如何在 C/C++ 中以编程方式读取 linux 文件权限
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How to read linux file permission programmatically in C/C++
提问by Bao Le
How can I read linux file permission programmatically instead using "ls" then parse the result.
如何以编程方式读取 linux 文件权限而不是使用“ls”然后解析结果。
采纳答案by Greg Hewgill
The stat(2)system call returns a struct statthat contains a st_modemember. This is the mode bits that ls -ldisplays.
该stat(2)系统调用返回一个struct stat包含st_mode成员。这是ls -l显示的模式位。
On my system, the man 2 statpage says:
在我的系统上，man 2 stat页面显示：
The following flags are defined for the st_mode field:
S_IFMT 0170000 bitmask for the file type bitfields
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
回答by Chalasani Arjith
This is a function in C, that returns file permissions in the string format "rwxr-r--"
这是 C 中的一个函数，它以字符串格式“rwxr-r--”返回文件权限
char* permissions(char *file){
struct stat st;
char *modeval = malloc(sizeof(char) * 9 + 1);
if(stat(file, &st) == 0){
mode_t perm = st.st_mode;
modeval[0] = (perm & S_IRUSR) ? 'r' : '-';
modeval[1] = (perm & S_IWUSR) ? 'w' : '-';
modeval[2] = (perm & S_IXUSR) ? 'x' : '-';
modeval[3] = (perm & S_IRGRP) ? 'r' : '-';
modeval[4] = (perm & S_IWGRP) ? 'w' : '-';
modeval[5] = (perm & S_IXGRP) ? 'x' : '-';
modeval[6] = (perm & S_IROTH) ? 'r' : '-';
modeval[7] = (perm & S_IWOTH) ? 'w' : '-';
modeval[8] = (perm & S_IXOTH) ? 'x' : '-';
modeval[9] = '##代码##';
return modeval;
}
else{
return strerror(errno);
}
}
