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>
This commit is contained in:
Sean Anderson 2022-03-22 16:59:20 -04:00 committed by Tom Rini
parent 8e1c9fe243
commit f676b45151
6 changed files with 160 additions and 2 deletions

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@ -455,7 +455,7 @@ int blk_get_device_part_str(const char *ifname, const char *dev_part_str,
int part; int part;
struct disk_partition tmpinfo; 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 * Special-case a pseudo block device "hostfs", to allow access to the
* host's own filesystem. * 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->blksz = 0;
info->bootable = 0; info->bootable = 0;
strcpy((char *)info->type, BOOT_PART_TYPE); 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) #if CONFIG_IS_ENABLED(PARTITION_UUIDS)
info->uuid[0] = 0; info->uuid[0] = 0;
#endif #endif

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@ -21,6 +21,7 @@ obj-$(CONFIG_FS_FAT) += fat/
obj-$(CONFIG_FS_JFFS2) += jffs2/ obj-$(CONFIG_FS_JFFS2) += jffs2/
obj-$(CONFIG_CMD_REISER) += reiserfs/ obj-$(CONFIG_CMD_REISER) += reiserfs/
obj-$(CONFIG_SANDBOX) += sandbox/ obj-$(CONFIG_SANDBOX) += sandbox/
obj-$(CONFIG_SEMIHOSTING) += semihostingfs.o
obj-$(CONFIG_CMD_UBIFS) += ubifs/ obj-$(CONFIG_CMD_UBIFS) += ubifs/
obj-$(CONFIG_YAFFS2) += yaffs2/ obj-$(CONFIG_YAFFS2) += yaffs2/
obj-$(CONFIG_CMD_ZFS) += zfs/ obj-$(CONFIG_CMD_ZFS) += zfs/

20
fs/fs.c
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@ -18,6 +18,7 @@
#include <fat.h> #include <fat.h>
#include <fs.h> #include <fs.h>
#include <sandboxfs.h> #include <sandboxfs.h>
#include <semihostingfs.h>
#include <ubifs_uboot.h> #include <ubifs_uboot.h>
#include <btrfs.h> #include <btrfs.h>
#include <asm/global_data.h> #include <asm/global_data.h>
@ -247,6 +248,25 @@ static struct fstype_info fstypes[] = {
.ln = fs_ln_unsupported, .ln = fs_ln_unsupported,
}, },
#endif #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 #ifdef CONFIG_CMD_UBIFS
{ {
.fstype = FS_TYPE_UBIFS, .fstype = FS_TYPE_UBIFS,

115
fs/semihostingfs.c Normal file
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@ -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;
}

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@ -18,6 +18,7 @@ struct cmd_tbl;
#define FS_TYPE_BTRFS 5 #define FS_TYPE_BTRFS 5
#define FS_TYPE_SQUASHFS 6 #define FS_TYPE_SQUASHFS 6
#define FS_TYPE_EROFS 7 #define FS_TYPE_EROFS 7
#define FS_TYPE_SEMIHOSTING 8
struct blk_desc; struct blk_desc;

21
include/semihostingfs.h Normal file
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@ -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