Improve the example getpass() implementation to show an error return

Also, modernize the code, so that it isn't trying to store a size_t
into an int, and then check the int's sign. :/

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6271)

(cherry picked from commit c8c250333cd254ab3f4d709ebc5ed86a7c065721)
(cherry picked from commit 50d06d1c7d2682b0042e921a76beb509d7ea68e1)

1 files changed, 5 insertions, 6 deletions

diff --git a/doc/crypto/pem.pod b/doc/crypto/pem.pod
index 811a5e532d..de9ecca648 100644
--- a/doc/crypto/pem.pod
+++ b/doc/crypto/pem.pod
@@ -409,17 +409,16 @@ Skeleton pass phrase callback:
 
  int pass_cb(char *buf, int size, int rwflag, void *u)
  {
-     int len;
-     char *tmp;
 
      /* We'd probably do something else if 'rwflag' is 1 */
      printf("Enter pass phrase for \"%s\"\n", u);
 
      /* get pass phrase, length 'len' into 'tmp' */
-     tmp = "hello";
-     len = strlen(tmp);
-     if (len <= 0)
-         return 0;
+     char *tmp = "hello";
+     if (tmp == NULL) /* An error occurred */
+         return -1;
+
+     size_t len = strlen(tmp);
 
      if (len > size)
          len = size;