Update module go-sql-driver/mysql to v1.5.0

go.mod

@@ -6,10 +6,11 @@ require (
 	git.autistici.org/ai3/go-common v0.0.0-20210110180225-a05c683cfe23
 	git.autistici.org/id/usermetadb v0.0.0-20210112103616-f674f50555fc
 	github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
-	github.com/cenkalti/backoff/v4 v4.1.0
+	github.com/cenkalti/backoff v2.2.1+incompatible
+	github.com/cenkalti/backoff/v4 v4.1.0 // indirect
 	github.com/coreos/go-systemd/v22 v22.1.0
 	github.com/go-ldap/ldap/v3 v3.2.4
-	github.com/go-sql-driver/mysql v1.4.0
+	github.com/go-sql-driver/mysql v1.5.0
 	github.com/google/go-cmp v0.5.4
 	github.com/lib/pq v0.0.0-20190326042056-d6156e141ac6
 	github.com/mattn/go-sqlite3 v0.0.0-20200618132256-aa77c03e2fcb

go.sum

@@ -111,6 +111,8 @@ github.com/go-logfmt/logfmt v0.4.0/go.mod h1:3RMwSq7FuexP4Kalkev3ejPJsZTpXXBr9+V
 github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG1KdI/P7A=
 github.com/go-sql-driver/mysql v1.4.0 h1:7LxgVwFb2hIQtMm87NdgAVfXjnt4OePseqT1tKx+opk=
 github.com/go-sql-driver/mysql v1.4.0/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
+github.com/go-sql-driver/mysql v1.5.0 h1:ozyZYNQW3x3HtqT1jira07DN2PArx2v7/mN66gGcHOs=
+github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/godbus/dbus/v5 v5.0.3/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gofrs/flock v0.8.0 h1:MSdYClljsF3PbENUUEx85nkWfJSGfzYI9yEBZOJz6CY=

vendor/github.com/go-sql-driver/mysql/.travis.yml

 sudo: false
 language: go
 go:
-  - 1.7.x
-  - 1.8.x
-  - 1.9.x
   - 1.10.x
+  - 1.11.x
+  - 1.12.x
+  - 1.13.x
   - master
 
 before_install:
@@ -99,6 +99,28 @@ matrix:
         - export MYSQL_TEST_ADDR=127.0.0.1:3307
         - export MYSQL_TEST_CONCURRENT=1
 
+    - os: osx
+      osx_image: xcode10.1
+      addons:
+        homebrew:
+          packages:
+            - mysql
+          update: true
+      go: 1.12.x
+      before_install:
+        - go get golang.org/x/tools/cmd/cover
+        - go get github.com/mattn/goveralls
+      before_script:
+        - echo -e "[server]\ninnodb_log_file_size=256MB\ninnodb_buffer_pool_size=512MB\nmax_allowed_packet=16MB\nlocal_infile=1" >> /usr/local/etc/my.cnf
+        - mysql.server start
+        - mysql -uroot -e 'CREATE USER gotest IDENTIFIED BY "secret"'
+        - mysql -uroot -e 'GRANT ALL ON *.* TO gotest'
+        - mysql -uroot -e 'create database gotest;'
+        - export MYSQL_TEST_USER=gotest
+        - export MYSQL_TEST_PASS=secret
+        - export MYSQL_TEST_ADDR=127.0.0.1:3306
+        - export MYSQL_TEST_CONCURRENT=1
+
 script:
   - go test -v -covermode=count -coverprofile=coverage.out
   - go vet ./...

