Check context pointers for null pointer on entry points.

22 files changed, 266 insertions, 6 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index cf5a5efd..3cbc41d4 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,43 @@
+2011-05-26  Marcus Brinkmann  <[email protected]>
+
+	* decrypt.c (gpgme_op_decrypt_start, gpgme_op_decrypt): Check CTX.
+	* decrypt-verify.c (gpgme_op_decrypt_verify_start)
+	(gpgme_op_decrypt_verify): Likewise.
+	* delete.c (gpgme_op_delete_start, gpgme_op_delete): Likewise.
+	* edit.c (gpgme_op_edit_start, gpgme_op_edit)
+	(gpgme_op_card_edit_start, gpgme_op_card_edit): Likewise.
+	* encrypt.c (gpgme_op_encrypt_start, gpgme_op_encrypt): Likewise.
+	* encrypt-sign.c (gpgme_op_encrypt_sign_start)
+	(gpgme_op_encrypt_sign): Likewise.
+	* export.c (gpgme_op_export_start, gpgme_op_export)
+	(gpgme_op_export_ext_start, gpgme_op_export_ext)
+	(gpgme_op_export_keys_start, gpgme_op_export_keys): Likewise.
+	* genkey.c (gpgme_op_genkey_start, gpgme_op_genkey): Likewise.
+	* getauditlog.c (gpgme_op_getauditlog_start)
+	(gpgme_op_getauditlog): Likewise.
+	* gpgconf.c (gpgme_op_conf_load, gpgme_op_conf_save): Likewise.
+	* import.c (gpgme_op_import_start, gpgme_op_import_keys_start)
+	(gpgme_op_import_keys, gpgme_op_import): Likewise.
+	* keylist.c (gpgme_op_keylist_start, gpgme_op_keylist_ext_start): Likewise.
+	* opassuan.c (gpgme_op_assuan_transact_start)
+	(gpgme_op_assuan_transact_ext): Likewise.
+	* passwd.c (gpgme_op_passwd_start, gpgme_op_passwd): Likewise.
+	* sign.c (gpgme_op_sign_start, gpgme_op_sign): Likewise.
+	* trustlist.c (gpgme_op_trustlist_start)
+	(gpgme_op_trustlist_next): Likewise.
+	* verify.c (gpgme_op_verify_start, gpgme_get_sig_key): Likewise.
+	* op-support.c (_gpgme_op_data_lookup): Likewise.
+	* vfs-create.c (gpgme_op_vfs_transact, gpgme_op_vfs_create): Likewise.
+	* vfs-mount.c (gpgme_op_vfs_mount, gpgme_op_vfs_transact): Likewise.
+	* gpgme.c (gpgme_set_protocol)
+	(gpgme_set_sub_protocol)
+	(gpgme_set_armor, gpgme_set_include_certs)
+	(gpgme_set_keylist_mode, gpgme_set_passphrase_cb)
+	(gpgme_set_progress_cb, gpgme_set_io_cbs, gpgme_set_locale)
+	(gpgme_ctx_set_engine_info, gpgme_sig_notation_clear): Likewise.
+	* gpgme.c (gpgme_new): Check for valid R_CTX.
+	(gpgme_cancel, gpgme_cancel_async, gpgme_release): Likewise.
+
 2011-04-06  Werner Koch  <[email protected]>
 
