vis: add new :set savemethod auto|atomic|inplace option

Specifies how the current file should be saved, `atomic` which uses
rename(2) to atomically replace the file, `inplace` which truncates the
file and then rewrites it or `auto` which tries the former before falling
back to the latter. The rename method fails for symlinks, hardlinks,
in case of insufficient directory permissions or when either the file
owner, group, POSIX ACL or SELinux labels can not be restored.

The option defaults to `auto`.

1 files changed, 9 insertions, 2 deletions

diff --git a/sam.c b/sam.c
index 960c670..dc4023c 100644
--- a/sam.c
+++ b/sam.c
@@ -294,6 +294,7 @@ enum {
 	OPTION_CURSOR_LINE,
 	OPTION_COLOR_COLUMN,
 	OPTION_HORIZON,
+	OPTION_SAVE_METHOD,
 };
 
 static const OptionDef options[] = {
@@ -372,6 +373,11 @@ static const OptionDef options[] = {
 		OPTION_TYPE_NUMBER, OPTION_FLAG_WINDOW,
 		"Number of bytes to consider for syntax highlighting",
 	},
+	[OPTION_SAVE_METHOD] = {
+		{ "savemethod" },
+		OPTION_TYPE_STRING, OPTION_FLAG_WINDOW,
+		"Save method to use for current file 'auto', 'atomic' or 'inplace'",
+	},
 };
 
 bool sam_init(Vis *vis) {
@@ -1349,9 +1355,10 @@ static bool cmd_write(Vis *vis, Win *win, Command *cmd, const char *argv[], Curs
 			return false;
 		}
 
-		TextSave *ctx = text_save_begin(text, *name, TEXT_SAVE_AUTO);
+		TextSave *ctx = text_save_begin(text, *name, file->save_method);
 		if (!ctx) {
-			vis_info_show(vis, "Can't write `%s': %s", *name, strerror(errno));
+			const char *msg = errno ? strerror(errno) : "try changing `:set savemethod`";
+			vis_info_show(vis, "Can't write `%s': %s", *name, msg);
 			return false;
 		}