vendor/github.com/go-sql-driver/mysql/AUTHORS

@@ -27,6 +27,7 @@ Daniël van Eeden <git at myname.nl>
 Dave Protasowski <dprotaso at gmail.com>
 DisposaBoy <disposaboy at dby.me>
 Egor Smolyakov <egorsmkv at gmail.com>
+Erwan Martin <hello at erwan.io>
 Evan Shaw <evan at vendhq.com>
 Frederick Mayle <frederickmayle at gmail.com>
 Gustavo Kristic <gkristic at gmail.com>
@@ -34,12 +35,16 @@ Hajime Nakagami <nakagami at gmail.com>
 Hanno Braun <mail at hannobraun.com>
 Henri Yandell <flamefew at gmail.com>
 Hirotaka Yamamoto <ymmt2005 at gmail.com>
+Huyiguang <hyg at webterren.com>
 ICHINOSE Shogo <shogo82148 at gmail.com>
+Ilia Cimpoes <ichimpoesh at gmail.com>
 INADA Naoki <songofacandy at gmail.com>
 Jacek Szwec <szwec.jacek at gmail.com>
 James Harr <james.harr at gmail.com>
 Jeff Hodges <jeff at somethingsimilar.com>
 Jeffrey Charles <jeffreycharles at gmail.com>
+Jerome Meyer <jxmeyer at gmail.com>
+Jiajia Zhong <zhong2plus at gmail.com>
 Jian Zhen <zhenjl at gmail.com>
 Joshua Prunier <joshua.prunier at gmail.com>
 Julien Lefevre <julien.lefevr at gmail.com>
@@ -58,6 +63,7 @@ Lucas Liu <extrafliu at gmail.com>
 Luke Scott <luke at webconnex.com>
 Maciej Zimnoch <maciej.zimnoch at codilime.com>
 Michael Woolnough <michael.woolnough at gmail.com>
+Nathanial Murphy <nathanial.murphy at gmail.com>
 Nicola Peduzzi <thenikso at gmail.com>
 Olivier Mengué <dolmen at cpan.org>
 oscarzhao <oscarzhaosl at gmail.com>
@@ -69,9 +75,15 @@ Richard Wilkes <wilkes at me.com>
 Robert Russell <robert at rrbrussell.com>
 Runrioter Wung <runrioter at gmail.com>
 Shuode Li <elemount at qq.com>
+Simon J Mudd <sjmudd at pobox.com>
 Soroush Pour <me at soroushjp.com>
 Stan Putrya <root.vagner at gmail.com>
 Stanley Gunawan <gunawan.stanley at gmail.com>
+Steven Hartland <steven.hartland at multiplay.co.uk>
+Thomas Wodarek <wodarekwebpage at gmail.com>
+Tim Ruffles <timruffles at gmail.com>
+Tom Jenkinson <tom at tjenkinson.me>
+Vladimir Kovpak <cn007b at gmail.com>
 Xiangyu Hu <xiangyu.hu at outlook.com>
 Xiaobing Jiang <s7v7nislands at gmail.com>
 Xiuming Chen <cc at cxm.cc>
@@ -81,9 +93,13 @@ Zhenye Xie <xiezhenye at gmail.com>
 
 Barracuda Networks, Inc.
 Counting Ltd.
+DigitalOcean Inc.
+Facebook Inc.
+GitHub Inc.
 Google Inc.
 InfoSum Ltd.
 Keybase Inc.
+Multiplay Ltd.
 Percona LLC
 Pivotal Inc.
 Stripe Inc.

vendor/github.com/go-sql-driver/mysql/CHANGELOG.md

+## Version 1.5 (2020-01-07)
+
+Changes:
+
+  - Dropped support Go 1.9 and lower (#823, #829, #886, #1016, #1017)
+  - Improve buffer handling (#890)
+  - Document potentially insecure TLS configs (#901)
+  - Use a double-buffering scheme to prevent data races (#943)
+  - Pass uint64 values without converting them to string (#838, #955)
+  - Update collations and make utf8mb4 default (#877, #1054)
+  - Make NullTime compatible with sql.NullTime in Go 1.13+ (#995)
+  - Removed CloudSQL support (#993, #1007)
+  - Add Go Module support (#1003)
+
+New Features:
+
+  - Implement support of optional TLS (#900)
+  - Check connection liveness (#934, #964, #997, #1048, #1051, #1052)
+  - Implement Connector Interface (#941, #958, #1020, #1035)
+
+Bugfixes:
+
+  - Mark connections as bad on error during ping (#875)
+  - Mark connections as bad on error during dial (#867)
+  - Fix connection leak caused by rapid context cancellation (#1024)
+  - Mark connections as bad on error during Conn.Prepare (#1030)
+
+
+## Version 1.4.1 (2018-11-14)
+
+Bugfixes:
+
+ - Fix TIME format for binary columns (#818)
+ - Fix handling of empty auth plugin names (#835)
+ - Fix caching_sha2_password with empty password (#826)
+ - Fix canceled context broke mysqlConn (#862)
+ - Fix OldAuthSwitchRequest support (#870)
+ - Fix Auth Response packet for cleartext password (#887)
+
 ## Version 1.4 (2018-06-03)
 
