549 lines
12 KiB
Markdown
549 lines
12 KiB
Markdown
# file Module
|
|
| Since | Origin / Contributor | Maintainer | Source |
|
|
| :----- | :-------------------- | :---------- | :------ |
|
|
| 2014-12-22 | [Zeroday](https://github.com/funshine) | [Zeroday](https://github.com/funshine) | [file.c](../../../components/modules/file.c)|
|
|
|
|
The file module provides access to the file system and its individual files.
|
|
|
|
The file system is a flat file system, with no notion of subdirectories/folders.
|
|
|
|
Besides the SPIFFS file system on internal flash, this module can also access FAT partitions on an external SD card if [FatFS is enabled](../sdcard.md).
|
|
|
|
```lua
|
|
-- open file in flash:
|
|
if file.open("init.lua") then
|
|
print(file.read())
|
|
file.close()
|
|
end
|
|
|
|
-- or with full pathspec
|
|
file.open("/FLASH/init.lua")
|
|
|
|
-- open file on SD card
|
|
if file.open("/SD0/somefile.txt") then
|
|
print(file.read())
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
## file.chdir()
|
|
|
|
Change current directory (and drive). This will be used when no drive/directory is prepended to filenames.
|
|
|
|
Current directory defaults to the root of internal SPIFFS (`/FLASH`) after system start.
|
|
|
|
!!! note
|
|
|
|
Function is only available when [FatFS support](../sdcard.md#enabling-fatfs) is compiled into the firmware.
|
|
|
|
#### Syntax
|
|
`file.chdir(dir)`
|
|
|
|
#### Parameters
|
|
`dir` directory name - `/FLASH`, `/SD0`, `/SD1`, etc.
|
|
|
|
#### Returns
|
|
`true` on success, `false` otherwise
|
|
|
|
## file.exists()
|
|
|
|
Determines whether the specified file exists.
|
|
|
|
#### Syntax
|
|
`file.exists(filename)`
|
|
|
|
#### Parameters
|
|
- `filename` file to check
|
|
|
|
#### Returns
|
|
true of the file exists (even if 0 bytes in size), and false if it does not exist
|
|
|
|
#### Example
|
|
|
|
```lua
|
|
files = file.list()
|
|
if files["device.config"] then
|
|
print("Config file exists")
|
|
end
|
|
|
|
if file.exists("device.config") then
|
|
print("Config file exists")
|
|
end
|
|
```
|
|
#### See also
|
|
[`file.list()`](#filelist)
|
|
|
|
## file.format()
|
|
|
|
Format the file system. Completely erases any existing file system and writes a new one. Depending on the size of the flash chip in the ESP, this may take several seconds.
|
|
|
|
!!! note
|
|
|
|
Function is not supported for SD cards.
|
|
|
|
#### Syntax
|
|
`file.format()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
#### See also
|
|
[`file.remove()`](#fileremove)
|
|
|
|
## file.fscfg ()
|
|
|
|
Returns the flash address and physical size of the file system area, in bytes.
|
|
|
|
!!! note
|
|
|
|
Function is not supported for SD cards.
|
|
|
|
#### Syntax
|
|
`file.fscfg()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
- `flash address` (number)
|
|
- `size` (number)
|
|
|
|
#### Example
|
|
```lua
|
|
print(string.format("0x%x", file.fscfg()))
|
|
```
|
|
|
|
## file.fsinfo()
|
|
|
|
Return size information for the file system. The unit is Byte for SPIFFS and kByte for FatFS.
|
|
|
|
#### Syntax
|
|
`file.fsinfo()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
- `remaining` (number)
|
|
- `used` (number)
|
|
- `total` (number)
|
|
|
|
#### Example
|
|
|
|
```lua
|
|
-- get file system info
|
|
remaining, used, total=file.fsinfo()
|
|
print("\nFile system info:\nTotal : "..total.." (k)Bytes\nUsed : "..used.." (k)Bytes\nRemain: "..remaining.." (k)Bytes\n")
|
|
```
|
|
|
|
## file.list()
|
|
|
|
Lists all files in the file system.
