go64: add elfload API

See dosemu2/dosemu2#2369

include/go64.h

@@ -3,5 +3,6 @@
 
 void pltcall32(__dpmi_regs *regs, __dpmi_paddr addr);
 int elfexec(const char *path, int argc, char **argv);
+int elfload(int num);
 
 #endif

src/djdev64/djexec.c

@@ -19,8 +19,13 @@
 #include <stdio.h>
 #include <setjmp.h>
 #include <dlfcn.h>
+#include <assert.h>
 #include "djdev64/djdev64.h"
 
+#define MAX_PATHS 10
+static const char *exec_path[MAX_PATHS];
+static int num_exec_path;
+
 struct exec_info {
     /* volatile because of longjmp() vs auto storage */
     /* unsigned char to not clash with go64/dj64 errors */
@@ -77,3 +82,17 @@ static void exit_exec(void *handle, int rc)
     ei->exit_code = rc;
     longjmp(ei->exit_jmp, 1);
 }
+
+int djdev64_add_load_path(const char *path)
+{
+    assert(num_exec_path < MAX_PATHS);
+    exec_path[num_exec_path] = path;
+    return num_exec_path++;
+}
+
+int djdev64_load(int num, unsigned flags)
+{
+    if (num >= num_exec_path)
+        return -1;
+    return djdev64_exec(exec_path[num], flags, 0, NULL);
+}

src/djdev64/include/djdev64/dj64init.h

@@ -25,7 +25,7 @@
 
 typedef int (dj64cdispatch_t)(int handle, int libid, int fn, unsigned esi,
         uint8_t *sp);
-#define DJ64_API_VER 13
+#define DJ64_API_VER 14
 enum { DJ64_PRINT_LOG, DJ64_PRINT_TERMINAL, DJ64_PRINT_SCREEN };
 
 /* pushal */
@@ -62,6 +62,7 @@ struct dj64_api {
     void (*exit)(int rc);
     void *(*malloc)(size_t size);
     void (*free)(void *ptr);
+    int (*elfload)(int num);
 };
 #define DJ64_INIT_ONCE_FN dj64init_once
 typedef int (dj64init_once_t)(const struct dj64_api *api, int api_ver);

src/djdev64/include/djdev64/djdev64.h

@@ -33,5 +33,7 @@ int djdev64_ctrl(int handle, int libid, int fn, unsigned esi,
 void djdev64_close(int handle);
 
 int djdev64_exec(const char *path, unsigned flags, int argc, char **argv);
+int djdev64_add_load_path(const char *path);
+int djdev64_load(int num, unsigned flags);
 
 #endif

src/djdev64/makefile

@@ -7,7 +7,7 @@ LIBELF := $(shell $(PKG_CONFIG) --silence-errors --libs libelf)
 ifeq ($(LIBELF),)
 $(error libelf not installed)
 endif
-CFLAGS += -iquote include -fpic -ggdb3 -Wall -Og -MD \
+CFLAGS += -iquote include -fpic -ggdb3 -Wall -Wmissing-prototypes -Og -MD \
   $(shell $(PKG_CONFIG) --cflags libelf) \
   -DCRT0=\"$(prefix)/i386-pc-dj64/lib/crt0.elf\"
 

src/libc/dj64/thunks.c

@@ -39,6 +39,7 @@
 #include <libc/djctx.h>
 #include <libc/internal.h>
 #include <dpmi.h>
+#include <go64.h>
 #include <sys/nearptr.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -605,3 +606,8 @@ void *djsbrk(int increment)
     assert(increment > 0);
     return dj64api->malloc(increment);
 }
+
+int elfload(int num)
+{
+    return dj64api->elfload(num);
+}