#include "patternprops.h"
#include "putilimp.h"
#include "cmemory.h"
+#include "cstr.h"
#include "cstring.h"
#include "uvectr32.h"
#include "uvectr64.h"
case 0x78: /* 'x' */ bit = UREGEX_COMMENTS; break;
case 0x2d: /* '-' */ fSetModeFlag = FALSE; break;
default:
- U_ASSERT(FALSE); // Should never happen. Other chars are filtered out
+ UPRV_UNREACHABLE; // Should never happen. Other chars are filtered out
// by the scanner.
}
if (fSetModeFlag) {
}
default:
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
- break;
+ UPRV_UNREACHABLE;
}
if (U_FAILURE(*fStatus)) {
return 0;
}
if (type < 0 || type > 255) {
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
- type = URX_RESERVED_OP;
+ UPRV_UNREACHABLE;
}
if (val > 0x00ffffff) {
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
- val = 0;
+ UPRV_UNREACHABLE;
}
if (val < 0) {
if (!(type == URX_RESERVED_OP_N || type == URX_RESERVED_OP)) {
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
- return -1;
+ UPRV_UNREACHABLE;
}
if (URX_TYPE(val) != 0xff) {
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
- return -1;
+ UPRV_UNREACHABLE;
}
type = URX_RESERVED_OP_N;
}
error(U_REGEX_LOOK_BEHIND_LIMIT);
break;
}
+ if (minML == INT32_MAX && maxML == 0) {
+ // This condition happens when no match is possible, such as with a
+ // [set] expression containing no elements.
+ // In principle, the generated code to evaluate the expression could be deleted,
+ // but it's probably not worth the complication.
+ minML = 0;
+ }
U_ASSERT(minML <= maxML);
// Insert the min and max match len bounds into the URX_LB_CONT op that
error(U_REGEX_LOOK_BEHIND_LIMIT);
break;
}
+ if (minML == INT32_MAX && maxML == 0) {
+ // This condition happens when no match is possible, such as with a
+ // [set] expression containing no elements.
+ // In principle, the generated code to evaluate the expression could be deleted,
+ // but it's probably not worth the complication.
+ minML = 0;
+ }
+
U_ASSERT(minML <= maxML);
// Insert the min and max match len bounds into the URX_LB_CONT op that
default:
- U_ASSERT(FALSE);
+ UPRV_UNREACHABLE;
}
// remember the next location in the compiled pattern.
if (c < UCHAR_MIN_VALUE || c > UCHAR_MAX_VALUE) {
// This function should never be called with an invalid input character.
- U_ASSERT(FALSE);
- starterChars->clear();
+ UPRV_UNREACHABLE;
} else if (u_hasBinaryProperty(c, UCHAR_CASE_SENSITIVE)) {
UChar32 caseFoldedC = u_foldCase(c, U_FOLD_CASE_DEFAULT);
starterChars->set(caseFoldedC, caseFoldedC);
case URX_LB_END:
case URX_LBN_CONT:
case URX_LBN_END:
- U_ASSERT(FALSE); // Shouldn't get here. These ops should be
+ UPRV_UNREACHABLE; // Shouldn't get here. These ops should be
// consumed by the scan in URX_LA_START and LB_START
-
- break;
-
default:
- U_ASSERT(FALSE);
+ UPRV_UNREACHABLE;
}
}
break;
default:
- U_ASSERT(FALSE);
+ UPRV_UNREACHABLE;
}
}
case URX_CTR_LOOP_NG:
// These opcodes will be skipped over by code for URX_CRT_INIT.
// We shouldn't encounter them here.
- U_ASSERT(FALSE);
- break;
+ UPRV_UNREACHABLE;
case URX_LOOP_SR_I:
case URX_LOOP_DOT_I:
// End of look-ahead ops should always be consumed by the processing at
// the URX_LA_START op.
- // U_ASSERT(FALSE);
- // break;
+ // UPRV_UNREACHABLE;
case URX_LB_START:
{
break;
default:
- U_ASSERT(FALSE);
+ UPRV_UNREACHABLE;
}
default:
// Some op is unaccounted for.
