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VFS: Implement pread() and pwrite()

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Closes https://github.com/espressif/esp-idf/issues/3515
This commit is contained in:
Roland Dobai
2019-07-01 11:08:57 +02:00
committed by bot
parent 1ea68e6093
commit 41062bea99
10 changed files with 307 additions and 0 deletions
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82
components/fatfs/vfs/vfs_fat.c
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@@ -68,6 +68,8 @@ static const char* TAG = "vfs_fat";
static ssize_t vfs_fat_write(void* p, int fd, const void * data, size_t size);
static off_t vfs_fat_lseek(void* p, int fd, off_t size, int mode);
static ssize_t vfs_fat_read(void* ctx, int fd, void * dst, size_t size);
static ssize_t vfs_fat_pread(void *ctx, int fd, void *dst, size_t size, off_t offset);
static ssize_t vfs_fat_pwrite(void *ctx, int fd, const void *src, size_t size, off_t offset);
static int vfs_fat_open(void* ctx, const char * path, int flags, int mode);
static int vfs_fat_close(void* ctx, int fd);
static int vfs_fat_fstat(void* ctx, int fd, struct stat * st);
@@ -129,6 +131,8 @@ esp_err_t esp_vfs_fat_register(const char* base_path, const char* fat_drive, siz
.write_p = &vfs_fat_write,
.lseek_p = &vfs_fat_lseek,
.read_p = &vfs_fat_read,
.pread_p = &vfs_fat_pread,
.pwrite_p = &vfs_fat_pwrite,
.open_p = &vfs_fat_open,
.close_p = &vfs_fat_close,
.fstat_p = &vfs_fat_fstat,
@@ -373,6 +377,84 @@ static ssize_t vfs_fat_read(void* ctx, int fd, void * dst, size_t size)
return read;
}
static ssize_t vfs_fat_pread(void *ctx, int fd, void *dst, size_t size, off_t offset)
{
ssize_t ret = -1;
vfs_fat_ctx_t *fat_ctx = (vfs_fat_ctx_t *) ctx;
_lock_acquire(&fat_ctx->lock);
FIL *file = &fat_ctx->files[fd];
const off_t prev_pos = f_tell(file);
FRESULT f_res = f_lseek(file, offset);
if (f_res != FR_OK) {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
errno = fresult_to_errno(f_res);
goto pread_release;
}
unsigned read = 0;
f_res = f_read(file, dst, size, &read);
if (f_res == FR_OK) {
ret = read;
} else {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
errno = fresult_to_errno(f_res);
// No return yet - need to restore previous position
}
f_res = f_lseek(file, prev_pos);
if (f_res != FR_OK) {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
if (ret >= 0) {
errno = fresult_to_errno(f_res);
} // else f_read failed so errno shouldn't be overwritten
ret = -1; // in case the read was successful but the seek wasn't
}
pread_release:
_lock_release(&fat_ctx->lock);
return ret;
}
static ssize_t vfs_fat_pwrite(void *ctx, int fd, const void *src, size_t size, off_t offset)
{
ssize_t ret = -1;
vfs_fat_ctx_t *fat_ctx = (vfs_fat_ctx_t *) ctx;
_lock_acquire(&fat_ctx->lock);
FIL *file = &fat_ctx->files[fd];
const off_t prev_pos = f_tell(file);
FRESULT f_res = f_lseek(file, offset);
if (f_res != FR_OK) {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
errno = fresult_to_errno(f_res);
goto pwrite_release;
}
unsigned wr = 0;
f_res = f_write(file, src, size, &wr);
if (f_res == FR_OK) {
ret = wr;
} else {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
errno = fresult_to_errno(f_res);
// No return yet - need to restore previous position
}
f_res = f_lseek(file, prev_pos);
if (f_res != FR_OK) {
ESP_LOGD(TAG, "%s: fresult=%d", __func__, f_res);
if (ret >= 0) {
errno = fresult_to_errno(f_res);
} // else f_write failed so errno shouldn't be overwritten
ret = -1; // in case the write was successful but the seek wasn't
}
pwrite_release:
_lock_release(&fat_ctx->lock);
return ret;
}
static int vfs_fat_fsync(void* ctx, int fd)
{
vfs_fat_ctx_t* fat_ctx = (vfs_fat_ctx_t*) ctx;