pa-host.c (pa_gt_pch_use_address): Use lseek and read to copy PCH file to anonymous private map.

	* pa-host.c (pa_gt_pch_use_address): Use lseek and read to copy PCH
	file to anonymous private map.

From-SVN: r92027

gcc/ChangeLog

+2004-12-10  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
+
+	* pa-host.c (pa_gt_pch_use_address): Use lseek and read to copy PCH
+	file to anonymous private map.
+
 2004-12-10  Roger Sayle  <roger@eyesopen.com>
 
 	PR target/18002

gcc/config/pa/pa-host.c

@@ -22,6 +22,7 @@
 #include "system.h"
 #include "coretypes.h"
 #include <sys/mman.h>
+#include <unistd.h>
 #include "hosthooks.h"
 #include "hosthooks-def.h"
 
@@ -70,11 +71,11 @@ pa_gt_pch_get_address (size_t size, int fd)
    It's not possibly to reliably mmap a file using MAP_PRIVATE to
    a specific START address on either hpux or linux.  First we see
    if mmap with MAP_PRIVATE works.  If it does, we are off to the
-   races.  If it doesn't, we try an anonymous MAP_PRIVATE since the
+   races.  If it doesn't, we try an anonymous private mmap since the
    kernel is more likely to honor the BASE address in anonymous maps.
-   We then mmap the file to an arbitrary location and copy the data
-   to the anonymous private map.  This assumes of course that we
-   don't need to change the PCH data after the file is created.
+   We then copy the data to the anonymous private map.  This assumes
+   of course that we don't need to change the data in the PCH file
+   after it is created.
 
    This approach obviously causes a performance penalty but there is
    little else we can do given the current PCH implementation.  */
@@ -82,7 +83,7 @@ pa_gt_pch_get_address (size_t size, int fd)
 static int
 pa_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
 {
-  void *addr, *faddr;
+  void *addr;
 
   /* We're called with size == 0 if we're not planning to load a PCH
      file at all.  This allows the hook to free any static space that
@@ -91,8 +92,7 @@ pa_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
     return -1;
 
   /* Try to map the file with MAP_PRIVATE.  */
-  addr = mmap (base, size, PROT_READ | PROT_WRITE,
-	       MAP_PRIVATE, fd, offset);
+  addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, offset);
 
   if (addr == base)
     return 1;
@@ -100,20 +100,22 @@ pa_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
   if (addr != (void *) MAP_FAILED)
     munmap (addr, size);
 
+  /* Try to make an anonymous private mmap at the desired location.  */
   addr = mmap (base, size, PROT_READ | PROT_WRITE,
 	       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 
   if (addr != base)
-    return -1;
+    {
+      if (addr != (void *) MAP_FAILED)
+        munmap (addr, size);
+      return -1;
+    }
 
-  faddr = mmap (NULL, size, PROT_READ, MAP_PRIVATE,
-		fd, offset);
-
-  if (faddr == (void *) MAP_FAILED)
+  if (lseek (fd, offset, SEEK_SET) == (off_t)-1)
     return -1;
 
-  memcpy (addr, faddr, size);
-  munmap (faddr, size);
+  if (read (fd, base, size) == -1)
+    return -1;
 
   return 1;
 }