|
|
|
|
#### Syntax
|
|
`file.list()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
a lua table which contains the {file name: file size} pairs
|
|
|
|
#### Example
|
|
```lua
|
|
l = file.list();
|
|
for k,v in pairs(l) do
|
|
print("name:"..k..", size:"..v)
|
|
end
|
|
```
|
|
|
|
## file.on()
|
|
|
|
Registers callback functions.
|
|
|
|
Trigger events are:
|
|
|
|
- `rtc` deliver current date & time to the file system. Function is expected to return a table containing the fields `year`, `mon`, `day`, `hour`, `min`, `sec` of current date and time. Not supported for internal flash.
|
|
|
|
#### Syntax
|
|
`file.on(event[, function()])`
|
|
|
|
#### Parameters
|
|
- `event` string
|
|
- `function()` callback function. Unregisters the callback if `function()` is omitted.
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
#### Example
|
|
```lua
|
|
sntp.sync(server_ip,
|
|
function()
|
|
print("sntp time sync ok")
|
|
file.on("rtc",
|
|
function()
|
|
return rtctime.epoch2cal(rtctime.get())
|
|
end)
|
|
end)
|
|
```
|
|
|
|
## file.open()
|
|
|
|
Opens a file for access, potentially creating it (for write modes).
|
|
|
|
When done with the file, it must be closed using `file.close()`.
|
|
|
|
#### Syntax
|
|
`file.open(filename, mode)`
|
|
|
|
#### Parameters
|
|
- `filename` file to be opened, directories are not supported
|
|
- `mode`:
|
|
- "r": read mode (the default)
|
|
- "w": write mode
|
|
- "a": append mode
|
|
- "r+": update mode, all previous data is preserved
|
|
- "w+": update mode, all previous data is erased
|
|
- "a+": append update mode, previous data is preserved, writing is only allowed at the end of file
|
|
|
|
#### Returns
|
|
file object if file opened ok. `nil` if file not opened, or not exists (read modes).
|
|
|
|
#### Example
|
|
```lua
|
|
-- open 'init.lua', print the first line.
|
|
if file.open("init.lua", "r") then
|
|
print(file.readline())
|
|
file.close()
|
|
end
|
|
```
|
|
#### Example (object model)
|
|
```lua
|
|
-- open 'init.lua', print the first line.
|
|
fd = file.open("init.lua", "r")
|
|
if fd then
|
|
print(fd:readline())
|
|
fd:close(); fd = nil
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
- [`file.close()`](#fileclose-fileobjclose)
|
|
- [`file.readline()`](#filereadline-fileobjreadline)
|
|
|
|
## file.remove()
|
|
|
|
Remove a file from the file system. The file must not be currently open.
|
|
|
|
###Syntax
|
|
`file.remove(filename)`
|
|
|
|
#### Parameters
|
|
`filename` file to remove
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
#### Example
|
|
|
|
```lua
|
|
-- remove "foo.lua" from file system.
|
|
file.remove("foo.lua")
|
|
```
|
|
#### See also
|
|
[`file.open()`](#fileopen)
|
|
|
|
## file.rename()
|
|
|
|
Renames a file. If a file is currently open, it will be closed first.
|
|
|
|
#### Syntax
|
|
`file.rename(oldname, newname)`
|
|
|
|
#### Parameters
|
|
- `oldname` old file name
|
|
- `newname` new file name
|
|
|
|
#### Returns
|
|
`true` on success, `false` on error.
|
|
|
|
#### Example
|
|
|
|
```lua
|
|
-- rename file 'temp.lua' to 'init.lua'.
|
|
file.rename("temp.lua","init.lua")
|
|
```
|
|
|
|
# File access functions
|
|
|
|
The `file` module provides several functions to access the content of a file after it has been opened with [`file.open()`](#fileopen). They can be used as part of a basic model or an object model:
|
|
|
|
## Basic model
|
|
In the basic model there is max one file opened at a time. The file access functions operate on this file per default. If another file is opened, the previous default file needs to be closed beforehand.