 Changes:

vendor/github.com/go-sql-driver/mysql/CONTRIBUTING.md

-# Contributing Guidelines
-
-## Reporting Issues
-
-Before creating a new Issue, please check first if a similar Issue [already exists](https://github.com/go-sql-driver/mysql/issues?state=open) or was [recently closed](https://github.com/go-sql-driver/mysql/issues?direction=desc&page=1&sort=updated&state=closed).
-
-## Contributing Code
-
-By contributing to this project, you share your code under the Mozilla Public License 2, as specified in the LICENSE file.
-Don't forget to add yourself to the AUTHORS file.
-
-### Code Review
-
-Everyone is invited to review and comment on pull requests.
-If it looks fine to you, comment with "LGTM" (Looks good to me).
-
-If changes are required, notice the reviewers with "PTAL" (Please take another look) after committing the fixes.
-
-Before merging the Pull Request, at least one [team member](https://github.com/go-sql-driver?tab=members) must have commented with "LGTM".
-
-## Development Ideas
-
-If you are looking for ideas for code contributions, please check our [Development Ideas](https://github.com/go-sql-driver/mysql/wiki/Development-Ideas) Wiki page.

vendor/github.com/go-sql-driver/mysql/README.md

@@ -40,7 +40,7 @@ A MySQL-Driver for Go's [database/sql](https://golang.org/pkg/database/sql/) pac
   * Optional placeholder interpolation
 
 ## Requirements
-  * Go 1.7 or higher. We aim to support the 3 latest versions of Go.
+  * Go 1.10 or higher. We aim to support the 3 latest versions of Go.
   * MySQL (4.1+), MariaDB, Percona Server, Google CloudSQL or Sphinx (2.2.3+)
 
 ---------------------------------------
@@ -166,18 +166,34 @@ Sets the charset used for client-server interaction (`"SET NAMES <value>"`). If
 Usage of the `charset` parameter is discouraged because it issues additional queries to the server.
 Unless you need the fallback behavior, please use `collation` instead.
 
+##### `checkConnLiveness`
+
+```
+Type:           bool
+Valid Values:   true, false
+Default:        true
+```
+
+On supported platforms connections retrieved from the connection pool are checked for liveness before using them. If the check fails, the respective connection is marked as bad and the query retried with another connection.
+`checkConnLiveness=false` disables this liveness check of connections.
+
 ##### `collation`
 
 ```
 Type:           string
 Valid Values:   <name>
-Default:        utf8_general_ci
+Default:        utf8mb4_general_ci
 ```
 
 Sets the collation used for client-server interaction on connection. In contrast to `charset`, `collation` does not issue additional queries. If the specified collation is unavailable on the target server, the connection will fail.
 
 A list of valid charsets for a server is retrievable with `SHOW COLLATION`.
 
