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upstream: fseek to end of known_hosts before writing to it. 

POSIX and ANSI C require that applications call fseek or similar between
read and writing to a RW file.  OpenBSD doesn't enforce this, but some
(System V derived) platforms need this to prevent it from writing a
spurious extra byte (in this case, a newline).  ok djm@ deraadt@

OpenBSD-Commit-ID: 33e680dcd8110582a93a40a8491024e961f45137
This commit is contained in:
dtucker@openbsd.org 2023-02-21 06:48:18 +00:00 committed by Darren Tucker
parent 357fb8ae14
commit fe0bd3cde9
No known key found for this signature in database
1 changed files with 9 additions and 8 deletions
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7
hostfile.c
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@ -1,4 +1,4 @@
/* $OpenBSD: hostfile.c,v 1.94 2023/02/09 09:54:11 dtucker Exp $ */ /* $OpenBSD: hostfile.c,v 1.95 2023/02/21 06:48:18 dtucker Exp $ */
/* /*
* Author: Tatu Ylonen <ylo@cs.hut.fi> * Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@ -515,7 +515,7 @@ add_host_to_hostfile(const char *filename, const char *host,
const struct sshkey *key, int store_hash) const struct sshkey *key, int store_hash)
{ {
FILE *f; FILE *f;
int success; int success, addnl = 0;
if (key == NULL) if (key == NULL)
return 1; /* XXX ? */ return 1; /* XXX ? */
@ -525,7 +525,8 @@ add_host_to_hostfile(const char *filename, const char *host,
return 0; return 0;
/* Make sure we have a terminating newline. */ /* Make sure we have a terminating newline. */
if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n') if (fseek(f, -1L, SEEK_END) == 0 && fgetc(f) != '\n')
if (fputc('\n', f) != '\n') { addnl = 1;
if (fseek(f, 0L, SEEK_END) != 0 || (addnl && fputc('\n', f) != '\n')) {
error("Failed to add terminating newline to %s: %s", error("Failed to add terminating newline to %s: %s",
filename, strerror(errno)); filename, strerror(errno));
fclose(f); fclose(f);