Merge pull request github#3843 from geoffw0/qldoc6

C++: Bit more QLDoc

Author: jbj

cpp/ql/src/semmle/code/cpp/commons/Synchronization.qll

@@ -23,8 +23,7 @@ abstract class MutexType extends Type {
   abstract predicate trylockAccess(FunctionCall fc, Expr arg);
 
   /**
-   * Holds if `fc` is a call that unlocks mutex `arg`
-   * of this type.
+   * Holds if `fc` is a call that unlocks mutex `arg` of this type.
    */
   abstract predicate unlockAccess(FunctionCall fc, Expr arg);
 
@@ -38,53 +37,52 @@ abstract class MutexType extends Type {
   }
 
   /**
-   * Holds if `fc` is a call that locks or tries to lock any
-   * mutex of this type.
+   * Gets a call that locks or tries to lock any mutex of this type.
    */
   FunctionCall getLockAccess() {
     result = getMustlockAccess() or
     result = getTrylockAccess()
   }
 
   /**
-   * Holds if `fc` is a call that always locks any mutex of this type.
+   * Gets a call that always locks any mutex of this type.
    */
   FunctionCall getMustlockAccess() { this.mustlockAccess(result, _) }
 
   /**
-   * Holds if `fc` is a call that tries to lock any mutex of this type,
+   * Gets a call that tries to lock any mutex of this type,
    * by may return without success.
    */
   FunctionCall getTrylockAccess() { this.trylockAccess(result, _) }
 
   /**
-   * Holds if `fc` is a call that unlocks any mutex of this type.
+   * Gets a call that unlocks any mutex of this type.
    */
   FunctionCall getUnlockAccess() { this.unlockAccess(result, _) }
 
   /**
-   * DEPRECATED: use mustlockAccess(fc, arg) instead
+   * DEPRECATED: use mustlockAccess(fc, arg) instead.
    */
   deprecated Function getMustlockFunction() { result = getMustlockAccess().getTarget() }
 
   /**
-   * DEPRECATED: use trylockAccess(fc, arg) instead
+   * DEPRECATED: use trylockAccess(fc, arg) instead.
    */
   deprecated Function getTrylockFunction() { result = getTrylockAccess().getTarget() }
 
   /**
-   * DEPRECATED: use lockAccess(fc, arg) instead
+   * DEPRECATED: use lockAccess(fc, arg) instead.
    */
   deprecated Function getLockFunction() { result = getLockAccess().getTarget() }
 
   /**
-   * DEPRECATED: use unlockAccess(fc, arg) instead
+   * DEPRECATED: use unlockAccess(fc, arg) instead.
    */
   deprecated Function getUnlockFunction() { result = getUnlockAccess().getTarget() }
 }
 
 /**
- * A function that looks like a lock function.
+ * Gets a function that looks like a lock function.
  */
 private Function mustlockCandidate() {
   exists(string name | name = result.getName() |
@@ -94,7 +92,7 @@ private Function mustlockCandidate() {
 }
 
 /**
- * A function that looks like a try-lock function.
+ * Gets a function that looks like a try-lock function.
  */
 private Function trylockCandidate() {
   exists(string name | name = result.getName() |
@@ -104,7 +102,7 @@ private Function trylockCandidate() {
 }
 
 /**
- * A function that looks like an unlock function.
+ * Gets a function that looks like an unlock function.
  */
 private Function unlockCandidate() {
   exists(string name | name = result.getName() |
@@ -171,7 +169,10 @@ class DefaultMutexType extends MutexType {
   }
 }
 
-/** Get the mutex argument of a call to lock or unlock. */
+/**
+ * Holds if `arg` is the mutex argument of a call to lock or unlock and
+ * `argType` is the type of the mutex.
+ */
 private predicate lockArg(Expr arg, MutexType argType, FunctionCall call) {
   argType = arg.getUnderlyingType().stripType() and
   (
@@ -184,18 +185,31 @@ private predicate lockArg(Expr arg, MutexType argType, FunctionCall call) {
   //       `MutexType.mustlockAccess`.
 }
 
+/**
+ * Holds if `call` is a call that locks or tries to lock its argument `arg`.
+ */
 predicate lockCall(Expr arg, FunctionCall call) {
   exists(MutexType t | lockArg(arg, t, call) and call = t.getLockAccess())
 }
 
+/**
+ * Holds if `call` is a call that always locks its argument `arg`.
+ */
 predicate mustlockCall(Expr arg, FunctionCall call) {
   exists(MutexType t | lockArg(arg, t, call) and call = t.getMustlockAccess())
 }
 
+/**
+ * Holds if `call` is a call that tries to lock its argument `arg`, but may
+ * return without success.
+ */
 predicate trylockCall(Expr arg, FunctionCall call) {
   exists(MutexType t | lockArg(arg, t, call) and call = t.getTrylockAccess())
 }
 
+/**
+ * Holds if `call` is a call that unlocks its argument `arg`.
+ */
 predicate unlockCall(Expr arg, FunctionCall call) {
   exists(MutexType t | lockArg(arg, t, call) and call = t.getUnlockAccess())
 }

cpp/ql/src/semmle/code/cpp/exprs/Literal.qll

@@ -1,3 +1,8 @@
+/**
+ * Provides classes for modeling literals in the source code such as `0`, `'c'`
+ * or `"string"`.
+ */
+
 import semmle.code.cpp.exprs.Expr
 