+The default collation (`utf8mb4_general_ci`) is supported from MySQL 5.5.  You should use an older collation (e.g. `utf8_general_ci`) for older MySQL.
+
+Collations for charset "ucs2", "utf16", "utf16le", and "utf32" can not be used ([ref](https://dev.mysql.com/doc/refman/5.7/en/charset-connection.html#charset-connection-impermissible-client-charset)).
+
+
 ##### `clientFoundRows`
 
 ```
@@ -328,11 +344,11 @@ Timeout for establishing connections, aka dial timeout. The value must be a deci
 
 ```
 Type:           bool / string
-Valid Values:   true, false, skip-verify, <name>
+Valid Values:   true, false, skip-verify, preferred, <name>
 Default:        false
 ```
 
-`tls=true` enables TLS / SSL encrypted connection to the server. Use `skip-verify` if you want to use a self-signed or invalid certificate (server side). Use a custom value registered with [`mysql.RegisterTLSConfig`](https://godoc.org/github.com/go-sql-driver/mysql#RegisterTLSConfig).
+`tls=true` enables TLS / SSL encrypted connection to the server. Use `skip-verify` if you want to use a self-signed or invalid certificate (server side) or use `preferred` to use TLS only when advertised by the server. This is similar to `skip-verify`, but additionally allows a fallback to a connection which is not encrypted. Neither `skip-verify` nor `preferred` add any reliable security. You can use a custom TLS config after registering it with [`mysql.RegisterTLSConfig`](https://godoc.org/github.com/go-sql-driver/mysql#RegisterTLSConfig).
 
 
 ##### `writeTimeout`
@@ -391,14 +407,9 @@ TCP on a remote host, e.g. Amazon RDS:
 id:password@tcp(your-amazonaws-uri.com:3306)/dbname
 ```
 
-Google Cloud SQL on App Engine (First Generation MySQL Server):
-```
-user@cloudsql(project-id:instance-name)/dbname
-```
-
-Google Cloud SQL on App Engine (Second Generation MySQL Server):
+Google Cloud SQL on App Engine:
 ```
-user@cloudsql(project-id:regionname:instance-name)/dbname
+user:password@unix(/cloudsql/project-id:region-name:instance-name)/dbname
 ```
 
 TCP using default port (3306) on localhost:
@@ -444,7 +455,7 @@ See the [godoc of Go-MySQL-Driver](https://godoc.org/github.com/go-sql-driver/my
 ### `time.Time` support
 The default internal output type of MySQL `DATE` and `DATETIME` values is `[]byte` which allows you to scan the value into a `[]byte`, `string` or `sql.RawBytes` variable in your program.
 
-However, many want to scan MySQL `DATE` and `DATETIME` values into `time.Time` variables, which is the logical opposite in Go to `DATE` and `DATETIME` in MySQL. You can do that by changing the internal output type from `[]byte` to `time.Time` with the DSN parameter `parseTime=true`. You can set the default [`time.Time` location](https://golang.org/pkg/time/#Location) with the `loc` DSN parameter.
+However, many want to scan MySQL `DATE` and `DATETIME` values into `time.Time` variables, which is the logical equivalent in Go to `DATE` and `DATETIME` in MySQL. You can do that by changing the internal output type from `[]byte` to `time.Time` with the DSN parameter `parseTime=true`. You can set the default [`time.Time` location](https://golang.org/pkg/time/#Location) with the `loc` DSN parameter.
 
 **Caution:** As of Go 1.1, this makes `time.Time` the only variable type you can scan `DATE` and `DATETIME` values into. This breaks for example [`sql.RawBytes` support](https://github.com/go-sql-driver/mysql/wiki/Examples#rawbytes).
 
@@ -452,13 +463,13 @@ Alternatively you can use the [`NullTime`](https://godoc.org/github.com/go-sql-d
 
 
 ### Unicode support
-Since version 1.1 Go-MySQL-Driver automatically uses the collation `utf8_general_ci` by default.
+Since version 1.5 Go-MySQL-Driver automatically uses the collation ` utf8mb4_general_ci` by default.
 
 Other collations / charsets can be set using the [`collation`](#collation) DSN parameter.
 
 Version 1.0 of the driver recommended adding `&charset=utf8` (alias for `SET NAMES utf8`) to the DSN to enable proper UTF-8 support. This is not necessary anymore. The [`collation`](#collation) parameter should be preferred to set another collation / charset than the default.
 
