1 files changed, 9 insertions, 2 deletions

diff --git a/src/coding.c b/src/coding.c
index debb2f27ffc..9f95c2c6777 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -8315,7 +8315,7 @@ is selected as the TARGET.  For example, if OPERATION does file I/O,
 whichever argument specifies the file name is TARGET.
 
 TARGET has a meaning which depends on OPERATION:
-  For file I/O, TARGET is a file name.
+  For file I/O, TARGET is a file name (except for the special case below).
   For process I/O, TARGET is a process name.
   For network I/O, TARGET is a service name or a port number
 
@@ -8327,6 +8327,13 @@ or a function symbol to call.
 In the last case, we call the function with one argument,
 which is a list of all the arguments given to this function.
 
+If OPERATION is `insert-file-contents', the argument corresponding to
+TARGET may be a cons (FILENAME . BUFFER).  In that case, FILENAME is a
+file name to look up, and BUFFER is a buffer that contains the file's
+contents (not yet decoded).  If `file-coding-system-alist' specifies a
+function to call for FILENAME, that function should examine the
+contents of BUFFER instead of reading the file.
+
 usage: (find-operation-coding-system OPERATION ARGUMENTS ...)  */)
      (nargs, args)
      int nargs;
@@ -8380,7 +8387,7 @@ usage: (find-operation-coding-system OPERATION ARGUMENTS ...)  */)
             return Fcons (val, val);
           if (! NILP (Ffboundp (val)))
             {
-              val = call1 (val, Flist (nargs, args));
+              val = safe_call1 (val, Flist (nargs, args));
               if (CONSP (val))
                 return val;
               if (SYMBOLP (val) && ! NILP (Fcoding_system_p (val)))