buf+3) < 0)\r\n        printf(2, "cannot cd %s\\n", buf+3);\r\n      continue;\r\n    }\r\n    if(fork1() == 0)\r\n      runcmd(parsecmd(buf));\r\n    wait();\r\n  }\r\n  exit();\r\n}<\/pre>\n
cd\u306f\u30b7\u30a7\u30eb\u81ea\u8eab\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u5909\u3048\u306a\u3051\u308c\u3070\u3044\u3051\u306a\u3044\u3068\u3044\u3046\u3053\u3068\u304c\u305d\u306e\u7406\u7531\u3067\u3042\u308b\u3002
\n\u3082\u3057cd\u304c\u901a\u5e38\u306e\u30b3\u30de\u30f3\u30c9\u3068\u540c\u3058\u3088\u3046\u306b\u5b9f\u884c\u3055\u308c\u308b\u3068\u3001\u30b7\u30a7\u30eb\u306f\u5b50\u30d7\u30ed\u30bb\u30b9\u3092fork\u3057\u3001\u5b50\u30d7\u30ed\u30bb\u30b9\u304ccd\u3092\u5b9f\u884c\u3059\u308b\u8a33\u3067\u3001\u3053\u308c\u3067\u306f\u5b50\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u304c\u5909\u308f\u308b\u3060\u3051\u3067\u3001\u89aa\u30d7\u30ed\u30bb\u30b9\uff08\u30b7\u30a7\u30eb\uff09\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u5909\u308f\u3089\u306a\u3044\u304b\u3089\u3067\u3042\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
cd\u30b3\u30de\u30f3\u30c9\u306e\u30b7\u30a7\u30eb\u3078\u306e\u7d44\u307f\u8fbc\u307e\u308c\u5177\u5408\u306b\u3061\u3087\u3063\u3068\u9a5a\u304d\u307e\u3057\u305f\u3002<\/p>\n
\u305d\u308c\u4ee5\u5916\u306f\u77e5\u3063\u3066\u308b\u3053\u3068\u3070\u304b\u308a\u3060\u3063\u305f\u306e\u3067\u7279\u306b\u30a2\u30ec\u3067\u3059\u3002<\/p>\n
\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u5b58\u5728\u3059\u308b\u3068unlink\u3057\u3066\u3082\u6d88\u3048\u305a\u3001close\u3055\u308c\u305f\u6bb5\u968e\u3067\u81ea\u52d5\u7684\u306b\u6d88\u3048\u308b\u3068\u3044\u3046\u306e\u306f\u4fbf\u5229\u304b\u306a\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n
\u6b21\u56de\u306fChapter 0\u306e\u6700\u5f8c\u306e\u7bc0\u3067\u3059\u3002
\n\u77ed\u304f\u30b3\u30fc\u30c9\u3082\u306a\u3044\u307f\u305f\u3044\u306a\u306e\u3067\u30b5\u30af\u3063\u3068\u8aad\u3081\u305d\u3046\u3067\u3059\u304c\u3001\u3055\u3089\u306b\u305d\u306e\u6b21\u306eChapter 1\u304c\u304b\u306a\u308a\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u5bc4\u308a\u5185\u5bb9\u307f\u305f\u3044\u3067\u7406\u89e3\u3067\u304d\u308b\u304b\u4e0d\u5b89\u3067\u3059\u3002
\n\u304c\u307e\u3041\u4e00\u65e5\u4e00\u7bc0\u3068\u884c\u304b\u306a\u304f\u3066\u3082\u306a\u3093\u3068\u304b\u307c\u3061\u307c\u3061\u3084\u3063\u3066\u3044\u3051\u308c\u3070\u3068\u601d\u3063\u3066\u304a\u308a\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u30c6\u30ad\u30b9\u30c8\u306e14\u301c15\u30da\u30fc\u30b8<\/p>\n
\u672c\u6587<\/h3>\n