-See http://dev.mysql.com/doc/refman/5.7/en/charset-unicode.html for more details on MySQL's Unicode support.
+See http://dev.mysql.com/doc/refman/8.0/en/charset-unicode.html for more details on MySQL's Unicode support.
 
 ## Testing / Development
 To run the driver tests you may need to adjust the configuration. See the [Testing Wiki-Page](https://github.com/go-sql-driver/mysql/wiki/Testing "Testing") for details.

vendor/github.com/go-sql-driver/mysql/auth.go

@@ -234,64 +234,64 @@ func (mc *mysqlConn) sendEncryptedPassword(seed []byte, pub *rsa.PublicKey) erro
 	if err != nil {
 		return err
 	}
-	return mc.writeAuthSwitchPacket(enc, false)
+	return mc.writeAuthSwitchPacket(enc)
 }
 
-func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, bool, error) {
+func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, error) {
 	switch plugin {
 	case "caching_sha2_password":
 		authResp := scrambleSHA256Password(authData, mc.cfg.Passwd)
-		return authResp, (authResp == nil), nil
+		return authResp, nil
 
 	case "mysql_old_password":
 		if !mc.cfg.AllowOldPasswords {
-			return nil, false, ErrOldPassword
+			return nil, ErrOldPassword
 		}
 		// Note: there are edge cases where this should work but doesn't;
 		// this is currently "wontfix":
 		// https://github.com/go-sql-driver/mysql/issues/184
-		authResp := scrambleOldPassword(authData[:8], mc.cfg.Passwd)
-		return authResp, true, nil
+		authResp := append(scrambleOldPassword(authData[:8], mc.cfg.Passwd), 0)
+		return authResp, nil
 
 	case "mysql_clear_password":
 		if !mc.cfg.AllowCleartextPasswords {
-			return nil, false, ErrCleartextPassword
+			return nil, ErrCleartextPassword
 		}
 		// http://dev.mysql.com/doc/refman/5.7/en/cleartext-authentication-plugin.html
 		// http://dev.mysql.com/doc/refman/5.7/en/pam-authentication-plugin.html
-		return []byte(mc.cfg.Passwd), true, nil
+		return append([]byte(mc.cfg.Passwd), 0), nil
 
 	case "mysql_native_password":
 		if !mc.cfg.AllowNativePasswords {
-			return nil, false, ErrNativePassword
+			return nil, ErrNativePassword
 		}
 		// https://dev.mysql.com/doc/internals/en/secure-password-authentication.html
 		// Native password authentication only need and will need 20-byte challenge.
 		authResp := scramblePassword(authData[:20], mc.cfg.Passwd)
-		return authResp, false, nil
+		return authResp, nil
 
 	case "sha256_password":
 		if len(mc.cfg.Passwd) == 0 {
-			return nil, true, nil
+			return []byte{0}, nil
 		}
 		if mc.cfg.tls != nil || mc.cfg.Net == "unix" {
 			// write cleartext auth packet
-			return []byte(mc.cfg.Passwd), true, nil
+			return append([]byte(mc.cfg.Passwd), 0), nil
 		}
 
 		pubKey := mc.cfg.pubKey
 		if pubKey == nil {
 			// request public key from server
-			return []byte{1}, false, nil
+			return []byte{1}, nil
 		}
 
 		// encrypted password
 		enc, err := encryptPassword(mc.cfg.Passwd, authData, pubKey)
-		return enc, false, err
+		return enc, err
 
 	default:
 		errLog.Print("unknown auth plugin:", plugin)
-		return nil, false, ErrUnknownPlugin
+		return nil, ErrUnknownPlugin
 	}
 }
 
@@ -315,11 +315,11 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 
 		plugin = newPlugin
 
-		authResp, addNUL, err := mc.auth(authData, plugin)
+		authResp, err := mc.auth(authData, plugin)
 		if err != nil {
 			return err
 		}
-		if err = mc.writeAuthSwitchPacket(authResp, addNUL); err != nil {
+		if err = mc.writeAuthSwitchPacket(authResp); err != nil {
 			return err
 		}
 
