fs: Add semihosting filesystem

This adds a filesystem which is backed by the host's filesystem. It is
modeled off of sandboxfs, which has very similar aims. Semihosting
doesn't support listing directories (except with SYS_SYSTEM), so neither
do we. it's possible to optimize a bit for the common case of reading a
whole file by omitting a call to smh_seek, but this is left as a future
optimization.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>

diff --git a/disk/part.c b/disk/part.c
index 49e39a24e86891247ec8362ed11a106195b8354f..b95405bb498f38428eabd335124f4bd3fbc19438 100644 (file)
--- a/disk/part.c
+++ b/disk/part.c
@@ -455,7 +455,7 @@ int blk_get_device_part_str(const char *ifname, const char *dev_part_str,
        int part;
        struct disk_partition tmpinfo;
 
-#ifdef CONFIG_SANDBOX
+#if IS_ENABLED(CONFIG_SANDBOX) || IS_ENABLED(CONFIG_SEMIHOSTING)
        /*
         * Special-case a pseudo block device "hostfs", to allow access to the
         * host's own filesystem.
@@ -467,7 +467,7 @@ int blk_get_device_part_str(const char *ifname, const char *dev_part_str,
                info->blksz = 0;
                info->bootable = 0;
                strcpy((char *)info->type, BOOT_PART_TYPE);
-               strcpy((char *)info->name, "Sandbox host");
+               strcpy((char *)info->name, "Host filesystem");
 #if CONFIG_IS_ENABLED(PARTITION_UUIDS)
                info->uuid[0] = 0;
 #endif

diff --git a/fs/Makefile b/fs/Makefile
index f05a21c9e6d5c6d280f85698fe0e779854923550..4bed2ff2d99cf02531bf08d517bb10aa10f1ac98 100644 (file)
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_FS_FAT) += fat/
 obj-$(CONFIG_FS_JFFS2) += jffs2/
 obj-$(CONFIG_CMD_REISER) += reiserfs/
 obj-$(CONFIG_SANDBOX) += sandbox/
+obj-$(CONFIG_SEMIHOSTING) += semihostingfs.o
 obj-$(CONFIG_CMD_UBIFS) += ubifs/
 obj-$(CONFIG_YAFFS2) += yaffs2/
 obj-$(CONFIG_CMD_ZFS) += zfs/

diff --git a/fs/fs.c b/fs/fs.c
index 99dac0fd79fe8b4e54a97136c5871ad906ea2b7a..c3a2ed97541c1a2dfbf28c4ca80ae72be1c86a41 100644 (file)
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -18,6 +18,7 @@
 #include <fat.h>
 #include <fs.h>
 #include <sandboxfs.h>
+#include <semihostingfs.h>
 #include <ubifs_uboot.h>
 #include <btrfs.h>
 #include <asm/global_data.h>
@@ -247,6 +248,25 @@ static struct fstype_info fstypes[] = {
                .ln = fs_ln_unsupported,
        },
 #endif
+#ifdef CONFIG_SEMIHOSTING
+       {
+               .fstype = FS_TYPE_SEMIHOSTING,
+               .name = "semihosting",
+               .null_dev_desc_ok = true,
+               .probe = smh_fs_set_blk_dev,
+               .close = fs_close_unsupported,
+               .ls = fs_ls_unsupported,
+               .exists = fs_exists_unsupported,
+               .size = smh_fs_size,
+               .read = smh_fs_read,
+               .write = smh_fs_write,
+               .uuid = fs_uuid_unsupported,
+               .opendir = fs_opendir_unsupported,
+               .unlink = fs_unlink_unsupported,
+               .mkdir = fs_mkdir_unsupported,
+               .ln = fs_ln_unsupported,
+       },
+#endif
 #ifdef CONFIG_CMD_UBIFS
        {
                .fstype = FS_TYPE_UBIFS,

