getgrouplist_unix.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build (dragonfly || freebsd || (!android && linux) || netbsd || openbsd || (solaris && !illumos)) && cgo && !osusergo
     6  
     7  package user
     8  
     9  /*
    10  #include <unistd.h>
    11  #include <sys/types.h>
    12  #include <grp.h>
    13  
    14  static int mygetgrouplist(const char* user, gid_t group, gid_t* groups, int* ngroups) {
    15  	return getgrouplist(user, group, groups, ngroups);
    16  }
    17  */
    18  import "C"
    19  import (
    20  	"fmt"
    21  	"unsafe"
    22  )
    23  
    24  func getGroupList(name *C.char, userGID C.gid_t, gids *C.gid_t, n *C.int) C.int {
    25  	return C.mygetgrouplist(name, userGID, gids, n)
    26  }
    27  
    28  // groupRetry retries getGroupList with much larger size for n. The result is
    29  // stored in gids.
    30  func groupRetry(username string, name []byte, userGID C.gid_t, gids *[]C.gid_t, n *C.int) error {
    31  	// More than initial buffer, but now n contains the correct size.
    32  	if *n > maxGroups {
    33  		return fmt.Errorf("user: %q is a member of more than %d groups", username, maxGroups)
    34  	}
    35  	*gids = make([]C.gid_t, *n)
    36  	rv := getGroupList((*C.char)(unsafe.Pointer(&name[0])), userGID, &(*gids)[0], n)
    37  	if rv == -1 {
    38  		return fmt.Errorf("user: list groups for %s failed", username)
    39  	}
    40  	return nil
    41  }
    42
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