@@ -352,7 +352,7 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 			case cachingSha2PasswordPerformFullAuthentication:
 				if mc.cfg.tls != nil || mc.cfg.Net == "unix" {
 					// write cleartext auth packet
-					err = mc.writeAuthSwitchPacket([]byte(mc.cfg.Passwd), true)
+					err = mc.writeAuthSwitchPacket(append([]byte(mc.cfg.Passwd), 0))
 					if err != nil {
 						return err
 					}
@@ -360,13 +360,15 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 					pubKey := mc.cfg.pubKey
 					if pubKey == nil {
 						// request public key from server
-						data := mc.buf.takeSmallBuffer(4 + 1)
+						data, err := mc.buf.takeSmallBuffer(4 + 1)
+						if err != nil {
+							return err
+						}
 						data[4] = cachingSha2PasswordRequestPublicKey
 						mc.writePacket(data)
 
 						// parse public key
-						data, err := mc.readPacket()
-						if err != nil {
+						if data, err = mc.readPacket(); err != nil {
 							return err
 						}
 

vendor/github.com/go-sql-driver/mysql/buffer.go

@@ -15,47 +15,69 @@ import (
 )
 
 const defaultBufSize = 4096
+const maxCachedBufSize = 256 * 1024
 
 // A buffer which is used for both reading and writing.
 // This is possible since communication on each connection is synchronous.
 // In other words, we can't write and read simultaneously on the same connection.
 // The buffer is similar to bufio.Reader / Writer but zero-copy-ish
 // Also highly optimized for this particular use case.
+// This buffer is backed by two byte slices in a double-buffering scheme
 type buffer struct {
-	buf     []byte
+	buf     []byte // buf is a byte buffer who's length and capacity are equal.
 	nc      net.Conn
 	idx     int
 	length  int
 	timeout time.Duration
+	dbuf    [2][]byte // dbuf is an array with the two byte slices that back this buffer
+	flipcnt uint      // flipccnt is the current buffer counter for double-buffering
 }
 
+// newBuffer allocates and returns a new buffer.
 func newBuffer(nc net.Conn) buffer {
-	var b [defaultBufSize]byte
+	fg := make([]byte, defaultBufSize)
 	return buffer{
-		buf: b[:],
-		nc:  nc,
+		buf:  fg,
+		nc:   nc,
+		dbuf: [2][]byte{fg, nil},
 	}
 }
 
+// flip replaces the active buffer with the background buffer
+// this is a delayed flip that simply increases the buffer counter;
+// the actual flip will be performed the next time we call `buffer.fill`
+func (b *buffer) flip() {
+	b.flipcnt += 1
+}
+
 // fill reads into the buffer until at least _need_ bytes are in it
 func (b *buffer) fill(need int) error {
 	n := b.length
+	// fill data into its double-buffering target: if we've called
+	// flip on this buffer, we'll be copying to the background buffer,
+	// and then filling it with network data; otherwise we'll just move
+	// the contents of the current buffer to the front before filling it
+	dest := b.dbuf[b.flipcnt&1]
+
+	// grow buffer if necessary to fit the whole packet.
+	if need > len(dest) {
+		// Round up to the next multiple of the default size
+		dest = make([]byte, ((need/defaultBufSize)+1)*defaultBufSize)
 
-	// move existing data to the beginning
-	if n > 0 && b.idx > 0 {
-		copy(b.buf[0:n], b.buf[b.idx:])
+		// if the allocated buffer is not too large, move it to backing storage
+		// to prevent extra allocations on applications that perform large reads
+		if len(dest) <= maxCachedBufSize {
+			b.dbuf[b.flipcnt&1] = dest
+		}
 	}
 
-	// grow buffer if necessary
-	// TODO: let the buffer shrink again at some point
-	//       Maybe keep the org buf slice and swap back?
-	if need > len(b.buf) {
-		// Round up to the next multiple of the default size
-		newBuf := make([]byte, ((need/defaultBufSize)+1)*defaultBufSize)
-		copy(newBuf, b.buf)
-		b.buf = newBuf
+	// if we're filling the fg buffer, move the existing data to the start of it.
+	// if we're filling the bg buffer, copy over the data
+	if n > 0 {
+		copy(dest[:n], b.buf[b.idx:])
 	}
 