 	* gpgme-config.in: Add option --host.  Change options --cflags and
diff --git a/src/decrypt-verify.c b/src/decrypt-verify.c
index 87d5223b..a5a751b3 100644
--- a/src/decrypt-verify.c
+++ b/src/decrypt-verify.c
@@ -91,6 +91,10 @@ gpgme_op_decrypt_verify_start (gpgme_ctx_t ctx, gpgme_data_t cipher,
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_decrypt_verify_start", ctx,
 	      "cipher=%p, plain=%p", cipher, plain);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = decrypt_verify_start (ctx, 0, cipher, plain);
   return TRACE_ERR (err);
 }
@@ -106,6 +110,10 @@ gpgme_op_decrypt_verify (gpgme_ctx_t ctx, gpgme_data_t cipher,
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_decrypt_verify", ctx,
 	      "cipher=%p, plain=%p", cipher, plain);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = decrypt_verify_start (ctx, 1, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/decrypt.c b/src/decrypt.c
index c017b907..b74c5081 100644
--- a/src/decrypt.c
+++ b/src/decrypt.c
@@ -375,6 +375,10 @@ gpgme_op_decrypt_start (gpgme_ctx_t ctx, gpgme_data_t cipher,
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_decrypt_start", ctx,
 	      "cipher=%p, plain=%p", cipher, plain);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = decrypt_start (ctx, 0, cipher, plain);
   return TRACE_ERR (err);
 }
@@ -389,6 +393,10 @@ gpgme_op_decrypt (gpgme_ctx_t ctx, gpgme_data_t cipher, gpgme_data_t plain)
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_decrypt", ctx,
 	      "cipher=%p, plain=%p", cipher, plain);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = decrypt_start (ctx, 1, cipher, plain);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/delete.c b/src/delete.c
index c5a92f1d..1a501d8e 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -100,6 +100,10 @@ gpgme_op_delete_start (gpgme_ctx_t ctx, const gpgme_key_t key,
 	      "key=%p (%s), allow_secret=%i", key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", allow_secret);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = delete_start (ctx, 0, key, allow_secret);
   return TRACE_ERR (err);
 }
@@ -116,6 +120,10 @@ gpgme_op_delete (gpgme_ctx_t ctx, const gpgme_key_t key, int allow_secret)
 	      "key=%p (%s), allow_secret=%i", key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", allow_secret);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = delete_start (ctx, 1, key, allow_secret);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/edit.c b/src/edit.c
index fbdcfdfb..4abf24fa 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -145,6 +145,10 @@ gpgme_op_edit_start (gpgme_ctx_t ctx, gpgme_key_t key,
 	      "key=%p (%s), fnc=%p fnc_value=%p, out=%p", key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", fnc, fnc_value, out);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = edit_start (ctx, 0, 0, key, fnc, fnc_value, out);
   return err;
 }
@@ -163,6 +167,9 @@ gpgme_op_edit (gpgme_ctx_t ctx, gpgme_key_t key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", fnc, fnc_value, out);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = edit_start (ctx, 1, 0, key, fnc, fnc_value, out);
 
