[lxc-devel] [PATCH] handle hashed command socket names (v2)

S.Çağlar Onur caglar at 10ur.org
Mon Aug 25 23:54:51 UTC 2014


With the new hashed command socket names (e85898415c), it's possible to have something like below;

[caglar at qop:~/go/src/github.com/lxc/go-lxc(master)] cat /proc/net/unix | grep lxc
0000000000000000: 00000002 00000000 00010000 0001 01 53465 @lxc/d086e835c86f4b8d/command
[...]

list_active_containers reads /proc/net/unix to find all running containers but this new format no longer includes the container name or its lxcpath.

This patch introduces two new commands (LXC_CMD_GET_NAME and LXC_CMD_GET_LXCPATH) and starts to use those in list_active_containers call.

changes since v1:
 - added sanity check proposed by Serge

Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>
Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>
---
 src/lxc/commands.c     | 118 ++++++++++++++++++++++++++++++++++++++++++-------
 src/lxc/commands.h     |   4 ++
 src/lxc/lxccontainer.c |  20 ++++++++-
 3 files changed, 124 insertions(+), 18 deletions(-)

diff --git a/src/lxc/commands.c b/src/lxc/commands.c
index f46efc5..2845614 100644
--- a/src/lxc/commands.c
+++ b/src/lxc/commands.c
@@ -75,13 +75,22 @@
 lxc_log_define(lxc_commands, lxc);
 
 static int fill_sock_name(char *path, int len, const char *name,
-			  const char *lxcpath)
+			  const char *lxcpath, const char *hashed_sock_name)
 {
 	char *tmppath;
 	size_t tmplen;
 	uint64_t hash;
 	int ret;
 
+	if (hashed_sock_name != NULL) {
+		ret = snprintf(path, len, "lxc/%s/command", hashed_sock_name);
+		if (ret < 0 || ret >= len) {
+			ERROR("Error writing to command sock path");
+			return -1;
+		}
+		return 0;
+	}
+
 	if (!lxcpath) {
 		lxcpath = lxc_global_config_value("lxc.lxcpath");
 		if (!lxcpath) {
@@ -89,9 +98,8 @@ static int fill_sock_name(char *path, int len, const char *name,
 			return -1;
 		}
 	}
-		
-	ret = snprintf(path, len, "%s/%s/command", lxcpath, name);
 
+	ret = snprintf(path, len, "%s/%s/command", lxcpath, name);
 	if (ret < 0) {
 		ERROR("Error writing to command sock path");
 		return -1;
@@ -108,7 +116,7 @@ static int fill_sock_name(char *path, int len, const char *name,
 		return -1;
 	}
 	hash = fnv_64a_buf(tmppath, ret, FNV1A_64_INIT);
-	ret = snprintf(path, len, "lxc/%016" PRIx64 "/cmd_sock", hash);
+	ret = snprintf(path, len, "lxc/%016" PRIx64 "/command", hash);
 	if (ret < 0 || ret >= len) {
 		ERROR("Command socket name too long");
 		return -1;
@@ -127,6 +135,8 @@ static const char *lxc_cmd_str(lxc_cmd_t cmd)
 		[LXC_CMD_GET_CLONE_FLAGS] = "get_clone_flags",
 		[LXC_CMD_GET_CGROUP]      = "get_cgroup",
 		[LXC_CMD_GET_CONFIG_ITEM] = "get_config_item",
+		[LXC_CMD_GET_NAME]        = "get_name",
+		[LXC_CMD_GET_LXCPATH]     = "get_lxcpath",
 	};
 
 	if (cmd >= LXC_CMD_MAX)
@@ -259,7 +269,7 @@ static int lxc_cmd_rsp_send(int fd, struct lxc_cmd_rsp *rsp)
  * returned in the cmd response structure.
  */
 static int lxc_cmd(const char *name, struct lxc_cmd_rr *cmd, int *stopped,
-		   const char *lxcpath)
+		   const char *lxcpath, const char *hashed_sock_name)
 {
 	int sock, ret = -1;
 	char path[sizeof(((struct sockaddr_un *)0)->sun_path)] = { 0 };
@@ -270,7 +280,7 @@ static int lxc_cmd(const char *name, struct lxc_cmd_rr *cmd, int *stopped,
 	*stopped = 0;
 