- U_ASSERT(FALSE);
- error(U_REGEX_INTERNAL_ERROR);
+ UPRV_UNREACHABLE;
}
}
//
//------------------------------------------------------------------------------
void RegexCompile::error(UErrorCode e) {
- if (U_SUCCESS(*fStatus)) {
+ if (U_SUCCESS(*fStatus) || e == U_MEMORY_ALLOCATION_ERROR) {
*fStatus = e;
// Hmm. fParseErr (UParseError) line & offset fields are int32_t in public
// API (see common/unicode/parseerr.h), while fLineNum and fCharNum are
//
//------------------------------------------------------------------------------
void RegexCompile::nextChar(RegexPatternChar &c) {
-
+ tailRecursion:
fScanIndex = UTEXT_GETNATIVEINDEX(fRXPat->fPattern);
c.fChar = nextCharLL();
c.fQuoted = FALSE;
c.fChar == (UChar32)-1) {
fQuoteMode = FALSE; // Exit quote mode,
nextCharLL(); // discard the E
- nextChar(c); // recurse to get the real next char
+ // nextChar(c); // recurse to get the real next char
+ goto tailRecursion; // Note: fuzz testing produced testcases that
+ // resulted in stack overflow here.
}
}
else if (fInBackslashQuote) {
else if (peekCharLL() == chQ) {
// "\Q" enter quote mode, which will continue until "\E"
fQuoteMode = TRUE;
- nextCharLL(); // discard the 'Q'.
- nextChar(c); // recurse to get the real next char.
+ nextCharLL(); // discard the 'Q'.
+ // nextChar(c); // recurse to get the real next char.
+ goto tailRecursion; // Note: fuzz testing produced test cases that
+ // resulted in stack overflow here.
}
else
{
// Includes trying the Java "properties" that aren't supported as
// normal ICU UnicodeSet properties
//
-static const UChar posSetPrefix[] = {0x5b, 0x5c, 0x70, 0x7b, 0}; // "[\p{"
-static const UChar negSetPrefix[] = {0x5b, 0x5c, 0x50, 0x7b, 0}; // "[\P{"
UnicodeSet *RegexCompile::createSetForProperty(const UnicodeString &propName, UBool negated) {
- UnicodeString setExpr;
- UnicodeSet *set;
- uint32_t usetFlags = 0;
if (U_FAILURE(*fStatus)) {
- return NULL;
+ return nullptr;
}
+ LocalPointer<UnicodeSet> set;
+ UErrorCode status = U_ZERO_ERROR;
- //
- // First try the property as we received it
- //
- if (negated) {
- setExpr.append(negSetPrefix, -1);
- } else {
- setExpr.append(posSetPrefix, -1);
- }
- setExpr.append(propName);
- setExpr.append(chRBrace);
- setExpr.append(chRBracket);
- if (fModeFlags & UREGEX_CASE_INSENSITIVE) {
- usetFlags |= USET_CASE_INSENSITIVE;
- }
- set = new UnicodeSet(setExpr, usetFlags, NULL, *fStatus);
- if (U_SUCCESS(*fStatus)) {
- return set;
- }
- delete set;
- set = NULL;
-
- //
- // The property as it was didn't work.
-
- // Do [:word:]. It is not recognized as a property by UnicodeSet. "word" not standard POSIX
- // or standard Java, but many other regular expression packages do recognize it.
-
- if (propName.caseCompare(UNICODE_STRING_SIMPLE("word"), 0) == 0) {
- *fStatus = U_ZERO_ERROR;
- set = new UnicodeSet(*(fRXPat->fStaticSets[URX_ISWORD_SET]));
- if (set == NULL) {
- *fStatus = U_MEMORY_ALLOCATION_ERROR;
- return set;
+ do { // non-loop, exists to allow breaks from the block.
+ //
+ // First try the property as we received it
+ //
+ UnicodeString setExpr;
+ uint32_t usetFlags = 0;
+ setExpr.append(u"[\\p{", -1);
+ setExpr.append(propName);
+ setExpr.append(u"}]", -1);
+ if (fModeFlags & UREGEX_CASE_INSENSITIVE) {
+ usetFlags |= USET_CASE_INSENSITIVE;
}
- if (negated) {
- set->complement();
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(setExpr, usetFlags, NULL, status), status);
+ if (U_SUCCESS(status) || status == U_MEMORY_ALLOCATION_ERROR) {
+ break;
}
- return set;
- }
+ //
+ // The incoming property wasn't directly recognized by ICU.
- // Do Java fixes -
- // InGreek -> InGreek or Coptic, that being the official Unicode name for that block.
- // InCombiningMarksforSymbols -> InCombiningDiacriticalMarksforSymbols.
