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Bug 5163 - clang static analyser error if strlcpy and strlcat are not available
Summary: clang static analyser error if strlcpy and strlcat are not available
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: build (show other bugs)
Version: HG 2.0
Hardware: All Linux
: P2 minor
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords: target-2.0.14
Depends on:
Blocks:
 
Reported: 2020-05-28 11:51 UTC by Martin Gerhardy
Modified: 2020-06-28 21:52 UTC (History)
2 users (show)

See Also:

Attachments
check for strl* (1.18 KB, patch)
2020-05-30 13:19 UTC, Mathieu Eyraud 		Details | Diff
check for strl* v2 (1.04 KB, patch)
2020-06-27 14:03 UTC, Mathieu Eyraud 		Details | Diff
Show Obsolete (1) View All Add an attachment (proposed patch, testcase, etc.)

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Description Martin Gerhardy 2020-05-28 11:51:33 UTC 
If I run clang-tidy-10 I get some errors that are related to 

   #if defined(__clang_analyzer__) && !defined(SDL_DISABLE_ANALYZE_MACROS)
   #define SDL_strlcpy strlcpy
   #define SDL_strlcat strlcat

I wonder whether it would be a good idea to check for HAVE_STRLCPY before overriding them?

The error for strlcpy is:

------------------------------------------------
error: use of undeclared identifier 'strlcpy'; did you mean 'strncpy'? [clang-diagnostic-error]
                                SDL_strlcpy(&buf[idx], value.c_str(), remaining);
                                ^~~~~~~~~~~
                                strncpy
/usr/include/SDL2/SDL_stdinc.h:578:21: note: expanded from macro 'SDL_strlcpy'
#define SDL_strlcpy strlcpy
                    ^
/usr/include/string.h:125:14: note: 'strncpy' declared here
extern char *strncpy (char *__restrict __dest,
             ^
46 warnings and 1 error generated.
------------------------------------------------
Comment 1 Mathieu Eyraud 2020-05-29 10:53:18 UTC 
Clang-tidy (and clang) finds more warning if you use standard functions. You should install libbsd-dev and add '#include <bsd/string.h>' before '#define SDL_strlcpy strlcpy' to get the missing functions.
Comment 2 Ryan C. Gordon 2020-05-29 18:02:36 UTC 
We already make sure SDL_malloc becomes standard malloc() when doing static analysis, it would be smart to handle these, too.
Comment 3 Mathieu Eyraud 2020-05-30 13:19:49 UTC 
Created attachment 4360 [details]
check for strl*

Here a patch that checks for HAVE_STRLCPY and HAVE_STRLCAT, then fallback to include bsd/string.h.
It uses '__has_include", which is a clang extension. But that should be fine as this code is only used for clang static analysis.
It also defines SDL_wcs* functions to standard functions.
Comment 4 Ryan C. Gordon 2020-06-26 23:39:04 UTC 
(In reply to meyraud705 from comment #3)
> Here a patch that checks for HAVE_STRLCPY and HAVE_STRLCAT, then fallback to
> include bsd/string.h.

But I assume Clang static analysis can't perform any special strlcpy() checks if you have to install libbsd-dev to get this function, right...?

--ryan.
Comment 5 Mathieu Eyraud 2020-06-27 14:03:21 UTC 
Created attachment 4399 [details]
check for strl* v2

I use clang-tidy and it knows standard functions enough to perform checks as long as the function is declared.

Attached version 2 of my patch: libbsd is actually not needed, only declares strlcat and strlcpy if not available.
Comment 6 Ryan C. Gordon 2020-06-28 21:52:57 UTC 
I made a slight change to the #ifdefs in this patch--we want SDL_strlcpy defined to strlcpy no matter what, and just declare the C runtime function if the system didn't provide it--but otherwise, this looks good, and I've put it in revision control as https://hg.libsdl.org/SDL/rev/92ea0212b095

Thanks!

--ryan.