Add routine for checking database existence

1 files changed, 23 insertions, 1 deletions

diff --git a/src/main.c b/src/main.c
index bef3926..ab10055 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,8 +1,10 @@
 #include <assert.h>
+#include <errno.h>
 #include <sqlite3.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 #include <unistd.h>
 
 #define DATABASE_PATH (FTAG_ROOT "/ftag.sqlite3")
@@ -42,6 +44,26 @@ static void __sqlite3_check(int rc, sqlite3 *db, const char *file, int line, con
 
 #define sqlite3_check(RC, DB) __sqlite3_check(RC, DB, __FILE__, __LINE__, __func__)
 
+static void assert_db_exists(void)
+{
+	struct stat statbuf __attribute__((unused));
+	int rc = stat(DATABASE_PATH, &statbuf);
+
+	if (rc == 0)
+		return;
+
+	if (errno == ENOENT) {
+		fprintf(stderr,
+			"ftag: database not found at \"%s\", "
+			"have you run \"ftag init\"?\n",
+			DATABASE_PATH);
+	}
+	else {
+		perror(DATABASE_PATH);
+	}
+	exit(EXIT_FAILURE);
+}
+
 static void ftag_init(int, char **)
 {
 	char cmd[1024];
@@ -153,6 +175,7 @@ static void ftag_tag_list(int argc, char **argv)
 
 static void ftag_tag(int argc, char **argv)
 {
+	assert_db_exists();
 	const struct ftag_command tag_commands[] = {
 		{.name = "add",  .func = ftag_tag_add},
 		{.name = "list", .func = ftag_tag_list}
@@ -184,6 +207,5 @@ int main(int argc, char *argv[])
 	}
 
 	parse_args(argc-1, argv+1, toplevel_commands, toplevel_command_count);
-
 	return EXIT_SUCCESS;
 }