xv6\u306f\u3001\u30c7\u30fc\u30bf\u30d5\u30a1\u30a4\u30eb\uff08\u89e3\u91c8\u3055\u308c\u3066\u3044\u306a\u3044\u751f\u306e\u30d0\u30a4\u30c8\u5217\uff09\u3068\u3001\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\uff08\u4ed6\u306e\u30c7\u30fc\u30bf\u30d5\u30a1\u30a4\u30eb\u3084\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u542b\u3080\uff09\u3092\u63d0\u4f9b\u3059\u308b\u3002
\nxv6\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u3001\u7279\u5225\u306a\u7a2e\u985e\u306e\u30d5\u30a1\u30a4\u30eb\u3068\u3057\u3066\u5b9f\u88c5\u3057\u3066\u3044\u308b\u3002
\n\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u3001root\u3068\u547c\u3070\u308c\u308b\u7279\u6b8a\u306a\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u304b\u3089\u59cb\u307e\u308b\u30c4\u30ea\u30fc\u306e\u4e2d\u306b\u914d\u7f6e\u3055\u308c\u308b\u3002
\n\/a\/b\/c \u306e\u3088\u3046\u306a\u30d1\u30b9\u306f\u3001\u30eb\u30fc\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea”\/”\u306e\u4e2d\u306b\u3042\u308ba\u3068\u3044\u3046\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306e\u4e2d\u306b\u3042\u308bb\u3068\u3044\u3046\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306e\u4e2d\u306b\u3042\u308bc\u3068\u540d\u4ed8\u3051\u3089\u308c\u305f\u30d5\u30a1\u30a4\u30eb\uff08\u3082\u3057\u304f\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\uff09\u3092\u6307\u3057\u793a\u3059\u3002
\n“\/”\u304b\u3089\u59cb\u307e\u3063\u3066\u306a\u3044\u30d1\u30b9\u306f\u3001\u305d\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea(current directory)\u3092\u8d77\u70b9\u306b\u76f8\u5bfe\u7684\u306b\u8a55\u4fa1\u3055\u308c\u308b\u3002
\n\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u3001chdir\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3067\u5909\u66f4\u51fa\u6765\u308b\u3002
\n\u4ee5\u4e0b\u306e2\u3064\u306e\u30b3\u30fc\u30c9\u306f\u540c\u3058\u30d5\u30a1\u30a4\u30eb\u3092\u958b\u304f\u3002<\/p>\n
chdir("\/a");\r\nchdir("b");\r\nopen("c", O_RDONLY);<\/pre>\n
open("\/a\/b\/c", O_RDONLY);<\/pre>\n
\u6700\u521d\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092”\/a\/b”\u306b\u5909\u66f4\u3059\u308b\u3002
\n2\u3064\u3081\u306e\u30b3\u30fc\u30c9\u306f\u3001\u30d7\u30ed\u30bb\u30b9\u306e\u73fe\u5728\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u5909\u66f4\u3057\u306a\u3044\u3002<\/p>\n
\u65b0\u3057\u3044\u30d5\u30a1\u30a4\u30eb\u3084\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u4f5c\u308b\u305f\u3081\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u304c\u3044\u304f\u3064\u304b\u3042\u308b\u3002
\nmkdir\u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u4f5c\u6210\u3059\u308b\u3002
\nopen\u3092O_CREATE\u30d5\u30e9\u30b0\u3067\u547c\u3076\u3068\u65b0\u3057\u3044\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3059\u308b\u3002
\nmknod\u3067\u65b0\u3057\u3044\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3059\u308b\u3002
\n\u4ee5\u4e0a3\u3064\u5168\u3066\u306b\u3064\u3044\u3066\u6b21\u3067\u4f8b\u793a\u3059\u308b\u3002<\/p>\n
