Double size of buffer for SkString::printf()

Double size of buffer for SkString::printf()
Committed: https://code.google.com/p/skia/source/detail?r=5555

[rileya, 2012-09-14 18:56:18]

The size of this was resulting in cut off results from the pinspect tool, and
since we use SkString::appendf() extensively in shader building, hitting this
limit on a really long line (unlikely, but still...) could result in incorrect
shaders.

That said, I dunno if allocating something this much larger on the stack would
hurt performance anywhere (esp. on Android).

[reed1, 2012-09-14 19:02:37]

lgtm

[bsalomon, 2012-09-14 19:03:51]

On 2012/09/14 18:56:18, rileya wrote:
> The size of this was resulting in cut off results from the pinspect tool, and
> since we use SkString::appendf() extensively in shader building, hitting this
> limit on a really long line (unlikely, but still...) could result in incorrect
> shaders.
> 
> That said, I dunno if allocating something this much larger on the stack would
> hurt performance anywhere (esp. on Android).

I once looked into whether there was a way to get vsnprintf to give the buffer
size that would be required to print the whole string. Someone on the Internet
concluded that the only portable way to do it (without parsing the format string
and varargs yourself) was to repeatedly call vsnprintf with larger buffers until
the output size stopped increasing.

LGTM.