From ef087c3849cfbe58f4f77e09367d6fbf152e5498 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Sat, 12 Oct 2024 17:06:50 +0200
Subject: Make writemoves (and solver) safer by checking buffer size

---
 src/core/io_moves.h | 27 +++++++++++++++++++++------
 src/core/io_trans.h |  8 ++++----
 2 files changed, 25 insertions(+), 10 deletions(-)

(limited to 'src/core')

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;
 }
diff --git a/src/core/io_trans.h b/src/core/io_trans.h
index f4e8ace..f0db095 100644
--- a/src/core/io_trans.h
+++ b/src/core/io_trans.h
@@ -1,8 +1,8 @@
-STATIC uint8_t readtrans(const char *);
-STATIC void writetrans(uint8_t, char *);
+STATIC uint8_t readtrans(const char [static NISSY_SIZE_TRANSFORMATION]);
+STATIC void writetrans(uint8_t, char [static NISSY_SIZE_TRANSFORMATION]);
 
 STATIC uint8_t
-readtrans(const char *buf)
+readtrans(const char buf[static NISSY_SIZE_TRANSFORMATION])
 {
 	uint8_t t;
 
@@ -14,7 +14,7 @@ readtrans(const char *buf)
 }
 
 STATIC void
-writetrans(uint8_t t, char *buf)
+writetrans(uint8_t t, char buf[static NISSY_SIZE_TRANSFORMATION])
 {
 	if (t >= 48)
 		memcpy(buf, "error trans", 11);
-- 
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