Initial revision

1 files changed, 293 insertions, 0 deletions

diff --git a/src/unexhp9k800.c b/src/unexhp9k800.c
new file mode 100644
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+/* Unexec for HP 9000 Series 800 machines.
+   Bob Desinger <[email protected]>
+
+   Note that the GNU project considers support for HP operation a
+   peripheral activity which should not be allowed to divert effort
+   from development of the GNU system.  Changes in this code will be
+   installed when users send them in, but aside from that we don't
+   plan to think about it, or about whether other Emacs maintenance
+   might break it.
+
+
+  Unexec creates a copy of the old a.out file, and replaces the old data
+  area with the current data area.  When the new file is executed, the
+  process will see the same data structures and data values that the
+  original process had when unexec was called.
+  
+  Unlike other versions of unexec, this one copies symbol table and
+  debug information to the new a.out file.  Thus, the new a.out file
+  may be debugged with symbolic debuggers.
+  
+  If you fix any bugs in this, I'd like to incorporate your fixes.
+  Send them to uunet!hpda!hpsemc!jmorris or jmorris%[email protected].
+  
+  CAVEATS:
+  This routine saves the current value of all static and external
+  variables.  This means that any data structure that needs to be
+  initialized must be explicitly reset.  Variables will not have their
+  expected default values.
+  
+  Unfortunately, the HP-UX signal handler has internal initialization
+  flags which are not explicitly reset.  Thus, for signals to work in
+  conjunction with this routine, the following code must executed when
+  the new process starts up.
+  
+  void _sigreturn();
+  ...
+  sigsetreturn(_sigreturn);
+*/
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <a.out.h>
+
+#define NBPG 2048
+#define roundup(x,n) ( ( (x)+(n-1) ) & ~(n-1) )  /* n is power of 2 */
+#define min(x,y)  ( ((x)<(y))?(x):(y) )
+
+
+/* Create a new a.out file, same as old but with current data space */
+
+unexec(new_name, old_name, new_end_of_text, dummy1, dummy2)
+     char new_name[];		/* name of the new a.out file to be created */
+     char old_name[];		/* name of the old a.out file */
+     char *new_end_of_text;	/* ptr to new edata/etext; NOT USED YET */
+     int dummy1, dummy2;	/* not used by emacs */
+{
+  int old, new;
+  int old_size, new_size;
+  struct header hdr;
+  struct som_exec_auxhdr auxhdr;
+  
+  /* For the greatest flexibility, should create a temporary file in
+     the same directory as the new file.  When everything is complete,
+     rename the temp file to the new name.
+     This way, a program could update its own a.out file even while
+     it is still executing.  If problems occur, everything is still
+     intact.  NOT implemented.  */
+  
+  /* Open the input and output a.out files */
+  old = open(old_name, O_RDONLY);
+  if (old < 0)
+    { perror(old_name); exit(1); }
+  new = open(new_name, O_CREAT|O_RDWR|O_TRUNC, 0777);
+  if (new < 0)
+    { perror(new_name); exit(1); }
+  
+  /* Read the old headers */
+  read_header(old, &hdr, &auxhdr);
+  
+  /* Decide how large the new and old data areas are */
+  old_size = auxhdr.exec_dsize;
+  new_size = sbrk(0) - auxhdr.exec_dmem;
+  
+  /* Copy the old file to the new, up to the data space */
+  lseek(old, 0, 0);
+  copy_file(old, new, auxhdr.exec_dfile);
+  
+  /* Skip the old data segment and write a new one */
+  lseek(old, old_size, 1);
+  save_data_space(new, &hdr, &auxhdr, new_size);
+  
+  /* Copy the rest of the file */
+  copy_rest(old, new);
+  
+  /* Update file pointers since we probably changed size of data area */
+  update_file_ptrs(new, &hdr, &auxhdr, auxhdr.exec_dfile, new_size-old_size);
+  
+  /* Save the modified header */
+  write_header(new, &hdr, &auxhdr);
+  
+  /* Close the binary file */
+  close(old);
+  close(new);
+  exit(0);
+}
+
+/* Save current data space in the file, update header.  */
+
+save_data_space(file, hdr, auxhdr, size)
+     int file;
+     struct header *hdr;
+     struct som_exec_auxhdr *auxhdr;
+     int size;
+{
+  /* Write the entire data space out to the file */
+  if (write(file, auxhdr->exec_dmem, size) != size)
+    { perror("Can't save new data space"); exit(1); }
+  
+  /* Update the header to reflect the new data size */
+  auxhdr->exec_dsize = size;
+  auxhdr->exec_bsize = 0;
+}
+
+/* Update the values of file pointers when something is inserted.  */
+
+update_file_ptrs(file, hdr, auxhdr, location, offset)
+     int file;
+     struct header *hdr;
+     struct som_exec_auxhdr *auxhdr;
+     unsigned int location;
+     int offset;
+{
+  struct subspace_dictionary_record subspace;
