Corrupted utf-8 cell value if TotalCellChars reached

[IAkumaI]

Description

Excel has upper limit of character count which is 32767, but excelize checks value length by bytes instead by characters.
If I put utf-8 value (repeated 17000 times two-bytes symbol "Ы", for example) to a cell, excelize won't show any error, but file will be corrupted. Excel will show error on this file. Mac Numbers doesn't show any error, but empty cell and half-empty file.

I've already created pull request: #1517

Steps to reproduce the issue:

long_value := strings.Repeat("Ы", 17000)
f.SetCellValue("Sheet1", "A1", long_value) // No errors here
// Save file and so on

String long_value contains 17000 chars, but it will go into if len(value) > TotalCellChars because...Go works so. Let's fix it.

Output of go version:

go version go1.19.1 darwin/arm64

Excelize version or commit ID:

v2.7.1

Environment details (OS, Microsoft Excel™ version, physical, etc.):

It doesn't rely on an environment.

[IAkumaI]

The worst is that without the fix you can not fix this from outside, because if len(value) > TotalCellChars is true for every utf-8 TotalCellChars/2 len string and next line value[:TotalCellChars] will corrupt the string because you must not slice strings in Go in this way.

[xuri]

Thanks for your issue. I have merged the pull request #1517 to fix this.