file.read() causes reboot

[Gatulibu]

According to the documentation file.read() should:

if nothing passed in, read up to LUAL_BUFFERSIZE bytes (default 1024) or the entire file (whichever is smaller)

Returns
File content as a string, or nil when EOF

But when I try:

file1 = file.open("file1k5") -- 1.5kB file
print(file1.read())  -- prints first 1024 B
print(file1.read())  -- prints remaining data
print(file1.read())  -- does not return nil but causes a reboot "cause:2"
file1.close()

The same happens on an empty file:

file1 = file.open("empty1", "w")  --create empty file
file1.close()

file2 = file.open("empty1")
print(file2.read())  -- module reboots
file2.close()

Version used:

NodeMCU custom build by frightanic.com
branch: dev
commit: 7987599
SSL: true
modules: adc,crypto,file,gpio,i2c,net,node,pwm,struct,tmr,uart,websocket,wifi,ws2812
build built on: 2016-11-13 18:46
powered by Lua 5.1.4 on SDK 1.5.4.1(39cb9a32)

[jmattsson]

When using the returned file object, you need to either use the : syntactic sugar (recommended), or explicitly pass the file object as the first argument. I.e.

file1 = file.open("empty1")
print(file1:read())
file1:close()

or

file1 = file.open("empty1")
print(file1.read(file1))
file1.close(file1)

This is the way Lua works with "objects", it's not something NodeMCU specific. See e.g. https://www.lua.org/pil/16.html

[Gatulibu]

Thank you for clarifying the correct use of the new object model for files (which was recently merged into the dev branch #1532).

Unfortunately I have to report that both suggested ways fail the same way as before (dev branch).

In the master branch the following commands work without a problem:

file.open("empty1", "w")
print(file.read())
file.close()

In the dev branch I get a reboot at the read command.

As previously described a read on a non empty file (after EOF has been reached) also causes a reboot.

_flash_used_end:402639c3
fs.start:70000,max:38a000
_flash_used_end:402639c3
fs.start:80000,max:37a000
mount res: 0, 0
Task task_lua started.
nul mode, fpm auto sleep set:enalbe

NodeMCU custom build by frightanic.com
    branch: dev
    commit: 1d0cf5e8d050ab1970593c9306d356bf70abfdf5
    SSL: false
    modules: file,gpio,net,node,tmr,uart,wifi
 build  built on: 2016-11-16 22:19
 powered by Lua 5.1.4 on SDK 1.5.4.1(39cb9a32)
lua: cannot open init.lua
> Heap size::44320.
scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt 

connected with wifi123, channel 13
dhcp client start...

    wifi_event_monitor_handle_event_cb is called
ip:192.168.2.31,mask:255.255.255.0,gw:192.168.2.1

    wifi_event_monitor_handle_event_cb is called
pm open,type:2 0
f1 = file.open("empty1", "w")  --create empty file
> f1:close()
> f2 = file.open("empty1")
> print(f2:read())
Fatal exception 28(LoadProhibitedCause):
epc1=0x402475d7, epc2=0x00000000, epc3=0x00000000, excvaddr=0x1ffef66c, depc=0x00000000

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)
load 0x40100000, len 25864, room 16 
tail 8
chksum 0x14
load 0x3ffe8000, len 2200, room 0 
tail 8
chksum 0x7b
load 0x3ffe8898, len 8, room 0 
tail 8
chksum 0x28
csum 0x28

[devsaurus]

The symptoms look strange, I'll have a look later that day.

[Gatulibu]

I can confirm that #1599 fixed the issue. Thank you.