File content corrupted for large file on SPIFFS

[mytrain]

Hi,
I met some issues when try to download then write a file on the SPIFFS file system.
In my project the file is stored with the same size but its content is altered. Therefore I wrote a small sketch to help you analyzing the issue but the sketch ends up with a truncated file that is also an abnormal file.
The sketch downloads a file (on one of my public server), computes it its CRC32 then saves it on the SPIFFS file system.
When reading back the file and computing the CRC32 I get a different result, moreover in the case of the scketch the file size is not equals to the number of byte downloaded.

The sketch is available on http://37.59.92.209/cms/images/mytrain/private/SPIFFSWriteError.ino
The downloaded file : http://37.59.92.209/cms/images/mytrain/private/steelseries-min.js (size=228467,CRC=0x6e3cc165 - polynim 0xEDB88320)
The logs of the serial dump when running the sketch : http://37.59.92.209/cms/images/mytrain/private/logs.txt

I would like to know what's wrong in my scketch.
Thanks you.

PS: Moreover from time to time I got the following exception:

: 3ffec4b0 end: 3ffec7c0 offset: 01b0

stack>>>
3ffec660: 0001a4df 3ffeae18 402017ec 3ffeb7a0
3ffec670: 402010ae 00000005 00000005 3ffeae18
3ffec680: 0001a4df 3ffec6d8 3ffec818 402095bb
3ffec690: 3fff52c8 00000001 00000000 00000100
3ffec6a0: 0000001f 00000000 3fff5318 00000066
3ffec6b0: 00000066 3ffec854 3ffec850 3fff46d8
3ffec6c0: 3ffe9ad0 00000000 000003e8 40203e08
3ffec6d0: 3fff52c8 3fff5318 3ffe96d0 00000000
3ffec6e0: 000003e8 0000b231 00000000 3fff51d0
3ffec6f0: 3ffe9b30 d15c3b25 0000000b 3fff53d8
3ffec700: 0000002d 00000001 00000005 4020188f
3ffec710: 000005b4 3ffec76c 00000095 402018c8
3ffec720: 00000040 3fff46d8 3fff4360 3ffea764
3ffec730: 3ffec848 000255ab 3ffec818 40209957
3ffec740: 3ffe9ad0 00000000 000003e8 00000000
3ffec750: 3fff5110 3fff5160 3fff5188 00000016
3ffec760: 00000016 00000000 00000000 3fff46b8
3ffec770: 3fff50e8 00000000 00000000 00000000
3ffec780: 3fff5188 00000000 00000000 00000000

3ffec790: 00000000 00000000 00000000 3ffec7ec
3ffec7a0: 3fffdc20 00000000 3ffec7e4 4020185f
3ffec7b0: 00000000 00000000 3ffeb7a0 40100398
<<<stack<<<

ets Jan 8 2013,rst cause:2, boot mode:(1,6)

[igrr]

Thanks for the detailed report. I'll look into this.
Which flash size/configuration do you have selected in the IDE Tools menu?

[mytrain]

igrr,
I'm using a 1M + 3M SPIFFS on an ESP-12 with 4M memory
My IDE is in staging version 1.6.5-1106-g8253b82

[mytrain]

For you information, I found a workaround by downloading a gzipped version of the files (so file size is lower than 64K now).