1 files changed, 101 insertions, 5 deletions
diff --git a/stdlib/header.c b/stdlib/header.c
index 6e86ab551..6166aa965 100644
--- a/stdlib/header.c
+++ b/stdlib/header.c
@@ -4,19 +4,115 @@
 /*                                                                     */
 /*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         */
 /*                                                                     */
-/*  Copyright 1996 Institut National de Recherche en Informatique et   */
+/*  Copyright 1998 Institut National de Recherche en Informatique et   */
 /*  Automatique.  Distributed only by permission.                      */
 /*                                                                     */
 /***********************************************************************/
 
 /* $Id$ */
 
-char runtime_name [] = RUNTIME_NAME;
-char errmsg [] = "Cannot exec ocamlrun.\n";
+/* The launcher for bytecode executables (if #! is not working) */
+
+#include <stdlib.h>
+#include <string.h>
+#include "../config/s.h"
+#ifdef HAS_UNISTD
+#include <unistd.h>
+#endif
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "../byterun/exec.h"
+
+#define MAXPATHLEN 1024
+
+#ifndef S_ISREG
+#define S_ISREG(mode) (((mode) & S_IFMT) == S_IFREG)
+#endif
+
+#ifndef SEEK_END
+#define SEEK_END 2
+#endif
+
+static char * searchpath(char * name)
+{
+  static char fullname[MAXPATHLEN + 1];
+  char * path;
+  char * p;
+  char * q;
+  struct stat st;
+
+  for (p = name; *p != 0; p++) {
+    if (*p == '/') return name;
+  }
+  path = getenv("PATH");
+  if (path == NULL) return name;
+  while(1) {
+    for (p = fullname; *path != 0 && *path != ':'; p++, path++)
+      if (p < fullname + MAXPATHLEN) *p = *path;
+    if (p != fullname && p < fullname + MAXPATHLEN)
+      *p++ = '/';
+    for (q = name; *q != 0; p++, q++)
+      if (p < fullname + MAXPATHLEN) *p = *q;
+    *p = 0;
+    if (stat(fullname, &st) == 0 && S_ISREG(st.st_mode)) break;
+    if (*path == 0) return name;
+    path++;
+  }
+  return fullname;
+}
+
+static unsigned long read_size(char * ptr)
+{
+  unsigned char * p = (unsigned char *) ptr;
+  return ((unsigned long) p[0] << 24) + ((unsigned long) p[1] << 16) +
+         ((unsigned long) p[2] << 8) + p[3];
+}
+
+static int read_runtime_path(int fd, char *runtime_path)
+{
+  char buffer[TRAILER_SIZE];
+  unsigned path_size, code_size, prim_size, data_size;
+  unsigned symbol_size, debug_size, size;
+
+  lseek(fd, (long) -TRAILER_SIZE, SEEK_END);
+  if (read(fd, buffer, TRAILER_SIZE) < TRAILER_SIZE) return -1;
+  path_size = read_size(buffer);
+  code_size = read_size(buffer + 4);
+  prim_size = read_size(buffer + 8);
+  data_size = read_size(buffer + 12);
+  symbol_size = read_size(buffer + 16);
+  debug_size = read_size(buffer + 20);
+  if (path_size > MAXPATHLEN) return -1;
+  size = path_size + code_size + prim_size +
+         data_size + symbol_size + debug_size + TRAILER_SIZE;
+  lseek(fd, -size, SEEK_END);
+  if (read(fd, runtime_path, path_size) != path_size) return -1;
+  runtime_path[path_size - 1] = 0;
+  return 0;
+}
+
+static void errwrite(char * msg)
+{
+  write(2, msg, strlen(msg));
+}
 
 int main(int argc, char ** argv)
 {
-  execv(runtime_name, argv);
-  write(2, errmsg, sizeof(errmsg)-1);
+  char * truename;
+  int fd;
+  char runtime_path[MAXPATHLEN];
+
+  truename = searchpath(argv[0]);
+  fd = open(truename, O_RDONLY);
+  if (fd == -1 || read_runtime_path(fd, runtime_path) == -1) {
+    errwrite(truename);
+    errwrite(" not found or is not a bytecode executable file\n");
+    return 2;
+  }
+  execv(runtime_path, argv);
+  errwrite("Cannot exec ");
+  errwrite(runtime_path);
+  errwrite("\n");
   return 2;
 }