Merge pull request #17034 from MathiasVP/more-alias-and-side-effect-m…

…odels

C++: Add more alias and side effect models

cpp/ql/lib/semmle/code/cpp/models/Models.qll

@@ -27,6 +27,11 @@ private import implementations.StdPair
 private import implementations.StdMap
 private import implementations.StdSet
 private import implementations.StdString
+private import implementations.StdFunction
+private import implementations.StdException
+private import implementations.StdAllocator
+private import implementations.StdAlgorithm
+private import implementations.StdMath
 private import implementations.Swap
 private import implementations.GetDelim
 private import implementations.SmartPointer

cpp/ql/lib/semmle/code/cpp/models/implementations/Iterator.qll

@@ -86,6 +86,41 @@ private class StdIterator extends Iterator, Class {
   override Type getValueType() { result = this.getTemplateArgument(1).(Type).getUnderlyingType() }
 }
 
+private class StdReverseIterator extends Iterator, Class {
+  StdReverseIterator() { this.hasQualifiedName(["std", "bsl"], "reverse_iterator") }
+
+  override Type getValueType() { result = this.getTemplateArgument(1).(Type).getUnderlyingType() }
+}
+
+private class StdIstreamBufIterator extends Iterator, Class {
+  StdIstreamBufIterator() { this.hasQualifiedName(["std", "bsl"], "istreambuf_iterator") }
+
+  override Type getValueType() { result = this.getTemplateArgument(1).(Type).getUnderlyingType() }
+}
+
+private class StdIstreambufIteratorConstructor extends Constructor, SideEffectFunction,
+  AliasFunction
+{
+  StdIstreambufIteratorConstructor() { this.getDeclaringType() instanceof StdIstreamBufIterator }
+
+  override predicate parameterNeverEscapes(int index) { index = -1 }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    i = -1 and buffer = false and mustWrite = true
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    this.getParameter(i).getUnspecifiedType() instanceof ReferenceType and
+    buffer = false
+  }
+}
+
 /**
  * Gets the `FunctionInput` corresponding to an iterator parameter to
  * user-defined operator `op`, at `index`.
@@ -579,31 +614,51 @@ private class IteratorAssignmentMemberOperatorModel extends IteratorAssignmentMe
   override predicate parameterEscapesOnlyViaReturn(int index) { index = -1 }
 }
 
+private string beginName() {
+  result = ["begin", "cbegin", "rbegin", "crbegin", "before_begin", "cbefore_begin"]
+}
+
 /**
  * A `begin` member function, or a related function, that returns an iterator.
  */
-class BeginFunction extends MemberFunction {
+class BeginFunction extends Function {
   BeginFunction() {
-    this.hasName(["begin", "cbegin", "rbegin", "crbegin", "before_begin", "cbefore_begin"]) and
-    this.getType().getUnspecifiedType() instanceof Iterator
+    this.getUnspecifiedType() instanceof Iterator and
+    (
+      this.hasName(beginName()) and
+      this instanceof MemberFunction
+      or
+      this.hasGlobalOrStdOrBslName(beginName()) and
+      not this instanceof MemberFunction and
+      this.getNumberOfParameters() = 1
+    )
   }
 }
 
+private string endName() { result = ["end", "cend", "rend", "crend"] }
+
 /**
  * An `end` member function, or a related function, that returns an iterator.
  */
-class EndFunction extends MemberFunction {
+class EndFunction extends Function {
   EndFunction() {
-    this.hasName(["end", "cend", "rend", "crend"]) and
-    this.getType().getUnspecifiedType() instanceof Iterator
+    this.getUnspecifiedType() instanceof Iterator and
+    (
+      this.hasName(endName()) and
+      this instanceof MemberFunction
+      or
+      this.hasGlobalOrStdOrBslName(endName()) and
+      this instanceof MemberFunction and
+      this.getNumberOfParameters() = 1
+    )
   }
 }
 
 /**
  * A `begin` or `end` member function, or a related member function, that
  * returns an iterator.
  */
-class BeginOrEndFunction extends MemberFunction {
+class BeginOrEndFunction extends Function {
   BeginOrEndFunction() {
     this instanceof BeginFunction or
     this instanceof EndFunction

cpp/ql/lib/semmle/code/cpp/models/implementations/Printf.qll

@@ -7,6 +7,7 @@
 
 import semmle.code.cpp.models.interfaces.FormattingFunction
 import semmle.code.cpp.models.interfaces.Alias
+import semmle.code.cpp.models.interfaces.SideEffect
 
