Remove the C plugins mechanism (#1867)

The mechanism complicates the runtime system and is not very general
(only a few system functions are instrumented).  There are other ways
to intercept system calls that are more general and require no
modification to the source code of the runtime system.

Changes

@@ -106,7 +106,10 @@ Working version
 - GPR#1723: Remove internal Meta.static_{alloc,free} primitives.
   (Stephen Dolan, review by Gabriel Scherer)
 
-### Tools:
+- GPR#1867: Remove the C plugins mechanism.
+  (Xavier Leroy, review by David Allsopp, Damien Doligez, Sébastien Hinderer)
+
+### Tools
 
 - GPR#1711: the new 'open' flag in OCAMLRUNPARAM takes a comma-separated list of
   modules to open as if they had been passed via the command line -open flag.

configure

@@ -66,7 +66,6 @@ force_safe_string=false
 default_safe_string=true
 afl_instrument=false
 max_testsuite_dir_retries=0
-with_cplugins=false
 with_fpic=false
 flat_float_array=true
 with_flambda_invariants=false
@@ -224,7 +223,7 @@ while : ; do
     -with-flambda-invariants|--with-flambda-invariants)
         with_flambda_invariants=true;;
     -with-cplugins|--with-cplugins)
-        with_cplugins=true;;
+        err "--with-cplugins is no longer supported";;
     -no-cplugins|--no-cplugins)
         ;; # Ignored for backward compatibility
     -fPIC|--fPIC)
@@ -2046,20 +2045,12 @@ if $with_spacetime; then
   fi
 fi
 
-if ! $shared_libraries_supported; then
-  with_cplugins=false
-fi
-
 if $with_fpic; then
   common_cflags="$common_cflags $sharedlib_cflags"
   aspp="$aspp $sharedlib_cflags"
 fi
 
 
-if $with_cplugins; then
-  echo "#define CAML_WITH_CPLUGINS" >> m.h
-fi
-
 if $with_fpic; then
   echo "#define CAML_WITH_FPIC" >> m.h
 fi
@@ -2151,7 +2142,6 @@ config LIBUNWIND_AVAILABLE "$libunwind_available"
 config LIBUNWIND_INCLUDE_FLAGS "$libunwind_include"
 config LIBUNWIND_LINK_FLAGS "$libunwind_lib"
 config PROFINFO_WIDTH "$profinfo_width"
-config WITH_CPLUGINS "$with_cplugins"
 config WITH_FPIC "$with_fpic"
 config TARGET "$target"
 config HOST "$host"
@@ -2263,11 +2253,6 @@ else
     *)
       ;;
   esac
-  if $with_cplugins; then
-  inf "        C plugins................. yes"
-  else
-  inf "        C plugins................. no"
-  fi
   if $with_fpic; then
   inf "        compile with -fPIC........ yes"
   else

runtime/caml/misc.h

@@ -244,105 +244,6 @@ extern int caml_umul_overflow(uintnat a, uintnat b, uintnat * res);
 #endif /* _WIN32 */
 
