master 31279f9 2/2: Make "emacs --script /dev/stdin work again when that's a pipe

[Lars Ingebrigtsen]

branch: master
commit 31279f92ae35f651d68104846268d64dadc6a943
Author: Bryan C. Mills <bcmills@google.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Make "emacs --script /dev/stdin work again when that's a pipe
    
    * src/lread.c (Fload): Adjust callers.
    
    * src/lread.c (safe_to_load_version): Check lseek errors
    (Bug#48940).
    
    Copyright-paperwork-exempt: yes
---
 src/lread.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/lread.c b/src/lread.c
index b3f9e6f..39cab19 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -1045,12 +1045,18 @@ lisp_file_lexically_bound_p (Lisp_Object readcharfun)
    safe to load.  Only files compiled with Emacs can be loaded.  */
 
 static int
-safe_to_load_version (int fd)
+safe_to_load_version (Lisp_Object file, int fd)
 {
+  struct stat st;
   char buf[512];
   int nbytes, i;
   int version = 1;
 
+  /* If the file is not regular, then we cannot safely seek it.
+     Assume that it is not safe to load as a compiled file.  */
+  if (fstat(fd, &st) == 0 && !S_ISREG (st.st_mode))
+    return 0;
+
   /* Read the first few bytes from the file, and look for a line
      specifying the byte compiler version used.  */
   nbytes = emacs_read_quit (fd, buf, sizeof buf);
@@ -1068,7 +1074,9 @@ safe_to_load_version (int fd)
        version = 0;
     }
 
-  lseek (fd, 0, SEEK_SET);
+  if (lseek (fd, 0, SEEK_SET) < 0)
+    report_file_error ("Seeking to start of file", file);
+
   return version;
 }
 
@@ -1401,7 +1409,7 @@ Return t if the file exists and loads successfully.  */)
   if (is_elc
       /* version = 1 means the file is empty, in which case we can
         treat it as not byte-compiled.  */
-      || (fd >= 0 && (version = safe_to_load_version (fd)) > 1))
+      || (fd >= 0 && (version = safe_to_load_version (file, fd)) > 1))
     /* Load .elc files directly, but not when they are
        remote and have no handler!  */
     {
@@ -1411,7 +1419,7 @@ Return t if the file exists and loads successfully.  */)
          int result;
 
          if (version < 0
-             && ! (version = safe_to_load_version (fd)))
+       && ! (version = safe_to_load_version (file, fd)))
            {
              error ("File `%s' was not compiled in Emacs", SDATA (found));
            }