[lxc-devel] [go-lxc/v2] container: add ConsoleLog() API extension

[brauner on Github]

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From fb735da937253900d770ab9d8811552328dc0762 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Thu, 9 Nov 2017 10:23:34 +0100
Subject: [PATCH 1/2] lxc-binding: export VERSION_AT_LEAST()

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 lxc-binding.c | 5 -----
 lxc-binding.h | 5 +++++
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/lxc-binding.c b/lxc-binding.c
index 53542b8..02fc15f 100644
--- a/lxc-binding.c
+++ b/lxc-binding.c
@@ -19,11 +19,6 @@
 #define LXC_DEVEL 0
 #endif
 
-#define VERSION_AT_LEAST(major, minor, micro)							\
-	((LXC_DEVEL == 1) || (!(major > LXC_VERSION_MAJOR ||					\
-	major == LXC_VERSION_MAJOR && minor > LXC_VERSION_MINOR ||				\
-	major == LXC_VERSION_MAJOR && minor == LXC_VERSION_MINOR && micro > LXC_VERSION_MICRO)))
-
 bool go_lxc_defined(struct lxc_container *c) {
 	return c->is_defined(c);
 }
diff --git a/lxc-binding.h b/lxc-binding.h
index cbf9ce2..34ca2c0 100644
--- a/lxc-binding.h
+++ b/lxc-binding.h
@@ -2,6 +2,11 @@
 // Use of this source code is governed by a LGPLv2.1
 // license that can be found in the LICENSE file.
 
+#define VERSION_AT_LEAST(major, minor, micro)							\
+	((LXC_DEVEL == 1) || (!(major > LXC_VERSION_MAJOR ||					\
+	major == LXC_VERSION_MAJOR && minor > LXC_VERSION_MINOR ||				\
+	major == LXC_VERSION_MAJOR && minor == LXC_VERSION_MINOR && micro > LXC_VERSION_MICRO)))
+
 extern bool go_lxc_add_device_node(struct lxc_container *c, const char *src_path, const char *dest_path);
 extern void go_lxc_clear_config(struct lxc_container *c);
 extern bool go_lxc_clear_config_item(struct lxc_container *c, const char *key);

From eafbe8a65020a617b0a863d40570de61af366949 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Thu, 9 Nov 2017 10:24:11 +0100
Subject: [PATCH 2/2] container: add ConsoleLog() API extension

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 container.go  | 29 +++++++++++++++++++++++++++++
 lxc-binding.c |  8 ++++++++
 lxc-binding.h | 12 ++++++++++++
 options.go    |  8 ++++++++
 4 files changed, 57 insertions(+)

diff --git a/container.go b/container.go
index af5485a..b338857 100644
--- a/container.go
+++ b/container.go
@@ -22,6 +22,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"syscall"
 	"time"
 	"unsafe"
 )
@@ -1866,3 +1867,31 @@ func (c *Container) SetRunningConfigItem(key string, value string) error {
 	}
 	return nil
 }
+
+// ConsoleLog allows to perform operations on the container's in-memory console
+// buffer.
+func (c *Container) ConsoleLog(opt ConsoleLogOptions) ([]byte, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	readMax := C.uint64_t(opt.ReadMax)
+	lxcConsoleLog := C.struct_lxc_console_log{
+		clear:         C.bool(opt.ClearLog),
+		read:          C.bool(opt.ReadLog),
+		read_max:      &readMax,
+		data:          nil,
+		write_logfile: C.bool(opt.WriteToLogFile),
+	}
+
+	ret := C.go_lxc_console_log(c.container, &lxcConsoleLog)
+	if ret < 0 {
+		return nil, syscall.Errno(-ret)
+	}
+
+	numBytes := C.int(*lxcConsoleLog.read_max)
+	if C.uint64_t(numBytes) != *lxcConsoleLog.read_max {
+		return nil, syscall.ERANGE
+	}
+
+	return C.GoBytes(unsafe.Pointer(lxcConsoleLog.data), numBytes), nil
+}
diff --git a/lxc-binding.c b/lxc-binding.c
index 02fc15f..9ac5bc5 100644
--- a/lxc-binding.c
+++ b/lxc-binding.c
@@ -458,3 +458,11 @@ bool go_lxc_set_running_config_item(struct lxc_container *c, const char *key, co
 	return false;
 #endif
 }
+
+int go_lxc_console_log(struct lxc_container *c, struct lxc_console_log *log) {
+#if VERSION_AT_LEAST(3, 0, 0)
+	return c->console_log(c, log);
+#else
+	return false;
+#endif
+}
diff --git a/lxc-binding.h b/lxc-binding.h
index 34ca2c0..6412f70 100644
--- a/lxc-binding.h
+++ b/lxc-binding.h
@@ -113,3 +113,15 @@ int go_lxc_migrate(struct lxc_container *c, unsigned int cmd, struct migrate_opt
 
 extern bool go_lxc_attach_interface(struct lxc_container *c, const char *dev, const char *dst_dev);
 extern bool go_lxc_detach_interface(struct lxc_container *c, const char *dev, const char *dst_dev);
+
+#if !VERSION_AT_LEAST(3, 0, 0)
+struct lxc_console_log {
+	bool clear;
+	bool read;
+	uint64_t *read_max;
+	char *data;
+	bool write_logfile;
+};
+#endif
+
+extern int go_lxc_console_log(struct lxc_container *c, struct lxc_console_log *log);
diff --git a/options.go b/options.go
index 7130851..df5ee22 100644
--- a/options.go
+++ b/options.go
@@ -198,3 +198,11 @@ type MigrateOptions struct {
 	PreservesInodes bool
 	GhostLimit      uint64
 }
+
+// ConsoleLogOptioins type is used for defining console log options.
+type ConsoleLogOptions struct {
+	ClearLog       bool
+	ReadLog        bool
+	ReadMax        uint64
+	WriteToLogFile bool
+}