Add new option --keep-badhash to keep Metalink's files with a bad hash

* src/init.c: Add keepbadhash
* src/main.c: Add keep-badhash
* src/options.h: Add keep_badhash
* doc/wget.texi: Add docs for --keep-badhash
* src/metalink.h: Add prototypes badhash_suffix(), badhash_or_remove()
* src/metalink.c: New functions badhash_suffix(), badhash_or_remove().
  (retrieve_from_metalink): Call badhash_or_remove() on download error

With --keep-badhash, append .badhash to Metalink's files with checksum
mismatch. (retrieve_from_metalink): unique_create() may append another
suffix to avoid overwriting existing files.

Without --keep-badhash, remove downloaded files with checksum mismatch
(this conforms to the old behaviour).

doc/wget.texi

@@ -512,6 +512,12 @@ href if none was specified.
 Downloads files covered in local Metalink @var{file}. Metalink version 3
 and 4 are supported.
 
+@cindex keep-badhash
+@item --keep-badhash
+Keeps downloaded Metalink's files with a bad hash. It appends .badhash
+to the name of Metalink's files which have a checksum mismatch, except
+without overwriting existing files.
+
 @cindex metalink-over-http
 @item --metalink-over-http
 Issues HTTP HEAD request instead of GET and extracts Metalink metadata

src/init.c

@@ -237,6 +237,7 @@ static const struct {
   { "input-metalink",   &opt.input_metalink,    cmd_file },
 #endif
   { "iri",              &opt.enable_iri,        cmd_boolean },
+  { "keepbadhash",      &opt.keep_badhash,      cmd_boolean },
   { "keepsessioncookies", &opt.keep_session_cookies, cmd_boolean },
   { "limitrate",        &opt.limit_rate,        cmd_bytes },
   { "loadcookies",      &opt.cookies_input,     cmd_file },

src/main.c

@@ -343,6 +343,7 @@ static struct cmdline_option option_data[] =
     { "input-metalink", 0, OPT_VALUE, "input-metalink", -1 },
 #endif
     { "iri", 0, OPT_BOOLEAN, "iri", -1 },
+    { "keep-badhash", 0, OPT_BOOLEAN, "keepbadhash", -1 },
     { "keep-session-cookies", 0, OPT_BOOLEAN, "keepsessioncookies", -1 },
     { "level", 'l', OPT_VALUE, "reclevel", -1 },
     { "limit-rate", 0, OPT_VALUE, "limitrate", -1 },
@@ -702,6 +703,8 @@ Download:\n"),
     N_("\
        --unlink                    remove file before clobber\n"),
 #ifdef HAVE_METALINK
+    N_("\
+       --keep-badhash              keep files with checksum mismatch (append .badhash)\n"),
     N_("\
        --metalink-over-http        use Metalink metadata from HTTP response headers\n"),
     N_("\

src/metalink.c

@@ -120,13 +120,20 @@ retrieve_from_metalink (const metalink_t* metalink)
           retr_err = METALINK_RETR_ERROR;
 
           /* If output_stream is not NULL, then we have failed on
-             previous resource and are retrying. Thus, remove the file.  */
+             previous resource and are retrying. Thus, rename/remove
+             the file.  */
           if (output_stream)
             {
               fclose (output_stream);
               output_stream = NULL;
-              if (unlink (filename))
-                logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
+              badhash_or_remove (filename);
+              xfree (filename);
+            }
+          else if (filename)
+            {
+              /* Rename/remove the file downloaded previously before
+                 downloading it again.  */
+              badhash_or_remove (filename);
               xfree (filename);
             }
 
@@ -525,15 +532,13 @@ gpg_skip_verification:
 #endif
       last_retr_err = retr_err == RETROK ? last_retr_err : retr_err;
 
-      /* Remove the file if error encountered or if option specified.
+      /* Rename the file if error encountered; remove if option specified.
          Note: the file has been downloaded using *_loop. Therefore, it
          is not necessary to keep the file for continuated download.  */
       if ((retr_err != RETROK || opt.delete_after)
            && filename != NULL && file_exists_p (filename))
         {
-          logprintf (LOG_VERBOSE, _("Removing %s.\n"), quote (filename));
-          if (unlink (filename))
-            logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
+          badhash_or_remove (filename);
         }
       if (output_stream)
         {
@@ -551,6 +556,47 @@ gpg_skip_verification:
   return last_retr_err;
 }
 
+/* Append the suffix ".badhash" to the file NAME, except without
+   overwriting an existing file with that name and suffix.  */
+void
+badhash_suffix (char *name)
+{
+  char *bhash, *uname;
+
+  bhash = concat_strings (name, ".badhash", (char *)0);
+  uname = unique_name (bhash, false);
+
+  logprintf (LOG_VERBOSE, _("Renaming ‘%s’ to ‘%s’.\n"), name, uname);
+
+  if (link (name, uname))
+    logprintf (LOG_NOTQUIET, "link: %s\n", strerror (errno));
+  else if (unlink (name))
+    logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
+
+  xfree (bhash);
+  xfree (uname);
+}
+
+/* Append the suffix ".badhash" to the file NAME, except without
+   overwriting an existing file with that name and suffix.
+
+   Remove the file NAME if the option --delete-after is specified, or
+   if the option --keep-badhash isn't set.  */
+void
+badhash_or_remove (char *name)
+{
+  if (opt.delete_after || !opt.keep_badhash)
+    {
+      logprintf (LOG_VERBOSE, _("Removing %s.\n"), quote (name));
+      if (unlink (name))
+        logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
+    }
+  else
+    {
+      badhash_suffix(name);
+    }
+}
+
 int metalink_res_cmp (const void* v1, const void* v2)
 {
   const metalink_resource_t *res1 = *(metalink_resource_t **) v1,

src/metalink.h

@@ -47,6 +47,9 @@ uerr_t retrieve_from_metalink (const metalink_t *metalink);
 
 int metalink_res_cmp (const void *res1, const void *res2);
 
+void badhash_suffix (char *name);
+void badhash_or_remove (char *name);
+
 bool find_key_value (const char *start,
                      const char *end,
                      const char *key,

src/options.h

@@ -260,6 +260,7 @@ struct options
   bool cookies;                 /* whether cookies are used. */
   char *cookies_input;          /* file we're loading the cookies from. */
   char *cookies_output;         /* file we're saving the cookies to. */
+  bool keep_badhash;            /* Keep files with checksum mismatch. */
   bool keep_session_cookies;    /* whether session cookies should be
                                    saved and loaded. */