[24/30] resolv: Move __res_context_hostalias into its own file and into libc

  And reformat it to GNU style.  Remove the unecessary setbuf call.
Use __fgets_unlocked for PLT avoidance; no locking is required here.
---
 resolv/Makefile                |   1 +
 resolv/Versions                |   2 +-
 resolv/res_context_hostalias.c | 132 +++++++++++++++++++++++++++++++++
 resolv/res_query.c             |  40 ----------
 resolv/resolv-internal.h       |   2 +-
 5 files changed, 135 insertions(+), 42 deletions(-)
 create mode 100644 resolv/res_context_hostalias.c
  

On 7/8/21 11:06 AM, Florian Weimer via Libc-alpha wrote:
> And reformat it to GNU style.  Remove the unecessary setbuf call.
> Use __fgets_unlocked for PLT avoidance; no locking is required here.

OK for glibc 2.34.

Tested without regression on x86_64 and i686.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

> ---
>  resolv/Makefile                |   1 +
>  resolv/Versions                |   2 +-
>  resolv/res_context_hostalias.c | 132 +++++++++++++++++++++++++++++++++
>  resolv/res_query.c             |  40 ----------
>  resolv/resolv-internal.h       |   2 +-
>  5 files changed, 135 insertions(+), 42 deletions(-)
>  create mode 100644 resolv/res_context_hostalias.c
> 
> diff --git a/resolv/Makefile b/resolv/Makefile
> index 83ba39cb52..bfcca70f26 100644
> --- a/resolv/Makefile
> +++ b/resolv/Makefile
> @@ -48,6 +48,7 @@ routines := \
>    res-close \
>    res-name-checking \
>    res-state \
> +  res_context_hostalias \

OK.

>    res_get_nsaddr \
>    res_hconf \
>    res_init \
> diff --git a/resolv/Versions b/resolv/Versions
> index 5bbda96230..b084660dde 100644
> --- a/resolv/Versions
> +++ b/resolv/Versions
> @@ -85,6 +85,7 @@ libc {
>      __ns_name_skip;
>      __ns_name_uncompress;
>      __ns_name_unpack;
> +    __res_context_hostalias;

OK.

>      __res_get_nsaddr;
>      __res_iclose;
>      __resolv_context_get;
> @@ -192,7 +193,6 @@ libresolv {
>    GLIBC_PRIVATE {
>      __ns_get16;
>      __ns_get32;
> -    __res_context_hostalias;

OK.

>      __res_context_query;
>      __res_context_search;
>    }
> diff --git a/resolv/res_context_hostalias.c b/resolv/res_context_hostalias.c
> new file mode 100644
> index 0000000000..b4dc1763db
> --- /dev/null
> +++ b/resolv/res_context_hostalias.c
> @@ -0,0 +1,132 @@
> +/* HOSTALIASES-based name resolution.  Internal function.

OK.

> +   Copyright (C) 2015-2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +/*
> + * Copyright (c) 1988, 1993
> + *    The Regents of the University of California.  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.
> + * 4. Neither the name of the University nor the names of its contributors
> + *    may be used to endorse or promote products derived from this software
> + *    without specific prior written permission.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
> + */
> +
> +/*
> + * Portions Copyright (c) 1993 by Digital Equipment Corporation.
> + *
> + * Permission to use, copy, modify, and distribute this software for any
> + * purpose with or without fee is hereby granted, provided that the above
> + * copyright notice and this permission notice appear in all copies, and that
> + * the name of Digital Equipment Corporation not be used in advertising or
> + * publicity pertaining to distribution of the document or software without
> + * specific, written prior permission.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
> + * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
> + * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
> + * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
> + * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
> + * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
> + * SOFTWARE.
> + */
> +
> +/*
> + * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
> + *
> + * Permission to use, copy, modify, and distribute this software for any
> + * purpose with or without fee is hereby granted, provided that the above
> + * copyright notice and this permission notice appear in all copies.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
> + * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
> + * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
> + * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
> + * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
> + * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
> + * SOFTWARE.
> + */
> +
> +#include <arpa/nameser.h>
> +#include <ctype.h>
> +#include <resolv-internal.h>
> +#include <resolv_context.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +
> +const char *
> +__res_context_hostalias (struct resolv_context *ctx,
> +                         const char *name, char *dst, size_t siz)
> +{
> +  char *file, *cp1, *cp2;
> +  char buf[BUFSIZ];
> +  FILE *fp;
> +
> +  if (ctx->resp->options & RES_NOALIASES)
> +    return NULL;
> +  file = getenv ("HOSTALIASES");
> +  if (file == NULL || (fp = fopen (file, "rce")) == NULL)
> +    return NULL;

OK. Drop setbuf as not required.

