Class Configuration

A configuration of interprocedural data flow analysis. This defines sources, sinks, and any other configurable aspect of the analysis. Each use of the global data flow library must define its own unique extension of this abstract class. To create a configuration, extend this class with a subclass whose characteristic predicate is a unique singleton string. For example, write

class MyAnalysisConfiguration extends DataFlow::Configuration {
  MyAnalysisConfiguration() { this = "MyAnalysisConfiguration" }
  // Override `isSource` and `isSink`.
  // Optionally override `isBarrier`.
  // Optionally override `isAdditionalFlowStep`.
}

Conceptually, this defines a graph where the nodes are DataFlow::Nodes and the edges are those data-flow steps that preserve the value of the node along with any additional edges defined by isAdditionalFlowStep. Specifying nodes in isBarrier will remove those nodes from the graph, and specifying nodes in isBarrierIn and/or isBarrierOut will remove in-going and/or out-going edges from those nodes, respectively.

Then, to query whether there is flow between some source and sink, write

exists(MyAnalysisConfiguration cfg | cfg.hasFlow(source, sink))

Multiple configurations can coexist, but two classes extending DataFlow::Configuration should never depend on each other. One of them should instead depend on a DataFlow2::Configuration, a DataFlow3::Configuration, or a DataFlow4::Configuration.

Import path

import semmle.code.cpp.dataflow.internal.DataFlowImpl3

Direct supertypes

string

Known direct subtypes

Predicates

explorationLimit	Gets the exploration limit for `hasPartialFlow` and `hasPartialFlowRev` measured in approximate number of interprocedural steps.
fieldFlowBranchLimit	Gets the virtual dispatch branching limit when calculating field flow. This can be overridden to a smaller value to improve performance (a value of 0 disables field flow), or a larger value to get more results.
hasFlow	Holds if data may flow from `source` to `sink` for this configuration.
hasFlowPath	Holds if data may flow from `source` to `sink` for this configuration.
hasFlowTo	Holds if data may flow from some source to `sink` for this configuration.
hasFlowToExpr	Holds if data may flow from some source to `sink` for this configuration.
hasPartialFlow	Holds if there is a partial data flow path from `source` to `node`. The approximate distance between `node` and the closest source is `dist` and is restricted to be less than or equal to `explorationLimit()`. This predicate completely disregards sink definitions.
hasPartialFlowRev	Holds if there is a partial data flow path from `node` to `sink`. The approximate distance between `node` and the closest sink is `dist` and is restricted to be less than or equal to `explorationLimit()`. This predicate completely disregards source definitions.
isAdditionalFlowStep	Holds if the additional flow step from `node1` to `node2` must be taken into account in the analysis.
isBarrier	Holds if data flow through `node` is prohibited. This completely removes `node` from the data flow graph.
isBarrierGuard	Holds if data flow through nodes guarded by `guard` is prohibited.
isBarrierIn	Holds if data flow into `node` is prohibited.
isBarrierOut	Holds if data flow out of `node` is prohibited.
isSink	Holds if `sink` is a relevant data flow sink.
isSource	Holds if `source` is a relevant data flow source.

Inherited predicates

charAt	Returns a one-character string containing the character in the receiver at the given index (which ranges from 0 through length minus one)	from string
indexOf	Returns all the offsets (starting at 0) at which the given string occurs in the receiver. Has no result if the string does not occur in the receiver.	from string
indexOf	Returns the index of the n’th (starting at 0) occurrence of the given string within the receiver, starting at the given 0-based offset. Has no result if the string does not occur in the receiver.	from string
isLowercase	Holds when the receiver contains no upper-case letters. This includes the case where the receiver contains no letters at all, for example, if it’s an empty string or only consists of non-letter symbols.	from string
isUppercase	Holds when the receiver contains no lower-case letters. This includes the case where the receiver contains no letters at all, for example, if it’s an empty string or only consists of non-letter symbols.	from string
length	Returns the length of the receiver (in UTF-16 code units)	from string
matches	Holds when the receiver matches the pattern. Patterns are matched by case sensitive string matching, and there are two wildcards: _ matches a single character, and % matches any sequence of characters. To match the actual characters _ or % in the pattern, they must be escaped using backslashes. For example, `"anythingstring%".matches("%string\\%")` holds. To match a literal backslash in front of _ or %, you must escape the backslash. In other cases, you don’t need to escape the backslash.	from string
prefix	Returns the substring of the receiver ending at the given 0-based exclusive offset	from string
regexpCapture	When the given regular expression matches the entire receiver, returns the substring matched by the given capture group (starting at 1). The regex format used is Java’s Pattern.	from string
regexpFind	Returns a substring of the receiver which matches the given regular expression. Also returns the offset within the receiver (starting at 0) at which the match occurred (occurrenceOffset), and the number of matches which occur at smaller offsets (occurrenceIndex). The regex format used is Java’s Pattern.	from string
regexpMatch	Holds when the given regular expression matches the entire receiver. The regex format used is Java’s Pattern.	from string
regexpReplaceAll	Returns a copy of the receiver with every substring which matches the given regular expression is replaced by the replacement. The regex format used is Java’s Pattern. The replacement string can contain references to captured groups as described in Java’s appendReplacement docs.	from string
replaceAll	Returns a copy of the receiver with all occurrences of the target replaced by the replacement	from string
splitAt	Returns all the substrings obtained by splitting the receiver at every occurrence of the argument. Trailing empty substrings are omitted. Splitting at an empty string returns all the characters that the receiver consists of.	from string
splitAt	Returns the n’th (starting at 0) substring obtained by splitting the receiver at every occurrence of the argument. Trailing empty substrings are omitted. Splitting at an empty string returns all the characters that the receiver consists of.	from string
substring	Returns the substring of the receiver which starts and ends at the given indices. Both indices are 0-based. The start index is inclusive and the end index is exclusive.	from string
suffix	Returns the substring of the receiver starting at the given 0-based inclusive offset	from string
toDate	Returns the date, if any, obtained by parsing the receiver. The recognized formats are described in the documentation.	from string
toFloat	Returns the 64-bit floating point number, if any, obtained by parsing the receiver. The parsing rules are described in Java’s valueOf docs.	from string
toInt	Returns the 32-bit signed integer, if any, obtained by parsing the receiver. The number may consist of an optional leading `+` or `-`, followed by one or more digits. Has no result if the value exceeds the value range supported by the `int` type.	from string
toLowerCase	Returns a copy of the receiver with all uppercase characters replaced by lowercase ones according to Unicode case conversion rules.	from string
toString	Returns the receiver	from string
toUpperCase	Returns a copy of the receiver with all lowercase characters replaced by uppercase ones according to Unicode case conversion rules.	from string
trim	Returns a copy of the receiver with all whitespace removed from the beginning and end of the string (where whitespace is defined as Unicode code points ‘\u0000’ through ‘\u0020’ inclusive)	from string

Charpred

Configuration