Add sha2 defines.

[openssl.git] / FAQ

diff --git a/FAQ b/FAQ
index 9f6dc63d4fcf6781834008bd958463a44182c333..d337d90ff09a3194d6ed8b7a3c38b0df3b22e59f 100644 (file)
--- a/FAQ
+++ b/FAQ
@@ -67,6 +67,8 @@ OpenSSL  -  Frequently Asked Questions
 * Why doesn't my server application receive a client certificate?
 * Why does compilation fail due to an undefined symbol NID_uniqueIdentifier?
 * I think I've detected a memory leak, is this a bug?
+* Why does Valgrind complain about the use of uninitialized data?
+* Why doesn't a memory BIO work when a file does?
 
 ===============================================================================
 
@@ -75,7 +77,7 @@ OpenSSL  -  Frequently Asked Questions
 * Which is the current version of OpenSSL?
 
 The current version is available from <URL: http://www.openssl.org>.
-OpenSSL 0.9.8a was released on October 11th, 2005.
+OpenSSL 0.9.8g was released on October 19th, 2007.
 
 In addition to the current stable release, you can also access daily
 snapshots of the OpenSSL development version at <URL:
@@ -430,7 +432,7 @@ encryption so these certificates are now obsolete.
 
 It doesn't: this extension is often the cause of confusion.
 
-Consider a certificate chain A->B->C so that A signs, B and B signs C. Suppose
+Consider a certificate chain A->B->C so that A signs B and B signs C. Suppose
 certificate C contains AKID.
 
 The purpose of this extension is to identify the authority certificate B. This
@@ -699,8 +701,11 @@ libraries.  If your platform is not one of these, consult the INSTALL
 file.
 
 Multi-threaded applications must provide two callback functions to
-OpenSSL.  This is described in the threads(3) manpage.
-
+OpenSSL by calling CRYPTO_set_locking_callback() and
+CRYPTO_set_id_callback().  (For OpenSSL 0.9.9 or later, the new
+function CRYPTO_set_idptr_callback() may be used in place of
+CRYPTO_set_id_callback().)  This is described in the threads(3)
+manpage.
 
 * I've compiled a program under Windows and it crashes: why?
 
@@ -913,5 +918,36 @@ thread-safe):
   ERR_free_strings(), EVP_cleanup() and CRYPTO_cleanup_all_ex_data().
 
 
+* Why does Valgrind complain about the use of uninitialized data?
+
+When OpenSSL's PRNG routines are called to generate random numbers the supplied
+buffer contents are mixed into the entropy pool: so it technically does not
+matter whether the buffer is initialized at this point or not.  Valgrind (and
+other test tools) will complain about this. When using Valgrind, make sure the
+OpenSSL library has been compiled with the PURIFY macro defined (-DPURIFY)
+to get rid of these warnings.
+
+
+* Why doesn't a memory BIO work when a file does?
+
+This can occur in several cases for example reading an S/MIME email message.
+The reason is that a memory BIO can do one of two things when all the data
+has been read from it.
+
+The default behaviour is to indicate that no more data is available and that
+the call should be retried, this is to allow the application to fill up the BIO
+again if necessary.
+
+Alternatively it can indicate that no more data is available and that EOF has
+been reached.
+
+If a memory BIO is to behave in the same way as a file this second behaviour
+is needed. This must be done by calling:
+
+   BIO_set_mem_eof_return(bio, 0);
+
+See the manual pages for more details.
+
+
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