macOS xattr-acls extra stuff

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```bash rm -rf /tmp/test* echo test >/tmp/test chmod +a "everyone deny write,writeattr,writeextattr,writesecurity,chown" /tmp/test ./get_acls test ACL for test: !#acl 1 group:ABCDEFAB-CDEF-ABCD-EFAB-CDEF0000000C:everyone:12:deny:write,writeattr,writeextattr,writesecurity,chown

ACL in hex: \x21\x23\x61\x63\x6c\x20\x31\x0a\x67\x72\x6f\x75\x70\x3a\x41\x42\x43\x44\x45\x46\x41\x42\x2d\x43\x44\x45\x46\x2d\x41\x42\x43\x44\x2d\x45\x46\x41\x42\x2d\x43\x44\x45\x46\x30\x30\x30\x30\x30\x30\x30\x43\x3a\x65\x76\x65\x72\x79\x6f\x6e\x65\x3a\x31\x32\x3a\x64\x65\x6e\x79\x3a\x77\x72\x69\x74\x65\x2c\x77\x72\x69\x74\x65\x61\x74\x74\x72\x2c\x77\x72\x69\x74\x65\x65\x78\x74\x61\x74\x74\x72\x2c\x77\x72\x69\x74\x65\x73\x65\x63\x75\x72\x69\x74\x79\x2c\x63\x68\x6f\x77\x6e\x0a

<details>

<summary>获取 ACLs 的代码</summary>
```c
// gcc -o get_acls get_acls
#include <stdio.h>
#include <stdlib.h>
#include <sys/acl.h>

int main(int argc, char *argv[]) {
if (argc != 2) {
fprintf(stderr, "Usage: %s <filepath>\n", argv[0]);
return 1;
}

const char *filepath = argv[1];
acl_t acl = acl_get_file(filepath, ACL_TYPE_EXTENDED);
if (acl == NULL) {
perror("acl_get_file");
return 1;
}

char *acl_text = acl_to_text(acl, NULL);
if (acl_text == NULL) {
perror("acl_to_text");
acl_free(acl);
return 1;
}

printf("ACL for %s:\n%s\n", filepath, acl_text);

// Convert acl_text to hexadecimal and print it
printf("ACL in hex: ");
for (char *c = acl_text; *c != '\0'; c++) {
printf("\\x%02x", (unsigned char)*c);
}
printf("\n");

acl_free(acl);
acl_free(acl_text);
return 0;
}

```bash # Lets add the xattr com.apple.xxx.xxxx with the acls mkdir start mkdir start/protected ./set_xattr start/protected echo something > start/protected/something ```

set_xattr 的代码

```c // gcc -o set_xattr set_xattr.c #include #include #include #include #include

void print_xattrs(const char *filepath) { ssize_t buflen = listxattr(filepath, NULL, 0, XATTR_NOFOLLOW); if (buflen < 0) { perror("listxattr"); return; }

char *buf = malloc(buflen); if (buf == NULL) { perror("malloc"); return; }

buflen = listxattr(filepath, buf, buflen, XATTR_NOFOLLOW); if (buflen < 0) { perror("listxattr"); free(buf); return; }

printf("All current extended attributes for %s:\n", filepath); for (char *name = buf; name < buf + buflen; name += strlen(name) + 1) { printf("%s: ", name); ssize_t valuelen = getxattr(filepath, name, NULL, 0, 0, XATTR_NOFOLLOW); if (valuelen < 0) { perror("getxattr"); continue; }

char *value = malloc(valuelen + 1); if (value == NULL) { perror("malloc"); continue; }

valuelen = getxattr(filepath, name, value, valuelen, 0, XATTR_NOFOLLOW); if (valuelen < 0) { perror("getxattr"); free(value); continue; }

value[valuelen] = '\0'; // Null-terminate the value printf("%s\n", value); free(value); }

free(buf); }

int main(int argc, char *argv[]) { if (argc != 2) { fprintf(stderr, "Usage: %s \n", argv[0]); return 1; }

const char *hex = "\x21\x23\x61\x63\x6c\x20\x31\x0a\x67\x72\x6f\x75\x70\x3a\x41\x42\x43\x44\x45\x46\x41\x42\x2d\x43\x44\x45\x46\x2d\x41\x42\x43\x44\x2d\x45\x46\x41\x42\x2d\x43\x44\x45\x46\x30\x30\x30\x30\x30\x30\x30\x43\x3a\x65\x76\x65\x72\x79\x6f\x6e\x65\x3a\x31\x32\x3a\x64\x65\x6e\x79\x3a\x77\x72\x69\x74\x65\x2c\x77\x72\x69\x74\x65\x61\x74\x74\x72\x2c\x77\x72\x69\x74\x65\x65\x78\x74\x61\x74\x74\x72\x2c\x77\x72\x69\x74\x65\x73\x65\x63\x75\x72\x69\x74\x79\x2c\x63\x68\x6f\x77\x6e\x0a"; const char *filepath = argv[1];

int result = setxattr(filepath, "com.apple.xxx.xxxx", hex, strlen(hex), 0, 0); if (result == 0) { printf("Extended attribute set successfully.\n\n"); } else { perror("setxattr"); return 1; }

print_xattrs(filepath);

return 0; }

</details>

<div data-gb-custom-block data-tag="code" data-overflow='wrap'>

```bash
# Create appledoublefile with the xattr entitlement
ditto -c -k start protected.zip
rm -rf start
# extract the files
unzip protected.zip
# Replace the name of the xattr here (if you put it before ditto would have destroyed it)
python3 -c "with open('._protected', 'rb+') as f: content = f.read().replace(b'com.apple.xxx.xxxx', b'com.apple.acl.text'); f.seek(0); f.write(content); f.truncate()"
# zip everything back together
rm -rf protected.zip
zip -r protected.zip protected ._protected
rm -rf protected
rm ._*

</div>
# Check if it worked
ditto -x -k --rsrc protected.zip .
xattr -l protected

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