   if (!err)
@@ -182,6 +189,10 @@ gpgme_op_card_edit_start (gpgme_ctx_t ctx, gpgme_key_t key,
 	      "key=%p (%s), fnc=%p fnc_value=%p, out=%p", key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", fnc, fnc_value, out);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = edit_start (ctx, 0, 1, key, fnc, fnc_value, out);
   return err;
 }
@@ -199,6 +210,10 @@ gpgme_op_card_edit (gpgme_ctx_t ctx, gpgme_key_t key,
 	      "key=%p (%s), fnc=%p fnc_value=%p, out=%p", key,
 	      (key->subkeys && key->subkeys->fpr) ? 
 	      key->subkeys->fpr : "invalid", fnc, fnc_value, out);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+  
   err = edit_start (ctx, 1, 1, key, fnc, fnc_value, out);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/encrypt-sign.c b/src/encrypt-sign.c
index 3b862be8..78286004 100644
--- a/src/encrypt-sign.c
+++ b/src/encrypt-sign.c
@@ -99,6 +99,9 @@ gpgme_op_encrypt_sign_start (gpgme_ctx_t ctx, gpgme_key_t recp[],
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_encrypt_sign_start", ctx,
 	      "flags=0x%x, plain=%p, cipher=%p", flags, plain, cipher);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   
   if (_gpgme_debug_trace () && recp)
     {
@@ -130,6 +133,9 @@ gpgme_op_encrypt_sign (gpgme_ctx_t ctx, gpgme_key_t recp[],
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_encrypt_sign", ctx,
 	      "flags=0x%x, plain=%p, cipher=%p", flags, plain, cipher);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   
   if (_gpgme_debug_trace () && recp)
     {
diff --git a/src/encrypt.c b/src/encrypt.c
index c9599b5c..641e9004 100644
--- a/src/encrypt.c
+++ b/src/encrypt.c
@@ -231,6 +231,9 @@ gpgme_op_encrypt_start (gpgme_ctx_t ctx, gpgme_key_t recp[],
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_encrypt_start", ctx,
 	      "flags=0x%x, plain=%p, cipher=%p", flags, plain, cipher);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   
   if (_gpgme_debug_trace () && recp)
     {
@@ -261,7 +264,10 @@ gpgme_op_encrypt (gpgme_ctx_t ctx, gpgme_key_t recp[],
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_encrypt", ctx,
 	      "flags=0x%x, plain=%p, cipher=%p", flags, plain, cipher);
-  
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && recp)
     {
       int i = 0;
diff --git a/src/export.c b/src/export.c
index 42f55977..9c1c79c0 100644
--- a/src/export.c
+++ b/src/export.c
@@ -80,6 +80,10 @@ gpgme_op_export_start (gpgme_ctx_t ctx, const char *pattern,
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_export_start", ctx,
 	      "pattern=%s, mode=0x%x, keydata=%p", pattern, mode, keydata);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = export_start (ctx, 0, pattern, mode, keydata);
   return TRACE_ERR (err);
 }
@@ -95,6 +99,9 @@ gpgme_op_export (gpgme_ctx_t ctx, const char *pattern,
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_export", ctx,
 	      "pattern=%s, mode=0x%x, keydata=%p", pattern, mode, keydata);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = export_start (ctx, 1, pattern, mode, keydata);
   if (!err)
     err = _gpgme_wait_one (ctx);
@@ -144,6 +151,9 @@ gpgme_op_export_ext_start (gpgme_ctx_t ctx, const char *pattern[],
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_export_ext_start", ctx,
 	      "mode=0x%x, keydata=%p", mode, keydata);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && pattern)
     {
       int i = 0;
@@ -170,6 +180,9 @@ gpgme_op_export_ext (gpgme_ctx_t ctx, const char *pattern[],
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_export_ext_start", ctx,
 	      "mode=0x%x, keydata=%p", mode, keydata);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && pattern)
     {
       int i = 0;
@@ -256,6 +269,9 @@ gpgme_op_export_keys_start (gpgme_ctx_t ctx,
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_export_keys_start", ctx,
 	      "mode=0x%x, keydata=%p", mode, keydata);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   
   if (_gpgme_debug_trace () && keys)
     {
@@ -284,6 +300,9 @@ gpgme_op_export_keys (gpgme_ctx_t ctx,
 