 /**

cpp/ql/src/semmle/code/cpp/security/FunctionWithWrappers.qll

@@ -1,3 +1,20 @@
+/**
+ * Provides predicates for identifying functions that wrap other functions,
+ * passing the same arguments from the outer call into the inner call. In the
+ * following example `MyMalloc` wraps a call to `malloc`, passing in the `size`
+ * parameter:
+ * ```
+ * void *MyMalloc(size_t size)
+ * {
+ *   void *ptr = malloc(size);
+ *
+ *   // ... additional logic?
+ *
+ *   return ptr;
+ * }
+ * ```
+ */
+
 import cpp
 import PrintfLike
 private import TaintTracking
@@ -152,6 +169,9 @@ abstract class FunctionWithWrappers extends Function {
   }
 }
 
+/**
+ * A `printf`-like formatting function.
+ */
 class PrintfLikeFunction extends FunctionWithWrappers {
   PrintfLikeFunction() { printfLikeFunction(this, _) }
 

cpp/ql/src/semmle/code/cpp/security/Overflow.qll

@@ -1,19 +1,25 @@
+/**
+ * Provides predicates for reasoning about when the value of an expression is
+ * guarded by an operation such as `<`, which confines its range.
+ */
+
 import cpp
 import semmle.code.cpp.controlflow.Dominance
 
-/*
- * Guarding
+/**
+ * Holds if the value of `use` is guarded using `abs`.
  */
-
-/** is the size of this use guarded using 'abs'? */
 predicate guardedAbs(Operation e, Expr use) {
   exists(FunctionCall fc | fc.getTarget().getName() = "abs" |
     fc.getArgument(0).getAChild*() = use and
     guardedLesser(e, fc)
   )
 }
 
-/** This is `BasicBlock.getNode`, restricted to `Stmt` for performance. */
+/**
+ * Gets the position of `stmt` in basic block `block` (this is a thin layer
+ * over `BasicBlock.getNode`, intended to improve performance).
+ */
 pragma[noinline]
 private int getStmtIndexInBlock(BasicBlock block, Stmt stmt) { block.getNode(result) = stmt }
 
@@ -30,7 +36,9 @@ private predicate stmtDominates(Stmt dominator, Stmt dominated) {
   bbStrictlyDominates(dominator.getBasicBlock(), dominated.getBasicBlock())
 }
 
-/** is the size of this use guarded to be less than something? */
+/**
+ * Holds if the value of `use` is guarded to be less than something.
+ */
 pragma[nomagic]
 predicate guardedLesser(Operation e, Expr use) {
   exists(IfStmt c, RelationalOperation guard |
@@ -54,7 +62,9 @@ predicate guardedLesser(Operation e, Expr use) {
   guardedAbs(e, use)
 }
 
-/** is the size of this use guarded to be greater than something? */
+/**
+ * Holds if the value of `use` is guarded to be greater than something.
+ */
 pragma[nomagic]
 predicate guardedGreater(Operation e, Expr use) {
   exists(IfStmt c, RelationalOperation guard |
@@ -78,10 +88,14 @@ predicate guardedGreater(Operation e, Expr use) {
   guardedAbs(e, use)
 }
 
-/** a use of a given variable */
+/**
+ * Gets a use of a given variable `v`.
+ */
 VariableAccess varUse(LocalScopeVariable v) { result = v.getAnAccess() }
 
-/** is e not guarded against overflow by use? */
+/**
+ * Holds if `e` is not guarded against overflow by `use`.
+ */
 predicate missingGuardAgainstOverflow(Operation e, VariableAccess use) {
   use = e.getAnOperand() and
   exists(LocalScopeVariable v | use.getTarget() = v |
@@ -100,7 +114,9 @@ predicate missingGuardAgainstOverflow(Operation e, VariableAccess use) {
   )
 }
 
-/** is e not guarded against underflow by use? */
+/**
+ * Holds if `e` is not guarded against underflow by `use`.
+ */
 predicate missingGuardAgainstUnderflow(Operation e, VariableAccess use) {
   use = e.getAnOperand() and
   exists(LocalScopeVariable v | use.getTarget() = v |

cpp/ql/src/semmle/code/cpp/security/SensitiveExprs.qll

@@ -1,5 +1,14 @@
+/**
+ * Provides classes for heuristically identifying variables and functions that
+ * might contain or return a password or other sensitive information.
+ */
+
 import cpp
 
+/**
+ * Holds if the name `s` suggests something might contain or return a password
+ * or other sensitive information.
+ */
 bindingset[s]
 private predicate suspicious(string s) {
   (
@@ -16,14 +25,23 @@ private predicate suspicious(string s) {
   )
 }
 
+/**
+ * A variable that might contain a password or other sensitive information.
+ */
 class SensitiveVariable extends Variable {
   SensitiveVariable() { suspicious(getName().toLowerCase()) }
 }
 
+/**
+ * A function that might return a password or other sensitive information.
+ */
 class SensitiveFunction extends Function {
   SensitiveFunction() { suspicious(getName().toLowerCase()) }
 }
 
+/**
+ * An expression whose value might be a password or other sensitive information.
+ */
 class SensitiveExpr extends Expr {
   SensitiveExpr() {
     this.(VariableAccess).getTarget() instanceof SensitiveVariable or