Bug 41553 – Make StringExtras.h versions of snprintf and vsnprintf match the unix versions

• Status: RESOLVED
• Resolution: FIXED
• Component: Web Template Framework

[Sam Weinig]

Make StringExtras.h versions of snprintf and vsnprintf match the unix versions.  MSVC does not ensure the buffers are null terminated as the unix versions do.

[Sam Weinig]

Created attachment 60424 [details]
Patch

[Darin Adler]

Comment on attachment 60424 [details]
Patch

> +    // In the case where the string entirely filled the buffer, _vsnprintf will not
> +    // null-terminate it, but vsnprintf must.
> +    if (count > 0)
> +        buffer[count - 1] = '\0';

But what about the case where Windows *does* have vsnprintf, but it has the wrong behavior and does not terminate the buffer with a nul character? As I understand it, this is the case with MSVC 8 and newer!

[Sam Weinig]

Created attachment 60426 [details]
Updated patch

[WebKit Review Bot]

Attachment 60426 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
JavaScriptCore/wtf/StringExtras.h:56:  wtf_vsnprintf is incorrectly named. Don't use underscores in your identifier names.  [readability/naming] [4]
Total errors found: 1 in 4 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[WebKit Review Bot]

Attachment 60426 [details] did not build on win:
Build output: http://webkit-commit-queue.appspot.com/results/3399146

[Darin Adler]

Comment on attachment 60426 [details]
Updated patch

> +// Work around a bug in Microsoft's implementation of vsnprintf, where 
> +// vsnprintf does not null terminate the buffer
> +#define vsnprintf(x, y) wtf_vsnprintf(x, y)

vsnprintf has 4 arguments, not 2, which is presumably why the bot is failing to build

[Sam Weinig]

Created attachment 60457 [details]
Patch 3

[WebKit Review Bot]

Attachment 60457 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
JavaScriptCore/wtf/StringExtras.h:56:  wtf_vsnprintf is incorrectly named. Don't use underscores in your identifier names.  [readability/naming] [4]
Total errors found: 1 in 4 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Sam Weinig]

Landed in r62457.