feat(bmp): Implement ff_bmp_isvalid function for BMP signature validation

1 files changed, 27 insertions, 0 deletions

diff --git a/src/format/image/bmp.c b/src/format/image/bmp.c
new file mode 100644
index 0000000..d947a83
--- /dev/null
+++ b/src/format/image/bmp.c
@@ -0,0 +1,27 @@
+#include "tinyff/image/bmp.h"
+#include "tinyff/dbg.h"
+#include "bmp.h"
+
+ff_result ff_bmp_isvalid(ff_stream* stream) 
+{
+    ff_dprintf("png: validating signature\n");
+
+    char raw_sig[2];
+    if (stream->read(raw_sig, 2, stream->user) != 2) {
+        ff_dprintf("bmp: failed to read signature bytes\n");
+        return FF_RESULT_ERROR_INVALID_FILE;
+    }
+
+    ff_dprintf(
+        "bmp: signature read: %02X %02X \n",
+        raw_sig[0], raw_sig[1]
+    );
+
+    if (memcmp(raw_sig, BMP_SIGNATURE, 2) != 0) {
+        ff_dprintf("bmp: signature mismatch\n");
+        return FF_RESULT_ERROR_INVALID_PNG_SIGNITURE;
+    }
+
+    ff_dprintf("bmp: signature valid\n");
+    return FF_RESULT_OK;
+}
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