Patch to encourage third-parties to compile own packages instead
of using hosted by Termux.

diff -uNr coreutils-8.32/src/coreutils.c coreutils-8.32.mod/src/coreutils.c
--- coreutils-8.32/src/coreutils.c	2020-01-01 16:13:12.000000000 +0200
+++ coreutils-8.32.mod/src/coreutils.c	2020-09-27 23:37:17.025160590 +0300
@@ -26,6 +26,8 @@
 # include <sys/prctl.h>
 #endif
 
+#include <unistd.h>
+
 #include "system.h"
 #include "die.h"
 #include "error.h"
@@ -133,6 +135,26 @@
   char *prog_name = last_component (argv[0]);
   int optc;
 
+  // Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
+  // by using equal-size prefixes.
+  const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
+  char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
+  int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
+
+  // Decode.
+  for (int i=0; i<termux_prefix_len; i++) {
+    termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
+  }
+
+  // Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
+  // If checks failed, then we probably running in incompatible environment.
+  // In this case warn user and exit with status 1.
+  if (access(termux_prefix, R_OK) != 0) {
+    fprintf(stderr, "Warning: aborting execution because %s is not accessible.\n", termux_prefix);
+    fprintf(stderr, "Please make sure that program is compiled with correct prefix.\n");
+    return 1;
+  }
+
   /* Map external name to internal name.  */
   char ginstall[] = "ginstall";
   if (STREQ (prog_name, "install"))