Handle the lock error and show message to user

src/lxc/checkpoint.c

@@ -36,6 +36,7 @@
 #include <netinet/in.h>
 #include <net/if.h>
 
+#include "error.h"
 #include <lxc.h>
 
 #define MAXPIDLEN 20
@@ -70,17 +71,13 @@ int lxc_checkpoint(const char *name, int cfd, unsigned long flags)
 	size_t pid;
 
 	lock = lxc_get_lock(name);
-	if (lock > 0) {
-		lxc_log_error("'%s' is not running", name);
+	if (lock >= 0) {
 		lxc_put_lock(lock);
-		return -1;
+		return -LXC_ERROR_EMPTY;
 	}
 
-	if (lock < 0) {
-		lxc_log_error("failed to acquire the lock on '%s':%s", 
-			      name, strerror(-lock));
-		return -1;
-	}
+	if (lock < 0 && lock != -EWOULDBLOCK)
+		return -LXC_ERROR_LOCK;
 
 	snprintf(init, MAXPATHLEN, LXCPATH "/%s/init", name);
 	fd = open(init, O_RDONLY);

src/lxc/create.c

@@ -56,17 +56,13 @@ static int create_lxc_directory(const char *dirname)
 {
 	char path[MAXPATHLEN];
 
-	if (mkdir(LXCPATH, 0755) && errno != EEXIST) {
-		lxc_log_syserror("failed to created %s directory", LXCPATH);
-		return -1;
-	}
+	if (mkdir(LXCPATH, 0755) && errno != EEXIST)
+		return -errno;
 
 	sprintf(path, LXCPATH "/%s", dirname);
 
-	if (mkdir(path, 0755)) {
-		lxc_log_syserror("failed to created %s directory", path);
-		return -1;
-	}
+	if (mkdir(path, 0755))
+		return -errno;
 
 	return 0;
 }
@@ -94,25 +90,18 @@ static int remove_lxc_directory(const char *dirname)
 
 int lxc_create(const char *name, struct lxc_conf *conf)
 {
-	int lock, err = -LXC_ERROR_INTERNAL;
-
-	if (create_lxc_directory(name)) {
-		lxc_log_error("failed to create %s directory", name);
-		return -LXC_ERROR_INTERNAL;
-	}
+	int lock, err;
 
+	err = create_lxc_directory(name);
+	if (err < 0)
+		return err == -EEXIST ?
+			-LXC_ERROR_ALREADY_EXISTS:LXC_ERROR_INTERNAL;
+	
 	lock = lxc_get_lock(name);
-	if (!lock) {
-		lxc_log_error("'%s' is busy", name);
-		return -LXC_ERROR_ALREADY_EXISTS;
-	}
-
-	if (lock < 0) {
-		lxc_log_error("failed to acquire lock on '%s':%s",
-			      name, strerror(-lock));
-		goto err;
-	}
+	if (lock < 0)
+		return -LXC_ERROR_LOCK;
 
+	err = LXC_ERROR_INTERNAL;
 	if (lxc_mkstate(name)) {
 		lxc_log_error("failed to create the state file for %s", name);
 		goto err;

src/lxc/destroy.c

@@ -52,15 +52,12 @@ int lxc_destroy(const char *name)
 	char path[MAXPATHLEN];
 
 	lock = lxc_get_lock(name);
-	if (!lock) {
-		lxc_log_error("'%s' is busy", name);
-		return -LXC_ERROR_BUSY;
-	}
-
 	if (lock < 0) {
-		lxc_log_error("failed to acquire the lock for '%s':%s", 
-			      name, strerror(-lock));
-		goto out;
+		if (lock == -EWOULDBLOCK)
+			return -LXC_ERROR_BUSY;
+		if (lock == -ENOENT)
+			return -LXC_ERROR_NOT_FOUND;
+		return -LXC_ERROR_INTERNAL;
 	}
 
 	if (lxc_rmstate(name)) {

src/lxc/error.c

@@ -22,11 +22,14 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include "error.h"
 
