Merge pull request #1629 from wiredtiger/session-strerror

WT_SESSION.strerror

12 files changed, 110 insertions, 91 deletions

diff --git a/src/config/config_def.c b/src/config/config_def.c
index b04cd823055..43d87c518e4 100644
--- a/src/config/config_def.c
+++ b/src/config/config_def.c
@@ -668,6 +668,10 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  "force=0",
 	  confchk_session_salvage
 	},
+	{ "session.strerror",
+	  "",
+	  NULL
+	},
 	{ "session.truncate",
 	  "",
 	  NULL
diff --git a/src/conn/api_strerror.c b/src/conn/api_strerror.c
index 4b2f6f12f7c..f08d70969dd 100644
--- a/src/conn/api_strerror.c
+++ b/src/conn/api_strerror.c
@@ -5,7 +5,7 @@
 /*
  * Historically, there was only the wiredtiger_strerror call because the POSIX
  * port didn't need anything more complex; Windows requires memory allocation
- * of error strings, so we added the wiredtiger_strerror_r call. Because we
+ * of error strings, so we added the WT_SESSION.strerror method. Because we
  * want wiredtiger_strerror to continue to be as thread-safe as possible, errors
  * are split into three categories: WiredTiger constant strings, system constant
  * strings and Everything Else, and we check constant strings before Everything
@@ -16,8 +16,8 @@
  * __wiredtiger_error --
  *	Return a constant string for the WiredTiger errors.
  */
-static const char *
-__wiredtiger_error(int error)
+const char *
+__wt_wiredtiger_error(int error)
 {
 	switch (error) {
 	case WT_ROLLBACK:
@@ -49,34 +49,15 @@ wiredtiger_strerror(int error)
 	const char *p;
 
 	/* Check for a constant string. */
-	if ((p = __wiredtiger_error(error)) != NULL ||
-	    (p = __wt_strerror(error)) != NULL)
+	if ((p = __wt_wiredtiger_error(error)) != NULL)
+		return (p);
+	if ((p = __wt_strerror(error)) != NULL)
 		return (p);
 
 	/* Else, fill in the non-thread-safe static buffer. */
-	if (wiredtiger_strerror_r(error, buf, sizeof(buf)) != 0)
-		(void)snprintf(buf, sizeof(buf), "error return: %d", error);
-
-	return (buf);
-}
-
-/*
- * wiredtiger_strerror_r --
- *	Return a string for any error value, thread-safe version.
- */
-int
-wiredtiger_strerror_r(int error, char *buf, size_t buflen)
-{
-	const char *p;
-
-	/* Require at least 2 bytes, printable character and trailing nul. */
-	if (buflen < 2)
-		return (ENOMEM);
-
-	/* Check for a constant string. */
-	if ((p = __wiredtiger_error(error)) != NULL ||
-	    (p = __wt_strerror(error)) != NULL)
-		return (snprintf(buf, buflen, "%s", p) > 0 ? 0 : ENOMEM);
+	if (snprintf(buf, sizeof(buf), "error return: %d", error) > 0)
+		return (buf);
 