- //
- // Note on Spaces: either "InCombiningMarksForSymbols" or "InCombining Marks for Symbols"
- // is accepted by Java. The property part of the name is compared
- // case-insenstively. The spaces must be exactly as shown, either
- // all there, or all omitted, with exactly one at each position
- // if they are present. From checking against JDK 1.6
- //
- // This code should be removed when ICU properties support the Java compatibility names
- // (ICU 4.0?)
- //
- UnicodeString mPropName = propName;
- if (mPropName.caseCompare(UNICODE_STRING_SIMPLE("InGreek"), 0) == 0) {
- mPropName = UNICODE_STRING_SIMPLE("InGreek and Coptic");
- }
- if (mPropName.caseCompare(UNICODE_STRING_SIMPLE("InCombining Marks for Symbols"), 0) == 0 ||
- mPropName.caseCompare(UNICODE_STRING_SIMPLE("InCombiningMarksforSymbols"), 0) == 0) {
- mPropName = UNICODE_STRING_SIMPLE("InCombining Diacritical Marks for Symbols");
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("all")) == 0) {
- mPropName = UNICODE_STRING_SIMPLE("javaValidCodePoint");
- }
+ // Check [:word:] and [:all:]. These are not recognized as a properties by ICU UnicodeSet.
+ // Java accepts 'word' with mixed case.
+ // Java accepts 'all' only in all lower case.
- // See if the property looks like a Java "InBlockName", which
- // we will recast as "Block=BlockName"
- //
- static const UChar IN[] = {0x49, 0x6E, 0}; // "In"
- static const UChar BLOCK[] = {0x42, 0x6C, 0x6f, 0x63, 0x6b, 0x3d, 00}; // "Block="
- if (mPropName.startsWith(IN, 2) && propName.length()>=3) {
- setExpr.truncate(4); // Leaves "[\p{", or "[\P{"
- setExpr.append(BLOCK, -1);
- setExpr.append(UnicodeString(mPropName, 2)); // Property with the leading "In" removed.
- setExpr.append(chRBrace);
- setExpr.append(chRBracket);
- *fStatus = U_ZERO_ERROR;
- set = new UnicodeSet(setExpr, usetFlags, NULL, *fStatus);
- if (U_SUCCESS(*fStatus)) {
- return set;
+ status = U_ZERO_ERROR;
+ if (propName.caseCompare(u"word", -1, 0) == 0) {
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(*(fRXPat->fStaticSets[URX_ISWORD_SET])), status);
+ break;
+ }
+ if (propName.compare(u"all", -1) == 0) {
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(0, 0x10ffff), status);
+ break;
}
- delete set;
- set = NULL;
- }
- if (propName.startsWith(UNICODE_STRING_SIMPLE("java")) ||
- propName.compare(UNICODE_STRING_SIMPLE("all")) == 0)
- {
- UErrorCode localStatus = U_ZERO_ERROR;
- //setExpr.remove();
- set = new UnicodeSet();
- //
- // Try the various Java specific properties.
- // These all begin with "java"
+
+ // Do Java InBlock expressions
//
- if (mPropName.compare(UNICODE_STRING_SIMPLE("javaDefined")) == 0) {
- addCategory(set, U_GC_CN_MASK, localStatus);
- set->complement();
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaDigit")) == 0) {
- addCategory(set, U_GC_ND_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaIdentifierIgnorable")) == 0) {
- addIdentifierIgnorable(set, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaISOControl")) == 0) {
- set->add(0, 0x1F).add(0x7F, 0x9F);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaJavaIdentifierPart")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- addCategory(set, U_GC_SC_MASK, localStatus);
- addCategory(set, U_GC_PC_MASK, localStatus);
- addCategory(set, U_GC_ND_MASK, localStatus);
- addCategory(set, U_GC_NL_MASK, localStatus);
- addCategory(set, U_GC_MC_MASK, localStatus);
- addCategory(set, U_GC_MN_MASK, localStatus);
- addIdentifierIgnorable(set, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaJavaIdentifierStart")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- addCategory(set, U_GC_NL_MASK, localStatus);
- addCategory(set, U_GC_SC_MASK, localStatus);