+  int i;
+  
+  /* Increase the overall size of the module */
+  hdr->som_length += offset;
+  
+  /* Update the various file pointers in the header */
+#define update(ptr) if (ptr > location) ptr = ptr + offset
+  update(hdr->aux_header_location);
+  update(hdr->space_strings_location);
+  update(hdr->init_array_location);
+  update(hdr->compiler_location);
+  update(hdr->symbol_location);
+  update(hdr->fixup_request_location);
+  update(hdr->symbol_strings_location);
+  update(hdr->unloadable_sp_location);
+  update(auxhdr->exec_tfile);
+  update(auxhdr->exec_dfile);
+  
+  /* Do for each subspace dictionary entry */
+  lseek(file, hdr->subspace_location, 0);
+  for (i = 0; i < hdr->subspace_total; i++)
+    {
+      if (read(file, &subspace, sizeof(subspace)) != sizeof(subspace))
+	{ perror("Can't read subspace record"); exit(1); }
+      
+      /* If subspace has a file location, update it */
+      if (subspace.initialization_length > 0 
+	  && subspace.file_loc_init_value > location)
+	{
+	  subspace.file_loc_init_value += offset;
+	  lseek(file, -sizeof(subspace), 1);
+	  if (write(file, &subspace, sizeof(subspace)) != sizeof(subspace))
+	    { perror("Can't update subspace record"); exit(1); }
+	}
+    } 
+  
+  /* Do for each initialization pointer record */
+  /* (I don't think it applies to executable files, only relocatables) */
+#undef update
+}
+
+/* Read in the header records from an a.out file.  */
+
+read_header(file, hdr, auxhdr)
+     int file;
+     struct header *hdr;
+     struct som_exec_auxhdr *auxhdr;
+{
+  
+  /* Read the header in */
+  lseek(file, 0, 0);
+  if (read(file, hdr, sizeof(*hdr)) != sizeof(*hdr))
+    { perror("Couldn't read header from a.out file"); exit(1); }
+  
+  if (hdr->a_magic != EXEC_MAGIC && hdr->a_magic != SHARE_MAGIC
+      &&  hdr->a_magic != DEMAND_MAGIC)
+    {
+      fprintf(stderr, "a.out file doesn't have legal magic number\n"); 
+      exit(1);  
+    }
+  
+  lseek(file, hdr->aux_header_location, 0);
+  if (read(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr))
+    {
+      perror("Couldn't read auxiliary header from a.out file");
+      exit(1);
+    }  
+}
+
+/* Write out the header records into an a.out file.  */
+
+write_header(file, hdr, auxhdr)
+     int file;
+     struct header *hdr;
+     struct som_exec_auxhdr *auxhdr;
+{
+  /* Update the checksum */
+  hdr->checksum = calculate_checksum(hdr);
+  
+  /* Write the header back into the a.out file */
+  lseek(file, 0, 0);
+  if (write(file, hdr, sizeof(*hdr)) != sizeof(*hdr))
+    { perror("Couldn't write header to a.out file"); exit(1); }
+  lseek(file, hdr->aux_header_location, 0);
+  if (write(file, auxhdr, sizeof(*auxhdr)) != sizeof(*auxhdr))
+    { perror("Couldn't write auxiliary header to a.out file"); exit(1); }
+}
+
+/* Calculate the checksum of a SOM header record. */
+
+calculate_checksum(hdr)
+     struct header *hdr;
+{
+  int checksum, i, *ptr;
+  
+  checksum = 0;  ptr = (int *) hdr;
+  
+  for (i=0; i<sizeof(*hdr)/sizeof(int)-1; i++)
+    checksum ^= ptr[i];
+  
+  return(checksum);
+}
+
+/* Copy size bytes from the old file to the new one.  */
+
+copy_file(old, new, size)
+     int new, old;
+     int size;
+{
+  int len;
+  int buffer[8196];  /* word aligned will be faster */
+  
+  for (; size > 0; size -= len)
+    {
+      len = min(size, sizeof(buffer));
+      if (read(old, buffer, len) != len)
+	{ perror("Read failure on a.out file"); exit(1); }
+      if (write(new, buffer, len) != len)
+	{ perror("Write failure in a.out file"); exit(1); }
+    }
+}
+
+/* Copy the rest of the file, up to EOF.  */
+
+copy_rest(old, new)
+     int new, old;
+{
+  int buffer[4096];
+  int len;
+  
+  /* Copy bytes until end of file or error */
+  while ( (len = read(old, buffer, sizeof(buffer))) > 0)
+    if (write(new, buffer, len) != len) break;
+  
+  if (len != 0)
+    { perror("Unable to copy the rest of the file"); exit(1); }
+}
+
+#ifdef	DEBUG
+display_header(hdr, auxhdr)
+     struct header *hdr;
+     struct som_exec_auxhdr *auxhdr;
+{
+  /* Display the header information (debug) */
+  printf("\n\nFILE HEADER\n");
+  printf("magic number %d \n", hdr->a_magic); 
+  printf("text loc %.8x   size %d \n", auxhdr->exec_tmem, auxhdr->exec_tsize);
+  printf("data loc %.8x   size %d \n", auxhdr->exec_dmem, auxhdr->exec_dsize);
+  printf("entry     %x \n",   auxhdr->exec_entry);
+  printf("Bss  segment size %u\n", auxhdr->exec_bsize);
+  printf("\n");
+  printf("data file loc %d    size %d\n",
+	 auxhdr->exec_dfile, auxhdr->exec_dsize);
+  printf("som_length %d\n", hdr->som_length);
+  printf("unloadable sploc %d    size %d\n",
+	 hdr->unloadable_sp_location, hdr->unloadable_sp_size);
+}
+#endif /* DEBUG */