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Initial Handling of Non-Void Java Method Calls in GnuCOBOL #174

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@xevor11 xevor11 commented Aug 23, 2024

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xevor11 and others added 3 commits August 22, 2024 19:19
Changes mostly include:
* New option `--with{out}-java` for `configure` script
* Runtime support for calling `static void (void)` methods
* Lookup of JVM library when JAVA_HOME is set, and pre-load when
  possible
* Two preliminary tests

Co-authored-by: Nicolas Berthier <[email protected]>
Co-authored-by: Simon Sobisch <[email protected]>
cobc/codegen.c Outdated
@@ -7098,7 +7098,9 @@ output_java_call (struct cb_call *p)
char *last_dot;
char *method_name;
const char *class_name;
char method_signature[256] = "(";
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For internal buffer sizes you have COB_*_BUFF definitions in libcob/common.h that you can use here as well. Typical signature length could exceed 256 without much effort I think (with long-enough Java package names). I'd go for COB_NORMAL_BUFF (2048) for now.

cobc/codegen.c Outdated
@@ -7115,18 +7117,103 @@ output_java_call (struct cb_call *p)
method_name = last_dot + 1;
class_name = class_and_method_name;

for(ptr = p->args; ptr != NULL; ptr = ptr->next) {
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Note: indentation is strange here. I think you need to adjust that in your settings for this project.

cobc/codegen.c Outdated
lookup_java_call(mangled);
output_line("if (call_java_%s == NULL)", mangled);
output_block_open();

output_prefix();
output_line("call_java_%s = ", mangled);
output("cob_resolve_java(\"%s\", \"%s\", \"()V\");", class_name, method_name);
output("cob_resolve_java(\"%s\", \"%s\", \"()V\");", class_name, method_name, method_signature);
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Here you should probable replace ()V with %s so the method signature is included.

cobc/codegen.c Outdated
output_newline ();
output_prefix ();
output_line("cob_call_java(call_java_%s);\n", mangled);
output_newline();
output_block_close();
cobc_free(mangled);
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This will likely cause a use-after-free since mangled is referenced in the list created by lookup_java_call.

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next bigger part here is likely adding a testcase that has a return value and a second that has parameters (or both one, for example a simple longJava.Test.addMe (int, int[]))

cobc/codegen.c Outdated
Comment on lines 7103 to 7104
char return_type_signature[32];
char method_signature[2048] = "(";
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use COB_MINI_BUFF and COB_NORMAL_BUFF for those and down use strncat with the _MAX defines

cobc/codegen.c Outdated
Comment on lines 7182 to 7192
cobc_err_msg(_("Unsupported array element type in Java method call"));
COBC_ABORT();
}
}
}
list_elements = inner_list;
}

if (array_dimension > 2) {
cobc_err_msg(_("Unsupported array dimension: %d"), array_dimension);
COBC_ABORT();
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those two messages should be errors in cb_check_conformance as well as a check for "only field identifiers" (= no literals/functions/...) - which then also allows above to directly cast to a field pointer and operate on this; additional, for parameters passed BY REFERENCE that are a String/BigDecimal mapping item there should be a warning "immutable type implicit passed BY CONTENT".

Comment on lines +82 to +83
(*env)->ExceptionDescribe(env);
(*env)->ExceptionClear(env);
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fine during development, needs to be adjusted later - see review on the other PR

cobc/codegen.c Outdated
Comment on lines 7163 to 7165
case CB_TAG_INTEGER:
strcat(method_signature, "[I");
break;
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In case of integer we further have to check the type per usage

pic/type java type
PIC S9(n) COMP-5, where ≥ 1 n ≤ 4 short
PIC S9(n) COMP-5, where ≥ 5 n ≤ 9 int
PIC S9(n) COMP-5, where ≥ 10 n ≤ 18 long
usage COMP-3/PACKED-DECIMAL/DISPLAY numeric java.math.BigDecimal

Note that checking the TAGs and USAGEs and CLASSes in a single switch doesn't work (check with the debugger to get more details).

Also note that PIC X (=single byte) is a special case:

  • if it has two or one level88 below it with value x'01' / x'00' --> boolean
  • otherwise: byte

For all of the types you have (after addition of the above) there needs to be a check for the occurs attribute ("more than 1 dimension" will already be checked in the conformance checks) and if existing just add [].

As the valid types are identical for both arguments and returning items, their generation should be moved out to a static helper function called for each of the parameters (the loop here) and the returning item below.

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3 participants