mkdir("\/dir");\r\nfd = open("\/dir\/file", O_CREATE|O_WRONLY);\r\nclose(fd);\r\nmknod("\/console", 1, 1);<\/pre>\n
mknod\u306f\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u306e\u4e2d\u306b\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u308b\u304c\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u306f\u4e2d\u8eab\u3092\u6301\u305f\u306a\u3044\u3002
\n\u3057\u304b\u3057\u306a\u304c\u3089\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u306b\u306f\u305d\u308c\u304c\u30c7\u30d0\u30a4\u30b9\u30d5\u30a1\u30a4\u30eb\u3067\u3042\u308b\u3068\u3044\u3046\u60c5\u5831\u304c\u30de\u30fc\u30af\u3055\u308c\u3001\u30ab\u30fc\u30cd\u30eb\u30c7\u30d0\u30a4\u30b9\u3092\u4e00\u610f\u306b\u8b58\u5225\u3059\u308b\u305f\u3081\u306e\u30e1\u30b8\u30e3\u30fc\u305d\u3057\u3066\u30de\u30a4\u30ca\u30fc\u30c7\u30d0\u30a4\u30b9\u756a\u53f7\uff08mknod\u306e\u5f15\u6570\u306e\u5f8c\u308d\u4e8c\u3064\u306b\u5bfe\u5fdc\uff09\u304c\u8a18\u9332\u3055\u308c\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u304c\u5f8c\u3067\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u958b\u3044\u305f\u3068\u304d\u3001\u30ab\u30fc\u30cd\u30eb\u306fread\u3084write\u306e\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u3092\u3001\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u3078read\u3057\u305f\u308awrite\u3057\u305f\u308a\u3059\u308b\u4ee3\u308f\u308a\u306b\u3001\u30ab\u30fc\u30cd\u30eb\u30c7\u30d0\u30a4\u30b9\u306e\u5b9f\u88c5\u3078\u3059\u308a\u66ff\u3048\u308b\u3002<\/p>\n
fstat\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u6307\u3057\u793a\u3057\u3066\u3044\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u3064\u3044\u3066\u306e\u60c5\u5831\u3092\u53d6\u308a\u51fa\u3059\u3002
\nstat.h\u306b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308bstat\u69cb\u9020\u4f53\u3067\u7d50\u679c\u304c\u8fd4\u3063\u3066\u304f\u308b\u3002
\n\uff08\u3061\u306a\u307f\u306b\u4ee5\u4e0b\u306fstat.h\u306e\u4e00\u90e8\u3067\u306f\u306a\u304f\u5168\u3066\u3067\u3059\uff09<\/p>\n
#define T_DIR  1   \/\/ Directory\r\n#define T_FILE 2   \/\/ File\r\n#define T_DEV  3   \/\/ Special device\r\n\r\nstruct stat {\r\n  short type;  \/\/ Type of file\r\n  int dev;     \/\/ Device number\r\n  uint ino;    \/\/ Inode number on device\r\n  short nlink; \/\/ Number of links to file\r\n  uint size;   \/\/ Size of file in bytes\r\n};<\/pre>\n
\u30d5\u30a1\u30a4\u30eb\u540d\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u81ea\u4f53\u3068\u306f\u5225\u306b\u306a\u3063\u3066\u3044\u308b\u3002\uff08stat\u69cb\u9020\u4f53\u306b\u306fname\u306a\u3093\u3066\u30e1\u30f3\u30d0\u306f\u306a\u3044\uff09
\n1\u3064\u306e\u30d5\u30a1\u30a4\u30eb\uff08inode\uff09\u306f\u8907\u6570\u306e\u540d\u524d\uff08link\uff09\u3092\u6301\u3064\u3053\u3068\u304c\u51fa\u6765\u308b\u3002