 	len = sizeof(path)-1;
-	if (fill_sock_name(offset, len, name, lxcpath))
+	if (fill_sock_name(offset, len, name, lxcpath, hashed_sock_name))
 		return -1;
 
 	sock = lxc_abstract_unix_connect(path);
@@ -329,7 +339,7 @@ int lxc_try_cmd(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_GET_INIT_PID },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 
 	if (stopped)
 		return 0;
@@ -369,7 +379,7 @@ pid_t lxc_cmd_get_init_pid(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_GET_INIT_PID },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -399,7 +409,7 @@ int lxc_cmd_get_clone_flags(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_GET_CLONE_FLAGS },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -438,7 +448,7 @@ char *lxc_cmd_get_cgroup_path(const char *name, const char *lxcpath,
 		},
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return NULL;
 
@@ -497,7 +507,7 @@ char *lxc_cmd_get_config_item(const char *name, const char *item,
 		       },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return NULL;
 
@@ -548,7 +558,7 @@ lxc_state_t lxc_cmd_get_state(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_GET_STATE }
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0 && stopped)
 		return STOPPED;
 
@@ -589,7 +599,7 @@ int lxc_cmd_stop(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_STOP },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0) {
 		if (stopped) {
 			INFO("'%s' is already stopped", name);
@@ -650,7 +660,7 @@ int lxc_cmd_console_winch(const char *name, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_CONSOLE_WINCH },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -685,7 +695,7 @@ int lxc_cmd_console(const char *name, int *ttynum, int *fd, const char *lxcpath)
 		.req = { .cmd = LXC_CMD_CONSOLE, .data = INT_TO_PTR(*ttynum) },
 	};
 
-	ret = lxc_cmd(name, &cmd, &stopped, lxcpath);
+	ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -744,7 +754,81 @@ out_close:
 	return 1;
 }
 
+/*
+ * lxc_cmd_get_name: Returns the name of the container
+ *
+ * @hashed_sock_name: hashed socket name
+ *
+ * Returns the name on success, NULL on failure.
+ */
+char *lxc_cmd_get_name(const char *hashed_sock_name)
+{
+	int ret, stopped;
+	struct lxc_cmd_rr cmd = {
+		.req = { .cmd = LXC_CMD_GET_NAME},
+	};
+
+	ret = lxc_cmd(NULL, &cmd, &stopped, NULL, hashed_sock_name);
+	if (ret < 0) {
+		return NULL;
+	}
+
+	if (cmd.rsp.ret == 0)
+		return cmd.rsp.data;
+	return NULL;
+}
+
+static int lxc_cmd_get_name_callback(int fd, struct lxc_cmd_req *req,
+					    struct lxc_handler *handler)
+{
+	struct lxc_cmd_rsp rsp;
+
+	memset(&rsp, 0, sizeof(rsp));
+
+	rsp.data = handler->name;
+	rsp.datalen = strlen(handler->name) + 1;
+	rsp.ret = 0;
+
+	return lxc_cmd_rsp_send(fd, &rsp);
+}
+
+/*
+ * lxc_cmd_get_lxcpath: Returns the lxcpath of the container
+ *
+ * @hashed_sock_name: hashed socket name
+ *
+ * Returns the lxcpath on success, NULL on failure.
+ */
+char *lxc_cmd_get_lxcpath(const char *hashed_sock_name)
+{
+	int ret, stopped;
+	struct lxc_cmd_rr cmd = {
+		.req = { .cmd = LXC_CMD_GET_LXCPATH},
+	};
 
+	ret = lxc_cmd(NULL, &cmd, &stopped, NULL, hashed_sock_name);
+	if (ret < 0) {
+		return NULL;
+	}
+
+	if (cmd.rsp.ret == 0)
+		return cmd.rsp.data;
+	return NULL;
+}
+
+static int lxc_cmd_get_lxcpath_callback(int fd, struct lxc_cmd_req *req,
+					struct lxc_handler *handler)
+{
+	struct lxc_cmd_rsp rsp;
+
+	memset(&rsp, 0, sizeof(rsp));
+
+	rsp.data = (char *)handler->lxcpath;
+	rsp.datalen = strlen(handler->lxcpath) + 1;
+	rsp.ret = 0;
+
+	return lxc_cmd_rsp_send(fd, &rsp);
+}
 
