Import C bindings from NixOS/nix#8699

Co-authored-by: Yorick van Pelt <[email protected]> Co-authored-by: José Luis Lafuente <[email protected]> Change-Id: I48aa262d880aa75aa5b230553f663c35c283d5f6
chshbit · Mar 17, 2024 · e425a1d · e425a1d
1 parent de17a2f
commit e425a1d
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diff --git a/src/libexpr/c/meson.build b/src/libexpr/c/meson.build
@@ -0,0 +1,31 @@
+pkg = import('pkgconfig')
+
+libexprc_sources = files(
+  'nix_api_expr.cc',
+  'nix_api_external.cc',
+  'nix_api_value.cc',
+)
+
+all_sources += {
+  'libexprc': libexprc_sources
+}
+
+libexprc = library(
+  'nix-expr-c',
+  libexprc_sources,
+  dependencies : [
+    liblixutil,
+    liblixstore,
+    liblixexpr,
+    liblixutilc,
+    liblixstorec,
+    boehm,
+  ],
+)
+
+pkg.generate(libexprc, requires: [ 'nix-store-c' ])
+
+liblixexprc = declare_dependency(
+  include_directories : include_directories('.'),
+  link_with : libexprc,
+)
diff --git a/src/libexpr/c/nix_api_expr.cc b/src/libexpr/c/nix_api_expr.cc
@@ -0,0 +1,178 @@
+#include <cstring>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+#include "config.hh"
+#include "eval.hh"
+#include "globals.hh"
+#include "util.hh"
+
+#include "nix_api_expr.h"
+#include "nix_api_expr_internal.h"
+#include "nix_api_store.h"
+#include "nix_api_store_internal.h"
+#include "nix_api_util.h"
+#include "nix_api_util_internal.h"
+
+#ifdef HAVE_BOEHMGC
+#include <mutex>
+#define GC_INCLUDE_NEW 1
+#include "gc_cpp.h"
+#endif
+
+nix_err nix_libexpr_init(nix_c_context * context)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    {
+        auto ret = nix_libutil_init(context);
+        if (ret != NIX_OK)
+            return ret;
+    }
+    {
+        auto ret = nix_libstore_init(context);
+        if (ret != NIX_OK)
+            return ret;
+    }
+    try {
+        nix::initGC();
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_expr_eval_from_string(
+    nix_c_context * context, EvalState * state, const char * expr, const char * path, Value * value)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::Expr * parsedExpr = state->state.parseExprFromString(expr, state->state.rootPath(nix::CanonPath(path)));
+        state->state.eval(parsedExpr, *(nix::Value *) value);
+        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, Value * arg, Value * value)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        state->state.callFunction(*(nix::Value *) fn, *(nix::Value *) arg, *(nix::Value *) value, nix::noPos);
+        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * value)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, Value * value)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        state->state.forceValueDeep(*(nix::Value *) value);
+    }
+    NIXC_CATCH_ERRS
+}
+
+EvalState * nix_state_create(nix_c_context * context, const char ** searchPath_c, Store * store)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        nix::Strings searchPath;
+        if (searchPath_c != nullptr)
+            for (size_t i = 0; searchPath_c[i] != nullptr; i++)
+                searchPath.push_back(searchPath_c[i]);
+
+        return new EvalState{nix::EvalState(nix::SearchPath::parse(searchPath), store->ptr)};
+    }
+    NIXC_CATCH_ERRS_NULL
+}
+
+void nix_state_free(EvalState * state)
+{
+    delete state;
+}
+
+#ifdef HAVE_BOEHMGC
+std::unordered_map<
+    const void *,
+    unsigned int,
+    std::hash<const void *>,
+    std::equal_to<const void *>,
+    traceable_allocator<std::pair<const void * const, unsigned int>>>
+    nix_refcounts;
+
+std::mutex nix_refcount_lock;
+
+nix_err nix_gc_incref(nix_c_context * context, const void * p)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        std::scoped_lock lock(nix_refcount_lock);
+        auto f = nix_refcounts.find(p);
+        if (f != nix_refcounts.end()) {
+            f->second++;
+        } else {
+            nix_refcounts[p] = 1;
+        }
+    }
+    NIXC_CATCH_ERRS
+}
+
+nix_err nix_gc_decref(nix_c_context * context, const void * p)
+{
+
+    if (context)
+        context->last_err_code = NIX_OK;
+    try {
+        std::scoped_lock lock(nix_refcount_lock);
+        auto f = nix_refcounts.find(p);
+        if (f != nix_refcounts.end()) {
+            if (--f->second == 0)
+                nix_refcounts.erase(f);
+        } else
+            throw std::runtime_error("nix_gc_decref: object was not referenced");
+    }
+    NIXC_CATCH_ERRS
+}
+
+void nix_gc_now()
+{
+    GC_gcollect();
+}
+
+#else
+void nix_gc_incref(nix_c_context * context, const void *)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    return NIX_OK;
+}
+void nix_gc_decref(nix_c_context * context, const void *)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    return NIX_OK;
+}
+void nix_gc_now() {}
+#endif
+
+void nix_gc_register_finalizer(void * obj, void * cd, void (*finalizer)(void * obj, void * cd))
+{
+#ifdef HAVE_BOEHMGC
+    GC_REGISTER_FINALIZER(obj, finalizer, cd, 0, 0);
+#endif
+}