\nlink\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306f\u3001\u65e2\u5b58\u306e\u30d5\u30a1\u30a4\u30eb\u306a\u3069\u3068\u540c\u3058inode\u3092\u6307\u3057\u793a\u3059\u3088\u3046\u306a\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u4e0a\u306e\u5225\u540d\u3092\u4f5c\u6210\u3059\u308b\u3002
\n\u6b21\u306e\u30b3\u30fc\u30c9\u306f\u3001a\u3068\u3044\u3046\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u6210\u3057\u3001b\u3068\u3044\u3046\u5225\u540d\u3092\u3064\u3051\u308b\u3002<\/p>\n
open("a", O_CREATE|O_WRONLY);\r\nlink("a", "b");<\/pre>\n
a\u306b\u5bfe\u3059\u308b\u8aad\u307f\u66f8\u304d\u306f\u3001b\u306b\u5bfe\u3059\u308b\u8aad\u307f\u66f8\u304d\u3068\u540c\u3058\u3067\u3042\u308b\u3002
\n\u3069\u306einode\u3082\u4e00\u610f\u306einode\u756a\u53f7\u3067\u8b58\u5225\u3055\u308c\u308b\u3002
\n\u4e0a\u306e\u30b3\u30fc\u30c9\u304c\u5b9f\u884c\u3055\u308c\u305f\u3042\u3068\u3001fstat\u306e\u7d50\u679c\u3092\u8abf\u3079\u308b\u3068a\u3068b\u304c\u540c\u3058\u5185\u5bb9\u3092\u53c2\u7167\u3057\u3066\u308b\u3068\u3044\u3046\u3053\u3068\u304c\u5206\u304b\u308b\u3002
\n\u3064\u307e\u308a\u4e21\u65b9\u3068\u3082\u540c\u3058inode\u756a\u53f7\uff08ino\uff09\u304c\u8fd4\u3063\u3066\u304f\u308b\u306f\u305a\u3067\u3042\u308b\u3002
\n\u305d\u3057\u3066nlink\u306b\u306f2\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u306f\u305a\u3067\u3042\u308b\u3002<\/p>\n
unlink\u30b7\u30b9\u30c6\u30e0\u30b3\u30fc\u30eb\u306f\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u304b\u3089\u540d\u524d\u3092\u53d6\u308a\u9664\u304f\u3002
\n\u30d5\u30a1\u30a4\u30eb\u306einode\u3068\u30c7\u30a3\u30b9\u30af\u30b9\u30da\u30fc\u30b9\u304c\u89e3\u653e\u3055\u308c\u308b\u306e\u306f\u3001\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3078\u306e\u30ea\u30f3\u30af\u6570\u304c\u30bc\u30ed\u306b\u306a\u3063\u305f\u3068\u304d\u3001\u304b\u3064\u305d\u306e\u30d5\u30a1\u30a4\u30eb\u3092\u53c2\u7167\u3059\u308b\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u306a\u3044\u3068\u304d\u3060\u3051\u3067\u3042\u308b\u3002
\n\u306a\u306e\u3067\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u306e\u6700\u5f8c\u306b<\/p>\n
unlink("a");<\/pre>\n
\u3092\u8ffd\u52a0\u3057\u3066\u3082\u3001b\u3068\u3057\u3066\u30a2\u30af\u30bb\u30b9\u53ef\u80fd\u306ainode\u3068\u305d\u306e\u5185\u5bb9\u306f\u6d88\u3048\u306a\u3044\u3002<\/p>\n
fd = open("\/tmp\/xyz", O_CREATE|O_RDWR);\r\nunlink("\/tmp\/xyz");<\/pre>\n
\u3053\u306e\u30b3\u30fc\u30c9\u306f\u3001\u4e00\u6642\u7684\u306ainode\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306b\u7406\u306b\u304b\u306a\u3063\u305f\u65b9\u6cd5\u3067\u3042\u308b\u3002
