esp-idf/components/vfs/vfs_semihost.c

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/*
* SPDX-FileCopyrightText: 2020-2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
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#include <stdarg.h>
#include <stdbool.h>
#include <string.h>
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#include <sys/errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "esp_log.h"
#include "esp_vfs.h"
#include "hal/cpu_hal.h"
#include "openocd_semihosting.h"
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#ifndef CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS
#define CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS 1
#endif
#ifndef CONFIG_VFS_SEMIHOSTFS_HOST_PATH_MAX_LEN
#define CONFIG_VFS_SEMIHOSTFS_HOST_PATH_MAX_LEN 128
#endif
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const static char *TAG = "esp_semihost";
/* Additional open flags */
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/* ESP-specific file open flag.
* Indicates that path passed to open() is absolute host path.
*/
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#define ESP_O_SEMIHOST_ABSPATH 0x80000000
/* There is no O_BINARY flag defined in newlib, as well as on Linux,
* but we are leaving it to have the flags table identical to OpenOCD.
*/
#define O_BINARY 0
/* The table is identical to the one in OpenOCD semihosting_common.c */
static const int open_modeflags[12] = {
O_RDONLY,
O_RDONLY | O_BINARY,
O_RDWR,
O_RDWR | O_BINARY,
O_WRONLY | O_CREAT | O_TRUNC,
O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
O_RDWR | O_CREAT | O_TRUNC,
O_RDWR | O_CREAT | O_TRUNC | O_BINARY,
O_WRONLY | O_CREAT | O_APPEND,
O_WRONLY | O_CREAT | O_APPEND | O_BINARY,
O_RDWR | O_CREAT | O_APPEND,
O_RDWR | O_CREAT | O_APPEND | O_BINARY
};
/**
* @brief Get the number of appropriate file open mode set from open_modeflags and add some esp flags to them
*
* @param flags value, every bit of which reflects state of some open-file flag
* @return index of the flag from @ref open_modeflags[], or -1 if invalid flags combination is given.
*/
static inline int get_o_mode(int flags) {
if (flags & O_EXCL) { // bypassing lacking of this at table above
flags &= ~(O_EXCL);
flags |= O_CREAT;
}
for (int i = 0; i < sizeof(open_modeflags) / sizeof(open_modeflags[0]); i++) {
if (flags == open_modeflags[i]) {
return i;
}
}
return -1; // there is no corresponding mode in the table
}
typedef struct {
char base_path[ESP_VFS_PATH_MAX + 1]; /* base path in VFS where host semihosting dir is mounted */
char host_path[CONFIG_VFS_SEMIHOSTFS_HOST_PATH_MAX_LEN + 1]; /* host path to use as base dir for open files */
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} vfs_semihost_ctx_t;
static vfs_semihost_ctx_t s_semhost_ctx[CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS];
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static inline bool ctx_is_unused(const vfs_semihost_ctx_t* ctx)
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{
return ctx->base_path[0] == 0;
}
static inline bool ctx_uses_abspath(const vfs_semihost_ctx_t* ctx)
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{
return ctx->host_path[0];
}
#define FAIL_IF_NO_DEBUGGER() \
do { \
if (!cpu_hal_is_debugger_attached()) { \
errno = EIO; \
return -1; \
} \
} while(0)
#if __XTENSA__
static esp_err_t vfs_semihost_drvinfo(vfs_semihost_ctx_t *ctx)
{
FAIL_IF_NO_DEBUGGER();
int ret = semihosting_ver_info();
if (ret == -1) {
/* Unsupported syscall - old version of OpenOCD */
return ESP_ERR_INVALID_VERSION;
}
return ESP_OK;
}
#endif // __XTENSA__
static int vfs_semihost_open(void* ctx, const char* path, int flags, int mode)
{
int ret_fd = -1;
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char *host_path;
vfs_semihost_ctx_t *semi_ctx = ctx;
FAIL_IF_NO_DEBUGGER();
ESP_LOGV(TAG, "%s: %p '%s 0x%x 0x%x'", __func__, semi_ctx, path, flags, mode);
int o_mode = get_o_mode(flags);
if (o_mode == -1) { /* if wrong flags - error */
errno = EINVAL;
} else {
if (ctx_uses_abspath(semi_ctx)) {
/* Create full absolute path on the host by concatenating host base
* path and file path relative to the filesystem root.
*/
host_path = malloc(strlen(semi_ctx->host_path) + strlen(path) + 1);
if (host_path == NULL) { /* if no valid pointer - error and return */
errno = ENOMEM;
return -1;
}
strcpy(host_path, semi_ctx->host_path);
strcat(host_path, path);
#ifdef __XTENSA__
/* By default, OpenOCD for Xtensa prepends ESP_SEMIHOST_BASEDIR to
* the path passed from the target. Adding this special flag to o_mode
* inhibits this behavior.
* This is not necessary for RISC-V since standard semihosting
* implementation is used there and paths aren't mangled on OpenOCD side.
