# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1652194221 -7200
# Node ID 6589577799e69a7b82420db0166b5e61dfe3d965
# Parent  73ba6235bd59e119acfa8e153938b0062c8c582a
Added ELF payload decoding to obtain the entry point.

diff -r 73ba6235bd59 -r 6589577799e6 tests/dstest_exec.cc
--- a/tests/dstest_exec.cc	Mon May 09 01:00:51 2022 +0200
+++ b/tests/dstest_exec.cc	Tue May 10 16:50:21 2022 +0200
@@ -884,6 +884,51 @@
 
 
 
+class PayloadBase
+{
+public:
+  virtual l4_addr_t entry_point() = 0;
+  virtual offset_t header_size() = 0;
+};
+
+template <typename HEADER>
+class Payload : public PayloadBase
+{
+protected:
+  HEADER *_header;
+
+public:
+  explicit Payload(HEADER *header)
+  : _header(header)
+  {
+  }
+
+  l4_addr_t entry_point()
+  {
+    return _header->e_entry;
+  }
+
+  offset_t header_size()
+  {
+    return sizeof(HEADER);
+  }
+};
+
+static PayloadBase *get_payload(char *buf)
+{
+  switch (buf[EI_CLASS])
+  {
+    case (char) 1:
+      return new Payload<Elf32_Ehdr>((Elf32_Ehdr *) buf);
+    case (char) 2:
+      return new Payload<Elf64_Ehdr>((Elf64_Ehdr *) buf);
+    default:
+      return NULL;
+  }
+}
+
+
+
 static ExecPager exec_pager;
 
 static void init_pager(ipc_server_config_type *config)
@@ -926,10 +971,41 @@
     return 1;
   }
 
+  /* Obtain metadata from the file. */
+
+  char buf[4096];
+  offset_t nread;
+
+  nread = client_read(file, buf, EI_NIDENT);
+  if ((nread < EI_NIDENT) || memcmp(buf, "\x7f" "ELF", 4))
+  {
+    printf("Not an ELF payload: %s\n", argv[1]);
+    return 1;
+  }
+
+  PayloadBase *payload = get_payload(buf);
+
+  if (payload == NULL)
+  {
+    printf("Unrecognised object size.\n");
+    return 1;
+  }
+
+  client_seek(file, 0, SEEK_SET);
+  nread = client_read(file, buf, payload->header_size());
+
+  if (nread < payload->header_size())
+  {
+    printf("Header incomplete.\n");
+    return 1;
+  }
+
+  printf("Program start: %lx\n", payload->entry_point());
+
   /* Copy the payload regions to new dataspaces.
      NOTE: This should be directed by the ELF metadata. */
 
-  address_t program_start = 0x1000b43;
+  address_t program_start = payload->entry_point();
   offset_t initial_stack_size = 16 * L4_PAGESIZE;
 
   Segment program(0x1000000, 0x28326, L4_FPAGE_RWX, 0, 0x28326);