Re: [PATCH] vasnprintf: Don't use %n on android

[Tim Rühsen]

On 23.01.19 01:25, Bruno Haible wrote:
> Hi Tim and Hugo,
> 
>>> I also don't see much here (Debian unstable):
>>>
>>> $ grep -A1 -i 'checking.*printf' config.log
>>> configure:6305: checking for vasnprintf
>>> configure:6305: result: no
>>> configure:6305: checking for snprintf
>>> configure:6305: result: yes
>>> --
>>> configure:8450: checking whether snprintf returns a byte count as in C99
>>> configure:8548: result: yes
>>> configure:8559: checking for snprintf
>>> configure:8559: result: yes
>>> --
>>> configure:8568: checking whether _snprintf is declared
>>> configure:8568: result: no
>>>
>>> What does that grep look for you ?
>>
>> $ grep -A1 'checking .*printf' config.log
>> configure:6326: checking for vasnprintf
>> configure:6326: gcc -o conftest -g -O2   conftest.c  >&5
>> --
>> configure:6326: checking for snprintf
>> configure:6326: gcc -o conftest -g -O2   conftest.c  >&5
>> --
>> configure:8471: checking whether snprintf returns a byte count as in C99
>> configure:8558: gcc -o conftest -g -O2   conftest.c  >&5
>> --
>> configure:8580: checking for snprintf
>> configure:8580: result: yes
>> --
>> configure:8589: checking whether _snprintf is declared
>> configure:8589: gcc -c -g -O2  conftest.c >&5
> 
> I did these steps:
> 1) Create a testdir
>    ./gnulib-tool --create-testdir --dir=../testdir-printf-posix 
> --single-configure \
>                  dprintf-posix fprintf-posix printf-posix snprintf-posix \
>                  sprintf-posix vasnprintf-posix vasprintf-posix 
> vdprintf-posix \
>                  vfprintf-posix vprintf-posix vsnprintf-posix vsprintf-posix
> 2) Tarred the resulting directory
> 3) Transfered it to the device (Android 4.3 with 'Terminal IDE' app in my 
> case),
> 4) Unpacked it there,
> 5) configured it,
> 6) Copy&pasted the configure output.
> 
> The configure output contains the lines
> 
> checking whether printf supports size specifiers as in C99... yes
> checking whether printf supports 'long double' arguments... yes
> checking whether printf supports infinite 'double' arguments... no
> checking whether printf supports infinite 'long double' arguments... no
> checking whether printf supports the 'a' and 'A' directives... no
> checking whether printf supports the 'F' directive... no
> checking whether printf supports the 'n' directive... no
> checking whether printf supports the 'ls' directive... no
> checking whether printf supports POSIX/XSI format strings with positions... 
> yes
> checking whether printf supports the grouping flag... no
> checking whether printf supports the left-adjust flag correctly... yes
> checking whether printf supports the zero flag correctly... no
> checking whether printf supports large precisions... yes
> checking whether printf survives out-of-memory conditions... no
> checking for snprintf... yes
> checking whether snprintf truncates the result as in C99... yes
> checking whether snprintf returns a byte count as in C99... yes
> checking whether snprintf fully supports the 'n' directive... no
> checking whether snprintf respects a size of 1... yes
> checking whether vsnprintf respects a zero size as in C99... yes
> 
> With this, I am in the position to update the results in printf.m4, and
> even add cross-compilation guesses.
> 
> Since snprintf is behaving well enough, we can disable the use of %n,
> like you suggested.
> 
> Done through the attached patches.
> 
> Bruno

Thanks you, Bruno and Hugo.

Already committed it successfully into GnuTLS :-)

Regards, Tim

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