vim-patch:8.0.1660: the terminal API "drop" command doesn't support options

Problem:    The terminal API "drop" command doesn't support options.
Solution:   Implement the options.
333b80acf3

src/nvim/eval.c

@@ -9151,10 +9151,7 @@ char_u *v_throwpoint(char_u *oldval)
  */
 char_u *set_cmdarg(exarg_T *eap, char_u *oldarg)
 {
-  char_u      *oldval;
-  char_u      *newval;
-
-  oldval = vimvars[VV_CMDARG].vv_str;
+  char_u *oldval = vimvars[VV_CMDARG].vv_str;
   if (eap == NULL) {
     xfree(oldval);
     vimvars[VV_CMDARG].vv_str = oldarg;
@@ -9170,14 +9167,18 @@ char_u *set_cmdarg(exarg_T *eap, char_u *oldarg)
   if (eap->read_edit)
     len += 7;
 
-  if (eap->force_ff != 0)
-    len += STRLEN(eap->cmd + eap->force_ff) + 6;
-  if (eap->force_enc != 0)
+  if (eap->force_ff != 0) {
+    len += 10;  // " ++ff=unix"
+  }
+  if (eap->force_enc != 0) {
     len += STRLEN(eap->cmd + eap->force_enc) + 7;
-  if (eap->bad_char != 0)
-    len += 7 + 4;      /* " ++bad=" + "keep" or "drop" */
+  }
+  if (eap->bad_char != 0) {
+    len += 7 + 4;  // " ++bad=" + "keep" or "drop"
+  }
 
-  newval = xmalloc(len + 1);
+  const size_t newval_len = len + 1;
+  char_u *newval = xmalloc(newval_len);
 
   if (eap->force_bin == FORCE_BIN)
     sprintf((char *)newval, " ++bin");
@@ -9189,18 +9190,23 @@ char_u *set_cmdarg(exarg_T *eap, char_u *oldarg)
   if (eap->read_edit)
     STRCAT(newval, " ++edit");
 
-  if (eap->force_ff != 0)
-    sprintf((char *)newval + STRLEN(newval), " ++ff=%s",
-        eap->cmd + eap->force_ff);
-  if (eap->force_enc != 0)
-    sprintf((char *)newval + STRLEN(newval), " ++enc=%s",
-        eap->cmd + eap->force_enc);
-  if (eap->bad_char == BAD_KEEP)
+  if (eap->force_ff != 0) {
+    snprintf((char *)newval + STRLEN(newval), newval_len, " ++ff=%s",
+             eap->force_ff == 'u' ? "unix" :
+             eap->force_ff == 'd' ? "dos" : "mac");
+  }
+  if (eap->force_enc != 0) {
+    snprintf((char *)newval + STRLEN(newval), newval_len, " ++enc=%s",
+             eap->cmd + eap->force_enc);
+  }
+  if (eap->bad_char == BAD_KEEP) {
     STRCPY(newval + STRLEN(newval), " ++bad=keep");
-  else if (eap->bad_char == BAD_DROP)
+  } else if (eap->bad_char == BAD_DROP) {
     STRCPY(newval + STRLEN(newval), " ++bad=drop");
-  else if (eap->bad_char != 0)
-    sprintf((char *)newval + STRLEN(newval), " ++bad=%c", eap->bad_char);
+  } else if (eap->bad_char != 0) {
+    snprintf((char *)newval + STRLEN(newval), newval_len, " ++bad=%c",
+             eap->bad_char);
+  }
   vimvars[VV_CMDARG].vv_str = newval;
   return oldval;
 }

src/nvim/ex_cmds_defs.h

@@ -160,7 +160,7 @@ struct exarg {
   int regname;                  ///< register name (NUL if none)
   int force_bin;                ///< 0, FORCE_BIN or FORCE_NOBIN
   int read_edit;                ///< ++edit argument
-  int force_ff;                 ///< ++ff= argument (index in cmd[])
+  int force_ff;                 ///< ++ff= argument (first char of argument)
   int force_enc;                ///< ++enc= argument (index in cmd[])
   int bad_char;                 ///< BAD_KEEP, BAD_DROP or replacement byte
   int useridx;                  ///< user command index