 
-/* Use macros for some system calls being called from OCaml itself.
-  These calls can be either traced for security reasons, or changed to
-  virtualize the program. */
-
-
-#ifndef CAML_WITH_CPLUGINS
-
-#define CAML_SYS_EXIT(retcode) exit(retcode)
-#define CAML_SYS_OPEN(filename,flags,perm) open_os(filename,flags,perm)
-#define CAML_SYS_CLOSE(fd) close(fd)
-#define CAML_SYS_STAT(filename,st) stat_os(filename,st)
-#define CAML_SYS_UNLINK(filename) unlink_os(filename)
-#define CAML_SYS_RENAME(old_name,new_name) rename_os(old_name, new_name)
-#define CAML_SYS_CHDIR(dirname) chdir_os(dirname)
-#define CAML_SYS_GETENV(varname) getenv(varname)
-#define CAML_SYS_SYSTEM(command) system_os(command)
-#define CAML_SYS_READ_DIRECTORY(dirname,tbl) caml_read_directory(dirname,tbl)
-
-#else
-
-
-#define CAML_CPLUGINS_EXIT 0
-#define CAML_CPLUGINS_OPEN 1
-#define CAML_CPLUGINS_CLOSE 2
-#define CAML_CPLUGINS_STAT 3
-#define CAML_CPLUGINS_UNLINK 4
-#define CAML_CPLUGINS_RENAME 5
-#define CAML_CPLUGINS_CHDIR 6
-#define CAML_CPLUGINS_GETENV 7
-#define CAML_CPLUGINS_SYSTEM 8
-#define CAML_CPLUGINS_READ_DIRECTORY 9
-#define CAML_CPLUGINS_PRIMS_MAX 9
-
-#define CAML_CPLUGINS_PRIMS_BITMAP  ((1 << CAML_CPLUGINS_PRIMS_MAX)-1)
-
-extern intnat (*caml_cplugins_prim)(int,intnat,intnat,intnat);
-
-#define CAML_SYS_PRIM_1(code,prim,arg1)               \
-  (caml_cplugins_prim == NULL) ? prim(arg1) :    \
-  caml_cplugins_prim(code,(intnat) (arg1),0,0)
-#define CAML_SYS_STRING_PRIM_1(code,prim,arg1)               \
-  (caml_cplugins_prim == NULL) ? prim(arg1) :    \
-  (char_os*)caml_cplugins_prim(code,(intnat) (arg1),0,0)
-#define CAML_SYS_VOID_PRIM_1(code,prim,arg1)               \
-  (caml_cplugins_prim == NULL) ? prim(arg1) :    \
-  (void)caml_cplugins_prim(code,(intnat) (arg1),0,0)
-#define CAML_SYS_PRIM_2(code,prim,arg1,arg2)                         \
-  (caml_cplugins_prim == NULL) ? prim(arg1,arg2) :              \
-  caml_cplugins_prim(code,(intnat) (arg1), (intnat) (arg2),0)
-#define CAML_SYS_PRIM_3(code,prim,arg1,arg2,arg3)                            \
-  (caml_cplugins_prim == NULL) ? prim(arg1,arg2,arg3) :                 \
-  caml_cplugins_prim(code,(intnat) (arg1), (intnat) (arg2),(intnat) (arg3))
-
-#define CAML_SYS_EXIT(retcode) \
-  CAML_SYS_VOID_PRIM_1(CAML_CPLUGINS_EXIT,exit,retcode)
-#define CAML_SYS_OPEN(filename,flags,perm)                      \
-  CAML_SYS_PRIM_3(CAML_CPLUGINS_OPEN,open_os,filename,flags,perm)
-#define CAML_SYS_CLOSE(fd)                      \
-  CAML_SYS_PRIM_1(CAML_CPLUGINS_CLOSE,close,fd)
-#define CAML_SYS_STAT(filename,st)                      \
-  CAML_SYS_PRIM_2(CAML_CPLUGINS_STAT,stat_os,filename,st)
-#define CAML_SYS_UNLINK(filename)                       \
-  CAML_SYS_PRIM_1(CAML_CPLUGINS_UNLINK,unlink_os,filename)
-#define CAML_SYS_RENAME(old_name,new_name)                              \
-  CAML_SYS_PRIM_2(CAML_CPLUGINS_RENAME,rename_os,old_name,new_name)
-#define CAML_SYS_CHDIR(dirname)                         \
-  CAML_SYS_PRIM_1(CAML_CPLUGINS_CHDIR,chdir_os,dirname)
-#define CAML_SYS_GETENV(varname)                        \
-  CAML_SYS_STRING_PRIM_1(CAML_CPLUGINS_GETENV,getenv,varname)
-#define CAML_SYS_SYSTEM(command)                        \
-  CAML_SYS_PRIM_1(CAML_CPLUGINS_SYSTEM,system_os,command)
-#define CAML_SYS_READ_DIRECTORY(dirname,tbl)                            \
-  CAML_SYS_PRIM_2(CAML_CPLUGINS_READ_DIRECTORY,caml_read_directory,     \
-                  dirname,tbl)
-
-#define CAML_CPLUGIN_CONTEXT_API 0
-
-struct cplugin_context {
-  int api_version;
-  int prims_bitmap;
-  char_os *exe_name;
-  char_os** argv;
-  char_os *plugin; /* absolute filename of plugin, do a copy if you need it ! */
-  char *ocaml_version;
-/* end of CAML_CPLUGIN_CONTEXT_API version 0 */
-};
-
-extern void caml_cplugins_init(char_os * exe_name, char_os **argv);
-
-/* A plugin MUST define a symbol "caml_cplugin_init" with the prototype:
-
-void caml_cplugin_init(struct cplugin_context *ctx)
-*/
-
-/* to write plugins for CAML_SYS_READ_DIRECTORY, we will need the
-   definition of struct ext_table to be public. */
-
-#endif /* CAML_WITH_CPLUGINS */
-
 /* Data structures */
 
 struct ext_table {

runtime/caml/sys.h

@@ -37,14 +37,9 @@ CAMLnoreturn_end;
 CAMLextern double caml_sys_time_unboxed(value);
 CAMLextern void caml_sys_init (char_os * exe_name, char_os ** argv);
 
-#ifndef CAML_WITH_CPLUGINS
 CAMLnoreturn_start
 CAMLextern value caml_sys_exit (value)
 CAMLnoreturn_end;
-#else
-CAMLextern value caml_sys_exit (value);
-         /* A plugin could cause caml_sys_exit to return normally */
-#endif
 
 extern double caml_sys_time_unboxed(value);
 CAMLextern value caml_sys_get_argv(value unit);

runtime/io.c

@@ -118,7 +118,7 @@ static void unlink_channel(struct channel *channel)
 
 CAMLexport void caml_close_channel(struct channel *channel)
 {
-  CAML_SYS_CLOSE(channel->fd);
+  close(channel->fd);
   if (channel->refcount > 0) return;
   if (caml_channel_mutex_free != NULL) (*caml_channel_mutex_free)(channel);
   unlink_channel(channel);
@@ -545,7 +545,7 @@ CAMLprim value caml_ml_close_channel(value vchannel)
 
   if (do_syscall) {
     caml_enter_blocking_section();
-    result = CAML_SYS_CLOSE(fd);
+    result = close(fd);
     caml_leave_blocking_section();
   }
 

runtime/printexc.c

@@ -149,7 +149,6 @@ void caml_fatal_uncaught_exception(value exn)
   if (caml_abort_on_uncaught_exn) {
     abort();
   } else {
-    CAML_SYS_EXIT(2);
-    exit(2); /* Second exit needed for the Noreturn flag */
+    exit(2);
   }
 }