RFR: 8261949: fileStream::readln returns incorrect line string

[David Holmes]

On Thu, 18 Feb 2021 16:15:11 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> When the last line does not contain a NEWLINE character, fileStream::readln would read
>> truncated line string:
>> 
>> $ cat file_content:
>> AA
>> BB
>> CC<EOF>
>> 
>> fileStream::readln result:
>> "AA"
>> "BB"
>> "C"
>> 
>> This patch address this problem, it works for Posix and Windows since the last character
>> of these systems is always '\n'.
>
> src/hotspot/share/utilities/ostream.cpp line 593:
> 
>> 591:     ret = ::fgets(data, count, _file);
>> 592:     // Get rid of annoying \n char only if it presents, it works for Posix
>> 593:     // and Windows since the last character of these systems is always '\n'
> 
> s/of these/on these/
> Please end the comment with a period.

I suggest simply:

// Get rid of \n char if it is present

> src/hotspot/share/utilities/ostream.cpp line 595:
> 
>> 593:     // and Windows since the last character of these systems is always '\n'
>> 594:     if (data[::strlen(data)-1] == '\n') {
>> 595:       data[::strlen(data)-1] = '\0';
> 
> Perhaps:
>     size_t last_char = ::strlen(data) - 1;
>     if (last_char >= 0 && data[last_char] == '\n') {
>       data[last_char] = '\0';

@dcubed-ojdk size_t is unsigned so by definition always >= 0. :) I suggest:
`size_t len = ::strlen(data);`
`if (len > 0 && data[len - 1] == '\n') {`
`  data[len - 1] = '\0';`
`}`

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PR: https://git.openjdk.java.net/jdk/pull/2626