|
|
|
|
```lua
|
|
-- open 'init.lua', print the first line.
|
|
if file.open("init.lua", "r") then
|
|
print(file.readline())
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
## Object model
|
|
Files are represented by file objects which are created by `file.open()`. File access functions are available as methods of this object, and multiple file objects can coexist.
|
|
|
|
```lua
|
|
src = file.open("init.lua", "r")
|
|
if src then
|
|
dest = file.open("copy.lua", "w")
|
|
if dest then
|
|
local line
|
|
repeat
|
|
line = src:read()
|
|
if line then
|
|
dest:write(line)
|
|
end
|
|
until line == nil
|
|
dest:close(); dest = nil
|
|
end
|
|
src:close(); dest = nil
|
|
end
|
|
```
|
|
|
|
!!! Attention
|
|
|
|
It is recommended to use only one single model within the application. Concurrent use of both models can yield unpredictable behavior: Closing the default file from basic model will also close the correspoding file object. Closing a file from object model will also close the default file if they are the same file.
|
|
|
|
!!! Note
|
|
|
|
The maximum number of open files on SPIFFS is determined at compile time by `SPIFFS_MAX_OPEN_FILES` in `user_config.h`.
|
|
|
|
## file.close(), file.obj:close()
|
|
|
|
Closes the open file, if any.
|
|
|
|
#### Syntax
|
|
`file.close()`
|
|
|
|
`fd:close()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
#### See also
|
|
[`file.open()`](#fileopen)
|
|
|
|
## file.flush(), file.obj:flush()
|
|
|
|
Flushes any pending writes to the file system, ensuring no data is lost on a restart. Closing the open file using [`file.close()` / `fd:close()`](#fileclose-fileobjclose) performs an implicit flush as well.
|
|
|
|
#### Syntax
|
|
`file.flush()`
|
|
|
|
`fd:flush()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
`nil`
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
-- open 'init.lua' in 'a+' mode
|
|
if file.open("init.lua", "a+") then
|
|
-- write 'foo bar' to the end of the file
|
|
file.write('foo bar')
|
|
file.flush()
|
|
-- write 'baz' too
|
|
file.write('baz')
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
[`file.close()` / `file.obj:close()`](#fileclose-fileobjclose)
|
|
|
|
## file.read(), file.obj:read()
|
|
|
|
Read content from the open file.
|
|
|
|
!!! note
|
|
|
|
The function temporarily allocates 2 * (number of requested bytes) on the heap for buffering and processing the read data. Default chunk size (`FILE_READ_CHUNK`) is 1024 bytes and is regarded to be safe. Pushing this by 4x or more can cause heap overflows depending on the application. Consider this when selecting a value for parameter `n_or_char`.
|
|
|
|
#### Syntax
|
|
`file.read([n_or_char])`
|
|
|
|
`fd:read([n_or_char])`
|
|
|
|
#### Parameters
|
|
- `n_or_char`:
|
|
- if nothing passed in, then read up to `FILE_READ_CHUNK` bytes or the entire file (whichever is smaller).
|
|
- if passed a number `n`, then read up to `n` bytes or the entire file (whichever is smaller).
|
|
- if passed a string containing the single character `char`, then read until `char` appears next in the file, `FILE_READ_CHUNK` bytes have been read, or EOF is reached.
|
|
|
|
#### Returns
|
|
File content as a string, or nil when EOF
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
-- print the first line of 'init.lua'
|
|
if file.open("init.lua", "r") then
|
|
print(file.read('\n'))
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
#### Example (object model)
|
|
```lua
|
|
-- print the first 5 bytes of 'init.lua'
|
|
fd = file.open("init.lua", "r")
|
|
if fd then
|
|
print(fd:read(5))
|
|
fd:close(); fd = nil
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
- [`file.open()`](#fileopen)
|
|
- [`file.readline()` / `file.obj:readline()`](#filereadline-fileobjreadline)
|
|
|
|
## file.readline(), file.obj:readline()
|
|
|
|
Read the next line from the open file. Lines are defined as zero or more bytes ending with a EOL ('\n') byte. If the next line is longer than 1024, this function only returns the first 1024 bytes.
