Import Upstream version 5b3upstream/5b3

1 files changed, 378 insertions, 0 deletions

diff --git a/unexsunos4.c b/unexsunos4.c
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--- /dev/null
+++ b/unexsunos4.c
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+/* Unexec for Sunos 4 using shared libraries.
+   Copyright (C) 1990, 1994 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Contributed by Viktor Dukhovni.  */
+/*
+ * Unexec for Berkeley a.out format + SUNOS shared libraries
+ * The unexeced executable contains the __DYNAMIC area from the
+ * original text file,  and then the rest of data + bss + malloced area of
+ * the current process.  (The __DYNAMIC area is at the top of the process
+ * data segment,  we use "data_start" defined externally to mark the start
+ * of the "real" data segment.)
+ *
+ * For programs that want to remap some of the data segment read only
+ * a run_time_remap is provided.  This attempts to remap largest area starting
+ * and ending on page boundaries between "data_start" and "bndry"
+ * For this it to figure out where the text file is located.  A path search
+ * is attempted after trying argv[0] and if all fails we simply do not remap
+ *
+ * One feature of run_time_remap () is mandatory:  reseting the break.
+ *
+ *  Note that we can no longer map data into the text segment,  as this causes
+ *  the __DYNAMIC struct to become read only,  breaking the runtime loader.
+ *  Thus we no longer need to mess with a private crt0.c,  the standard one
+ *  will do just fine,  since environ can live in the writable area between
+ *  __DYNAMIC and data_start,  just make sure that pre-crt0.o (the name
+ *  is somewhat abused here) is loaded first!
+ *
+ */
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <sys/file.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <stdio.h>
+#include <a.out.h>
+
+/* Do this after the above #include's in case a configuration file wants
+   to define things for this file based on what <a.out.h> defines.  */
+#ifdef emacs
+#include <config.h>
+#endif
+
+#if defined (SUNOS4) || defined (__FreeBSD__) || defined (__NetBSD__)
+#define UNDO_RELOCATION
+#endif
+
+#ifdef UNDO_RELOCATION
+#include <link.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+/* NetBSD needs this bit, but SunOS does not have it.  */
+#ifndef MAP_FILE
+#define MAP_FILE 0
+#endif
+
+
+/*
+ * for programs other than emacs
+ * define data_start + initialized here,  and make sure
+ * this object is loaded first!
+ * emacs will define these elsewhere,  and load the object containing
+ * data_start (pre-crt0.o or firstfile.o?) first!
+ * The custom crt0.o *must not* be loaded!
+ */
+#ifndef emacs
+  static int data_start = 0;
+  static int initialized = 0;
+#else
+  extern int initialized;
+  extern unsigned data_start;
+  extern int pureptr;
+#endif
+
+extern char *getenv ();
+static unsigned brk_value;
+static struct exec nhdr;
+static int rd_only_len;
+static long cookie;
+
+
+unexec (new_name, a_name, bndry, bss_start, entry) 
+     char *new_name, *a_name;
+     unsigned bndry, bss_start, entry;
+{
+  int fd, new;
+  char *old;
+  struct exec ohdr;		/* Allocate on the stack,  not needed in the next life */
+  struct stat stat;
+
+  if ((fd = open (a_name, O_RDONLY)) < 0)
+    {
+      fprintf (stderr, "%s: open: ", a_name);
+      perror (a_name);
+      exit (1);
+    }
+  if ((new = open (new_name, O_WRONLY | O_CREAT, 0666)) == -1)
+    {
+      fprintf (stderr, "%s: open: ", a_name);
+      perror (new_name);
+      exit (1);
+    }
+
+  if ((fstat (fd, &stat) == -1))
+    {
+      fprintf (stderr, "%s: ", a_name);
+      perror ("fstat");
+      exit (1);
+    }
+
+  old = (char *)mmap (0, stat.st_size, PROT_READ, MAP_FILE|MAP_SHARED, fd, 0);
+  if (old == (char *)-1)
+    {
+      fprintf (stderr, "%s: ", a_name);
+      perror ("mmap");
+      exit (1);
+    }
+  close (fd);
+
+  nhdr = ohdr = (*(struct exec *)old);
+
+
+  /*
+   * Remember a magic cookie so we know we've got the right binary
+   * when remapping.