\n\u30d7\u30ed\u30bb\u30b9\u304cfd\u3092close\u3057\u305f\u3068\u304d\u3001\u3082\u3057\u304f\u306f\u30d7\u30ed\u30bb\u30b9\u304c\u7d42\u4e86\u3057\u305f\u3068\u304d\u306b\u3001\u81ea\u52d5\u7684\u306b\u4e00\u6642\u30d5\u30a1\u30a4\u30eb\u304c\u6d88\u53bb\u3055\u308c\u308b\u3002<\/p>\n
\u30d5\u30a1\u30a4\u30eb\u30b7\u30b9\u30c6\u30e0\u3092\u64cd\u4f5c\u3059\u308bxv6\u306e\u30b3\u30de\u30f3\u30c9\u306f\u3001mkdir, ln, rm\u7b49\u306e\u3088\u3046\u306b\u30e6\u30fc\u30b6\u30ec\u30d9\u30eb\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u3068\u3057\u3066\u5b9f\u88c5\u3055\u308c\u3066\u3044\u308b\u3002
\n\u3053\u306e\u30c7\u30b6\u30a4\u30f3\u306b\u3088\u3063\u3066\u3001\u65b0\u3057\u3044\u30e6\u30fc\u30b6\u30fc\u30b3\u30de\u30f3\u30c9\u306b\u3088\u3063\u3066\u30b7\u30a7\u30eb\u3092\u62e1\u5f35\u3059\u308b\u4e8b\u304c\u53ef\u80fd\u3068\u306a\u308b\u3002
\n\u4eca\u3068\u306a\u3063\u3066\u306f\u3001\u3053\u306e\u8a2d\u8a08\u306e\u5229\u70b9\u306f\u660e\u3089\u304b\u3060\u304c\u3001Unix\u304c\u751f\u307e\u308c\u305f\u6642\u4ee3\u306b\u8a2d\u8a08\u3055\u308c\u305f\u4ed6\u306e\u30b7\u30b9\u30c6\u30e0\u306f\u3001\u3057\u3070\u3057\u3070\u305d\u306e\u3088\u3046\u306a\u30b3\u30de\u30f3\u30c9\u3092\u30b7\u30a7\u30eb\u306e\u4e2d\u306b\u7d44\u307f\u8fbc\u3093\u3067\u3042\u308b\u3002\uff08\u305d\u3057\u3066\u30b7\u30a7\u30eb\u81ea\u4f53\u3082\u30e6\u30fc\u30b6\u7a7a\u9593\u3067\u306f\u306a\u304f\u30ab\u30fc\u30cd\u30eb\u7a7a\u9593\u3067\u5b9f\u884c\u3055\u308c\u308b\u3088\u3046\u306b\u306a\u3063\u3066\u305f\u308a\u3059\u308b\u3002\uff09<\/p>\n
1\u3064\u306e\u4f8b\u5916\u304ccd\u3067\u3001\u30b7\u30a7\u30eb\u306e\u4e2d\u306b\u7d44\u307f\u8fbc\u307e\u308c\u3066\u3044\u308b\u3002
\n\uff08sh.c\u306emain\u95a2\u6570\u3002\u4e8c\u3064\u76ee\u306ewhile\u6587\u306e\u4e2d\u306e\u6700\u521d\u306eif\u6587\u306b\u6ce8\u76ee\uff09<\/p>\n
int\r\nmain(void)\r\n{\r\n  static char buf[100];\r\n  int fd;\r\n  \r\n  \/\/ Assumes three file descriptors open.\r\n  while((fd = open("console", O_RDWR)) >= 0){\r\n    if(fd >= 3){\r\n      close(fd);\r\n      break;\r\n    }\r\n  }\r\n  \r\n  \/\/ Read and run input commands.\r\n  while(getcmd(buf, sizeof(buf)) >= 0){\r\n    if(buf[0] == 'c' && buf[1] == 'd' && buf[2] == ' '){\r\n      \/\/ Clumsy but will have to do for now.\r\n      \/\/ Chdir has no effect on the parent if run in the child.\r\n      buf[strlen(buf)-1] = 0;  \/\/ chop \\n\r\n      if(chdir(buf+3) < 0)\r\n        printf(2, "cannot cd %s\\n", buf+3);\r\n      continue;\r\n    }\r\n    if(fork1() == 0)\r\n      runcmd(parsecmd(buf));\r\n    wait();\r\n  }\r\n  exit();\r\n}<\/pre>\n
cd\u306f\u30b7\u30a7\u30eb\u81ea\u8eab\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3092\u5909\u3048\u306a\u3051\u308c\u3070\u3044\u3051\u306a\u3044\u3068\u3044\u3046\u3053\u3068\u304c\u305d\u306e\u7406\u7531\u3067\u3042\u308b\u3002