 /**
  * The standard functions `printf`, `wprintf` and their glib variants.
@@ -96,7 +97,7 @@ private class Sprintf extends FormattingFunction {
 /**
  * Implements `Snprintf`.
  */
-private class SnprintfImpl extends Snprintf {
+private class SnprintfImpl extends Snprintf, AliasFunction, SideEffectFunction {
   SnprintfImpl() {
     this instanceof TopLevelFunction and
     (
@@ -143,6 +144,26 @@ private class SnprintfImpl extends Snprintf {
   }
 
   override int getSizeParameterIndex() { result = 1 }
+
+  override predicate parameterNeverEscapes(int index) {
+    // We don't know how many parameters are passed to the function since it's varargs, but they also don't escape.
+    index = this.getFormatParameterIndex()
+  }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    i = this.getOutputParameterIndex(false) and buffer = true and mustWrite = false
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    // We don't know how many parameters are passed to the function since it's varargs, but they also have read side effects.
+    i = this.getFormatParameterIndex() and buffer = true
+  }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/models/implementations/StdAlgorithm.qll

@@ -0,0 +1,115 @@
+/**
+ * Provides models for C++ functions from the `algorithms` header.
+ */
+
+import semmle.code.cpp.models.interfaces.Taint
+import semmle.code.cpp.models.interfaces.DataFlow
+import semmle.code.cpp.models.interfaces.Iterator
+import semmle.code.cpp.models.interfaces.SideEffect
+import semmle.code.cpp.models.interfaces.Alias
+
+private class StdPartialSort extends Function, SideEffectFunction, AliasFunction {
+  StdPartialSort() { this.hasGlobalOrStdName("partial_sort") }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    i = this.getAnIteratorParameterIndex() and buffer = true and mustWrite = false
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    i = this.getAnIteratorParameterIndex() and
+    buffer = true and
+    this.getParameter(i).getUnspecifiedType() instanceof ReferenceType and
+    buffer = false
+  }
+
+  private int getAnIteratorParameterIndex() {
+    this.getParameter(result).getUnspecifiedType() instanceof Iterator
+  }
+
+  override predicate parameterNeverEscapes(int index) {
+    index = this.getAnIteratorParameterIndex()
+    or
+    this.getParameter(index).getUnspecifiedType() instanceof ReferenceType
+  }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+}
+
+private class StdSortHeap extends Function, SideEffectFunction, AliasFunction {
+  StdSortHeap() { this.hasGlobalOrStdName("sort_heap") }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    i = this.getAnIteratorParameterIndex() and buffer = true and mustWrite = false
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    i = this.getAnIteratorParameterIndex() and
+    buffer = true
+  }
+
+  private int getAnIteratorParameterIndex() {
+    this.getParameter(result).getUnspecifiedType() instanceof Iterator
+  }
+
+  override predicate parameterNeverEscapes(int index) { index = this.getAnIteratorParameterIndex() }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+}
+
+private class StdGenerateN extends Function, SideEffectFunction, AliasFunction {
+  StdGenerateN() { this.hasGlobalOrStdName("generate_n") }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
+    i = this.getAnIteratorParameterIndex() and buffer = true and mustWrite = false
+  }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    this.getParameter(i).getUnspecifiedType() instanceof ReferenceType and buffer = false
+  }
+
+  private int getAnIteratorParameterIndex() {
+    this.getParameter(result).getUnspecifiedType() instanceof Iterator
+  }
+
+  override predicate parameterNeverEscapes(int index) { index = this.getAnIteratorParameterIndex() }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) { none() }
+}
+
+private class StdFindIfOrIfNot extends Function, SideEffectFunction, AliasFunction {
+  StdFindIfOrIfNot() { this.hasGlobalOrStdName(["find_if", "find_if_not"]) }
+
+  override predicate hasOnlySpecificReadSideEffects() { any() }
+
+  override predicate hasOnlySpecificWriteSideEffects() { any() }
+
+  override predicate hasSpecificReadSideEffect(ParameterIndex i, boolean buffer) {
+    i = this.getAnIteratorParameterIndex() and buffer = true
+    or
+    this.getParameter(i).getUnspecifiedType() instanceof ReferenceType and buffer = false
+  }
+
+  private int getAnIteratorParameterIndex() {
+    this.getParameter(result).getUnspecifiedType() instanceof Iterator
+  }
+
+  override predicate parameterNeverEscapes(int index) {
+    this.getParameter(index).getUnspecifiedType() instanceof ReferenceType
+  }
+
+  override predicate parameterEscapesOnlyViaReturn(int index) {
+    index = this.getAnIteratorParameterIndex()
+  }
+}