+   */
+  cookie = time (0);
+
+  /* Save the break, it is reset to &_end (by ld.so?).  */
+  brk_value = (unsigned) sbrk (0);
+
+  /*
+   * Round up data start to a page boundary (Lose if not a 2 power!)
+   */
+  data_start = ((((int)&data_start) - 1) & ~(N_PAGSIZ (nhdr) - 1)) + N_PAGSIZ (nhdr);
+
+  /*
+   * Round down read only pages to a multiple of the page size
+   */
+  if (bndry)
+    rd_only_len = ((int)bndry & ~(N_PAGSIZ (nhdr) - 1)) - data_start;
+
+#ifndef emacs
+  /* Have to do this some time before dumping the data */
+  initialized = 1;
+#endif
+  
+  /* Handle new data and bss sizes and optional new entry point.
+     No one actually uses bss_start and entry,  but tradition compels
+     one to support them.
+     Could complain if bss_start > brk_value,
+     but the caller is *supposed* to know what she is doing.  */
+  nhdr.a_data = (bss_start ? bss_start : brk_value) - N_DATADDR (nhdr);
+  nhdr.a_bss  = bss_start ? brk_value - bss_start : 0;
+  if (entry) 
+    nhdr.a_entry = entry;
+
+  /*
+   * Write out the text segment with new header
+   * Dynamic executables are ZMAGIC with N_TXTOFF==0 and the header
+   * part of the text segment, but no need to rely on this.
+   * So write the TEXT first,  then go back replace the header.
+   * Doing it in the other order is less general!
+   */
+  lseek (new, N_TXTOFF (nhdr), L_SET);
+  write (new, old + N_TXTOFF (ohdr), N_TXTOFF (ohdr) + ohdr.a_text);
+  lseek (new, 0L, L_SET);
+  write (new, &nhdr, sizeof (nhdr));
+
+  /*
+   * Write out the head of the old data segment from the file not
+   * from core, this has the unresolved __DYNAMIC relocation data
+   * we need to reload
+   */
+  lseek (new, N_DATOFF (nhdr), L_SET);
+  write (new, old + N_DATOFF (ohdr), (int)&data_start - N_DATADDR (ohdr));
+
+  /*
+   * Copy the rest of the data from core
+   */
+  write (new, &data_start, N_BSSADDR (nhdr) - (int)&data_start);
+
+  /*
+   * Copy the symbol table and line numbers
+   */
+  lseek (new, N_TRELOFF (nhdr), L_SET);
+  write (new, old + N_TRELOFF (ohdr), stat.st_size - N_TRELOFF (ohdr));
+
+  /* Some other BSD systems use this file.
+     We don't know whether this change is right for them.  */
+#ifdef UNDO_RELOCATION
+  /* Undo the relocations done at startup by ld.so.
+     It will do these relocations again when we start the dumped Emacs.
+     Doing them twice gives incorrect results.  */
+  {
+    unsigned long daddr = N_DATADDR (ohdr);
+    unsigned long rel, erel;
+#ifdef SUNOS4
+#ifdef SUNOS4_SHARED_LIBRARIES
+    extern struct link_dynamic _DYNAMIC;
+
+    /*  SunOS4.x's ld_rel is relative to N_TXTADDR. */
+    if (!ohdr.a_dynamic)
+      /* This was statically linked.  */
+      rel = erel = 0;
+    else if (_DYNAMIC.ld_version < 2)
+      {
+	rel = _DYNAMIC.ld_un.ld_1->ld_rel + N_TXTADDR (ohdr);
+	erel = _DYNAMIC.ld_un.ld_1->ld_hash + N_TXTADDR (ohdr);
+      }
+    else
+      {
+	rel = _DYNAMIC.ld_un.ld_2->ld_rel + N_TXTADDR (ohdr);
+	erel = _DYNAMIC.ld_un.ld_2->ld_hash + N_TXTADDR (ohdr);
+      }
+#else /* not SUNOS4_SHARED_LIBRARIES */
+    rel = erel = 0;
+#endif /* not SUNOS4_SHARED_LIBRARIES */
+#ifdef sparc
+#define REL_INFO_TYPE		struct reloc_info_sparc
+#else
+#define REL_INFO_TYPE		struct relocation_info
+#endif /* sparc */
+#define REL_TARGET_ADDRESS(r)	(((REL_INFO_TYPE *)(r))->r_address)
+#endif /* SUNOS4 */
+#if defined (__FreeBSD__) || defined (__NetBSD__)