-	return (__wt_strerror_r(error, buf, buflen));
+	/* OK, we're done. */
+	return ("Unable to return error string");
 }
diff --git a/src/conn/conn_api.c b/src/conn/conn_api.c
index 5be55a77f24..0562f9cfc34 100644
--- a/src/conn/conn_api.c
+++ b/src/conn/conn_api.c
@@ -117,7 +117,7 @@ __conn_get_extension_api(WT_CONNECTION *wt_conn)
 	conn->extension_api.conn = wt_conn;
 	conn->extension_api.err_printf = __wt_ext_err_printf;
 	conn->extension_api.msg_printf = __wt_ext_msg_printf;
-	conn->extension_api.strerror = wiredtiger_strerror;
+	conn->extension_api.strerror = __wt_ext_strerror;
 	conn->extension_api.scr_alloc = __wt_ext_scr_alloc;
 	conn->extension_api.scr_free = __wt_ext_scr_free;
 	conn->extension_api.collator_config = ext_collator_config;
diff --git a/src/include/config.h b/src/include/config.h
index 65757c2ef6d..046f515188c 100644
--- a/src/include/config.h
+++ b/src/include/config.h
@@ -73,14 +73,15 @@ struct __wt_config_parser_impl {
 #define	WT_CONFIG_ENTRY_session_rename			24
 #define	WT_CONFIG_ENTRY_session_rollback_transaction	25
 #define	WT_CONFIG_ENTRY_session_salvage			26
-#define	WT_CONFIG_ENTRY_session_truncate		27
-#define	WT_CONFIG_ENTRY_session_upgrade			28
-#define	WT_CONFIG_ENTRY_session_verify			29
-#define	WT_CONFIG_ENTRY_table_meta			30
-#define	WT_CONFIG_ENTRY_wiredtiger_open			31
-#define	WT_CONFIG_ENTRY_wiredtiger_open_all		32
-#define	WT_CONFIG_ENTRY_wiredtiger_open_basecfg		33
-#define	WT_CONFIG_ENTRY_wiredtiger_open_usercfg		34
+#define	WT_CONFIG_ENTRY_session_strerror		27
+#define	WT_CONFIG_ENTRY_session_truncate		28
+#define	WT_CONFIG_ENTRY_session_upgrade			29
+#define	WT_CONFIG_ENTRY_session_verify			30
+#define	WT_CONFIG_ENTRY_table_meta			31
+#define	WT_CONFIG_ENTRY_wiredtiger_open			32
+#define	WT_CONFIG_ENTRY_wiredtiger_open_all		33
+#define	WT_CONFIG_ENTRY_wiredtiger_open_basecfg		34
+#define	WT_CONFIG_ENTRY_wiredtiger_open_usercfg		35
 /*
  * configuration section: END
  * DO NOT EDIT: automatically built by dist/flags.py.
diff --git a/src/include/extern.h b/src/include/extern.h
index 40493b4aab4..3b08d79e842 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -198,6 +198,7 @@ extern void __wt_conn_config_discard(WT_SESSION_IMPL *session);
 extern int __wt_ext_config_parser_open(WT_EXTENSION_API *wt_ext, WT_SESSION *wt_session, const char *config, size_t len, WT_CONFIG_PARSER **config_parserp);
 extern int __wt_ext_config_get(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, WT_CONFIG_ARG *cfg_arg, const char *key, WT_CONFIG_ITEM *cval);
 extern int __wt_config_upgrade(WT_SESSION_IMPL *session, WT_ITEM *buf);
+extern const char *__wt_wiredtiger_error(int error);
 extern int __wt_collator_config(WT_SESSION_IMPL *session, const char *uri, WT_CONFIG_ITEM *cname, WT_CONFIG_ITEM *metadata, WT_COLLATOR **collatorp, int *ownp);
 extern int __wt_conn_remove_collator(WT_SESSION_IMPL *session);
 extern int __wt_conn_remove_compressor(WT_SESSION_IMPL *session);
@@ -438,7 +439,7 @@ extern int __wt_dlsym(WT_SESSION_IMPL *session, WT_DLH *dlh, const char *name, i
 extern int __wt_dlclose(WT_SESSION_IMPL *session, WT_DLH *dlh);
 extern int __wt_errno(void);
 extern const char *__wt_strerror(int error);
-extern int __wt_strerror_r(int error, char *buf, size_t buflen);
+extern const char *__wt_session_strerror(WT_SESSION_IMPL *session, int error);
 extern int __wt_exist(WT_SESSION_IMPL *session, const char *filename, int *existp);
 extern void __wt_fallocate_config(WT_SESSION_IMPL *session, WT_FH *fh);
 extern int __wt_fallocate( WT_SESSION_IMPL *session, WT_FH *fh, wt_off_t offset, wt_off_t len);
@@ -574,6 +575,7 @@ extern void __wt_errx(WT_SESSION_IMPL *session, const char *fmt, ...) WT_GCC_FUN
 extern int __wt_ext_err_printf( WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 3, 4)));
 extern int __wt_msg(WT_SESSION_IMPL *session, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 2, 3)));
 extern int __wt_ext_msg_printf( WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 3, 4)));
+extern const char *__wt_ext_strerror(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, int error);
 extern int __wt_progress(WT_SESSION_IMPL *session, const char *s, uint64_t v);
 extern void __wt_assert(WT_SESSION_IMPL *session, int error, const char *file_name, int line_number, const char *fmt, ...) WT_GCC_FUNC_DECL_ATTRIBUTE((format (printf, 5, 6)));
 extern int __wt_panic(WT_SESSION_IMPL *session);
diff --git a/src/include/session.h b/src/include/session.h
index 909f1daf5a4..36df35a104e 100644
--- a/src/include/session.h
+++ b/src/include/session.h
@@ -111,6 +111,8 @@ struct WT_COMPILER_TYPE_ALIGN(WT_CACHE_LINE_ALIGNMENT) __wt_session_impl {
 	} *scratch_track;
 #endif
 