+static const char *const catalogue[] = {
 
-static char *catalogue[] = {
-	[LXC_ERROR_EMPTY] = "The container is not running",
+	[LXC_ERROR_LOCK] = "Failed to lock the container",
+
+	[LXC_ERROR_EMPTY] = "The container is empty",
 	[LXC_ERROR_ALREADY_EXISTS] = "The container already exists",
 	[LXC_ERROR_BUSY] = "The container is busy",
 	[LXC_ERROR_NOT_FOUND] = "The container was not found",
@@ -50,7 +53,10 @@ static char *catalogue[] = {
 
 const char *const lxc_strerror(int error)
 {
-	if (error < 0 || error >= LXC_LAST_ERROR)
+	error = abs(error);
+
+	if (error >= LXC_LAST_ERROR)
 		return NULL;
+
 	return catalogue[error];
 }

src/lxc/error.h

@@ -24,6 +24,10 @@
 #define __lxc_error_h
 
 typedef enum {
+	LXC_SUCCESS, /* 0 == success ;) */
+
+	LXC_ERROR_LOCK,
+
 	LXC_ERROR_EMPTY,
 	LXC_ERROR_BUSY,
 	LXC_ERROR_ALREADY_EXISTS,

src/lxc/lxc.h

@@ -171,7 +171,7 @@ extern int lxc_cgroup_get(const char *name, const char *subsystem,
  * @error : the value of the error
  * Returns a string on success or NULL otherwise.
  */
-extern int lxc_strerror(int error);
+extern const char *const lxc_strerror(int error);
 
 /*
  * Checkpoint a container previously frozen

src/lxc/lxc_create.c

@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
 {
 	const char *name = NULL, *file = NULL;
 	struct lxc_conf lxc_conf;
-	int opt;
+	int err, opt;
 
 	while ((opt = getopt(argc, argv, "f:n:")) != -1) {
 		switch (opt) {
@@ -72,8 +72,9 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
-	if (lxc_create(name, &lxc_conf)) {
-		fprintf(stderr, "failed to create the container '%s'\n", name);
+	err = lxc_create(name, &lxc_conf);
+	if (err) {
+		fprintf(stderr, "%s\n", lxc_strerror(err));
 		return 1;
 	}
 

src/lxc/lxc_destroy.c

@@ -39,6 +39,7 @@ int main(int argc, char *argv[])
 	char opt;
 	char *name = NULL;
 	int nbargs = 0;
+	int err;
 
 	while ((opt = getopt(argc, argv, "n:")) != -1) {
 		switch (opt) {
@@ -53,8 +54,9 @@ int main(int argc, char *argv[])
 	if (!name)
 		usage(argv[0]);
 
-	if (lxc_destroy(name)) {
-		fprintf(stderr, "failed to destroy '%s'\n", name);
+	err = lxc_destroy(name);
+	if (err) {
+		fprintf(stderr, "%s\n", lxc_strerror(err));
 		return 1;
 	}
 

src/lxc/lxc_execute.c

@@ -104,8 +104,9 @@ int main(int argc, char *argv[])
 	for (opt = 0; opt < argc; opt++)
 		args[nbargs++] = argv[optind++];
 
-	if (lxc_start(name, args)) {
-		fprintf(stderr, "failed to execute '%s'\n", name);
+	ret = lxc_start(name, args);
+	if (ret) {
+		fprintf(stderr, "%s\n", lxc_strerror(ret));
 		goto out;
 	}
 

src/lxc/lxc_lock.c

@@ -47,7 +47,7 @@ int lxc_get_lock(const char *name)
         fcntl(fd, F_SETFD, FD_CLOEXEC);
 
 	if (flock(fd, LOCK_EX|LOCK_NB)) {
-		ret = errno == EWOULDBLOCK ? 0 : -errno;
+		ret = -errno;
 		close(fd);
 		goto out;
 	}

src/lxc/lxc_start.c

@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
 	char opt;
 	char *name = NULL;
 	char **args;
-	int nbargs = 0;
+	int err, nbargs = 0;
 	char *default_args[] = {
 		"/sbin/init",
 		'\0',
@@ -72,8 +72,9 @@ int main(int argc, char *argv[])
 	if (!name)
 		usage(argv[0]);
 