src/nvim/ex_docmd.c

@@ -4538,6 +4538,19 @@ skip_cmd_arg (
   return p;
 }
 
+int get_bad_opt(const char_u *p, exarg_T *eap)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (STRICMP(p, "keep") == 0) {
+    eap->bad_char = BAD_KEEP;
+  } else if (STRICMP(p, "drop") == 0) {
+    eap->bad_char = BAD_DROP;
+  } else if (MB_BYTE2LEN(*p) == 1 && p[1] == NUL) {
+    eap->bad_char = *p;
+  }
+  return FAIL;
+}
+
 /*
  * Get "++opt=arg" argument.
  * Return FAIL or OK.
@@ -4596,8 +4609,10 @@ static int getargopt(exarg_T *eap)
   *arg = NUL;
 
   if (pp == &eap->force_ff) {
-    if (check_ff_value(eap->cmd + eap->force_ff) == FAIL)
+    if (check_ff_value(eap->cmd + eap->force_ff) == FAIL) {
       return FAIL;
+    }
+    eap->force_ff = eap->cmd[eap->force_ff];
   } else if (pp == &eap->force_enc) {
     /* Make 'fileencoding' lower case. */
     for (p = eap->cmd + eap->force_enc; *p != NUL; ++p)
@@ -4605,15 +4620,9 @@ static int getargopt(exarg_T *eap)
   } else {
     /* Check ++bad= argument.  Must be a single-byte character, "keep" or
      * "drop". */
-    p = eap->cmd + bad_char_idx;
-    if (STRICMP(p, "keep") == 0)
-      eap->bad_char = BAD_KEEP;
-    else if (STRICMP(p, "drop") == 0)
-      eap->bad_char = BAD_DROP;
-    else if (MB_BYTE2LEN(*p) == 1 && p[1] == NUL)
-      eap->bad_char = *p;
-    else
+    if (get_bad_opt(eap->cmd + bad_char_idx, eap) == FAIL) {
       return FAIL;
+    }
   }
 
   return OK;

src/nvim/fileio.c

@@ -2032,14 +2032,16 @@ readfile_linenr(
  * Fill "*eap" to force the 'fileencoding', 'fileformat' and 'binary to be
  * equal to the buffer "buf".  Used for calling readfile().
  */
-void prep_exarg(exarg_T *eap, buf_T *buf)
+void prep_exarg(exarg_T *eap, const buf_T *buf)
+  FUNC_ATTR_NONNULL_ALL
 {
-  eap->cmd = xmalloc(STRLEN(buf->b_p_ff) + STRLEN(buf->b_p_fenc) + 15);
+  const size_t cmd_len = 15 + STRLEN(buf->b_p_fenc);
+  eap->cmd = xmalloc(cmd_len);
 
-  sprintf((char *)eap->cmd, "e ++ff=%s ++enc=%s", buf->b_p_ff, buf->b_p_fenc);
-  eap->force_enc = 14 + (int)STRLEN(buf->b_p_ff);
+  snprintf((char *)eap->cmd, cmd_len, "e ++enc=%s", buf->b_p_fenc);
+  eap->force_enc = 8;
   eap->bad_char = buf->b_bad_char;
-  eap->force_ff = 7;
+  eap->force_ff = *buf->b_p_ff;
 
   eap->force_bin = buf->b_p_bin ? FORCE_BIN : FORCE_NOBIN;
   eap->read_edit = FALSE;

src/nvim/option.c

@@ -7294,12 +7294,13 @@ int get_fileformat(buf_T *buf)
 /// argument.
 ///
 /// @param eap  can be NULL!
-int get_fileformat_force(buf_T *buf, exarg_T *eap)
+int get_fileformat_force(const buf_T *buf, const exarg_T *eap)
+  FUNC_ATTR_NONNULL_ARG(1)
 {
   int c;
 
   if (eap != NULL && eap->force_ff != 0) {
-    c = eap->cmd[eap->force_ff];
+    c = eap->force_ff;
   } else {
     if ((eap != NULL && eap->force_bin != 0)
         ? (eap->force_bin == FORCE_BIN) : buf->b_p_bin) {