fs: Add simple shell support

Add a simple shell that allows exploring the contents of the file
system.

Jira: ZEP-1235

Change-Id: Iaa49f0be18980dd740e9552ddf4761196a818884
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

subsys/fs/Kconfig

@@ -24,6 +24,13 @@ config FILE_SYSTEM
 
 if FILE_SYSTEM
 
+config FILE_SYSTEM_SHELL
+	bool "Enable file system shell"
+	depends on ENABLE_SHELL
+	help
+	This shell provides basic browsing of the contents of the
+	file system.
+
 config FILE_SYSTEM_FAT
 	bool "FAT file system support"
 	default y

subsys/fs/Makefile

@@ -1,3 +1,4 @@
 obj-$(CONFIG_FS_FAT_RAM_DISK) += fat_ram_diskio.o
 obj-$(CONFIG_FS_FAT_FLASH_DISK) += fat_flash_diskio.o
 obj-$(CONFIG_FILE_SYSTEM_FAT) += fat_fs.o
+obj-$(CONFIG_FILE_SYSTEM_SHELL) += shell.o

subsys/fs/shell.c

@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <misc/printk.h>
+#include <misc/shell.h>
+#include <init.h>
+#include <fs.h>
+
+#define MAX_PATH_LEN 128
+
+static char cwd[MAX_PATH_LEN] = "/";
+
+static int cmd_ls(int argc, char *argv[])
+{
+	char path[MAX_PATH_LEN];
+	fs_dir_t dir;
+	int err;
+
+	if (argc < 2) {
+		strcpy(path, cwd);
+	} else if (argv[1][0] == '/') {
+		strncpy(path, argv[1], sizeof(path) - 1);
+		path[MAX_PATH_LEN - 1] = '\0';
+	} else {
+		if (strcmp(cwd, "/") == 0) {
+			snprintf(path, sizeof(path), "/%s", argv[1]);
+		} else {
+			snprintf(path, sizeof(path), "%s/%s", cwd, argv[1]);
+		}
+	}
+
+	err = fs_opendir(&dir, path);
+	if (err) {
+		printk("Unable to open %s (err %d)\n", path, err);
+		return 0;
+	}
+
+	while (1) {
+		struct fs_dirent entry;
+
+		err = fs_readdir(&dir, &entry);
+		if (err) {
+			printk("Unable to read directory\n");
+			break;
+		}
+
+		/* Check for end of directory listing */
+		if (entry.name[0] == '\0') {
+			break;
+		}
+
+		if (entry.type == FS_DIR_ENTRY_DIR) {
+			printk("%s/\n", entry.name);
+		} else {
+			printk("%s\n", entry.name);
+		}
+	}
+
+	fs_closedir(&dir);
+
+	return 0;
+}
+
+static int cmd_pwd(int argc, char *argv[])
+{
+	printk("%s\n", cwd);
+	return 0;
+}
+
+static int cmd_cd(int argc, char *argv[])
+{
+	char path[MAX_PATH_LEN];
+	struct fs_dirent entry;
+	int err;
+
+	if (argc < 2) {
+		strcpy(cwd, "/");
+		return 0;
+	}
+
+	if (strcmp(argv[1], "..") == 0) {
+		char *prev = strrchr(cwd, '/');
+
+		if (!prev || prev == cwd) {
+			strcpy(cwd, "/");
+		} else {
+			*prev = '\0';
+		}
+
+		/* No need to test that a parent exists */
+		return 0;
+	}
+
+	if (argv[1][0] == '/') {
+		strncpy(path, argv[1], sizeof(path) - 1);
+		path[MAX_PATH_LEN - 1] = '\0';
+	} else {
+		if (strcmp(cwd, "/") == 0) {
+			snprintf(path, sizeof(path), "/%s", argv[1]);
+		} else {
+			snprintf(path, sizeof(path), "%s/%s", cwd, argv[1]);
+		}
+	}
+
+	err = fs_stat(path, &entry);
+	if (err) {
+		printk("%s doesn't exist\n", path);
+		return 0;
+	}
+
+	if (entry.type != FS_DIR_ENTRY_DIR) {
+		printk("%s is not a directory\n", path);
+		return 0;
+	}
+
+	strcpy(cwd, path);
+
+	return 0;
+}
+
+struct shell_cmd fs_commands[] = {
+	{ "ls",    cmd_ls,    "List files in current directory" },
+	{ "cd",    cmd_cd,    "Change working directory" },
+	{ "pwd",   cmd_pwd,   "Print current working directory" },
+	{ NULL, NULL }
+};
+
+
+SHELL_REGISTER("fs", fs_commands);