handle directory destination for a file volume binding

If the destination directoroy does not exist in the base image,
create it as a file instead, following docker's practice.

[hyperpublic@hyperhq]$docker run -t -i -v /home/bergwolf/bin/procmuttmail:/vol/data/ busybox
/ # ls -l /vol/data
-rwxr-xr-x    1 1000     1000            28 Apr 17 05:38 /vol/data
/ #

Signed-off-by: Peng Tao <bergwolf@gmail.com>

src/container.c

@@ -144,6 +144,7 @@ static int container_setup_volume(struct hyper_container *container)
 				}
 			}
 		} else {
+			hyper_filize(mountpoint);
 			if (hyper_create_file(mountpoint) < 0) {
 				perror("create volume file failed");
 				return -1;

src/util.c

@@ -208,6 +208,21 @@ int hyper_getgrouplist(const char *user, gid_t group, gid_t *groups, int *ngroup
 	return ret;
 }
 
+/* Trim all trailing '/' of a hyper_path except for the prefix one. */
+void hyper_filize(char *hyper_path)
+{
+	char *p;
+
+	if (strlen(hyper_path) == 0)
+		return;
+
+	p = &hyper_path[strlen(hyper_path) - 1];
+
+	for (; *p == '/' && p != hyper_path; p--) {
+		*p = '\0';
+	}
+}
+
 static int hyper_create_parent_dir(const char *hyper_path)
 {
 	char *p, *path = strdup(hyper_path);
@@ -225,6 +240,7 @@ static int hyper_create_parent_dir(const char *hyper_path)
 	return ret;
 }
 
+/* hyper_path must point to a file rather than a directory, e.g., having trailing '/' */
 int hyper_create_file(const char *hyper_path)
 {
 	int fd;

src/util.h

@@ -26,6 +26,7 @@ void online_cpu(void);
 void online_memory(void);
 int hyper_cmd(char *cmd);
 int hyper_create_file(const char *hyper_path);
+void hyper_filize(char *hyper_path);
 int hyper_mkdir(char *path, mode_t mode);
 int hyper_open_channel(char *channel, int mode);
 int hyper_open_serial_dev(char *tty);