From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH 2/5] resolv: Use <file_change_detection.h> in __resolv_conf_get_current
Date: Thu, 13 Feb 2020 20:53:00 -0000 [thread overview]
Message-ID: <6bb92349-0f68-dc7b-0b57-1f68a028b55a@linaro.org> (raw)
In-Reply-To: <c657cfe9aedbc48a368f11442f453190ed1cf1e9.1579631655.git.fweimer@redhat.com>
On 21/01/2020 15:41, Florian Weimer wrote:
> Only minor functional changes (i.e., regarding the handling of
> directories, which are now treated as empty files).
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> resolv/resolv_conf.c | 43 ++++++++-----------------------------------
> 1 file changed, 8 insertions(+), 35 deletions(-)
>
> diff --git a/resolv/resolv_conf.c b/resolv/resolv_conf.c
> index 08c50ef19e..d954ba9a5a 100644
> --- a/resolv/resolv_conf.c
> +++ b/resolv/resolv_conf.c
> @@ -24,6 +24,7 @@
> #include <resolv-internal.h>
> #include <sys/stat.h>
> #include <libc-symbols.h>
> +#include <file_change_detection.h>
>
> /* _res._u._ext.__glibc_extension_index is used as an index into a
> struct resolv_conf_array object. The intent of this construction
> @@ -68,12 +69,8 @@ struct resolv_conf_global
> /* Cached current configuration object for /etc/resolv.conf. */
> struct resolv_conf *conf_current;
>
> - /* These properties of /etc/resolv.conf are used to check if the
> - configuration needs reloading. */
> - struct timespec conf_mtime;
> - struct timespec conf_ctime;
> - off64_t conf_size;
> - ino64_t conf_ino;
> + /* File system identification for /etc/resolv.conf. */
> + struct file_change_detection file_resolve_conf;
> };
>
> /* Lazily allocated storage for struct resolv_conf_global. */
Ok.
> @@ -123,37 +120,16 @@ conf_decrement (struct resolv_conf *conf)
> struct resolv_conf *
> __resolv_conf_get_current (void)
> {
> - struct stat64 st;
> - if (stat64 (_PATH_RESCONF, &st) != 0)
> - {
> - switch (errno)
> - {
> - case EACCES:
> - case EISDIR:
> - case ELOOP:
> - case ENOENT:
> - case ENOTDIR:
> - case EPERM:
> - /* Ignore errors due to file system contents. */
> - memset (&st, 0, sizeof (st));
> - break;
> - default:
> - /* Other errors are fatal. */
> - return NULL;
> - }
> - }
> + struct file_change_detection initial;
> + if (!file_change_detection_for_path (&initial, _PATH_RESCONF))
> + return NULL;
>
Ok.
> struct resolv_conf_global *global_copy = get_locked_global ();
> if (global_copy == NULL)
> return NULL;
> struct resolv_conf *conf;
> if (global_copy->conf_current != NULL
> - && (global_copy->conf_mtime.tv_sec == st.st_mtim.tv_sec
> - && global_copy->conf_mtime.tv_nsec == st.st_mtim.tv_nsec
> - && global_copy->conf_ctime.tv_sec == st.st_ctim.tv_sec
> - && global_copy->conf_ctime.tv_nsec == st.st_ctim.tv_nsec
> - && global_copy->conf_ino == st.st_ino
> - && global_copy->conf_size == st.st_size))
> + && file_is_unchanged (&initial, &global_copy->file_resolve_conf))
> /* We can reuse the cached configuration object. */
> conf = global_copy->conf_current;
> else
> @@ -171,10 +147,7 @@ __resolv_conf_get_current (void)
> read could be a newer version of the file, but this does
> not matter because this will lead to an extraneous reload
> later. */
> - global_copy->conf_mtime = st.st_mtim;
> - global_copy->conf_ctime = st.st_ctim;
> - global_copy->conf_ino = st.st_ino;
> - global_copy->conf_size = st.st_size;
> + global_copy->file_resolve_conf = initial;
> }
> }
>
>
Ok.
next prev parent reply other threads:[~2020-02-13 20:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 18:41 [PATCH 0/5] Race condition in /etc/resolv.conf reloading (bug 25420) Florian Weimer
2020-01-21 18:41 ` [PATCH 1/5] Add internal <file_change_detection.h> header file Florian Weimer
2020-02-10 19:47 ` Adhemerval Zanella
2020-02-10 19:58 ` Florian Weimer
2020-02-10 20:57 ` Adhemerval Zanella
2020-01-21 18:42 ` [PATCH 4/5] resolv: Enhance __resolv_conf_load to capture file change data Florian Weimer
2020-02-13 21:33 ` Adhemerval Zanella
2020-01-21 18:42 ` [PATCH 3/5] resolv: Fix file handle leak in __resolv_conf_load [BZ #25429] Florian Weimer
2020-02-13 21:01 ` Adhemerval Zanella
2020-02-13 21:08 ` Florian Weimer
2020-02-13 21:30 ` Adhemerval Zanella
2020-01-21 18:42 ` [PATCH 2/5] resolv: Use <file_change_detection.h> in __resolv_conf_get_current Florian Weimer
2020-02-13 20:53 ` Adhemerval Zanella [this message]
2020-01-21 21:28 ` [PATCH 5/5] resolv: Fix ABA race in /etc/resolv.conf change detection [BZ #25420] Florian Weimer
2020-02-13 21:59 ` Adhemerval Zanella
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