Re: [libsmi] [PATCH] smidiff: dont rely on udefined behavior

Thanks Wouter,

I have committed the patch (revision 1833).

/js

On Sun, Feb 07, 2016 at 06:02:45PM +0100, Wouter van Kesteren wrote:

From man sprintf:

NOTES Some programs imprudently rely on code such as the following

    sprintf(buf, "%s some further text", buf);

to append text to buf.  However, the standards explicitly note that the
results are undefined if source and destination buffers overlap when
calling  sprintf(),  snprintf(), vsprintf(), and vsnprintf().  Depending
on the version of gcc(1) used, and the compiler options employed, calls
such as the above will not produce the expected results.

On my system with gcc-5.3, glibc-2.22 this makes the tests on 0.4.8 fail. With this patch the tests pass. This patch is also applicable to 0.5.0, however the testsuite of 0.5.0 fails with:

116,118c122,123 < ../../mibs/ietf/IF-MIB:1741 warning: legal status change from `current' to `deprecated' for `ifCompliance' < ../../mibs/ietf/IF-MIB:1741 warning: description of MODULE-COMPLIANCE `ifCompliance' changed

< ./IF-MIB.old:1244 info: previous definition of `ifCompliance'

...

./IF-MIB.old:1244 compliance `ifCompliance' has been deleted ../../mibs/ietf/IF-MIB:1741 warning: compliance `ifCompliance' has been added

So consider this email both a patch, and a bugreport.

tools/smidiff.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/tools/smidiff.c b/tools/smidiff.c index dcd2166..c94a143 100644 --- a/tools/smidiff.c +++ b/tools/smidiff.c @@ -941,15 +941,17 @@ getStringRange(SmiType *smiType) SmiRange *range; int i; char *str, *subRange;

• size_t strLen;

  str = NULL; for(i = 0, range = smiGetFirstRange(smiType); range; i++, range = smiGetNextRange(range)) {

  if (i) {

•    str = realloc( str, strlen( str ) +2 );
  

•    strLen = strlen( str );
  

•    str = realloc( str, strLen +2 );
   if( str ) {
  

• sprintf(str, "%s|", str);
  

• sprintf(str + strLen, "|");
  

  }

  }

@@ -961,16 +963,18 @@ getStringRange(SmiType *smiType) if( !subRange ) { return NULL; }

• str = realloc( str, strlen( str ) + strlen( subRange ) + 1 );

• strLen = strlen( str );
• str = realloc( str, strLen + strlen( subRange ) + 1 ); if( !str ) { return NULL; }

• sprintf( str, "%s%s", str, subRange );

• sprintf( str + strLen, "%s", subRange );

  }

• str = realloc( str, strlen( str ) + 2 );

• strLen = strlen( str );
• str = realloc( str, strLen + 2 ); if( str ) {

• sprintf(str, "%s)", str);

• sprintf(str + strLen, ")"); } return str;

} @@ -1613,6 +1617,7 @@ getStringIndexList( SmiNode *smiNode ) SmiNode *indexNode; SmiElement *smiElement; char *strIdxLst;

• size_t strIdxLstLen;

  smiElement = smiGetFirstElement( smiNode ); indexNode = smiGetElementNode( smiElement );

@@ -1623,10 +1628,11 @@ getStringIndexList( SmiNode *smiNode ) smiElement = smiGetNextElement( smiElement ); while ( smiElement ) { indexNode = smiGetElementNode( smiElement );

• strIdxLstLen = strlen( strIdxLst ); strIdxLst = (char *)realloc( strIdxLst,

• 		     strlen( strIdxLst ) +
  

• 		     strIdxLstLen +
  	     strlen( indexNode->name ) + 4 );
  

• sprintf( strIdxLst, "%s, `%s'", strIdxLst, indexNode->name );

• sprintf( strIdxLst + strIdxLstLen, ", `%s'", indexNode->name ); smiElement = smiGetNextElement( smiElement ); } return strIdxLst;

-- 2.7.0

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