+    extern struct _dynamic _DYNAMIC;
+
+    /*  FreeBSD's LD_REL is a virtual address itself. */
+    rel = LD_REL (&_DYNAMIC);
+    erel = rel + LD_RELSZ (&_DYNAMIC);
+#define REL_INFO_TYPE		struct relocation_info
+#define REL_TARGET_ADDRESS(r)	(((REL_INFO_TYPE *)(r))->r_address)
+#endif
+
+    for (; rel < erel; rel += sizeof (REL_INFO_TYPE))
+      {
+	/*  This is the virtual address where ld.so will do relocation.  */
+	unsigned long target = REL_TARGET_ADDRESS (rel);
+	/*  This is the offset in the data segment.  */
+	unsigned long segoffset = target - daddr;
+
+	/*  If it is located below data_start, we have to do nothing here,
+	    because the old data has been already written to the location. */
+	if (target < (unsigned long)&data_start)
+	    continue;
+
+	lseek (new, N_DATOFF (nhdr) + segoffset, L_SET);
+	write (new, old + N_DATOFF (ohdr) + segoffset, sizeof (unsigned long));
+      }
+  }
+#endif /* UNDO_RELOCATION */
+
+  fchmod (new, 0755);
+}
+
+void
+run_time_remap (progname)
+     char *progname;
+{
+  char aout[MAXPATHLEN];
+  register char *path, *p;
+
+  /* Just in case */
+  if (!initialized)
+    return;
+
+  /* Restore the break */
+  brk ((char *) brk_value);
+
+  /*  If nothing to remap:  we are done! */
+  if (rd_only_len == 0)
+    return;
+
+  /*
+   * Attempt to find the executable
+   * First try argv[0],  will almost always succeed as shells tend to give
+   * the full path from the hash list rather than using execvp ()
+   */
+  if (is_it (progname)) 
+    return;
+
+  /*
+   * If argv[0] is a full path and does not exist,  not much sense in
+   * searching further
+   */
+  if (strchr (progname, '/')) 
+    return;
+
+  /*
+   * Try to search for  argv[0] on the PATH
+   */
+  path = getenv ("PATH");
+  if (path == NULL)
+    return;
+
+  while (*path)
+    {
+      /* copy through ':' or end */
+      for (p = aout; *p = *path; ++p, ++path)
+	if (*p == ':')
+	  {
+	    ++path;		/* move past ':' */
+	    break;
+	  }
+      *p++ = '/';
+      strcpy (p, progname);
+      /*
+       * aout is a candidate full path name
+       */
+      if (is_it (aout))
+	return;
+    }
+}
+
+is_it (filename)
+  char *filename;
+{
+  int fd;
+  long filenames_cookie;
+  struct exec hdr;
+
+  /*
+   * Open an executable  and check for a valid header!
+   * Can't bcmp the header with what we had,  it may have been stripped!
+   * so we may save looking at non executables with the same name, mostly
+   * directories.
+   */
+  fd = open (filename, O_RDONLY);
+  if (fd != -1)
+    {
+      if (read (fd, &hdr, sizeof (hdr)) == sizeof (hdr)
+	  && !N_BADMAG (hdr) && N_DATOFF (hdr) == N_DATOFF (nhdr)
+	  && N_TRELOFF (hdr) == N_TRELOFF (nhdr))
+	{
+	  /* compare cookies */
+	  lseek (fd, N_DATOFF (hdr) + (int)&cookie - N_DATADDR (hdr), L_SET);
+	  read (fd, &filenames_cookie, sizeof (filenames_cookie));
+	  if (filenames_cookie == cookie)
+	    {			/* Eureka */
+
+	      /*
+	       * Do the mapping
+	       * The PROT_EXEC may not be needed,  but it is safer this way.
+	       * should the shared library decide to indirect through
+	       * addresses in the data segment not part of __DYNAMIC
+	       */
+	      mmap ((char *) data_start, rd_only_len, PROT_READ | PROT_EXEC,
+		    MAP_FILE | MAP_SHARED | MAP_FIXED, fd,
+		    N_DATOFF (hdr) + data_start - N_DATADDR (hdr));
+	      close (fd);
+	      return 1;
+	    }
+	}
+      close (fd);
+    }
+  return 0;
+}