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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;
+}