find_editor: remove the env_error argument

There is no case where we should fail to find an editor just because
the values of EDITOR, VISUAL and SUDO_EDITOR are unavailable.  Both
sudoedit and the "env_editor" sudoers setting are documented as
falling back on the hard-coded list of editors in the "editors"
sudoers setting.  Bug #1000

doc/sudoers.man.in

@@ -25,7 +25,7 @@
 .nr BA @BAMAN@
 .nr LC @LCMAN@
 .nr PS @PSMAN@
-.TH "SUDOERS" "@mansectform@" "September 17, 2021" "Sudo @PACKAGE_VERSION@" "File Formats Manual"
+.TH "SUDOERS" "@mansectform@" "September 29, 2021" "Sudo @PACKAGE_VERSION@" "File Formats Manual"
 .nh
 .if n .ad l
 .SH "NAME"
@@ -2471,7 +2471,7 @@ An alternative is to place a colon-separated list of
 \(lqsafe\(rq
 editors int the
 \fIeditor\fR
-variable.
+setting.
 \fBvisudo\fR
 will then only use
 \fRSUDO_EDITOR\fR,

doc/sudoers.mdoc.in

@@ -24,7 +24,7 @@
 .nr BA @BAMAN@
 .nr LC @LCMAN@
 .nr PS @PSMAN@
-.Dd September 17, 2021
+.Dd September 29, 2021
 .Dt SUDOERS @mansectform@
 .Os Sudo @PACKAGE_VERSION@
 .Sh NAME
@@ -2325,7 +2325,7 @@ An alternative is to place a colon-separated list of
 .Dq safe
 editors int the
 .Em editor
-variable.
+setting.
 .Nm visudo
 will then only use
 .Ev SUDO_EDITOR ,

plugins/sudoers/editor.c

@@ -205,8 +205,6 @@ oom:
 /*
  * Determine which editor to use based on the SUDO_EDITOR, VISUAL and
  * EDITOR environment variables as well as the editor path in sudoers.
- * If env_error is true, an editor environment variable that cannot be
- * resolved is an error.
  *
  * Returns the path to be executed on success, else NULL.
  * The caller is responsible for freeing the returned editor path
@@ -214,7 +212,7 @@ oom:
  */
 char *
 find_editor(int nfiles, char **files, int *argc_out, char ***argv_out,
-     char * const *allowlist, const char **env_editor, bool env_error)
+     char * const *allowlist, const char **env_editor)
 {
     char *ev[3], *editor_path = NULL;
     unsigned int i;
@@ -240,15 +238,16 @@ find_editor(int nfiles, char **files, int *argc_out, char ***argv_out,
 		debug_return_str(NULL);
 	}
     }
+
+    /*
+     * If SUDO_EDITOR, VISUAL and EDITOR were either not set or not
+     * allowed (based on the values of def_editor and def_env_editor),
+     * choose the first one in def_editor that exists.
+     */
     if (editor_path == NULL) {
 	const char *def_editor_end = def_editor + strlen(def_editor);
 	const char *cp, *ep;
 
-	if (env_error && *env_editor != NULL) {
-	    /* User-specified editor could not be found. */
-	    debug_return_str(NULL);
-	}
-
 	/* def_editor could be a path, split it up, avoiding strtok() */
 	for (cp = sudo_strsplit(def_editor, def_editor_end, ":", &ep);
 	    cp != NULL; cp = sudo_strsplit(NULL, def_editor_end, ":", &ep)) {

plugins/sudoers/regress/editor/check_editor.c

@@ -105,7 +105,7 @@ main(int argc, char *argv[])
 
 	putenv(data->editor_var);
 	editor_path = find_editor(data->nfiles, data->files, &edit_argc,
-	    &edit_argv, NULL, &env_editor, false);
+	    &edit_argv, NULL, &env_editor);
 	ntests++;
 	if (strcmp(editor_path, data->editor_path) != 0) {
 	    sudo_warnx("test %d: editor_path: expected \"%s\", got \"%s\"",

plugins/sudoers/sudoers.c

@@ -769,7 +769,7 @@ sudoers_policy_main(int argc, char * const argv[], int pwflag, char *env_add[],
 
 	free(safe_cmnd);
 	safe_cmnd = find_editor(NewArgc - 1, NewArgv + 1, &edit_argc,
-	    &edit_argv, NULL, &env_editor, false);
+	    &edit_argv, NULL, &env_editor);
 	if (safe_cmnd == NULL) {
 	    if (errno != ENOENT)
 		goto done;

plugins/sudoers/sudoers.h

@@ -445,7 +445,7 @@ extern const char *path_plugin_dir;
 
 /* editor.c */
 char *find_editor(int nfiles, char **files, int *argc_out, char ***argv_out,
-     char * const *allowlist, const char **env_editor, bool env_error);
+     char * const *allowlist, const char **env_editor);
 
 /* exptilde.c */
 bool expand_tilde(char **path, const char *user);

plugins/sudoers/visudo.c

@@ -331,7 +331,7 @@ get_editor(int *editor_argc, char ***editor_argv)
     }
 
     editor_path = find_editor(2, files, editor_argc, editor_argv, allowlist,
-	&env_editor, true);
+	&env_editor);
     if (editor_path == NULL) {
 	if (def_env_editor && env_editor != NULL) {
 	    /* We are honoring $EDITOR so this is a fatal error. */