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_export_keys", ctx,
 	      "mode=0x%x, keydata=%p", mode, keydata);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   
   if (_gpgme_debug_trace () && keys)
     {
diff --git a/src/genkey.c b/src/genkey.c
index 6de3bb8b..bfc7c2af 100644
--- a/src/genkey.c
+++ b/src/genkey.c
@@ -203,6 +203,10 @@ gpgme_op_genkey_start (gpgme_ctx_t ctx, const char *parms,
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_genkey_start", ctx,
 	      "pubkey=%p, seckey=%p", pubkey, seckey);
   TRACE_LOGBUF (parms, strlen (parms));
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = genkey_start (ctx, 0, parms, pubkey, seckey);
   return TRACE_ERR (err);
 }
@@ -221,6 +225,9 @@ gpgme_op_genkey (gpgme_ctx_t ctx, const char *parms, gpgme_data_t pubkey,
 	      "pubkey=%p, seckey=%p", pubkey, seckey);
   TRACE_LOGBUF (parms, strlen (parms));
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = genkey_start (ctx, 1, parms, pubkey, seckey);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/getauditlog.c b/src/getauditlog.c
index 6bd5cd78..d8435ac5 100644
--- a/src/getauditlog.c
+++ b/src/getauditlog.c
@@ -67,6 +67,10 @@ gpgme_op_getauditlog_start (gpgme_ctx_t ctx,
   gpg_error_t err;
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_getauditlog_start", ctx,
 	      "output=%p, flags=0x%x", output, flags);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = getauditlog_start (ctx, 0, output, flags);
   return TRACE_ERR (err);
 }
@@ -84,6 +88,9 @@ gpgme_op_getauditlog (gpgme_ctx_t ctx, gpgme_data_t output, unsigned int flags)
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_getauditlog", ctx,
 	      "output=%p, flags=0x%x", output, flags);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = getauditlog_start (ctx, 1, output, flags);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/gpgconf.c b/src/gpgconf.c
index 3c9d16b5..f3411d51 100644
--- a/src/gpgconf.c
+++ b/src/gpgconf.c
@@ -94,8 +94,12 @@ gpgme_op_conf_load (gpgme_ctx_t ctx, gpgme_conf_comp_t *conf_p)
 {
 #ifdef ENABLE_GPGCONF
   gpgme_error_t err;
-  gpgme_protocol_t proto = ctx->protocol;
+  gpgme_protocol_t proto;
 
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
+  proto = ctx->protocol;
   ctx->protocol = GPGME_PROTOCOL_GPGCONF;
   err = _gpgme_op_reset (ctx, 1);
   if (err)
@@ -116,8 +120,12 @@ gpgme_op_conf_save (gpgme_ctx_t ctx, gpgme_conf_comp_t comp)
 {
 #ifdef ENABLE_GPGCONF
   gpgme_error_t err;
-  gpgme_protocol_t proto = ctx->protocol;
+  gpgme_protocol_t proto;
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
 
+  proto = ctx->protocol;
   ctx->protocol = GPGME_PROTOCOL_GPGCONF;
   err = _gpgme_op_reset (ctx, 1);
   if (err)
diff --git a/src/gpgme.c b/src/gpgme.c
index 7feb3be9..c8e6a8b7 100644
--- a/src/gpgme.c
+++ b/src/gpgme.c
@@ -63,6 +63,9 @@ gpgme_new (gpgme_ctx_t *r_ctx)
   if (_gpgme_selftest)
     return TRACE_ERR (gpgme_error (_gpgme_selftest));
 
+  if (!r_ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   ctx = calloc (1, sizeof *ctx);
   if (!ctx)
     return TRACE_ERR (gpg_error_from_errno (errno));
@@ -160,6 +163,9 @@ gpgme_cancel (gpgme_ctx_t ctx)
 
   TRACE_BEG (DEBUG_CTX, "gpgme_cancel", ctx);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_cancel_with_err (ctx, gpg_error (GPG_ERR_CANCELED), 0);
 
   return TRACE_ERR (err);
@@ -172,6 +178,9 @@ gpgme_cancel_async (gpgme_ctx_t ctx)
 {
   TRACE_BEG (DEBUG_CTX, "gpgme_cancel_async", ctx);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   LOCK (ctx->lock);
   ctx->canceled = 1;
   UNLOCK (ctx->lock);
@@ -186,6 +195,9 @@ gpgme_release (gpgme_ctx_t ctx)
 {
   TRACE (DEBUG_CTX, "gpgme_release", ctx);
 
