Allow the empty string in wallet-backend arguments.

When writing to a file in the wallet client program, remove an old
backup file before creating a new backup and don't fail if the backup
already exists.

1 files changed, 5 insertions, 1 deletions

diff --git a/client/file.c b/client/file.c
index 5002d01..8e16103 100644
--- a/client/file.c
+++ b/client/file.c
@@ -40,9 +40,13 @@ write_file(const char *name, const void *data, size_t length)
         die("write to %s truncated", temp);
     if (close(fd) < 0)
         sysdie("close of %s failed (file probably truncated)", temp);
-    if (access(name, F_OK) == 0)
+    if (access(name, F_OK) == 0) {
+        if (access(backup, F_OK) == 0)
+            if (unlink(backup) < 0)
+                sysdie("unlink of old backup %s failed", backup);
         if (link(name, backup) < 0)
             sysdie("link of %s to %s failed", name, backup);
+    }
     if (rename(temp, name) < 0)
         sysdie("rename of %s to %s failed", temp, name);
     free(temp);