-	if (lxc_start(name, args)) {
-		fprintf(stderr, "failed to start %s\n", name);
+	err = lxc_start(name, args);
+	if (err) {
+		fprintf(stderr, "%s\n", lxc_strerror(err));
 		return 1;
 	}
 

src/lxc/lxc_stop.c

@@ -38,7 +38,7 @@ int main(int argc, char *argv[])
 {
 	char opt;
 	char *name = NULL;
-	int nbargs = 0;
+	int err, nbargs = 0;
 
 	while ((opt = getopt(argc, argv, "n:")) != -1) {
 		switch (opt) {
@@ -53,8 +53,9 @@ int main(int argc, char *argv[])
 	if (!name)
 		usage(argv[0]);
 
-	if (lxc_stop(name)) {
-		fprintf(stderr, "failed to stop %s\n", name);
+	err = lxc_stop(name);
+	if (err) {
+		fprintf(stderr, "%s\n", lxc_strerror(err));
 		return 1;
 	}
 

src/lxc/restart.c

@@ -37,6 +37,7 @@
 #include <sys/wait.h>
 #include <sys/mount.h>
 
+#include "error.h"
 #include <lxc/lxc.h>
 
 LXC_TTY_HANDLER(SIGINT);
@@ -73,16 +74,10 @@ int lxc_restart(const char *name, int cfd, unsigned long flags)
 	int clone_flags;
 
 	lock = lxc_get_lock(name);
-	if (!lock) {
-		lxc_log_error("'%s' is busy", name);
-		return -1;
-	}
-
-	if (lock < 0) {
-		lxc_log_error("failed to acquire lock on '%s':%s",
-			      name, strerror(-lock));
-		return -1;
-	}
+	if (lock < 0)
+		return lock == -EWOULDBLOCK ? 
+			-LXC_ERROR_BUSY : 
+			-LXC_ERROR_LOCK;
 
 	/* Begin the set the state to STARTING*/
 	if (lxc_setstate(name, STARTING)) {

src/lxc/start.c

@@ -55,20 +55,14 @@ int lxc_start(const char *name, char *argv[])
 	int clone_flags;
 
 	lock = lxc_get_lock(name);
-	if (!lock) {
-		lxc_log_error("'%s' is busy", name);
-		return -LXC_ERROR_BUSY;
-	}
-
-	if (lock < 0) {
-		lxc_log_error("failed to acquire lock on '%s':%s",
-			      name, strerror(-lock));
-		return -LXC_ERROR_INTERNAL;
-	}
+	if (lock < 0)
+		return lock == -EWOULDBLOCK ? 
+			-LXC_ERROR_BUSY : 
+			-LXC_ERROR_LOCK;
 
 	/* Begin the set the state to STARTING*/
 	if (lxc_setstate(name, STARTING)) {
-		lxc_log_error("failed to set state %s", lxc_state2str(STARTING));
+		lxc_log_error("failed to set state '%s'", lxc_state2str(STARTING));
 		goto out;
 	}
 

src/lxc/stop.c

@@ -44,16 +44,15 @@ int lxc_stop(const char *name)
 	size_t pid;
 
 	lock = lxc_get_lock(name);
-	if (lock > 0) {
-		lxc_log_error("'%s' is not running", name);
+	if (lock >= 0) {
 		lxc_put_lock(lock);
 		return -LXC_ERROR_EMPTY;
 	}
 
-	if (lock < 0) {
-		lxc_log_error("failed to acquire the lock on '%s':%s", 
-			      name, strerror(-lock));
-		return -LXC_ERROR_INTERNAL;
+	if (lock < 0 && lock != -EWOULDBLOCK) {
+		if (lock == -ENOENT)
+			return -LXC_ERROR_NOT_FOUND;
+		return -LXC_ERROR_LOCK;
 	}
 
 	snprintf(init, MAXPATHLEN, LXCPATH "/%s/init", name);