+  if (!ctx)
+    return;
+
   _gpgme_engine_release (ctx->engine);
   _gpgme_fd_table_deinit (&ctx->fdt);
   _gpgme_release_result (ctx);
@@ -278,6 +290,9 @@ gpgme_set_protocol (gpgme_ctx_t ctx, gpgme_protocol_t protocol)
       && protocol != GPGME_PROTOCOL_UISERVER)
     return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (ctx->protocol != protocol)
     {
       /* Shut down the engine when switching protocols.  */
@@ -301,6 +316,7 @@ gpgme_get_protocol (gpgme_ctx_t ctx)
 	  "ctx->protocol=%i (%s)", ctx->protocol,
 	  gpgme_get_protocol_name (ctx->protocol)
 	  ? gpgme_get_protocol_name (ctx->protocol) : "invalid");
+
   return ctx->protocol;
 }
 
@@ -311,6 +327,10 @@ gpgme_set_sub_protocol (gpgme_ctx_t ctx, gpgme_protocol_t protocol)
   TRACE2 (DEBUG_CTX, "gpgme_set_sub_protocol", ctx, "protocol=%i (%s)",
 	  protocol, gpgme_get_protocol_name (protocol)
 	  ? gpgme_get_protocol_name (protocol) : "invalid");
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
   ctx->sub_protocol = protocol;
   return 0;
 }
@@ -323,6 +343,7 @@ gpgme_get_sub_protocol (gpgme_ctx_t ctx)
 	  "ctx->sub_protocol=%i (%s)", ctx->sub_protocol,
 	  gpgme_get_protocol_name (ctx->sub_protocol)
 	  ? gpgme_get_protocol_name (ctx->sub_protocol) : "invalid");
+
   return ctx->sub_protocol;
 }
 
@@ -367,6 +388,10 @@ gpgme_set_armor (gpgme_ctx_t ctx, int use_armor)
 {
   TRACE2 (DEBUG_CTX, "gpgme_set_armor", ctx, "use_armor=%i (%s)",
 	  use_armor, use_armor ? "yes" : "no");
+
+  if (!ctx)
+    return;
+
   ctx->use_armor = use_armor;
 }
 
@@ -390,6 +415,10 @@ gpgme_set_textmode (gpgme_ctx_t ctx, int use_textmode)
 {
   TRACE2 (DEBUG_CTX, "gpgme_set_textmode", ctx, "use_textmode=%i (%s)",
 	  use_textmode, use_textmode ? "yes" : "no");
+
+  if (!ctx)
+    return;
+
   ctx->use_textmode = use_textmode;
 }
 
@@ -409,6 +438,9 @@ gpgme_get_textmode (gpgme_ctx_t ctx)
 void
 gpgme_set_include_certs (gpgme_ctx_t ctx, int nr_of_certs)
 {
+  if (!ctx)
+    return;
+
   if (nr_of_certs == GPGME_INCLUDE_CERTS_DEFAULT)
     ctx->include_certs = GPGME_INCLUDE_CERTS_DEFAULT;
   else if (nr_of_certs < -2)
@@ -441,6 +473,9 @@ gpgme_set_keylist_mode (gpgme_ctx_t ctx, gpgme_keylist_mode_t mode)
   TRACE1 (DEBUG_CTX, "gpgme_set_keylist_mode", ctx, "keylist_mode=0x%x",
 	  mode);
 
