feat: rcmem

CMakeLists.txt

@@ -14,6 +14,9 @@ target_include_directories(
 add_executable(strings ${CMAKE_CURRENT_SOURCE_DIR}/app/strings.c)
 target_link_libraries(strings PRIVATE c-libs)
 
+add_executable(rc ${CMAKE_CURRENT_SOURCE_DIR}/app/rc.c)
+target_link_libraries(rc PRIVATE c-libs)
+
 include(CTest)
 if(BUILD_TESTING)
   find_package(PkgConfig REQUIRED)
@@ -30,25 +33,26 @@ endif()
 include(CMakePackageConfigHelpers)
 include(GNUInstallDirs)
 
-install(DIRECTORY include/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
-
 install(
   TARGETS c-libs
   EXPORT c-libs
-  ARCHIVE DESTINATION lib
-  LIBRARY DESTINATION lib
-  RUNTIME DESTINATION bin)
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
+
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/include/c-libs
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
 install(
   EXPORT c-libs
   FILE c-libsTargets.cmake
   NAMESPACE c-libs::
-  DESTINATION lib/cmake/c-libs)
+  DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/c-libs)
 
 configure_package_config_file(
   ${CMAKE_CURRENT_SOURCE_DIR}/c-libsConfig.cmake.in
   ${CMAKE_CURRENT_BINARY_DIR}/c-libsConfig.cmake
-  INSTALL_DESTINATION lib/cmake/c-libs)
+  INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/c-libs)
 
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/c-libsConfig.cmake
-        DESTINATION lib/cmake/c-libs)
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/c-libs)

app/rc.c

@@ -0,0 +1,35 @@
+#include <c-libs/rcmem.h>
+#include <stdio.h>
+#include <string.h>
+
+void do_stuff(char *rc_s) { printf("Ptr %p -> %s\n", rc_s, rc_s); }
+
+char *mk_rc_str(const char *s) {
+  char *rc_s = rc_new(20);
+  strncpy(rc_s, s, 20);
+  return rc_s;
+}
+
+void rc_info(void *rc) { printf("RC: %d, WRC: %d\n", rc_rc(rc), rc_wrc(rc)); }
+
+static char *global_rc_s;
+
+int main() {
+  char *rc_s = mk_rc_str("Hello World!");
+
+  global_rc_s = rc_ref(rc_s);
+  rc_info(rc_s);
+  rc_unref(rc_s);
+  rc_info(global_rc_s);
+
+  do_stuff(global_rc_s);
+
+  global_rc_s = rc_realloc(global_rc_s, 20480);
+  memset(global_rc_s, 'A', 20480);
+  global_rc_s[50] = '\0';
+  do_stuff(global_rc_s);
+
+  rc_unref(global_rc_s);
+
+  return 0;
+}

flake.nix

@@ -17,7 +17,9 @@
 
         flake = {
           overlays.default = final: prev: {
-            c-libs = final.callPackage ./nix/c-libs.nix {};
+            c-libs = (final.callPackage ./nix/c-libs.nix {}).overrideAttrs {
+              enableShared = true;
+            };
           };
         };
 
@@ -49,6 +51,8 @@
             shellHook = ''
               export CMAKE_EXPORT_COMPILE_COMMANDS=ON
               export BUILD_TESTING=ON
+              export MANPATH="${pkgs.man-pages-posix}/share/man:$MANPATH"
+              export MANPATH="${pkgs.man-pages}/share/man:$MANPATH"
             '';
           };
         };

include/c-libs/rcmem.h

@@ -0,0 +1,108 @@
+#ifndef CLIBS_RCMEM_H
+#define CLIBS_RCMEM_H
+#define _GNU_SOURCE
+
+#include <memory.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/mman.h>
+
+typedef struct {
+  uint32_t rc;
+  uint32_t wrc;
+  size_t len;
+} RCHeader;
+
+void *rc_new(size_t size) {
+  RCHeader *hdr = mmap(NULL, sizeof(RCHeader) + size, PROT_READ | PROT_WRITE,
+                       MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
+  if (hdr == MAP_FAILED) {
+    return NULL;
+  }
+
+  hdr->rc = 1;
+  hdr->len = size;
+
+  return hdr + 1;
+}
+
+void *rc_ref(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+  hdr->rc += 1;
+
+  return ptr;
+}
+
+void *rc_wref(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+  hdr->wrc += 1;
+
+  return ptr;
+}
+
+uint32_t rc_rc(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+
+  return hdr->rc;
+}
+
+uint32_t rc_wrc(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+
+  return hdr->wrc;
+}
+
+void *rc_clone(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+
+  size_t len = sizeof(RCHeader) + hdr->len;
+
+  RCHeader *chdr = mmap(NULL, len, PROT_READ | PROT_WRITE,
+                        MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+
+  memcpy(chdr, hdr, len);
+
+  return chdr + 1;
+}
+
+void *rc_realloc(void *ptr, size_t size) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+  size_t old_size = sizeof(RCHeader) + hdr->len;
+  size_t new_size = sizeof(RCHeader) + size;
+
+  RCHeader *new = mremap(hdr, old_size, new_size, MREMAP_MAYMOVE);
+  new->len = size;
+
+  if (new == MAP_FAILED) {
+    return NULL;
+  }
+
+  return new + 1;
+}
+
+uint32_t rc_wunref(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+  hdr->wrc -= 1;
+  uint32_t wrc = hdr->wrc;
+
+  if (!hdr->wrc && !hdr->rc) {
+    munmap(hdr, sizeof(RCHeader) + hdr->len);
+  }
+
+  return wrc;
+}
+
+uint32_t rc_unref(void *ptr) {
+  RCHeader *hdr = ((RCHeader *)ptr) - 1;
+  hdr->rc -= 1;
+  uint32_t rc = hdr->rc;
+
+  if (!hdr->wrc && !hdr->rc) {
+    munmap(hdr, sizeof(RCHeader) + hdr->len);
+  }
+
+  return rc;
+}
+
+#endif

nix/c-libs.nix

@@ -10,12 +10,12 @@ stdenv.mkDerivation (finalAttrs: {
   pname = "c-libs";
   version = "0.1.0";
   src = ../.;
-  outputs = ["out" "dev"];
   nativeBuildInputs = [cmake] ++ lib.optional finalAttrs.doCheck pkg-config;
   buildInputs = [] ++ lib.optional finalAttrs.doCheck criterion;
 
   cmakeFlags = [
     (lib.cmakeBool "BUILD_TESTING" finalAttrs.doCheck)
+    (lib.cmakeBool "BUILD_SHARED_LIBS" finalAttrs.enableShared or false)
   ];
 
   doCheck = stdenv.buildPlatform.canExecute stdenv.hostPlatform;