+	b.buf = dest
 	b.idx = 0
 
 	for {
@@ -105,43 +127,56 @@ func (b *buffer) readNext(need int) ([]byte, error) {
 	return b.buf[offset:b.idx], nil
 }
 
-// returns a buffer with the requested size.
+// takeBuffer returns a buffer with the requested size.
 // If possible, a slice from the existing buffer is returned.
 // Otherwise a bigger buffer is made.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeBuffer(length int) []byte {
+func (b *buffer) takeBuffer(length int) ([]byte, error) {
 	if b.length > 0 {
-		return nil
+		return nil, ErrBusyBuffer
 	}
 
 	// test (cheap) general case first
-	if length <= defaultBufSize || length <= cap(b.buf) {
-		return b.buf[:length]
+	if length <= cap(b.buf) {
+		return b.buf[:length], nil
 	}
 
 	if length < maxPacketSize {
 		b.buf = make([]byte, length)
-		return b.buf
+		return b.buf, nil
 	}
-	return make([]byte, length)
+
+	// buffer is larger than we want to store.
+	return make([]byte, length), nil
 }
 
-// shortcut which can be used if the requested buffer is guaranteed to be
-// smaller than defaultBufSize
+// takeSmallBuffer is shortcut which can be used if length is
+// known to be smaller than defaultBufSize.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeSmallBuffer(length int) []byte {
+func (b *buffer) takeSmallBuffer(length int) ([]byte, error) {
 	if b.length > 0 {
-		return nil
+		return nil, ErrBusyBuffer
 	}
-	return b.buf[:length]
+	return b.buf[:length], nil
 }
 
 // takeCompleteBuffer returns the complete existing buffer.
 // This can be used if the necessary buffer size is unknown.
+// cap and len of the returned buffer will be equal.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeCompleteBuffer() []byte {
+func (b *buffer) takeCompleteBuffer() ([]byte, error) {
+	if b.length > 0 {
+		return nil, ErrBusyBuffer
+	}
+	return b.buf, nil
+}
+
+// store stores buf, an updated buffer, if its suitable to do so.
+func (b *buffer) store(buf []byte) error {
 	if b.length > 0 {
-		return nil
+		return ErrBusyBuffer
+	} else if cap(buf) <= maxPacketSize && cap(buf) > cap(b.buf) {
+		b.buf = buf[:cap(buf)]
 	}
-	return b.buf
+	return nil
 }

vendor/github.com/go-sql-driver/mysql/collations.go

@@ -8,183 +8,190 @@
 
 package mysql
 
-const defaultCollation = "utf8_general_ci"
+const defaultCollation = "utf8mb4_general_ci"
 const binaryCollation = "binary"
 
 // A list of available collations mapped to the internal ID.
 // To update this map use the following MySQL query:
-//     SELECT COLLATION_NAME, ID FROM information_schema.COLLATIONS
+//     SELECT COLLATION_NAME, ID FROM information_schema.COLLATIONS WHERE ID<256 ORDER BY ID
+//
+// Handshake packet have only 1 byte for collation_id.  So we can't use collations with ID > 255.
+//
+// ucs2, utf16, and utf32 can't be used for connection charset.
+// https://dev.mysql.com/doc/refman/5.7/en/charset-connection.html#charset-connection-impermissible-client-charset
+// They are commented out to reduce this map.
 var collations = map[string]byte{
-	"big5_chinese_ci":          1,
-	"latin2_czech_cs":          2,
-	"dec8_swedish_ci":          3,
-	"cp850_general_ci":         4,
-	"latin1_german1_ci":        5,
-	"hp8_english_ci":           6,
-	"koi8r_general_ci":         7,
-	"latin1_swedish_ci":        8,