* fileio.c (Finsert_file_contents): Don't put tail into head area,

as that confuses set-auto-coding, so insist on the head-read
returning the full 1024 bytes.  Let lseek compute the tail offset;
less work for us.  Do not ignore I/O errors when reading the tail.

2 files changed, 10 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 939fd61c87f..c64416a6454 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,10 @@
 2012-12-13  Paul Eggert  <eggert@cs.ucla.edu>
 
+        * fileio.c (Finsert_file_contents): Don't put tail into head area,
+        as that confuses set-auto-coding, so insist on the head-read
+        returning the full 1024 bytes.  Let lseek compute the tail offset;
+        less work for us.  Do not ignore I/O errors when reading the tail.
+
         * xdisp.c: Minor style fixes.
         (init_iterator): Hoist assignment out of if-expression.
         (markpos_of_region): Callers now test for sign, not for -1.
diff --git a/src/fileio.c b/src/fileio.c
index 874162c5bb6..c7df87bcdda 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3487,12 +3487,14 @@ variable `last-coding-system-used' to the coding system actually used.  */)
               else
                 {
                   nread = emacs_read (fd, read_buf, 1024);
-                  if (nread >= 0)
+                  if (nread == 1024)
                     {
-                      if (lseek (fd, st.st_size - (1024 * 3), SEEK_SET) < 0)
+                      int ntail;
+                      if (lseek (fd, - (1024 * 3), SEEK_END) < 0)
                         report_file_error ("Setting file position",
                                            Fcons (orig_filename, Qnil));
-                      nread += emacs_read (fd, read_buf + nread, 1024 * 3);
+                      ntail = emacs_read (fd, read_buf + nread, 1024 * 3);
+                      nread = ntail < 0 ? ntail : nread + ntail;
                     }
                 }