* pgstat_get_crashed_backend_activity() -
*
* Return a string representing the current activity of the backend with
- * the specified PID. Like the function above, but reads shared memory with
- * the expectation that it may be corrupt. Returns either a pointer to a
- * constant string, or writes into the 'buffer' argument and returns it.
+ * the specified PID. Like the function above, but reads shared memory with
+ * the expectation that it may be corrupt. On success, copy the string
+ * into the "buffer" argument and return that pointer. On failure,
+ * return NULL.
*
- * This function is only intended to be used by postmaster to report the
- * query that crashed the backend. In particular, no attempt is made to
+ * This function is only intended to be used by the postmaster to report the
+ * query that crashed a backend. In particular, no attempt is made to
* follow the correct concurrency protocol when accessing the
- * BackendStatusArray. But that's OK, in the worst case we'll return a
- * corrupted message. We also must take care not to trip on ereport(ERROR).
- *
- * Note: return strings for special cases match pg_stat_get_backend_activity.
+ * BackendStatusArray. But that's OK, in the worst case we'll return a
+ * corrupted message. We also must take care not to trip on ereport(ERROR).
* ----------
*/
const char *
-pgstat_get_crashed_backend_activity(int pid, char *buffer,
- int len)
+pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
{
volatile PgBackendStatus *beentry;
int i;
beentry = BackendStatusArray;
+
+ /*
+ * We probably shouldn't get here before shared memory has been set up,
+ * but be safe.
+ */
+ if (beentry == NULL || BackendActivityBuffer == NULL)
+ return NULL;
+
for (i = 1; i <= MaxBackends; i++)
{
if (beentry->st_procpid == pid)
const char *activity_last;
/*
- * We can't access activity pointer before we verify that it
- * falls into BackendActivityBuffer. To make sure that the entire
- * string including its ending is contained within the buffer,
- * we subtract one activity length from it.
+ * We mustn't access activity string before we verify that it
+ * falls within the BackendActivityBuffer. To make sure that the
+ * entire string including its ending is contained within the
+ * buffer, subtract one activity length from the buffer size.
*/
activity_last = BackendActivityBuffer + BackendActivityBufferSize
- - pgstat_track_activity_query_size;
+ - pgstat_track_activity_query_size;
if (activity < BackendActivityBuffer ||
activity > activity_last)
- return "<command string corrupt>";
+ return NULL;
- if (*(activity) == '\0')
- return "<command string empty>";
+ /* If no string available, no point in a report */
+ if (activity[0] == '\0')
+ return NULL;
/*
* Copy only ASCII-safe characters so we don't run into encoding
- * problems when reporting the message.
+ * problems when reporting the message; and be sure not to run
+ * off the end of memory.
*/
- ascii_safe_strncpy(buffer, activity, len);
+ ascii_safe_strlcpy(buffer, activity,
+ Min(buflen, pgstat_track_activity_query_size));
return buffer;
}
}
/* PID not found */
- return "<backend information not available>";
+ return NULL;
}
+
/* ------------------------------------------------------------
* Local support functions follow
* ------------------------------------------------------------
static void
LogChildExit(int lev, const char *procname, int pid, int exitstatus)
{
- char activity_buffer[1024]; /* default track_activity_query_size */
- const char *activity;
+ /*
+ * size of activity_buffer is arbitrary, but set equal to default
+ * track_activity_query_size
+ */
+ char activity_buffer[1024];
+ const char *activity = NULL;
- activity = pgstat_get_crashed_backend_activity(pid,
- activity_buffer,
- sizeof(activity_buffer));
+ if (!EXIT_STATUS_0(exitstatus))
+ activity = pgstat_get_crashed_backend_activity(pid,
+ activity_buffer,
+ sizeof(activity_buffer));
if (WIFEXITED(exitstatus))
ereport(lev,
"server process" */
(errmsg("%s (PID %d) exited with exit code %d",
procname, pid, WEXITSTATUS(exitstatus)),
- errdetail("Running query: %s", activity)));
+ activity ? errdetail("Failed process was running: %s", activity) : 0));
else if (WIFSIGNALED(exitstatus))
#if defined(WIN32)
ereport(lev,
(errmsg("%s (PID %d) was terminated by exception 0x%X",
procname, pid, WTERMSIG(exitstatus)),
errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."),
- errdetail("Running query: %s", activity)));
+ activity ? errdetail("Failed process was running: %s", activity) : 0));
#elif defined(HAVE_DECL_SYS_SIGLIST) && HAVE_DECL_SYS_SIGLIST
ereport(lev,
procname, pid, WTERMSIG(exitstatus),
WTERMSIG(exitstatus) < NSIG ?
sys_siglist[WTERMSIG(exitstatus)] : "(unknown)"),
- errdetail("Running query: %s", activity)));
+ activity ? errdetail("Failed process was running: %s", activity) : 0));
#else
ereport(lev,
"server process" */
(errmsg("%s (PID %d) was terminated by signal %d",
procname, pid, WTERMSIG(exitstatus)),
- errdetail("Running query: %s", activity)));
+ activity ? errdetail("Failed process was running: %s", activity) : 0));
#endif
else
ereport(lev,
"server process" */
(errmsg("%s (PID %d) exited with unrecognized status %d",
procname, pid, exitstatus),
- errdetail("Running query: %s", activity)));
+ activity ? errdetail("Failed process was running: %s", activity) : 0));
}
/*
}
/* ----------
- * "Escape" a string in unknown encoding to a valid ASCII string.
- * Replace non-ASCII bytes with '?'
- * This must not trigger ereport(ERROR), as it is called from postmaster.
+ * Copy a string in an arbitrary backend-safe encoding, converting it to a
+ * valid ASCII string by replacing non-ASCII bytes with '?'. Otherwise the
+ * behavior is identical to strlcpy(), except that we don't bother with a
+ * return value.
*
- * Unlike C strncpy(), the result is always terminated with exactly one null
- * byte.
+ * This must not trigger ereport(ERROR), as it is called in postmaster.
* ----------
*/
void
-ascii_safe_strncpy(char *dest, const char *src, int len)
+ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz)
{
- int i;
+ if (destsiz == 0) /* corner case: no room for trailing nul */
+ return;
- for (i = 0; i < (len - 1); i++)
+ while (--destsiz > 0)
{
- unsigned char ch = src[i]; /* use unsigned char here to avoid compiler warning */
+ /* use unsigned char here to avoid compiler warning */
+ unsigned char ch = *src++;
if (ch == '\0')
break;
/* Keep printable ASCII characters */
if (32 <= ch && ch <= 127)
- dest[i] = ch;
+ *dest = ch;
/* White-space is also OK */
else if (ch == '\n' || ch == '\r' || ch == '\t')
- dest[i] = ch;
+ *dest = ch;
/* Everything else is replaced with '?' */
else
- dest[i] = '?';
+ *dest = '?';
+ dest++;
}
- dest[i] = '\0';
+ *dest = '\0';
}
extern void pgstat_report_waiting(bool waiting);
extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
- int len);
+ int buflen);
extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
extern PgStat_BackendFunctionEntry *find_funcstat_entry(Oid func_id);
extern Datum to_ascii_encname(PG_FUNCTION_ARGS);
extern Datum to_ascii_enc(PG_FUNCTION_ARGS);
extern Datum to_ascii_default(PG_FUNCTION_ARGS);
-extern void ascii_safe_strncpy(char *dest, const char *src, int len);
+
+extern void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz);
#endif /* _ASCII_H_ */
projects / postgresql / commitdiff