Question

$ git ls-tree fb3a8bdd0ce
100644 blob 63c918c667fa005ff12ad89437f2fdc80926e21c    .gitignore
100644 blob 5529b198e8d14decbe4ad99db3f7fb632de0439d    .mailmap
100644 blob 6ff87c4664981e4397625791c8ea3bbb5f2279a3    COPYING
040000 tree 2fb783e477100ce076f6bf57e4a6f026013dc745    Documentation
100755 blob 3c0032cec592a765692234f1cba47dfdcc3a9200    GIT-VERSION-GEN
100644 blob 289b046a443c0647624607d471289b2c7dcd470b    INSTALL
100644 blob 4eb463797adc693dc168b926b6932ff53f17d0b1    Makefile
100644 blob 548142c327a6790ff8821d67c2ee1eff7a656b52    README
...

我知道最后3个八位数字是文件模式，但前三位数是多少？我无法在git用户手册中找到它。

Answer 1

从Git index-format.txt文件中，关于模式：

32-bit mode, split into (high to low bits)

    4-bit object type
      valid values in binary are 1000 (regular file), 1010 (symbolic link)
      and 1110 (gitlink)

    3-bit unused

    9-bit unix permission. Only 0755 and 0644 are valid for regular files.
    Symbolic links and gitlinks have value 0 in this field.

此外，如fsck.c fsck_tree方法所示，允许使用目录对象类型（二进制0100）和组可写（0664权限）常规文件。常规的非可执行组可写文件是早期版本的Git中支持的非标准模式。

这使得有效模式（二进制和八进制）：

0100000000000000（040000）：目录
1000000110100100（100644）：常规非可执行文件
1000000110110100（100664）：常规非可执行组可写文件
1000000111101101（100755）：常规可执行文件
1010000000000000（120000）：符号链接
1110000000000000（160000）：Gitlink

Answer 2

6位数字表示使用经典UNIX表示法的文件模式。前两位显示文件类型，第三位是set-uid / set-gid / sticky位，你知道最后三位。

以下是man 2 stat在我的GNU / Linux系统上记录它的方式：

   The following flags are defined for the st_mode field:

       S_IFMT     0170000   bit mask for the file type bit fields
       S_IFSOCK   0140000   socket
       S_IFLNK    0120000   symbolic link
       S_IFREG    0100000   regular file
       S_IFBLK    0060000   block device
       S_IFDIR    0040000   directory
       S_IFCHR    0020000   character device
       S_IFIFO    0010000   FIFO
       S_ISUID    0004000   set UID bit
       S_ISGID    0002000   set-group-ID bit (see below)
       S_ISVTX    0001000   sticky bit (see below)
       S_IRWXU    00700     mask for file owner permissions
       S_IRUSR    00400     owner has read permission
       S_IWUSR    00200     owner has write permission
       S_IXUSR    00100     owner has execute permission
       S_IRWXG    00070     mask for group permissions
       S_IRGRP    00040     group has read permission
       S_IWGRP    00020     group has write permission
       S_IXGRP    00010     group has execute permission
       S_IRWXO    00007     mask for permissions for others (not in group)
       S_IROTH    00004     others have read permission           
       S_IWOTH    00002     others have write permission
       S_IXOTH    00001     others have execute permission

如何读取git-ls-tree输出的mode字段

2 个答案: