kopia lustrzana https://github.com/espressif/esp-idf
312 wiersze
9.3 KiB
C
312 wiersze
9.3 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <sys/errno.h>
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#include "esp_vfs.h"
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#include "esp_log.h"
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/*
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* File descriptors visible by the applications are composed of two parts.
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* Lower CONFIG_MAX_FD_BITS bits are used for the actual file descriptor.
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* Next (16 - CONFIG_MAX_FD_BITS - 1) bits are used to identify the VFS this
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* descriptor corresponds to.
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* Highest bit is zero.
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* We can only use 16 bits because newlib stores file descriptor as short int.
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*/
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#ifndef CONFIG_MAX_FD_BITS
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#define CONFIG_MAX_FD_BITS 12
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#endif
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#define MAX_VFS_ID_BITS (16 - CONFIG_MAX_FD_BITS - 1)
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// mask of actual file descriptor (e.g. 0x00000fff)
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#define VFS_FD_MASK ((1 << CONFIG_MAX_FD_BITS) - 1)
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// max number of VFS entries
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#define VFS_MAX_COUNT ((1 << MAX_VFS_ID_BITS) - 1)
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// mask of VFS id (e.g. 0x00007000)
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#define VFS_INDEX_MASK (VFS_MAX_COUNT << CONFIG_MAX_FD_BITS)
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#define VFS_INDEX_S CONFIG_MAX_FD_BITS
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typedef struct vfs_entry_ {
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esp_vfs_t vfs; // contains pointers to VFS functions
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char path_prefix[ESP_VFS_PATH_MAX]; // path prefix mapped to this VFS
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size_t path_prefix_len; // micro-optimization to avoid doing extra strlen
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void* ctx; // optional pointer which can be passed to VFS
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int offset; // index of this structure in s_vfs array
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} vfs_entry_t;
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static vfs_entry_t* s_vfs[VFS_MAX_COUNT] = { 0 };
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static size_t s_vfs_count = 0;
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esp_err_t esp_vfs_register(const char* base_path, const esp_vfs_t* vfs, void* ctx)
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{
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size_t len = strlen(base_path);
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if (len < 2 || len > ESP_VFS_PATH_MAX) {
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return ESP_ERR_INVALID_ARG;
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}
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if (base_path[0] != '/' || base_path[len - 1] == '/') {
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return ESP_ERR_INVALID_ARG;
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}
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vfs_entry_t *entry = (vfs_entry_t*) malloc(sizeof(vfs_entry_t));
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if (entry == NULL) {
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return ESP_ERR_NO_MEM;
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}
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size_t index;
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for (index = 0; index < s_vfs_count; ++index) {
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if (s_vfs[index] == NULL) {
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break;
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}
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}
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if (index == s_vfs_count) {
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if (s_vfs_count >= VFS_MAX_COUNT) {
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free(entry);
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return ESP_ERR_NO_MEM;
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}
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++s_vfs_count;
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}
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s_vfs[index] = entry;
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strcpy(entry->path_prefix, base_path); // we have already verified argument length
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memcpy(&entry->vfs, vfs, sizeof(esp_vfs_t));
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entry->path_prefix_len = len;
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entry->ctx = ctx;
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entry->offset = index;
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return ESP_OK;
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}
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esp_err_t esp_vfs_unregister(const char* base_path)
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{
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for (size_t i = 0; i < s_vfs_count; ++i) {
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vfs_entry_t* vfs = s_vfs[i];
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if (memcmp(base_path, vfs->path_prefix, vfs->path_prefix_len) == 0) {
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free(vfs);
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s_vfs[i] = NULL;
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return ESP_OK;
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}
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}
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return ESP_ERR_INVALID_STATE;
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}
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static const vfs_entry_t* get_vfs_for_fd(int fd)
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{
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int index = ((fd & VFS_INDEX_MASK) >> VFS_INDEX_S);
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if (index >= s_vfs_count) {
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return NULL;
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}
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return s_vfs[index];
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}
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static int translate_fd(const vfs_entry_t* vfs, int fd)
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{
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return (fd & VFS_FD_MASK) + vfs->vfs.fd_offset;
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}
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static const char* translate_path(const vfs_entry_t* vfs, const char* src_path)
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{
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assert(strncmp(src_path, vfs->path_prefix, vfs->path_prefix_len) == 0);
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return src_path + vfs->path_prefix_len;
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}
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static const vfs_entry_t* get_vfs_for_path(const char* path)
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{
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size_t len = strlen(path);
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for (size_t i = 0; i < s_vfs_count; ++i) {
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const vfs_entry_t* vfs = s_vfs[i];
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if (len < vfs->path_prefix_len + 1) { // +1 is for the trailing slash after base path
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continue;
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}
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if (memcmp(path, vfs->path_prefix, vfs->path_prefix_len) != 0) { // match prefix
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continue;
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}
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if (path[vfs->path_prefix_len] != '/') { // don't match "/data" prefix for "/data1/foo.txt"
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continue;
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}
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return vfs;
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}
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return NULL;
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}
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/*
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* Using huge multi-line macros is never nice, but in this case
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* the only alternative is to repeat this chunk of code (with different function names)
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* for each syscall being implemented. Given that this define is contained within a single
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* file, this looks like a good tradeoff.
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*
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* First we check if syscall is implemented by VFS (corresponding member is not NULL),
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* then call the right flavor of the method (e.g. open or open_p) depending on
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* ESP_VFS_FLAG_CONTEXT_PTR flag. If ESP_VFS_FLAG_CONTEXT_PTR is set, context is passed
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* in as first argument and _p variant is used for the call.
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* It is enough to check just one of them for NULL, as both variants are part of a union.
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*/
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#define CHECK_AND_CALL(ret, r, pvfs, func, ...) \
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if (pvfs->vfs.func == NULL) { \
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__errno_r(r) = ENOSYS; \
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return -1; \
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} \
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if (pvfs->vfs.flags & ESP_VFS_FLAG_CONTEXT_PTR) { \
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ret = (*pvfs->vfs.func ## _p)(pvfs->ctx, __VA_ARGS__); \
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} else { \
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ret = (*pvfs->vfs.func)(__VA_ARGS__);\
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}
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int esp_vfs_open(struct _reent *r, const char * path, int flags, int mode)
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{
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const vfs_entry_t* vfs = get_vfs_for_path(path);
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if (vfs == NULL) {
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__errno_r(r) = ENOENT;
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return -1;
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}
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const char* path_within_vfs = translate_path(vfs, path);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, open, path_within_vfs, flags, mode);
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if (ret < 0) {
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return ret;
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}
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assert(ret >= vfs->vfs.fd_offset);
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return ret - vfs->vfs.fd_offset + (vfs->offset << VFS_INDEX_S);
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}
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ssize_t esp_vfs_write(struct _reent *r, int fd, const void * data, size_t size)
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{
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const vfs_entry_t* vfs = get_vfs_for_fd(fd);
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if (vfs == NULL) {
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__errno_r(r) = EBADF;
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return -1;
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}
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int local_fd = translate_fd(vfs, fd);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, write, local_fd, data, size);
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return ret;
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}
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off_t esp_vfs_lseek(struct _reent *r, int fd, off_t size, int mode)
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{
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const vfs_entry_t* vfs = get_vfs_for_fd(fd);
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if (vfs == NULL) {
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__errno_r(r) = EBADF;
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return -1;
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}
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int local_fd = translate_fd(vfs, fd);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, lseek, local_fd, size, mode);
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return ret;
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}
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ssize_t esp_vfs_read(struct _reent *r, int fd, void * dst, size_t size)
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{
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const vfs_entry_t* vfs = get_vfs_for_fd(fd);
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if (vfs == NULL) {
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__errno_r(r) = EBADF;
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return -1;
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}
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int local_fd = translate_fd(vfs, fd);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, read, local_fd, dst, size);
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return ret;
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}
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int esp_vfs_close(struct _reent *r, int fd)
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{
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const vfs_entry_t* vfs = get_vfs_for_fd(fd);
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if (vfs == NULL) {
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__errno_r(r) = EBADF;
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return -1;
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}
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int local_fd = translate_fd(vfs, fd);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, close, local_fd);
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return ret;
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}
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int esp_vfs_fstat(struct _reent *r, int fd, struct stat * st)
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{
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const vfs_entry_t* vfs = get_vfs_for_fd(fd);
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if (vfs == NULL) {
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__errno_r(r) = EBADF;
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return -1;
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}
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int local_fd = translate_fd(vfs, fd);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, fstat, local_fd, st);
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return ret;
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}
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int esp_vfs_stat(struct _reent *r, const char * path, struct stat * st)
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{
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const vfs_entry_t* vfs = get_vfs_for_path(path);
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if (vfs == NULL) {
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__errno_r(r) = ENOENT;
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return -1;
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}
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const char* path_within_vfs = translate_path(vfs, path);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, stat, path_within_vfs, st);
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return ret;
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}
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int esp_vfs_link(struct _reent *r, const char* n1, const char* n2)
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{
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const vfs_entry_t* vfs = get_vfs_for_path(n1);
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if (vfs == NULL) {
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__errno_r(r) = ENOENT;
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return -1;
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}
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const vfs_entry_t* vfs2 = get_vfs_for_path(n2);
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if (vfs != vfs2) {
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__errno_r(r) = EXDEV;
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return -1;
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}
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const char* path1_within_vfs = translate_path(vfs, n1);
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const char* path2_within_vfs = translate_path(vfs, n2);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, link, path1_within_vfs, path2_within_vfs);
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return ret;
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}
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int esp_vfs_unlink(struct _reent *r, const char *path)
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{
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const vfs_entry_t* vfs = get_vfs_for_path(path);
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if (vfs == NULL) {
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__errno_r(r) = ENOENT;
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return -1;
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}
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const char* path_within_vfs = translate_path(vfs, path);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, unlink, path_within_vfs);
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return ret;
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}
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int esp_vfs_rename(struct _reent *r, const char *src, const char *dst)
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{
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const vfs_entry_t* vfs = get_vfs_for_path(src);
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if (vfs == NULL) {
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__errno_r(r) = ENOENT;
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return -1;
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}
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const vfs_entry_t* vfs_dst = get_vfs_for_path(dst);
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if (vfs != vfs_dst) {
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__errno_r(r) = EXDEV;
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return -1;
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}
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const char* src_within_vfs = translate_path(vfs, src);
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const char* dst_within_vfs = translate_path(vfs, dst);
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int ret;
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CHECK_AND_CALL(ret, r, vfs, rename, src_within_vfs, dst_within_vfs);
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return ret;
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}
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