+	WT_ITEM err;			/* Error buffer */
+
 	WT_TXN_ISOLATION isolation;
 	WT_TXN	txn;			/* Transaction state */
 	u_int	ncursors;		/* Count of active file cursors. */
diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in
index 772295f7104..d0d0f9eec77 100644
--- a/src/include/wiredtiger.in
+++ b/src/include/wiredtiger.in
@@ -835,6 +835,17 @@ struct __wt_session {
 	int __F(reconfigure)(WT_SESSION *session, const char *config);
 
 	/*!
+	 * Return information about an error as a string.
+	 *
+	 * @snippet ex_all.c Display an error thread safe
+	 *
+	 * @param session the session handle
+	 * @param error a return value from a WiredTiger function
+	 * @returns a string representation of the error
+	 */
+	const char *__F(strerror)(WT_SESSION *session, int error);
+
+	/*!
 	 * @name Cursor handles
 	 * @{
 	 */
@@ -2092,18 +2103,6 @@ int wiredtiger_open(const char *home,
  */
 const char *wiredtiger_strerror(int error);
 
-/*!
- * Return information about a WiredTiger error as a string, thread-safe version.
- *
- * @snippet ex_all.c Display an error thread safe
- *
- * @param error a return value from a WiredTiger call
- * @param buf a buffer of at least \c buflen bytes
- * @param buflen the length of the buffer
- * @returns zero for success, non-zero to indicate an error.
- */
-int wiredtiger_strerror_r(int error, char *buf, size_t buflen);
-
 #if !defined(SWIG)
 /*!
  * The interface implemented by applications to accept notifications
diff --git a/src/include/wiredtiger_ext.h b/src/include/wiredtiger_ext.h
index ee27b32ddf7..28fd8e18329 100644
--- a/src/include/wiredtiger_ext.h
+++ b/src/include/wiredtiger_ext.h
@@ -118,16 +118,17 @@ struct __wt_extension_api {
 	    WT_EXTENSION_API *, WT_SESSION *session, const char *fmt, ...);
 
 	/*!
-	 * Return information about an error as a string; the strerror method
-	 * is a superset of the ISO C99/POSIX 1003.1-2001 function strerror.
+	 * Return information about an error as a string.
 	 *
 	 * @snippet ex_data_source.c WT_EXTENSION_API strerror
 	 *
-	 * @param err a return value from a WiredTiger, C library or POSIX
-	 * function
+	 * @param wt_api the extension handle
+	 * @param session the session handle (or NULL if none available)
+	 * @param error a return value from a WiredTiger function
 	 * @returns a string representation of the error
 	 */
-	const char *(*strerror)(int err);
+	const char *(*strerror)(
+	    WT_EXTENSION_API *, WT_SESSION *session, int error);
 
 	/*!
 	 * Allocate short-term use scratch memory.
diff --git a/src/os_posix/os_errno.c b/src/os_posix/os_errno.c
index a58f13583ce..c022cfda6bc 100644
--- a/src/os_posix/os_errno.c
+++ b/src/os_posix/os_errno.c
@@ -43,27 +43,23 @@ __wt_strerror(int error)
 }
 
 /*
- * __wt_strerror_r --
- *	POSIX implementation of wiredtiger_strerror_r.
+ * __wt_session_strerror --
+ *	POSIX implementation of WT_SESSION.strerror.
  */
-int
-__wt_strerror_r(int error, char *buf, size_t buflen)
+const char *
+__wt_session_strerror(WT_SESSION_IMPL *session, int error)
 {
 	const char *p;
 
-	/* Require at least 2 bytes, printable character and trailing nul. */
-	if (buflen < 2)
-		return (ENOMEM);
+	/* Check for POSIX errors. */
+	if ((p = __wt_strerror(error)) != NULL)
+		return (p);
 
-	/*
-	 * Check for POSIX errors then fallback to something generic.  Copy the
-	 * string into the user's buffer, return success if anything printed.
-	 */
-	p = __wt_strerror(error);
-	if (p != NULL && snprintf(buf, buflen, "%s", p) > 0)
-		return (0);
+	/* Fallback to a generic message. */
+	if (__wt_buf_fmt(
+	    session, &session->err, "error return: %d", error) == 0)
+		return (session->err.data);
 
-	/* Fallback to a generic message, then guess it's a memory problem. */
-	return (
-	    snprintf(buf, buflen, "error return: %d", error) > 0 ? 0 : ENOMEM);
+	/* Defeated. */
+	return ("Unable to return error string");
 }
diff --git a/src/os_win/os_errno.c b/src/os_win/os_errno.c
index 00ee638fbe3..c81432299a3 100644
--- a/src/os_win/os_errno.c
+++ b/src/os_win/os_errno.c
@@ -77,27 +77,23 @@ __wt_strerror(int error)
 }
 
