Make writemoves (and solver) safer by checking buffer size

1 files changed, 21 insertions, 6 deletions

diff --git a/src/core/io_moves.h b/src/core/io_moves.h
index a49a38b..be43568 100644
--- a/src/core/io_moves.h
+++ b/src/core/io_moves.h
@@ -1,6 +1,6 @@
 STATIC uint8_t readmove(char);
 STATIC uint8_t readmodifier(char);
-STATIC int writemoves(uint8_t *, int, char *);
+STATIC int64_t writemoves(uint8_t *, int, uint64_t, char *);
 
 STATIC uint8_t
 readmove(char c)
@@ -38,18 +38,29 @@ readmodifier(char c)
         }
 }
 
-STATIC int
-writemoves(uint8_t *m, int n, char *buf)
+STATIC int64_t
+writemoves(uint8_t *m, int n, uint64_t buf_size, char *buf)
 {
         int i;
-        size_t len;
+        uint64_t len;
         const char *s;
         char *b;
 
-        for (i = 0, b = buf; i < n; i++, b++) {
+        if (buf_size == 0) {
+                LOG("Error: cannot write moves to buffer of size 0.\n");
+                return NISSY_ERROR_BUFFER_SIZE;
+        }
+
+        for (i = 0, b = buf; i < n; i++, b++, buf_size--) {
                 s = movestr[m[i]];
                 len = strlen(s);
+                if (len >= buf_size) {
+                        LOG("Error: the given buffer is too small for "
+                             "writing the given moves.\n");
+                        goto writemoves_error;
+                }
                 memcpy(b, s, len);
+                buf_size -= len;
                 b += len;       
                 *b = ' ';
         }
@@ -58,5 +69,9 @@ writemoves(uint8_t *m, int n, char *buf)
                 b--; /* Remove last space */
         *b = '\0';
 
-        return b - buf;
+        return buf_size;
+
+writemoves_error:
+        *buf = '\0';
+        return NISSY_ERROR_BUFFER_SIZE;
 }