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
   ctx->keylist_mode = mode;
   return 0;
 }
@@ -464,6 +499,10 @@ gpgme_set_passphrase_cb (gpgme_ctx_t ctx, gpgme_passphrase_cb_t cb,
 {
   TRACE2 (DEBUG_CTX, "gpgme_set_passphrase_cb", ctx,
 	  "passphrase_cb=%p/%p", cb, cb_value);
+
+  if (!ctx)
+    return;
+
   ctx->passphrase_cb = cb;
   ctx->passphrase_cb_value = cb_value;
 }
@@ -492,6 +531,10 @@ gpgme_set_progress_cb (gpgme_ctx_t ctx, gpgme_progress_cb_t cb, void *cb_value)
 {
   TRACE2 (DEBUG_CTX, "gpgme_set_progress_cb", ctx, "progress_cb=%p/%p",
 	  cb, cb_value);
+
+  if (!ctx)
+    return;
+
   ctx->progress_cb = cb;
   ctx->progress_cb_value = cb_value;
 }
@@ -516,6 +559,9 @@ gpgme_get_progress_cb (gpgme_ctx_t ctx, gpgme_progress_cb_t *r_cb,
 void
 gpgme_set_io_cbs (gpgme_ctx_t ctx, gpgme_io_cbs_t io_cbs)
 {
+  if (!ctx)
+    return;
+
   if (io_cbs)
     {
       TRACE6 (DEBUG_CTX, "gpgme_set_io_cbs", ctx,
@@ -593,6 +639,9 @@ gpgme_set_locale (gpgme_ctx_t ctx, int category, const char *value)
   TRACE_BEG2 (DEBUG_CTX, "gpgme_set_locale", ctx,
 	       "category=%i, value=%s", category, value ? value : "(null)");
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
 #define PREPARE_ONE_LOCALE(lcat, ucat)				\
   if (!failed && value						\
       && (category == LC_ALL || category == LC_ ## ucat))	\
@@ -678,6 +727,9 @@ gpgme_ctx_set_engine_info (gpgme_ctx_t ctx, gpgme_protocol_t proto,
 	      ? gpgme_get_protocol_name (proto) : "unknown",
 	      file_name ? file_name : "(default)",
 	      home_dir ? home_dir : "(default)");
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
 	      
   /* Shut down the engine when changing engine info.  */
   if (ctx->engine)
@@ -715,6 +767,10 @@ void
 gpgme_sig_notation_clear (gpgme_ctx_t ctx)
 {
   TRACE (DEBUG_CTX, "gpgme_sig_notation_clear", ctx);
+
+  if (!ctx)
+    return;
+
   _gpgme_sig_notation_clear (ctx);
 }
 
diff --git a/src/import.c b/src/import.c
index 784ce165..3bc74413 100644
--- a/src/import.c
+++ b/src/import.c
@@ -289,6 +289,9 @@ gpgme_op_import_start (gpgme_ctx_t ctx, gpgme_data_t keydata)
   TRACE_BEG1 (DEBUG_CTX, "gpgme_op_import_start", ctx,
 	      "keydata=%p", keydata);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_op_import_start (ctx, 0, keydata);
   return TRACE_ERR (err);
 }
@@ -303,6 +306,9 @@ gpgme_op_import (gpgme_ctx_t ctx, gpgme_data_t keydata)
   TRACE_BEG1 (DEBUG_CTX, "gpgme_op_import", ctx,
 	      "keydata=%p", keydata);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_op_import_start (ctx, 1, keydata);
   if (!err)
     err = _gpgme_wait_one (ctx);
@@ -365,6 +371,10 @@ gpgme_op_import_keys_start (gpgme_ctx_t ctx, gpgme_key_t *keys)
   gpg_error_t err;
 
   TRACE_BEG (DEBUG_CTX, "gpgme_op_import_keys_start", ctx);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && keys)
     {
       int i = 0;
@@ -400,6 +410,10 @@ gpgme_op_import_keys (gpgme_ctx_t ctx, gpgme_key_t *keys)
   gpgme_error_t err;
 