|
|
|
|
#### Syntax
|
|
`file.readline()`
|
|
|
|
`fd:readline()`
|
|
|
|
#### Parameters
|
|
none
|
|
|
|
#### Returns
|
|
File content in string, line by line, including EOL('\n'). Return `nil` when EOF.
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
-- print the first line of 'init.lua'
|
|
if file.open("init.lua", "r") then
|
|
print(file.readline())
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
- [`file.open()`](#fileopen)
|
|
- [`file.close()` / `file.obj:close()`](#fileclose-fileobjclose)
|
|
- [`file.read()` / `file.obj:read()`](#fileread-fileobjread)
|
|
|
|
|
|
## file.seek(), file.obj:seek()
|
|
|
|
Sets and gets the file position, measured from the beginning of the file, to the position given by offset plus a base specified by the string whence.
|
|
|
|
#### Syntax
|
|
`file.seek([whence [, offset]])`
|
|
|
|
`fd:seek([whence [, offset]])`
|
|
|
|
#### Parameters
|
|
- `whence`
|
|
- "set": base is position 0 (beginning of the file)
|
|
- "cur": base is current position (default value)
|
|
- "end": base is end of file
|
|
- `offset` default 0
|
|
|
|
If no parameters are given, the function simply returns the current file offset.
|
|
|
|
#### Returns
|
|
the resulting file position, or `nil` on error
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
if file.open("init.lua", "r") then
|
|
-- skip the first 5 bytes of the file
|
|
file.seek("set", 5)
|
|
print(file.readline())
|
|
file.close()
|
|
end
|
|
```
|
|
#### See also
|
|
[`file.open()`](#fileopen)
|
|
|
|
## file.write(), file.obj:write()
|
|
|
|
Write a string to the open file.
|
|
|
|
#### Syntax
|
|
`file.write(string)`
|
|
|
|
`fd:write(string)`
|
|
|
|
#### Parameters
|
|
`string` content to be write to file
|
|
|
|
#### Returns
|
|
`true` if the write is ok, `nil` on error
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
-- open 'init.lua' in 'a+' mode
|
|
if file.open("init.lua", "a+") then
|
|
-- write 'foo bar' to the end of the file
|
|
file.write('foo bar')
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
#### Example (object model)
|
|
```lua
|
|
-- open 'init.lua' in 'a+' mode
|
|
fd = file.open("init.lua", "a+")
|
|
if fd then
|
|
-- write 'foo bar' to the end of the file
|
|
fd:write('foo bar')
|
|
fd:close()
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
- [`file.open()`](#fileopen)
|
|
- [`file.writeline()` / `file.obj:writeline()`](#filewriteline-fileobjwriteline)
|
|
|
|
## file.writeline(), file.obj:writeline()
|
|
|
|
Write a string to the open file and append '\n' at the end.
|
|
|
|
#### Syntax
|
|
`file.writeline(string)`
|
|
|
|
`fd:writeline(string)`
|
|
|
|
#### Parameters
|
|
`string` content to be write to file
|
|
|
|
#### Returns
|
|
`true` if write ok, `nil` on error
|
|
|
|
#### Example (basic model)
|
|
```lua
|
|
-- open 'init.lua' in 'a+' mode
|
|
if file.open("init.lua", "a+") then
|
|
-- write 'foo bar' to the end of the file
|
|
file.writeline('foo bar')
|
|
file.close()
|
|
end
|
|
```
|
|
|
|
#### See also
|
|
- [`file.open()`](#fileopen)
|
|
- [`file.readline()` / `file.obj:readline()`](#filereadline-fileobjreadline)
|