[Emacs-diffs] Changes to emacs/src/unexelf.c

[Gerd Moellmann]

Index: emacs/src/unexelf.c
diff -u emacs/src/unexelf.c:1.40 emacs/src/unexelf.c:1.41
--- emacs/src/unexelf.c:1.40    Mon Nov  5 17:17:42 2001
+++ emacs/src/unexelf.c Sat Nov 10 06:39:39 2001
@@ -668,6 +668,7 @@
   int old_data_index, new_data2_index;
   int old_mdebug_index;
   struct stat stat_buf;
+  int old_file_size;
 
   /* Open the old file, allocate a buffer of the right size, and read
      in the file contents.  */
@@ -680,16 +681,16 @@
   if (fstat (old_file, &stat_buf) == -1)
     fatal ("Can't fstat (%s): errno %d\n", old_name, errno);
 
-  old_base = malloc (stat_buf.st_size);
-
-  if (old_base == 0)
+  /* We cannot use malloc here because that may use sbrk.  If it does,
+     we'd dump our temporary buffers with Emacs, and we'd have to be
+     extra careful to use the correct value of sbrk(0) after
+     allocating all buffers in the code below, which we aren't.  */
+  old_file_size = stat_buf.st_size;
+  old_base = mmap (NULL, old_file_size, PROT_READ | PROT_WRITE,
+                  MAP_ANON | MAP_PRIVATE, -1, 0);
+  if (old_base == (caddr_t) -1)
     fatal ("Can't allocate buffer for %s\n", old_name);
 
-#ifdef DEBUG
-  fprintf (stderr, "%s: malloc(%d) -> %x\n", old_name, stat_buf.st_size,
-          old_base);
-#endif
-
   if (read (old_file, old_base, stat_buf.st_size) != stat_buf.st_size)
     fatal ("Didn't read all of %s: errno %d\n", old_name, errno);
 
@@ -774,16 +775,11 @@
   if (ftruncate (new_file, new_file_size))
     fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno);
 
-  new_base = malloc (new_file_size);
-
-  if (new_base == 0)
+  new_base = mmap (NULL, new_file_size, PROT_READ | PROT_WRITE,
+                  MAP_ANON | MAP_PRIVATE, -1, 0);
+  if (new_base == (caddr_t) -1)
     fatal ("Can't allocate buffer for %s\n", old_name);
 
-#ifdef DEBUG
-  fprintf (stderr, "%s: malloc(%d) -> %x\n", new_name, new_file_size
-          new_base);
-#endif
-
   new_file_h = (ElfW(Ehdr) *) new_base;
   new_program_h = (ElfW(Phdr) *) ((byte *) new_base + old_file_h->e_phoff);
   new_section_h = (ElfW(Shdr) *)
@@ -1202,8 +1198,8 @@
     fatal ("Didn't write %d bytes to %s: errno %d\n", 
           new_file_size, new_base, errno);
 
-  free (old_base);
-  free (new_base);
+  munmap (old_base, old_file_size);
+  munmap (new_base, new_file_size);
 
   /* Close the files and make the new file executable.  */