Fix some issues detected by Coverity

* src/connect.c (connect_to_ip): Check return value of setsockopt.
* src/ftp.c (ftp_retrieve_list): Check return value of chmod.
* src/http.c (digest_authentication_encode): Cleanup code.
* src/init.c (setval_internal): Explicitely check comind range.
* src/main.c (main): Explicitely check optarg.
* src/retr.c (retr_rate): Use snprintf instead sprintf,
  (retrieve_from_file): More verbose error message,
  (rotate_backups): Use snprintf instead sprintf, check return
  value of rename().
* src/url.c (mkalldirs): Check return value of unlink().
* src/utils.c (strdupdelim): Explicitely check beg and end for NULL,
  (merge_vecs): Fix sizeof argument to char *,
  (stable_sort): Use malloc instead of alloca.

src/connect.c

@@ -331,8 +331,10 @@ connect_to_ip (const ip_address *ip, int port, const char *print)
       if (bufsize < 512)
         bufsize = 512;          /* avoid pathologically small values */
 #ifdef SO_RCVBUF
-      setsockopt (sock, SOL_SOCKET, SO_RCVBUF,
-                  (void *)&bufsize, (socklen_t)sizeof (bufsize));
+      if (setsockopt (sock, SOL_SOCKET, SO_RCVBUF,
+                  (void *) &bufsize, (socklen_t) sizeof (bufsize)))
+        logprintf (LOG_NOTQUIET, _("setsockopt SO_RCVBUF failed: %s\n"),
+                   strerror (errno));
 #endif
       /* When we add limit_rate support for writing, which is useful
          for POST, we should also set SO_SNDBUF here.  */
@@ -471,7 +473,9 @@ bind_local (const ip_address *bind_address, int *port)
     return -1;
 
 #ifdef SO_REUSEADDR
-  setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, setopt_ptr, setopt_size);
+  if (setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, setopt_ptr, setopt_size))
+    logprintf (LOG_NOTQUIET, _("setsockopt SO_REUSEADDR failed: %s\n"),
+               strerror (errno));
 #endif
 
   xzero (ss);

src/ftp.c

@@ -2363,7 +2363,12 @@ Already have correct symlink %s -> %s\n\n"),
        (f->type == FT_PLAINFILE) && opt.preserve_perm)
         {
           if (f->perms)
-            chmod (actual_target, f->perms);
+            {
+              if (chmod (actual_target, f->perms))
+                logprintf (LOG_NOTQUIET,
+                           _("Failed to set permissions for %s.\n"),
+                           actual_target);
+            }
           else
             DEBUGP (("Unrecognized permissions for %s.\n", actual_target));
         }

src/http.c

@@ -4625,7 +4625,7 @@ digest_authentication_encode (const char *au, const char *user,
     { "algorithm", &algorithm }
   };
   char cnonce[16] = "";
-  char *res;
+  char *res = NULL;
   int res_len;
   size_t res_size;
   param_token name, value;
@@ -4648,29 +4648,22 @@ digest_authentication_encode (const char *au, const char *user,
           }
     }
 
-  if (qop != NULL && strcmp (qop,"auth"))
+  if (qop && strcmp (qop, "auth"))
     {
       logprintf (LOG_NOTQUIET, _("Unsupported quality of protection '%s'.\n"), qop);
-      xfree (qop); /* force freeing mem and return */
+      xfree (qop); /* force freeing mem and continue */
     }
-  else if (algorithm != NULL && strcmp (algorithm,"MD5") && strcmp (algorithm,"MD5-sess"))
+  else if (algorithm && strcmp (algorithm,"MD5") && strcmp (algorithm,"MD5-sess"))
     {
       logprintf (LOG_NOTQUIET, _("Unsupported algorithm '%s'.\n"), algorithm);
-      xfree (qop); /* force freeing mem and return */
+      xfree (algorithm); /* force freeing mem and continue */
     }
 
   if (!realm || !nonce || !user || !passwd || !path || !method)
     {
       *auth_err = ATTRMISSING;
-
-      xfree (realm);
-      xfree (opaque);
-      xfree (nonce);
-      xfree (qop);
-      xfree (algorithm);
-
-      return NULL;
-    }
+      goto cleanup;
+   }
 
   /* Calculate the digest value.  */
   {
@@ -4791,6 +4784,7 @@ digest_authentication_encode (const char *au, const char *user,
       }
   }
 
+cleanup:
   xfree (realm);
   xfree (opaque);
   xfree (nonce);

src/init.c

@@ -872,6 +872,10 @@ static bool
 setval_internal (int comind, const char *com, const char *val)
 {
   assert (0 <= comind && ((size_t) comind) < countof (commands));
+
+  if (comind < 0 || comind >= countof (commands))
+    return NULL;
+
   DEBUGP (("Setting %s (%s) to %s\n", com, commands[comind].name, val));
   return commands[comind].action (com, val, commands[comind].place);
 }

src/main.c

@@ -1454,7 +1454,8 @@ main (int argc, char **argv)
           append_to_log = true;
           break;
         case OPT__EXECUTE:
-          run_command (optarg);
+          if (optarg) /* check silences static analyzer */
+            run_command (optarg);
           break;
         case OPT__NO:
           {

src/retr.c

@@ -634,7 +634,7 @@ retr_rate (wgint bytes, double secs)
   double dlrate = calc_rate (bytes, secs, &units);
   /* Use more digits for smaller numbers (regardless of unit used),
      e.g. "1022", "247", "12.5", "2.38".  */
-  sprintf (res, "%.*f %s",
+  snprintf (res, sizeof(res), "%.*f %s",
            dlrate >= 99.95 ? 0 : dlrate >= 9.995 ? 1 : 2,
            dlrate, !opt.report_bps ? rate_names[units]: rate_names_bits[units]);
 