   TRACE_BEG (DEBUG_CTX, "gpgme_op_import_keys", ctx);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && keys)
     {
       int i = 0;
diff --git a/src/keylist.c b/src/keylist.c
index 8f61a261..29e30a0f 100644
--- a/src/keylist.c
+++ b/src/keylist.c
@@ -863,6 +863,9 @@ gpgme_op_keylist_start (gpgme_ctx_t ctx, const char *pattern, int secret_only)
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_keylist_start", ctx,
 	      "pattern=%s, secret_only=%i", pattern, secret_only);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_op_reset (ctx, 2);
   if (err)
     return TRACE_ERR (err);
@@ -900,6 +903,9 @@ gpgme_op_keylist_ext_start (gpgme_ctx_t ctx, const char *pattern[],
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_keylist_ext_start", ctx,
 	      "secret_only=%i, reserved=0x%x", secret_only, reserved);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_op_reset (ctx, 2);
   if (err)
     return TRACE_ERR (err);
diff --git a/src/op-support.c b/src/op-support.c
index 0a5639be..000560bb 100644
--- a/src/op-support.c
+++ b/src/op-support.c
@@ -37,7 +37,12 @@ gpgme_error_t
 _gpgme_op_data_lookup (gpgme_ctx_t ctx, ctx_op_data_id_t type, void **hook,
 		       int size, void (*cleanup) (void *))
 {
-  struct ctx_op_data *data = ctx->op_data;
+  struct ctx_op_data *data;
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
+  data = ctx->op_data;
   while (data && data->type != type)
     data = data->next;
   if (!data)
diff --git a/src/opassuan.c b/src/opassuan.c
index bd50089b..21c25cab 100644
--- a/src/opassuan.c
+++ b/src/opassuan.c
@@ -95,6 +95,9 @@ gpgme_op_assuan_transact_start (gpgme_ctx_t ctx,
 	      command, data_cb, data_cb_value, inq_cb, inq_cb_value,
 	      status_cb, status_cb_value);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = opassuan_start (ctx, 0, command, data_cb, data_cb_value,
 			inq_cb, inq_cb_value, status_cb, status_cb_value);
   return TRACE_ERR (err);
@@ -122,6 +125,9 @@ gpgme_op_assuan_transact_ext (gpgme_ctx_t ctx,
 	      command, data_cb, data_cb_value, inq_cb, inq_cb_value,
 	      status_cb, status_cb_value, op_err_p);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = opassuan_start (ctx, 1, command, 
                         data_cb, data_cb_value,
                         inq_cb, inq_cb_value,
@@ -212,6 +218,9 @@ gpgme_op_assuan_transact (gpgme_ctx_t ctx,
 
   TRACE (DEBUG_CTX, "gpgme_op_assuan_transact", ctx);
 
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
   /* Users of the old-style session based interfaces need to look at
      the result structure.  */
   err = gpgme_op_assuan_transact_ext (ctx, command, data_cb, data_cb_value,
diff --git a/src/passwd.c b/src/passwd.c
index ab61b4a4..97b69603 100644
--- a/src/passwd.c
+++ b/src/passwd.c
@@ -157,6 +157,10 @@ gpgme_op_passwd_start (gpgme_ctx_t ctx, gpgme_key_t key, unsigned int flags)
   gpg_error_t err;
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_passwd_start", ctx,
 	      "key=%p, flags=0x%x", key, flags);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = passwd_start (ctx, 0, key, flags);
   return TRACE_ERR (err);
 }
@@ -172,6 +176,9 @@ gpgme_op_passwd (gpgme_ctx_t ctx, gpgme_key_t key, unsigned int flags)
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_passwd", ctx,
 	      "key=%p, flags=0x%x", key, flags);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = passwd_start (ctx, 1, key, flags);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/sign.c b/src/sign.c
index 8aff542e..2f308a06 100644
--- a/src/sign.c
+++ b/src/sign.c
@@ -393,6 +393,10 @@ gpgme_op_sign_start (gpgme_ctx_t ctx, gpgme_data_t plain, gpgme_data_t sig,
   gpg_error_t err;
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_sign_start", ctx,
 	      "plain=%p, sig=%p, mode=%i", plain, sig, mode);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = sign_start (ctx, 0, plain, sig, mode);
   return TRACE_ERR (err);
 }
@@ -407,6 +411,10 @@ gpgme_op_sign (gpgme_ctx_t ctx, gpgme_data_t plain, gpgme_data_t sig,
 