> +  buf[sizeof (buf) - 1] = '\0';

OK. Terminate.

> +  while (__fgets_unlocked (buf, sizeof (buf), fp))

OK.

> +    {
> +      for (cp1 = buf; *cp1 && !isspace (*cp1); ++cp1)
> +        ;
> +      if (!*cp1)
> +        break;
> +      *cp1 = '\0';
> +      if (__libc_ns_samename (buf, name) == 1)
> +        {
> +          while (isspace (*++cp1))
> +            ;
> +          if (!*cp1)
> +            break;
> +          for (cp2 = cp1 + 1; *cp2 && !isspace (*cp2); ++cp2)
> +            ;
> +          *cp2 = '\0';
> +          strncpy (dst, cp1, siz - 1);
> +          dst[siz - 1] = '\0';
> +          fclose (fp);
> +          return dst;

OK.

> +        }
> +    }
> +  fclose (fp);
> +  return NULL;

OK.

> +}
> +libc_hidden_def (__res_context_hostalias)
> diff --git a/resolv/res_query.c b/resolv/res_query.c
> index 5b51af8451..45c591ae27 100644
> --- a/resolv/res_query.c
> +++ b/resolv/res_query.c
> @@ -635,46 +635,6 @@ res_querydomain (const char *name, const char *domain, int class, int type,
>      (__resolv_context_get (), name, domain, class, type, answer, anslen);
>  }
>  
> -const char *
> -__res_context_hostalias (struct resolv_context *ctx,
> -			 const char *name, char *dst, size_t siz)
> -{
> -	char *file, *cp1, *cp2;
> -	char buf[BUFSIZ];
> -	FILE *fp;
> -
> -	if (ctx->resp->options & RES_NOALIASES)
> -		return (NULL);
> -	file = getenv("HOSTALIASES");
> -	if (file == NULL || (fp = fopen(file, "rce")) == NULL)
> -		return (NULL);
> -	setbuf(fp, NULL);
> -	buf[sizeof(buf) - 1] = '\0';
> -	while (fgets(buf, sizeof(buf), fp)) {
> -		for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
> -			;
> -		if (!*cp1)
> -			break;
> -		*cp1 = '\0';
> -		if (__libc_ns_samename(buf, name) == 1) {
> -			while (isspace(*++cp1))
> -				;
> -			if (!*cp1)
> -				break;
> -			for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
> -				;
> -			*cp2 = '\0';
> -			strncpy(dst, cp1, siz - 1);
> -			dst[siz - 1] = '\0';
> -			fclose(fp);
> -			return (dst);
> -		}
> -	}
> -	fclose(fp);
> -	return (NULL);
> -}
> -libresolv_hidden_def (__res_context_hostalias)

OK. Remove.

> -
>  /* Common part of res_hostalias and hostalias.  */
>  static const char *
>  context_hostalias_common (struct resolv_context *ctx,
> diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h
> index c18b1d0472..7d37817232 100644
> --- a/resolv/resolv-internal.h
> +++ b/resolv/resolv-internal.h
> @@ -79,7 +79,7 @@ int __res_context_send (struct resolv_context *, const unsigned char *, int,
>  /* Internal function similar to res_hostalias.  */
>  const char *__res_context_hostalias (struct resolv_context *,
>                                       const char *, char *, size_t);
> -libresolv_hidden_proto (__res_context_hostalias);
> +libc_hidden_proto (__res_context_hostalias);

OK.

>  
>  /* Add an OPT record to a DNS query.  */
>  int __res_nopt (struct resolv_context *, int n0,
>