On 02/12/2012 05:27 PM, Eli Zaretskii wrote:
>> Date: Sun, 12 Feb 2012 05:07:48 +0100
>> From: Sebastian Pipping <sebast...@pipping.org>
>> CC: psm...@gnu.org, bug-make@gnu.org
>>
>> So far both of these have been requirements: (1) keep the overall format
>> translatable so other languages can adjust order of elements and (2) use
>> C89 functions, only. It seems that (1) requires function vsnprintf
>> which violates (2).
>
> Why does (1) violate (2)? (1) will only be possible with C libraries
> that support the n$ positional specifiers. AFAIK, when these are
> supported, they can be used with any of the *printf functions.
The problem is nesting. If we have
_("%s[%u]: %s%s%s%s")
^^
for the final output, the actual message (third %s above) needs to be
present in linear string form already. With constant messages that's
given, but we are dealing with
_("%s: Entering directory `%s'\n")
too. So that inner format needs to be written to a string buffer first
or we lose the gained abstraction. Since we would run into buffer
overflows with sprintf/vsprintf, we rely on snprintf/vsnprintf for that
task. Quoting from my "man 3 printf" output:
snprintf(), vsnprintf():
_BSD_SOURCE || _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE \
|| _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
That's my understanding of the situation.
Best,
Sebastian
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