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[PATCH] nscd: Eliminate compilation time dependency in the build output
- From: fweimer at redhat dot com (Florian Weimer)
- To: libc-alpha at sourceware dot org
- Date: Thu, 05 Oct 2017 16:49:57 +0200
- Subject: [PATCH] nscd: Eliminate compilation time dependency in the build output
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2017-10-05 Florian Weimer <fweimer@redhat.com>
nscd: Eliminate compilation time dependency in the build output.
* nscd/nscd_stat.c (STATDATA_VERSION)
(STATDATA_VERSION_SELINUX_FLAG, STATDATA_VERSION_FLAGS)
(STATDATA_VERSION_FULL): New macro definitions.
(compilation): Remove.
(struct statdata): Adjust version member.
(send_stats): Set version from STATDATA_VERSION_FULL.
(receive_print_stats): Verify version against STATDATA_VERSION_FULL.
diff --git a/nscd/nscd_stat.c b/nscd/nscd_stat.c
index feb1c98ac3..b1bc81bd6d 100644
--- a/nscd/nscd_stat.c
+++ b/nscd/nscd_stat.c
@@ -35,9 +35,23 @@
# include <selinux/avc.h>
#endif /* HAVE_SELINUX */
+/* We use this to make sure the receiver is the same. The lower 16
+ bits are reserved for flags indicating compilation variants. This
+ version needs to be updated if the definition of struct statdata
+ changes. */
+#define STATDATA_VERSION 0x01020000U
-/* We use this to make sure the receiver is the same. */
-static const char compilation[21] = __DATE__ " " __TIME__;
+#ifdef HAVE_SELINUX
+# define STATDATA_VERSION_SELINUX_FLAG 0x0001U
+#else
+# define STATDATA_VERSION_SELINUX_FLAG 0x0000U
+#endif
+
+/* All flags affecting the struct statdata layout. */
+#define STATDATA_VERSION_FLAGS STATDATA_VERSION_SELINUX_FLAG
+
+/* The full version number for struct statdata. */
+#define STATDATA_VERSION_FULL (STATDATA_VERSION | STATDATA_VERSION_FLAGS)
/* Statistic data for one database. */
struct dbstat
@@ -68,10 +82,11 @@ struct dbstat
uintmax_t addfailed;
};
-/* Record for transmitting statistics. */
+/* Record for transmitting statistics. If this definition changes,
+ update STATDATA_VERSION above. */
struct statdata
{
- char version[sizeof (compilation)];
+ unsigned int version; /* Must be STATDATA_VERSION_FULL. */
int debug_level;
time_t runtime;
unsigned long int client_queued;
@@ -96,7 +111,7 @@ send_stats (int fd, struct database_dyn dbs[lastdb])
memset (&data, 0, sizeof (data));
- memcpy (data.version, compilation, sizeof (compilation));
+ data.version = STATDATA_VERSION_FULL;
data.debug_level = debug_level;
data.runtime = time (NULL) - start_time;
data.client_queued = client_queued;
@@ -196,7 +211,7 @@ receive_print_stats (void)
/* Read as much data as we expect. */
if (TEMP_FAILURE_RETRY (read (fd, &data, sizeof (data))) != sizeof (data)
- || (memcmp (data.version, compilation, sizeof (compilation)) != 0
+ || (data.version != STATDATA_VERSION_FULL
/* Yes, this is an assignment! */
&& (errno = EINVAL)))
{