diff --git a/misc.h b/misc.h
index a8eb7a19..8573098d 100644
--- a/misc.h
+++ b/misc.h
@@ -97,6 +97,7 @@ static inline int toint(unsigned u)
 }
 
 char *fgetline(FILE *fp);
+bool read_file_into(BinarySink *bs, FILE *fp);
 char *chomp(char *str);
 bool strstartswith(const char *s, const char *t);
 bool strendswith(const char *s, const char *t);
diff --git a/utils.c b/utils.c
index 168a4a4f..17f67587 100644
--- a/utils.c
+++ b/utils.c
@@ -501,6 +501,20 @@ char *fgetline(FILE *fp)
     return ret;
 }
 
+/*
+ * Read an entire file into a BinarySink.
+ */
+bool read_file_into(BinarySink *bs, FILE *fp)
+{
+    char buf[4096];
+    while (1) {
+        size_t retd = fread(buf, 1, sizeof(buf), fp);
+        if (retd == 0)
+            return !ferror(fp);
+        put_data(bs, buf, retd);
+    }
+}
+
 /*
  * Perl-style 'chomp', for a line we just read with fgetline. Unlike
  * Perl chomp, however, we're deliberately forgiving of strange