Add the magic number to the dependency record.

The magic number will be used later to determine if a target has already
been rebuild.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/redo.c b/src/redo.c
index 69f9ade..0209a4f 100644
--- a/src/redo.c
+++ b/src/redo.c
@@ -3,12 +3,18 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <time.h>
+#include <math.h>
+#include <limits.h>
 #include <unistd.h>
 
 #include "build.h"
 #include "util.h"
 #include "dbg.h"
 
+static inline int digits(unsigned n) {
+  return (int) log10(n) + 1;
+}
 
 int main(int argc, char *argv[]) {
     /* create .redo directory */
@@ -26,6 +32,17 @@ int main(int argc, char *argv[]) {
 
     free(cwd);
 
+    srand(time(NULL)); /* TODO: error checking */
+    unsigned magic = rand();
+
+    char magic_str[digits(UINT_MAX) + 1];
+    sprintf(magic_str, "%u", magic);
+
+    printf("MAGIC: %s\n", magic_str);
+
+    if (setenv("REDO_MAGIC", magic_str, 0))
+        fatal("setenv()");
+
     if (argc < 2) {
         build_target("all");
     } else {