.

extension.c

@@ -0,0 +1,32 @@
+#include <magic.h>
+#include <libowfat/errmsg.h>
+#include <libowfat/byte.h>
+#include <libowfat/str.h>
+
+#include "pipeshare.h"
+
+#define MAX(a,b) (a>b?a:b)
+
+#define failmagic(...) do {                                \
+    carp(__VA_ARGS__,": ",magic_error(magic));             \
+    return 0;                                              \
+  } while(0)
+
+int extension(int64 fd,char result[16])
+{
+  magic_t magic=magic_open(MAGIC_EXTENSION);
+  if(!magic) failmagic("initialize libmagic");
+  if(magic_load(magic,NULL)<0) failmagic("load magic database");
+  const char *extensions=magic_descriptor(magic,fd);
+  if(!extensions) failmagic("get magic data");
+
+  size_t l=MAX(str_chr(extensions,'/'),16);
+  byte_copy(result,l,extensions);
+  result[l]=0;
+  magic_close(magic);
+  if(str_equal(result,"???"))
+    str_copy(result,"txt");
+  return 1;
+}
+
+#undef failmagic