- addCategory(set, U_GC_PC_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLetter")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLetterOrDigit")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- addCategory(set, U_GC_ND_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaLowerCase")) == 0) {
- addCategory(set, U_GC_LL_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaMirrored")) == 0) {
- set->applyIntPropertyValue(UCHAR_BIDI_MIRRORED, 1, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaSpaceChar")) == 0) {
- addCategory(set, U_GC_Z_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaSupplementaryCodePoint")) == 0) {
- set->add(0x10000, UnicodeSet::MAX_VALUE);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaTitleCase")) == 0) {
- addCategory(set, U_GC_LT_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUnicodeIdentifierStart")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- addCategory(set, U_GC_NL_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUnicodeIdentifierPart")) == 0) {
- addCategory(set, U_GC_L_MASK, localStatus);
- addCategory(set, U_GC_PC_MASK, localStatus);
- addCategory(set, U_GC_ND_MASK, localStatus);
- addCategory(set, U_GC_NL_MASK, localStatus);
- addCategory(set, U_GC_MC_MASK, localStatus);
- addCategory(set, U_GC_MN_MASK, localStatus);
- addIdentifierIgnorable(set, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaUpperCase")) == 0) {
- addCategory(set, U_GC_LU_MASK, localStatus);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaValidCodePoint")) == 0) {
- set->add(0, UnicodeSet::MAX_VALUE);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("javaWhitespace")) == 0) {
- addCategory(set, U_GC_Z_MASK, localStatus);
- set->removeAll(UnicodeSet().add(0xa0).add(0x2007).add(0x202f));
- set->add(9, 0x0d).add(0x1c, 0x1f);
- }
- else if (mPropName.compare(UNICODE_STRING_SIMPLE("all")) == 0) {
- set->add(0, UnicodeSet::MAX_VALUE);
+ UnicodeString mPropName = propName;
+ if (mPropName.startsWith(u"In", 2) && mPropName.length() >= 3) {
+ status = U_ZERO_ERROR;
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(), status);
+ if (U_FAILURE(status)) {
+ break;
+ }
+ UnicodeString blockName(mPropName, 2); // Property with the leading "In" removed.
+ set->applyPropertyAlias(UnicodeString(u"Block"), blockName, status);
+ break;
}
- if (U_SUCCESS(localStatus) && !set->isEmpty()) {
- *fStatus = U_ZERO_ERROR;
- if (usetFlags & USET_CASE_INSENSITIVE) {
+ // Check for the Java form "IsBooleanPropertyValue", which we will recast
+ // as "BooleanPropertyValue". The property value can be either a
+ // a General Category or a Script Name.
+
+ if (propName.startsWith(u"Is", 2) && propName.length()>=3) {
+ mPropName.remove(0, 2); // Strip the "Is"
+ if (mPropName.indexOf(u'=') >= 0) {
+ // Reject any "Is..." property expression containing an '=', that is,
+ // any non-binary property expression.
+ status = U_REGEX_PROPERTY_SYNTAX;
+ break;
+ }
+
+ if (mPropName.caseCompare(u"assigned", -1, 0) == 0) {
+ mPropName.setTo(u"unassigned", -1);
+ negated = !negated;
+ } else if (mPropName.caseCompare(u"TitleCase", -1, 0) == 0) {
+ mPropName.setTo(u"Titlecase_Letter", -1);
+ }
+
+ mPropName.insert(0, u"[\\p{", -1);
+ mPropName.append(u"}]", -1);
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(mPropName, *fStatus), status);
+
+ if (U_SUCCESS(status) && !set->isEmpty() && (usetFlags & USET_CASE_INSENSITIVE)) {
set->closeOver(USET_CASE_INSENSITIVE);
}
- if (negated) {
+ break;
+
+ }
+
+ if (propName.startsWith(u"java", -1)) {
+ status = U_ZERO_ERROR;
+ set.adoptInsteadAndCheckErrorCode(new UnicodeSet(), status);
+ if (U_FAILURE(status)) {
+ break;
+ }
+ //
+ // Try the various Java specific properties.