diff --git a/fs/semihostingfs.c b/fs/semihostingfs.c
new file mode 100644 (file)
index 0000000..96eb334
--- /dev/null
+++ b/fs/semihostingfs.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2022, Sean Anderson <sean.anderson@seco.com>
+ * Copyright (c) 2012, Google Inc.
+ */
+
+#include <common.h>
+#include <fs.h>
+#include <malloc.h>
+#include <os.h>
+#include <semihosting.h>
+#include <semihostingfs.h>
+
+int smh_fs_set_blk_dev(struct blk_desc *rbdd, struct disk_partition *info)
+{
+       /*
+        * Only accept a NULL struct blk_desc for the semihosting, which is when
+        * hostfs interface is used
+        */
+       return !!rbdd;
+}
+
+static int smh_fs_read_at(const char *filename, loff_t pos, void *buffer,
+                         loff_t maxsize, loff_t *actread)
+{
+       long fd, size, ret;
+
+       fd = smh_open(filename, MODE_READ | MODE_BINARY);
+       if (fd < 0)
+               return fd;
+       ret = smh_seek(fd, pos);
+       if (ret < 0) {
+               smh_close(fd);
+               return ret;
+       }
+       if (!maxsize) {
+               size = smh_flen(fd);
+               if (ret < 0) {
+                       smh_close(fd);
+                       return size;
+               }
+
+               maxsize = size;
+       }
+
+       size = smh_read(fd, buffer, maxsize);
+       smh_close(fd);
+       if (size < 0)
+               return size;
+
+       *actread = size;
+       return 0;
+}
+
+static int smh_fs_write_at(const char *filename, loff_t pos, void *buffer,
+                          loff_t towrite, loff_t *actwrite)
+{
+       long fd, size, ret;
+
+       fd = smh_open(filename, MODE_READ | MODE_BINARY | MODE_PLUS);
+       if (fd < 0)
+               return fd;
+       ret = smh_seek(fd, pos);
+       if (ret < 0) {
+               smh_close(fd);
+               return ret;
+       }
+
+       ret = smh_write(fd, buffer, towrite, &size);
+       smh_close(fd);
+       *actwrite = size;
+       return ret;
+}
+
+int smh_fs_size(const char *filename, loff_t *result)
+{
+       long fd, size;
+
+       fd = smh_open(filename, MODE_READ | MODE_BINARY);
+       if (fd < 0)
+               return fd;
+
+       size = smh_flen(fd);
+       smh_close(fd);
+
+       if (size < 0)
+               return size;
+
+       *result = size;
+       return 0;
+}
+
+int smh_fs_read(const char *filename, void *buf, loff_t offset, loff_t len,
+               loff_t *actread)
+{
+       int ret;
+
+       ret = smh_fs_read_at(filename, offset, buf, len, actread);
+       if (ret)
+               printf("** Unable to read file %s **\n", filename);
+
+       return ret;
+}
+
+int smh_fs_write(const char *filename, void *buf, loff_t offset,
+                loff_t len, loff_t *actwrite)
+{
+       int ret;
+
+       ret = smh_fs_write_at(filename, offset, buf, len, actwrite);
+       if (ret)
+               printf("** Unable to write file %s **\n", filename);
+
+       return ret;
+}

diff --git a/include/fs.h b/include/fs.h
index b607b0028dce8a98d368a73e0a5efb92bb2698dd..e2beba36b986ad7ccd43d11f51fddf7692d43949 100644 (file)
--- a/include/fs.h
+++ b/include/fs.h
@@ -18,6 +18,7 @@ struct cmd_tbl;
 #define FS_TYPE_BTRFS  5
 #define FS_TYPE_SQUASHFS 6
 #define FS_TYPE_EROFS   7
+#define FS_TYPE_SEMIHOSTING 8
 
 struct blk_desc;
 

diff --git a/include/semihostingfs.h b/include/semihostingfs.h
new file mode 100644 (file)
index 0000000..25ebdbb
--- /dev/null
+++ b/include/semihostingfs.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2022, Sean Anderson <sean.anderson@seco.com>
+ * Copyright (c) 2012, Google Inc.
+ */
+
+#ifndef __SEMIHOSTING_FS__
+#define __SEMIHOSTING_FS__
+
+struct blk_desc;
+struct disk_partition;
+
+int smh_fs_set_blk_dev(struct blk_desc *rbdd, struct disk_partition *info);
+void smh_fs_close(void);
+int smh_fs_size(const char *filename, loff_t *size);
+int smh_fs_read(const char *filename, void *buf, loff_t offset, loff_t len,
+               loff_t *actread);
+int smh_fs_write(const char *filename, void *buf, loff_t offset,
+                loff_t len, loff_t *actwrite);
+
+#endif