Add pw_dup(3), a function to copy 'struct passwd'. It is allocated as

a single chunk with the strings pointing elsewhere in the buffer so
a simple free() of the struct passwd * is all that is needed to decallocate.

1 files changed, 91 insertions, 0 deletions

diff --git a/lib/libc/gen/pw_dup.3 b/lib/libc/gen/pw_dup.3
new file mode 100644
index 00000000000..90905f28d94
--- /dev/null
+++ b/lib/libc/gen/pw_dup.3
@@ -0,0 +1,91 @@
+.\"	$OpenBSD: pw_dup.3,v 1.1 2000/11/21 00:49:58 millert Exp $
+.\"
+.\" Copyright (c) 2000 Todd C. Miller <Todd.Miller@courtesan.com>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. The name of the author may not be used to endorse or promote products
+.\"    derived from this software without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+.\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+.\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd November 15, 2000
+.Dt PW_DUP 3
+.Os
+.Sh NAME
+.Nm pw_dup
+.Nd make a copy of a struct passwd
+.Sh SYNOPSIS
+.Fd #include <pwd.h>
+.Ft struct passwd *
+.Fn pw_dup "cost struct passwd *pw"
+.Sh DESCRIPTION
+The
+.Fn pw_dup
+function allocates sufficient memory for a copy of the struct passwd
+.Fa pw ,
+does the copy, and returns a pointer to it.  This is useful as
+subsequent calls to
+.Fn getpwent ,
+.Fn getpwnam ,
+and
+.Fn getpwuid
+will overwrite the data from previous calls.
+.Pp
+The returned pointer may be deallocated by a single call to
+.Xr free 3 .
+Since
+.Fn pw_dup
+allocates space for the copy in one chunk it is not necessary to free
+the individual strings contained in the returned struct passwd.
+.Pp
+If insufficient memory is available,
+.Dv NULL
+is returned.
+.Sh EXAMPLES
+The following will make a copy of the struct passwd for root and
+store it in
+.Qq pw_save :
+.Bd -literal -offset indent
+struct passwd *pw, *pw_save;
+
+if ((pw = getpwnam("root")) == NULL) {
+	fprintf(stderr, "Cannot find root in the password file.\en");
+	exit(1);
+}
+if ((pw_save = pw_dup(pw)) == NULL) {
+	fprintf(stderr, "Out of memory.\en");
+	exit(1);
+}
+.Ed
+.Sh ERRORS
+.Fn pw_dup
+function may fail and set the external variable
+.Va errno
+for any of the errors specified for the library function
+.Xr malloc 3 .
+.Sh SEE ALSO
+.Xr free 3 ,
+.Xr getpwent 3 ,
+.Xr malloc 3
+.Sh HISTORY
+The
+.Fn pw_dup
+function first appeared in
+.Ox 2.9 .