Global variables not detected

[sciencemanx]

int x;

int main() {
    return 0;
}

shows no reference to variable x when run through joern.

Looking at fuzzyc2cpg 1 and 2, it appears this should be handled.

[fabsx00]

Yes, this should be handled. What do you mean by "shows no references to" exactly?

[sciencemanx]

@fabsx00 "shows no references to" means that "x" "int x" etc. does not exist in the cpg.zip database.

Additionally, I have found that while the database created from

typedef int size_t;
void *malloc(size_t x);

contains no information (or any reference to) malloc, the following does

typedef int size_t;
void *malloc(size_t x) {

}

[sciencemanx]

Therefore, it appears that any declarations are skipped while definitions are added to the database.

[GlassAndOneHalf]

Hi @sciencemanx

In regards to the first item, it seems that we only processes top-level identifier declarations if they are typedefs. See https://github.com/ShiftLeftSecurity/fuzzyc2cpg/blob/master/src/main/scala/io/shiftleft/fuzzyc2cpg/astnew/AstToCpgConverter.scala#L593-L594

At first glance, it seems we will need to change the existing code to create a LOCAL or IDENTIFIER node at the top level of the CPG. Alternatively we can start construction of the CPG with by beginning with a "global scope" pushed on the scope stack (currently the scope stack is initialized to be empty), and then add any corresponding nodes as before.

As for the second item (erased function declarations), with the code you have provided I am unable to reproduce the issue you are having:

Code:

typedef int size_t;
void *malloc(size_t x);

Query:

joern> cpg.method.l 
res12: List[Method] = List(
  Method(
    id -> 8L,
    name -> "malloc",
    fullName -> "malloc",
    isExternal -> false,
    signature -> "void*(size_t)",
    astParentType -> null,
    astParentFullName -> null,
    lineNumber -> Some(2),
    columnNumber -> Some(0),
    lineNumberEnd -> Some(2),
    columnNumberEnd -> Some(22),
    order -> null,
    hasMapping -> None,
    depthFirstOrder -> None,
    binarySignature -> None
  )
)

[GlassAndOneHalf]

See ShiftLeftSecurity/fuzzyc2cpg#156

[itsacoderepo]

@sciencemanx

Current version of joern (v1.1.440) is handling x as a local.

Based on your initial code snippet, you should be able to query for x with:

joern> cpg.local.l
res4: List[Local] = List(
  Local(
    id -> 3074457345618258674L,
    closureBindingId -> None,
    code -> "int x",
    columnNumber -> None,
    dynamicTypeHintFullName -> ArraySeq(),
    lineNumber -> Some(value = 1),
    name -> "x",
    order -> 1,
    typeFullName -> "int"
  )
)

Closing..