RFR(xs): 8076475: Misuses of strncpy/strncat

[Dmitry Samersoff]

Thomas,

Looks good for me!

Thank you for doing it.

-Dmitry

On 2015-04-10 10:50, Thomas Stüfe wrote:
> Hi Dimitry,
> 
> see new version here:
> 
> http://cr.openjdk.java.net/~stuefe/webrevs/8076475/webrev.01/webrev/
> 
> 
> On Wed, Apr 8, 2015 at 2:40 PM, Dmitry Samersoff
> <dmitry.samersoff at oracle.com <mailto:dmitry.samersoff at oracle.com>> wrote:
> 
>     Thomas,
> 
>     ** agent/src/os/bsd/libproc_impl.c
>     ** agent/src/os/linux/libproc_impl.c
> 
>     newlib->name has the size of (PATH_MAX + NAME_MAX + 1)
> 
>     see ./src/os/bsd/libproc_impl.h:92
> 
>     So no truncation is actually possible here.
> 
>     To make this code nice-looking it's better to add:
> 
>     if (strlen(libname) >  sizeof(newlib->name)) {
>     //  Bail out with debug message
>      ...
>     }
>     strcpy(newlib->name, libname);
> 
>     rather than use snprintf here.
> 
> 
> I changed the coding according to your suggestions. 
> 
> There is still the strlen vs strnlen question Kim mentioned, but we use
> strlen all over the place, and I am not sure if all platforms support it
> (AIX was known to have a broken strnlen implementation, one would need
> to check that first before changing strlen to strnlen)
>  
> 
>     ** arguments.cpp:3466
> 
>     It might be better to use snprintf here.
> 
> 
> Agree, done
>  
> 
>     ** arguments.cpp:3629
> 
>     It's better to just replace strncat/strncpy to strcat/strcpy
>     in the original code - as soon as we allocating memory with respect to
>     variable lenght, we don't need to check this length again.
> 
> 
> Sorry, I disagree here - I think using snprintf makes the code more
> readable. It comes down to a matter of taste, so lets see what others think.
> 
>  
> 
>     ** vmError.cpp:222
> 
>     It's better to keep original code.
> 
> 
> Agree, done
>  
> Best Regards, Thomas
> 
> 
> 
>     Other changes looks good for me!
>     -Dmitry
> 
> 
>     On 2015-04-08 11:09, Thomas Stüfe wrote:
>     > Hi,
>     >
>     > please review these small fixes around use of strncpy/strncat.
>     >
>     > Bug report: https://bugs.openjdk.java.net/browse/JDK-8076475
>     > Webrev:
>     > http://cr.openjdk.java.net/~stuefe/webrevs/8076475/webrev.00/webrev/
>     >
>     > Changes in detail are:
>     >
>     > agent/src/os/bsd/libproc_impl.c
>     > agent/src/os/linux/libproc_impl.c:
>     >                 - missing \0 on truncation. Replaced with
>     snprintf, add
>     > truncation handling
>     >
>     > src/os/bsd/dtrace/libjvm_db.c
>     > src/os/solaris/dtrace/libjvm_db.c
>     >                 @@ -580,17 +580,18 @@
>     >                 - overwrite on truncation
>     >                 @@ -1093,13 +1094,13 @@
>     >                 - overwrite on truncation
>     >
>     > src/share/vm/compiler/compileBroker.hpp
>     >                 - missing \0 on truncation.
>     >
>     > src/share/tools/hsdis/hsdis.c
>     >                 - missing \0
>     >
>     > src/os/bsd/vm/decoder_machO.cpp
>     >                 - missing \0 on truncation.
>     >
>     > src/share/vm/compiler/compilerOracle.cpp
>     >                 - Replaced with jio_snprintf, less awkward and
>     does not
>     > restrict each part to 255 chars each.
>     >
>     > src/share/vm/compiler/disassembler.cpp
>     >                 - missing \0 on truncation.
>     >
>     > src/share/vm/runtime/arguments.cpp
>     >                 @@ -2703,11 +2703,11 @@
>     >                 - replaced with strdup, easier to read
>     >                 @@ -3294,12 +3294,11 @@
>     >                 - the same
>     >                 @@ -3627,18 +3626,14 @@
>     >                 - replace strncpy/strncat sequence with jio_snprintf -
>     > easier to read.
>     >                 - replace malloc/strncpy with os::strdup
>     >
>     > src/share/vm/utilities/ostream.cpp
>     >                 - avoid \0 padding
>     >
>     > src/share/vm/utilities/vmError.cp
>     >                 @@ -219,7 +219,7 @@
>     >                 - avoid \0 padding
>     >                 @@ -463,14 +463,7 @@
>     >                 - simplified
>     >
>     > Kind regards, Thomas
>     >
> 
> 
>     --
>     Dmitry Samersoff
>     Oracle Java development team, Saint Petersburg, Russia
>     * I would love to change the world, but they won't give me the sources.
> 
> 


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.