Fix some errors reported by Coverity (#6797)

* coverity_20190905: Fix reported bugs

This commit has fixes for some bugs reported by Coverity in the present day

* coverity_20190905: Fix missing report

FIx a missing report of error

* coverity_20190905: Pipe close

The previous fix had an error that wolud allow a socket continue opened, this commit fixes this

* coverity_20190905: Error pattern

The call of perror would generate a different error report, instead I am using strerror() to keep pattern

* coverity_20190905: Error function

Rewrite the call to error function

* coverity_20190905: Fix missing tests

The previous fix did not have correct tests after to clean the variables

* coverity_20190905: Fix readable

I changed for an else instead a new if, it is more clean this way

* coverity_20190905: remove unecessary test

This commit is removing an unecessary test for a variable that will never be NULL.

* coverity_20190905: Add neccessary NULLL

After to clean the variable, I am setting NULL to variable to avoid clean again

* coverity_20190905: Remove false error

The condition added to fix Coverity was generating false positives, so we are changing to debug

* coverity_20190905: Remove false error

The condition added to fix Coverity was generating false positives, so we are changing to debug

* coverity_20190905: Bring else to avoid error

Bring an else to solve the problem to read a FD not opened

* coverity_20190905: Return

After to analyse the last changes, I decided to return, because they were not necessary

* coverity_20190905: Remove NULL

Remove unecessary set of variable to NULL

2 files changed, 7 insertions, 20 deletions

diff --git a/libnetdata/popen/popen.c b/libnetdata/popen/popen.c
index 177aebfc04..906b105357 100644
--- a/libnetdata/popen/popen.c
+++ b/libnetdata/popen/popen.c
@@ -68,7 +68,7 @@ static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, c
     int i;
     for(i = (int) (sysconf(_SC_OPEN_MAX) - 1); i >= 0; i--)
         if(i != STDIN_FILENO && i != STDERR_FILENO)
-            fcntl(i, F_SETFD, FD_CLOEXEC);
+            (void)fcntl(i, F_SETFD, FD_CLOEXEC);
 
     if (!posix_spawn_file_actions_init(&fa)) {
         // move the pipe to stdout in the child
@@ -97,7 +97,7 @@ static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, c
         debug(D_CHILDS, "Spawned command: '%s' on pid %d from parent pid %d.", command, pid, getpid());
     } else {
         error("Failed to spawn command: '%s' from parent pid %d.", command, getpid());
-        close(pipefd[PIPE_READ]);
+        fclose(fp);
         fp = NULL;
     }
     close(pipefd[PIPE_WRITE]);
@@ -116,7 +116,11 @@ error_after_posix_spawn_file_actions_init:
     if (posix_spawn_file_actions_destroy(&fa))
         error("posix_spawn_file_actions_destroy");
 error_after_pipe:
-    close(pipefd[PIPE_READ]);
+    if (fp)
+        fclose(fp);
+    else
+        close(pipefd[PIPE_READ]);
+
     close(pipefd[PIPE_WRITE]);
     return NULL;
 }
diff --git a/libnetdata/url/url.c b/libnetdata/url/url.c
index 7df9faaf02..d1d5081397 100644
--- a/libnetdata/url/url.c
+++ b/libnetdata/url/url.c
@@ -44,23 +44,6 @@ char *url_encode(char *str) {
 }
 
 /**
- * URL Decode
- *
- * Returns a url-decoded version of str
- * IMPORTANT: be sure to free() the returned string after use
- *
- * @param str the string that will be decode
- *
- * @return a pointer for the url decoded.
- */
-char *url_decode(char *str) {
-    size_t size = strlen(str) + 1;
-
-    char *buf = mallocz(size);
-    return url_decode_r(buf, str, size);
-}
-
-/**
  *  Percentage escape decode
  *
  *  Decode %XX character or return 0 if cannot