@@ -1147,7 +1147,7 @@ retrieve_from_file (const char *file, bool html, int *count)
 Removing file due to --delete-after in retrieve_from_file():\n"));
           logprintf (LOG_VERBOSE, _("Removing %s.\n"), filename);
           if (unlink (filename))
-            logprintf (LOG_NOTQUIET, "unlink: %s\n", strerror (errno));
+            logprintf (LOG_NOTQUIET, "Failed to unlink %s: (%d) %s\n", filename, errno, strerror (errno));
           dt &= ~RETROKF;
         }
 
@@ -1248,8 +1248,8 @@ rotate_backups(const char *fname)
 #endif
 
   int maxlen = strlen (fname) + sizeof (SEP) + numdigit (opt.backups) + AVSL;
-  char *from = (char *)alloca (maxlen);
-  char *to = (char *)alloca (maxlen);
+  char *from = alloca (maxlen);
+  char *to = alloca (maxlen);
   struct_stat sb;
   int i;
 
@@ -1267,17 +1267,21 @@ rotate_backups(const char *fname)
        */
       if (i == opt.backups)
         {
-          sprintf (to, "%s%s%d%s", fname, SEP, i, AVS);
+          snprintf (to, sizeof(to), "%s%s%d%s", fname, SEP, i, AVS);
           delete (to);
         }
 #endif
-      sprintf (to, "%s%s%d", fname, SEP, i);
-      sprintf (from, "%s%s%d", fname, SEP, i - 1);
-      rename (from, to);
+      snprintf (to, maxlen, "%s%s%d", fname, SEP, i);
+      snprintf (from, maxlen, "%s%s%d", fname, SEP, i - 1);
+      if (rename (from, to))
+        logprintf (LOG_NOTQUIET, "Failed to rename %s to %s: (%d) %s\n",
+                   from, to, errno, strerror (errno));
     }
 
-  sprintf (to, "%s%s%d", fname, SEP, 1);
-  rename(fname, to);
+  snprintf (to, maxlen, "%s%s%d", fname, SEP, 1);
+  if (rename(fname, to))
+    logprintf (LOG_NOTQUIET, "Failed to rename %s to %s: (%d) %s\n",
+               fname, to, errno, strerror (errno));
 }
 
 static bool no_proxy_match (const char *, const char **);

src/url.c

@@ -1275,7 +1275,9 @@ mkalldirs (const char *path)
              name exists, we just remove it and create the directory
              anyway.  */
           DEBUGP (("Removing %s because of directory danger!\n", t));
-          unlink (t);
+          if (unlink (t))
+            logprintf (LOG_NOTQUIET, "Failed to unlink %s (%d): %s\n",
+                       t, errno, strerror(errno));
         }
     }
   res = make_directory (t);

src/utils.c

@@ -235,14 +235,20 @@ xstrdup_lower (const char *s)
 
 /* Copy the string formed by two pointers (one on the beginning, other
    on the char after the last char) to a new, malloc-ed location.
-   0-terminate it.  */
+   0-terminate it.
+   If both pointers are NULL, the function returns an empty string.  */
 char *
 strdupdelim (const char *beg, const char *end)
 {
-  char *res = xmalloc (end - beg + 1);
-  memcpy (res, beg, end - beg);
-  res[end - beg] = '\0';
-  return res;
+  if (beg && beg <= end)
+    {
+      char *res = xmalloc (end - beg + 1);
+      memcpy (res, beg, end - beg);
+      res[end - beg] = '\0';
+      return res;
+    }
+
+  return xstrdup("");
 }
 
 /* Parse a string containing comma-separated elements, and return a
@@ -1327,7 +1333,7 @@ merge_vecs (char **v1, char **v2)
   for (j = 0; v2[j]; j++)
     ;
   /* Reallocate v1.  */
-  v1 = xrealloc (v1, (i + j + 1) * sizeof (char **));
+  v1 = xrealloc (v1, (i + j + 1) * sizeof (char *));
   memcpy (v1 + i, v2, (j + 1) * sizeof (char *));
   xfree (v2);
   return v1;
@@ -2425,8 +2431,9 @@ stable_sort (void *base, size_t nmemb, size_t size,
 {
   if (size > 1)
     {
-      void *temp = alloca (nmemb * size * sizeof (void *));
+      void *temp = malloc (nmemb * size * sizeof (void *));
       mergesort_internal (base, temp, size, 0, nmemb - 1, cmpfun);
+      xfree(temp);
     }
 }