\n\u3082\u3057cd\u304c\u901a\u5e38\u306e\u30b3\u30de\u30f3\u30c9\u3068\u540c\u3058\u3088\u3046\u306b\u5b9f\u884c\u3055\u308c\u308b\u3068\u3001\u30b7\u30a7\u30eb\u306f\u5b50\u30d7\u30ed\u30bb\u30b9\u3092fork\u3057\u3001\u5b50\u30d7\u30ed\u30bb\u30b9\u304ccd\u3092\u5b9f\u884c\u3059\u308b\u8a33\u3067\u3001\u3053\u308c\u3067\u306f\u5b50\u30d7\u30ed\u30bb\u30b9\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u304c\u5909\u308f\u308b\u3060\u3051\u3067\u3001\u89aa\u30d7\u30ed\u30bb\u30b9\uff08\u30b7\u30a7\u30eb\uff09\u306e\u30ab\u30ec\u30f3\u30c8\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306f\u5909\u308f\u3089\u306a\u3044\u304b\u3089\u3067\u3042\u308b\u3002<\/p>\n
\u611f\u60f3<\/h3>\n
cd\u30b3\u30de\u30f3\u30c9\u306e\u30b7\u30a7\u30eb\u3078\u306e\u7d44\u307f\u8fbc\u307e\u308c\u5177\u5408\u306b\u3061\u3087\u3063\u3068\u9a5a\u304d\u307e\u3057\u305f\u3002<\/p>\n
\u305d\u308c\u4ee5\u5916\u306f\u77e5\u3063\u3066\u308b\u3053\u3068\u3070\u304b\u308a\u3060\u3063\u305f\u306e\u3067\u7279\u306b\u30a2\u30ec\u3067\u3059\u3002<\/p>\n
\u30d5\u30a1\u30a4\u30eb\u30c7\u30a3\u30b9\u30af\u30ea\u30d7\u30bf\u304c\u5b58\u5728\u3059\u308b\u3068unlink\u3057\u3066\u3082\u6d88\u3048\u305a\u3001close\u3055\u308c\u305f\u6bb5\u968e\u3067\u81ea\u52d5\u7684\u306b\u6d88\u3048\u308b\u3068\u3044\u3046\u306e\u306f\u4fbf\u5229\u304b\u306a\u3068\u601d\u3044\u307e\u3059\u3002<\/p>\n
\u6b21\u56de\u306fChapter 0\u306e\u6700\u5f8c\u306e\u7bc0\u3067\u3059\u3002
\n\u77ed\u304f\u30b3\u30fc\u30c9\u3082\u306a\u3044\u307f\u305f\u3044\u306a\u306e\u3067\u30b5\u30af\u3063\u3068\u8aad\u3081\u305d\u3046\u3067\u3059\u304c\u3001\u3055\u3089\u306b\u305d\u306e\u6b21\u306eChapter 1\u304c\u304b\u306a\u308a\u30cf\u30fc\u30c9\u30a6\u30a7\u30a2\u5bc4\u308a\u5185\u5bb9\u307f\u305f\u3044\u3067\u7406\u89e3\u3067\u304d\u308b\u304b\u4e0d\u5b89\u3067\u3059\u3002
\n\u304c\u307e\u3041\u4e00\u65e5\u4e00\u7bc0\u3068\u884c\u304b\u306a\u304f\u3066\u3082\u306a\u3093\u3068\u304b\u307c\u3061\u307c\u3061\u3084\u3063\u3066\u3044\u3051\u308c\u3070\u3068\u601d\u3063\u3066\u304a\u308a\u307e\u3059\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[405],"class_list":["post-1241","post","type-post","status-publish","format-standard","hentry","category-tech","tag-xv6"],"_links":{"self":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1241","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/comments?post=1241"}],"version-history":[{"count":0,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1241\/revisions"}],"wp:attachment":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/media?parent=1241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/categories?post=1241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/tags?post=1241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}