*/
if (ctx_uses_abspath(semi_ctx)) {
o_mode |= ESP_O_SEMIHOST_ABSPATH;
}
#endif // __XTENSA__
} else {
host_path = (char *)path;
/* For Xtensa targets in OpenOCD there is additional logic related to
* semihosting paths handling that isn't there for other targets.
* When ESP_SEMIHOST_BASEDIR OpenOCD variable is not set, OpenOCD will
* by default prepend '.' to the path passed from the target.
* By contrast, for RISC-V there is no such logic and the path will be
* used as is, no matter whether it is absolute or relative.
* See esp_xtensa_semihosting_get_file_name in esp_xtensa_semihosting.c
* for details.
*/
#ifndef __XTENSA__
if (*host_path == '/') {
++host_path;
}
#endif // !__XTENSA__
}
/* everything is ready: syscall and cleanup */
ret_fd = semihosting_open(host_path, o_mode, mode);
if (ctx_uses_abspath(semi_ctx)) {
free(host_path);
}
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}
return ret_fd;
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}
static ssize_t vfs_semihost_write(void* ctx, int fd, const void * data, size_t size)
{
FAIL_IF_NO_DEBUGGER();
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ESP_LOGV(TAG, "%s: %d %u bytes", __func__, fd, size);
return semihosting_write(fd, data, size);
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}
static ssize_t vfs_semihost_read(void* ctx, int fd, void* data, size_t size)
{
FAIL_IF_NO_DEBUGGER();
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ESP_LOGV(TAG, "%s: %d %u bytes", __func__, fd, size);
return semihosting_read(fd, data, size);
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}
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static int vfs_semihost_close(void* ctx, int fd)
{
FAIL_IF_NO_DEBUGGER();
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ESP_LOGV(TAG, "%s: %d", __func__, fd);
return semihosting_close(fd);
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}
static off_t vfs_semihost_lseek(void* ctx, int fd, off_t offset, int mode)
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{
FAIL_IF_NO_DEBUGGER();
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return semihosting_seek(fd, offset, mode);
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}
esp_err_t esp_vfs_semihost_register(const char* base_path, const char* host_path)
{
const esp_vfs_t vfs = {
.flags = ESP_VFS_FLAG_CONTEXT_PTR,
.write_p = &vfs_semihost_write,
.open_p = &vfs_semihost_open,
.close_p = &vfs_semihost_close,
.read_p = &vfs_semihost_read,
.lseek_p = &vfs_semihost_lseek,
};
ESP_LOGD(TAG, "Register semihosting driver '%s' -> '%s'", base_path, host_path ? host_path : "null");
if (!cpu_hal_is_debugger_attached()) {
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ESP_LOGE(TAG, "OpenOCD is not connected!");
return ESP_ERR_NOT_SUPPORTED;
}
int i = 0;
for (i = 0; i < CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS; i++) {
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if (ctx_is_unused(&s_semhost_ctx[i])) {
break;
}
if (strcmp(base_path, s_semhost_ctx[i].base_path) == 0) {
return ESP_ERR_INVALID_STATE;
}
}
if (i == CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS) {
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return ESP_ERR_NO_MEM;
}
strlcpy(s_semhost_ctx[i].base_path, base_path, sizeof(s_semhost_ctx[i].base_path) - 1);
if (host_path) {
strlcpy(s_semhost_ctx[i].host_path, host_path, sizeof(s_semhost_ctx[i].host_path) - 1);
}
ESP_LOGD(TAG, "Register semihosting driver %d %p", i, &s_semhost_ctx[i]);
esp_err_t err;
#if __XTENSA__
/* Check for older OpenOCD versions */
err = vfs_semihost_drvinfo(&s_semhost_ctx[i]); // define semihosting version
if (err != ESP_OK) {
ESP_LOGE(TAG, "Incompatible OpenOCD version detected. Please follow the getting started guides to install the required version.");
}
#endif // __XTENSA__
err = esp_vfs_register(base_path, &vfs, &s_semhost_ctx[i]);
if (err != ESP_OK) {
ESP_LOGE(TAG, "Can't register the semihosting! Error: %s", esp_err_to_name(err));
return err;
}
return err;
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}
esp_err_t esp_vfs_semihost_unregister(const char* base_path)
{
ESP_LOGD(TAG, "Unregister semihosting driver @ '%s'", base_path);
int i = 0;
for (i = 0; i < CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS; i++) {
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if (s_semhost_ctx[i].base_path[0] != 0 && strcmp(base_path, s_semhost_ctx[i].base_path) == 0) {
break;
}
}
if (i == CONFIG_VFS_SEMIHOSTFS_MAX_MOUNT_POINTS) {
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return ESP_ERR_INVALID_ARG;
}
esp_err_t ret = esp_vfs_unregister(s_semhost_ctx[i].base_path);
if (ret != ESP_OK) {
return ret;
}
s_semhost_ctx[i].base_path[0] = 0;
s_semhost_ctx[i].host_path[0] = 0;
ESP_LOGD(TAG, "Unregistered semihosting driver @ '%s'", base_path);
return ESP_OK;
}