 static int lxc_cmd_process(int fd, struct lxc_cmd_req *req,
 			   struct lxc_handler *handler)
@@ -760,6 +844,8 @@ static int lxc_cmd_process(int fd, struct lxc_cmd_req *req,
 		[LXC_CMD_GET_CLONE_FLAGS] = lxc_cmd_get_clone_flags_callback,
 		[LXC_CMD_GET_CGROUP]      = lxc_cmd_get_cgroup_callback,
 		[LXC_CMD_GET_CONFIG_ITEM] = lxc_cmd_get_config_item_callback,
+		[LXC_CMD_GET_NAME]        = lxc_cmd_get_name_callback,
+		[LXC_CMD_GET_LXCPATH]     = lxc_cmd_get_lxcpath_callback,
 	};
 
 	if (req->cmd >= LXC_CMD_MAX) {
@@ -887,7 +973,7 @@ int lxc_cmd_init(const char *name, struct lxc_handler *handler,
 	int len;
 
 	len = sizeof(path)-1;
-	if (fill_sock_name(offset, len, name, lxcpath))
+	if (fill_sock_name(offset, len, name, lxcpath, NULL))
 		return -1;
 
 	fd = lxc_abstract_unix_open(path, SOCK_STREAM, 0);
diff --git a/src/lxc/commands.h b/src/lxc/commands.h
index 9efe2ad..e11a139 100644
--- a/src/lxc/commands.h
+++ b/src/lxc/commands.h
@@ -41,6 +41,8 @@ typedef enum {
 	LXC_CMD_GET_CLONE_FLAGS,
 	LXC_CMD_GET_CGROUP,
 	LXC_CMD_GET_CONFIG_ITEM,
+	LXC_CMD_GET_NAME,
+	LXC_CMD_GET_LXCPATH,
 	LXC_CMD_MAX,
 } lxc_cmd_t;
 
@@ -77,6 +79,8 @@ extern char *lxc_cmd_get_cgroup_path(const char *name, const char *lxcpath,
 			const char *subsystem);
 extern int lxc_cmd_get_clone_flags(const char *name, const char *lxcpath);
 extern char *lxc_cmd_get_config_item(const char *name, const char *item, const char *lxcpath);
+extern char *lxc_cmd_get_name(const char *hashed_sock);
+extern char *lxc_cmd_get_lxcpath(const char *hashed_sock);
 extern pid_t lxc_cmd_get_init_pid(const char *name, const char *lxcpath);
 extern lxc_state_t lxc_cmd_get_state(const char *name, const char *lxcpath);
 extern int lxc_cmd_stop(const char *name, const char *lxcpath);
diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index 172e667..9c34120 100644
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -3751,6 +3751,7 @@ int list_active_containers(const char *lxcpath, char ***nret,
 	char **ct_name = NULL;
 	size_t len = 0;
 	struct lxc_container *c;
+	bool is_hashed;
 
 	if (!lxcpath)
 		lxcpath = lxc_global_config_value("lxc.lxcpath");
@@ -3766,6 +3767,7 @@ int list_active_containers(const char *lxcpath, char ***nret,
 		return -1;
 
 	while (getline(&line, &len, f) != -1) {
+
 		char *p = strrchr(line, ' '), *p2;
 		if (!p)
 			continue;
@@ -3773,9 +3775,17 @@ int list_active_containers(const char *lxcpath, char ***nret,
 		if (*p != 0x40)
 			continue;
 		p++;
-		if (strncmp(p, lxcpath, lxcpath_len) != 0)
+
+		is_hashed = false;
+		if (strncmp(p, lxcpath, lxcpath_len) == 0) {
+			p += lxcpath_len;
+		} else if (strncmp(p, "lxc/", 4) == 0) {
+			p += 4;
+			is_hashed = true;
+		} else {
 			continue;
-		p += lxcpath_len;
+		}
+
 		while (*p == '/')
 			p++;
 
@@ -3785,6 +3795,12 @@ int list_active_containers(const char *lxcpath, char ***nret,
 			continue;
 		*p2 = '\0';
 
+		if (is_hashed) {
+			if (strncmp(lxcpath, lxc_cmd_get_lxcpath(p), lxcpath_len) != 0)
+				continue;
+			p = lxc_cmd_get_name(p);
+		}
+
 		if (array_contains(&ct_name, p, ct_name_cnt))
 			continue;
 
-- 
1.9.1



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