+ // These all begin with "java"
+ //
+ if (propName.compare(u"javaDefined", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_CN_MASK, status);
set->complement();
}
- return set;
+ else if (propName.compare(u"javaDigit", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_ND_MASK, status);
+ }
+ else if (propName.compare(u"javaIdentifierIgnorable", -1) == 0) {
+ addIdentifierIgnorable(set.getAlias(), status);
+ }
+ else if (propName.compare(u"javaISOControl", -1) == 0) {
+ set->add(0, 0x1F).add(0x7F, 0x9F);
+ }
+ else if (propName.compare(u"javaJavaIdentifierPart", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ addCategory(set.getAlias(), U_GC_SC_MASK, status);
+ addCategory(set.getAlias(), U_GC_PC_MASK, status);
+ addCategory(set.getAlias(), U_GC_ND_MASK, status);
+ addCategory(set.getAlias(), U_GC_NL_MASK, status);
+ addCategory(set.getAlias(), U_GC_MC_MASK, status);
+ addCategory(set.getAlias(), U_GC_MN_MASK, status);
+ addIdentifierIgnorable(set.getAlias(), status);
+ }
+ else if (propName.compare(u"javaJavaIdentifierStart", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ addCategory(set.getAlias(), U_GC_NL_MASK, status);
+ addCategory(set.getAlias(), U_GC_SC_MASK, status);
+ addCategory(set.getAlias(), U_GC_PC_MASK, status);
+ }
+ else if (propName.compare(u"javaLetter", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ }
+ else if (propName.compare(u"javaLetterOrDigit", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ addCategory(set.getAlias(), U_GC_ND_MASK, status);
+ }
+ else if (propName.compare(u"javaLowerCase", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_LL_MASK, status);
+ }
+ else if (propName.compare(u"javaMirrored", -1) == 0) {
+ set->applyIntPropertyValue(UCHAR_BIDI_MIRRORED, 1, status);
+ }
+ else if (propName.compare(u"javaSpaceChar", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_Z_MASK, status);
+ }
+ else if (propName.compare(u"javaSupplementaryCodePoint", -1) == 0) {
+ set->add(0x10000, UnicodeSet::MAX_VALUE);
+ }
+ else if (propName.compare(u"javaTitleCase", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_LT_MASK, status);
+ }
+ else if (propName.compare(u"javaUnicodeIdentifierStart", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ addCategory(set.getAlias(), U_GC_NL_MASK, status);
+ }
+ else if (propName.compare(u"javaUnicodeIdentifierPart", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_L_MASK, status);
+ addCategory(set.getAlias(), U_GC_PC_MASK, status);
+ addCategory(set.getAlias(), U_GC_ND_MASK, status);
+ addCategory(set.getAlias(), U_GC_NL_MASK, status);
+ addCategory(set.getAlias(), U_GC_MC_MASK, status);
+ addCategory(set.getAlias(), U_GC_MN_MASK, status);
+ addIdentifierIgnorable(set.getAlias(), status);
+ }
+ else if (propName.compare(u"javaUpperCase", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_LU_MASK, status);
+ }
+ else if (propName.compare(u"javaValidCodePoint", -1) == 0) {
+ set->add(0, UnicodeSet::MAX_VALUE);
+ }
+ else if (propName.compare(u"javaWhitespace", -1) == 0) {
+ addCategory(set.getAlias(), U_GC_Z_MASK, status);
+ set->removeAll(UnicodeSet().add(0xa0).add(0x2007).add(0x202f));
+ set->add(9, 0x0d).add(0x1c, 0x1f);
+ } else {
+ status = U_REGEX_PROPERTY_SYNTAX;
+ }
+
+ if (U_SUCCESS(status) && !set->isEmpty() && (usetFlags & USET_CASE_INSENSITIVE)) {
+ set->closeOver(USET_CASE_INSENSITIVE);
+ }
+ break;
+ }
+
+ // Unrecognized property. ICU didn't like it as it was, and none of the Java compatibility
+ // extensions matched it.
+ status = U_REGEX_PROPERTY_SYNTAX;
+ } while (false); // End of do loop block. Code above breaks out of the block on success or hard failure.
+
+ if (U_SUCCESS(status)) {
+ U_ASSERT(set.isValid());
+ if (negated) {
+ set->complement();
}
- delete set;
- set = NULL;
+ return set.orphan();
+ } else {
+ if (status == U_ILLEGAL_ARGUMENT_ERROR) {
+ status = U_REGEX_PROPERTY_SYNTAX;
+ }
+ error(status);
+ return nullptr;
}
- error(*fStatus);
- return NULL;
}
-
//
// SetEval Part of the evaluation of [set expressions].
// Perform any pending (stacked) operations with precedence
delete rightOperand;
break;
default:
- U_ASSERT(FALSE);
- break;
+ UPRV_UNREACHABLE;
}
}
}
projects / apple / icu.git / blobdiff