acl: implement removeEntry in C

Signed-off-by: Ophestra <cat@gensokyo.uk>

acl/acl-update.c

@@ -0,0 +1,47 @@
+#include "acl-update.h"
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/acl.h>
+#include <acl/libacl.h>
+
+acl_t f_acl_get_file(const char *path_p, acl_type_t type) {
+    acl_t acl = acl_get_file(path_p, type);
+    free((void *)path_p);
+    return acl;
+}
+
+int f_acl_set_file(const char *path_p, acl_type_t type, acl_t acl) {
+    if (acl_valid(acl) != 0) {
+        return -1;
+    }
+
+    int ret = acl_set_file(path_p, type, acl);
+    free((void *)path_p);
+    return ret;
+}
+
+void f_acl_delete_by_uid(acl_t acl, uid_t uid) {
+    acl_entry_t entry; // acl_get_entry does not store entry_p
+    acl_tag_t tag_type; // acl_get_tag_type does not store tag_type_p
+    void *qualifier_p;
+    bool res;
+
+    for (int r = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry); r == 1; r = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry)) {
+        if (acl_get_tag_type(entry, &tag_type) != 0)
+            return;
+        if (tag_type != ACL_USER)
+            continue;
+
+        qualifier_p = acl_get_qualifier(entry);
+        if (qualifier_p == NULL)
+            return;
+        res = *(uid_t *)qualifier_p == uid;
+        acl_free(qualifier_p);
+
+        if (!res)
+            continue;
+
+        acl_delete_entry(acl, entry);
+        break;
+    }
+}

acl/acl-update.h

@@ -0,0 +1,5 @@
+#include <sys/acl.h>
+
+acl_t f_acl_get_file(const char *path_p, acl_type_t type);
+int f_acl_set_file(const char *path_p, acl_type_t type, acl_t acl);
+void f_acl_delete_by_uid(acl_t acl, uid_t uid);

acl/acl.go

@@ -11,30 +11,12 @@ import (
 /*
 #cgo linux pkg-config: --static libacl
 
-#include <stdlib.h>
-#include <sys/acl.h>
-#include <acl/libacl.h>
-
-static acl_t _go_acl_get_file(const char *path_p, acl_type_t type) {
-	acl_t acl = acl_get_file(path_p, type);
-	free((void *)path_p);
-	return acl;
-}
-
-static int _go_acl_set_file(const char *path_p, acl_type_t type, acl_t acl) {
-	if (acl_valid(acl) != 0) {
-		return -1;
-	}
-
-	int ret = acl_set_file(path_p, type, acl);
-	free((void *)path_p);
-	return ret;
-}
+#include "acl-update.h"
 */
 import "C"
 
 func getFile(name string, t C.acl_type_t) (*ACL, error) {
-	a, err := C._go_acl_get_file(C.CString(name), t)
+	a, err := C.f_acl_get_file(C.CString(name), t)
 	if errors.Is(err, syscall.ENODATA) {
 		err = nil
 	}
@@ -43,7 +25,7 @@ func getFile(name string, t C.acl_type_t) (*ACL, error) {
 }
 
 func (acl *ACL) setFile(name string, t C.acl_type_t) error {
-	_, err := C._go_acl_set_file(C.CString(name), t, acl.acl)
+	_, err := C.f_acl_set_file(C.CString(name), t, acl.acl)
 	return err
 }
 
@@ -85,54 +67,9 @@ type (
 	Perm C.acl_perm_t
 )
 
-func (acl *ACL) removeEntry(tt C.acl_tag_t, tq int) error {
-	var e C.acl_entry_t
-
-	// get first entry
-	if r, err := C.acl_get_entry(acl.acl, C.ACL_FIRST_ENTRY, &e); err != nil {
-		return err
-	} else if r == 0 {
-		// return on acl with no entries
-		return nil
-	}
-
-	for {
-		if r, err := C.acl_get_entry(acl.acl, C.ACL_NEXT_ENTRY, &e); err != nil {
-			return err
-		} else if r == 0 {
-			// return on drained acl
-			return nil
-		}
-
-		var (
-			q int
-			t C.acl_tag_t
-		)
-
-		// get current entry tag type
-		if _, err := C.acl_get_tag_type(e, &t); err != nil {
-			return err
-		}
-
-		// get current entry qualifier
-		if rq, err := C.acl_get_qualifier(e); err != nil {
-			// neither ACL_USER nor ACL_GROUP
-			if errors.Is(err, syscall.EINVAL) {
-				continue
-			}
-
-			return err
-		} else {
-			q = *(*int)(rq)
-			C.acl_free(rq)
-		}
-
-		// delete on match
-		if t == tt && q == tq {
-			_, err := C.acl_delete_entry(acl.acl, e)
-			return err
-		}
-	}
+func (acl *ACL) removeEntry(uid int) error {
+	_, err := C.f_acl_delete_by_uid(acl.acl, C.uid_t(uid))
+	return err
 }
 
 // Update replaces ACL_USER entry with qualifier uid.
@@ -146,7 +83,7 @@ func Update(name string, uid int, perms ...Perm) error {
 	defer a.free()
 
 	// remove existing entry
-	if err = a.removeEntry(User, uid); err != nil {
+	if err = a.removeEntry(uid); err != nil {
 		return err
 	}