listgroups_unix.go

Documentation: os/user

		 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 || darwin || freebsd || (!android && linux) || netbsd || openbsd || (solaris && !illumos)) && cgo && !osusergo
		 6  // +build dragonfly darwin freebsd !android,linux netbsd openbsd solaris,!illumos
		 7  // +build cgo
		 8  // +build !osusergo
		 9  
		10  package user
		11  
		12  import (
		13  	"fmt"
		14  	"strconv"
		15  	"unsafe"
		16  )
		17  
		18  /*
		19  #include <unistd.h>
		20  #include <sys/types.h>
		21  */
		22  import "C"
		23  
		24  const maxGroups = 2048
		25  
		26  func listGroups(u *User) ([]string, error) {
		27  	ug, err := strconv.Atoi(u.Gid)
		28  	if err != nil {
		29  		return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
		30  	}
		31  	userGID := C.gid_t(ug)
		32  	nameC := make([]byte, len(u.Username)+1)
		33  	copy(nameC, u.Username)
		34  
		35  	n := C.int(256)
		36  	gidsC := make([]C.gid_t, n)
		37  	rv := getGroupList((*C.char)(unsafe.Pointer(&nameC[0])), userGID, &gidsC[0], &n)
		38  	if rv == -1 {
		39  		// Mac is the only Unix that does not set n properly when rv == -1, so
		40  		// we need to use different logic for Mac vs. the other OS's.
		41  		if err := groupRetry(u.Username, nameC, userGID, &gidsC, &n); err != nil {
		42  			return nil, err
		43  		}
		44  	}
		45  	gidsC = gidsC[:n]
		46  	gids := make([]string, 0, n)
		47  	for _, g := range gidsC[:n] {
		48  		gids = append(gids, strconv.Itoa(int(g)))
		49  	}
		50  	return gids, nil
		51  }
		52
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