 /*
- * __wt_strerror_r --
- *	Windows implementation of wiredtiger_strerror_r.
+ * __wt_session_strerror --
+ *	Windows implementation of WT_SESSION.strerror.
  */
-int
-__wt_strerror_r(int error, char *buf, size_t buflen)
+const char *
+__wt_session_strerror(WT_SESSION_IMPL *session, int error)
 {
 	DWORD lasterror;
 	const char *p;
-
-	/* Require at least 2 bytes, printable character and trailing nul. */
-	if (buflen < 2)
-		return (ENOMEM);
+	char buf[256];
 
 	/*
 	 * Check for POSIX errors, Windows errors, then fallback to something
 	 * generic.  Copy the string into the user's buffer, return success if
 	 * anything printed.
 	 */
-	p = __wt_strerror(error);
-	if (p != NULL && snprintf(buf, buflen, "%s", p) > 0)
-		return (0);
+	if ((p = __wt_strerror(error)) != NULL)
+		return (p);
 
 	if (error < 0) {
 		error = __wt_map_error_to_windows_error(error);
@@ -109,16 +105,16 @@ __wt_strerror_r(int error, char *buf, size_t buflen)
 			error,
 			0, /* let system choose the correct LANGID */
 			buf,
-			buflen,
+			sizeof(buf),
 			NULL);
 
-		if (lasterror != 0)
-			return (0);
+		if (lasterror != 0 &&
+		    __wt_buf_set(session, &session->err, buf, strlen(buf)) == 0)
+			return (session->err.data);
 
 		/* Fall through to the fallback error code */
 	}
 
-	/* Fallback to a generic message, then guess it's a memory problem. */
-	return (
-	    snprintf(buf, buflen, "error return: %d", error) > 0 ? 0 : ENOMEM);
+	/* Defeated. */
+	return ("Unable to return error string");
 }
diff --git a/src/session/session_api.c b/src/session/session_api.c
index 0affc567583..986473ae1cc 100644
--- a/src/session/session_api.c
+++ b/src/session/session_api.c
@@ -128,8 +128,9 @@ __session_close(WT_SESSION *wt_session, const char *config)
 	/* Discard metadata tracking. */
 	__wt_meta_track_discard(session);
 
-	/* Discard scratch buffers. */
+	/* Discard scratch buffers, error memory. */
 	__wt_scr_discard(session);
+	__wt_buf_free(session, &session->err);
 
 	/* Free transaction information. */
 	__wt_txn_destroy(session);
@@ -902,6 +903,27 @@ err:	F_CLR(session, WT_SESSION_CAN_WAIT | WT_SESSION_NO_CACHE_CHECK);
 }
 
 /*
+ * __session_strerror --
+ *	WT_SESSION->strerror method.
+ */
+static const char *
+__session_strerror(WT_SESSION *wt_session, int error)
+{
+	WT_SESSION_IMPL *session;
+	const char *p;
+
+	session = (WT_SESSION_IMPL *)wt_session;
+
+	/* Check for a constant string. */
+	if ((p = __wt_wiredtiger_error(error)) != NULL)
+		return (p);
+	if ((p = __wt_strerror(error)) != NULL)
+		return (p);
+
+	return (__wt_session_strerror(session, error));
+}
+
+/*
  * __wt_open_internal_session --
  *	Allocate a session for WiredTiger's use.
  */
@@ -963,6 +985,7 @@ __wt_open_session(WT_CONNECTION_IMPL *conn,
 		NULL,
 		__session_close,
 		__session_reconfigure,
+		__session_strerror,
 		__session_open_cursor,
 		__session_create,
 		__session_compact,
diff --git a/src/support/err.c b/src/support/err.c
index d766fcba33a..49a3891c58a 100644
--- a/src/support/err.c
+++ b/src/support/err.c
@@ -409,6 +409,20 @@ __wt_ext_msg_printf(
 }
 
 /*
+ * __wt_ext_strerror --
+ *	Extension API call to return an error as a string.
+ */
+const char *
+__wt_ext_strerror(WT_EXTENSION_API *wt_api, WT_SESSION *wt_session, int error)
+{
+	if (wt_session == NULL)
+		wt_session = (WT_SESSION *)
+		    ((WT_CONNECTION_IMPL *)wt_api->conn)->default_session;
+
+	return (wt_session->strerror(wt_session, error));
+}
+
+/*
  * __wt_progress --
  *	Progress message.
  */