[PATCH] fast-import: Create import-marks file when necessary

[Ramkumar Ramachandra <artagnon@gmail.com>]

When both --import-marks and --export-marks are given, and specify the
same file, that file should be created if it doesn't exist. Without
this patch, the caller would have to check for the existence of a
marks file and vary its fast-import invocation accordingly.

Requested-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 fast-import.c |   17 ++++++++++++++++-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/fast-import.c b/fast-import.c
index 5055504..cb7a9c9 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -3247,8 +3247,23 @@ static void parse_argv(void)
 		usage(fast_import_usage);
 
 	seen_data_command = 1;
-	if (import_marks_file)
+	if (import_marks_file) {
+		FILE *f = fopen(import_marks_file, "r");
+		if (!f) {
+			if (errno == ENOENT &&
+				!strcmp(import_marks_file, export_marks_file)) {
+				FILE *d = fopen(import_marks_file, "w");
+				if (!d)
+					die_errno("cannot create '%s'", import_marks_file);
+				fclose(d);
+			}
+			else
+				die_errno("cannot read '%s'", import_marks_file);
+		}
+		else
+			fclose(f);
 		read_marks();
+	}
 }
 
 int main(int argc, const char **argv)
-- 
1.7.4.rc1.8.g98938a.dirty