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_sign", ctx,
 	      "plain=%p, sig=%p, mode=%i", plain, sig, mode);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = sign_start (ctx, 1, plain, sig, mode);
   if (!err)
     err = _gpgme_wait_one (ctx);
diff --git a/src/trustlist.c b/src/trustlist.c
index 67c724fb..a96b6c72 100644
--- a/src/trustlist.c
+++ b/src/trustlist.c
@@ -177,7 +177,7 @@ gpgme_op_trustlist_start (gpgme_ctx_t ctx, const char *pattern, int max_level)
   TRACE_BEG2 (DEBUG_CTX, "gpgme_op_trustlist_start", ctx,
 	      "pattern=%s, max_level=%i", pattern, max_level);
 
-  if (!pattern || !*pattern)
+  if (!ctx || !pattern || !*pattern)
     return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
 
   err = _gpgme_op_reset (ctx, 2);
@@ -212,7 +212,7 @@ gpgme_op_trustlist_next (gpgme_ctx_t ctx, gpgme_trust_item_t *r_item)
 
   TRACE_BEG (DEBUG_CTX, "gpgme_op_trustlist_next", ctx);
 
-  if (!r_item)
+  if (!ctx || !r_item)
     return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
   *r_item = NULL;
   if (!ctx)
diff --git a/src/verify.c b/src/verify.c
index ed81b8ac..a8f67124 100644
--- a/src/verify.c
+++ b/src/verify.c
@@ -836,6 +836,10 @@ gpgme_op_verify_start (gpgme_ctx_t ctx, gpgme_data_t sig,
   TRACE_BEG3 (DEBUG_CTX, "gpgme_op_verify_start", ctx,
 	      "sig=%p, signed_text=%p, plaintext=%p",
 	      sig, signed_text, plaintext);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = verify_start (ctx, 0, sig, signed_text, plaintext);
   return TRACE_ERR (err);
 }
@@ -853,6 +857,9 @@ gpgme_op_verify (gpgme_ctx_t ctx, gpgme_data_t sig, gpgme_data_t signed_text,
 	      "sig=%p, signed_text=%p, plaintext=%p",
 	      sig, signed_text, plaintext);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = verify_start (ctx, 1, sig, signed_text, plaintext);
   if (!err)
     err = _gpgme_wait_one (ctx);
@@ -870,6 +877,9 @@ gpgme_get_sig_key (gpgme_ctx_t ctx, int idx, gpgme_key_t *r_key)
   gpgme_verify_result_t result;
   gpgme_signature_t sig;
 
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
   result = gpgme_op_verify_result (ctx);
   sig = result->signatures;
 
diff --git a/src/vfs-create.c b/src/vfs-create.c
index d7fd24f1..e8dab472 100644
--- a/src/vfs-create.c
+++ b/src/vfs-create.c
@@ -90,6 +90,9 @@ gpgme_op_vfs_transact (gpgme_ctx_t ctx,
 		       gpgme_error_t *op_err)
 {
   gpgme_error_t err;
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
   
   err = vfs_start (ctx, 1, command, data_cb, data_cb_value,
 		   inq_cb, inq_cb_value, status_cb, status_cb_value);
@@ -178,6 +181,9 @@ gpgme_op_vfs_create (gpgme_ctx_t ctx, gpgme_key_t recp[],
 	      "container_file=%s, flags=0x%x, op_err=%p",
 	      container_file, flags, op_err);
 
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   if (_gpgme_debug_trace () && recp)
     {
       int i = 0;
diff --git a/src/vfs-mount.c b/src/vfs-mount.c
index b9136895..327e3531 100644
--- a/src/vfs-mount.c
+++ b/src/vfs-mount.c
@@ -147,6 +147,9 @@ gpgme_op_vfs_transact (gpgme_ctx_t ctx,
 		       gpgme_error_t *op_err)
 {
   gpgme_error_t err;
+
+  if (!ctx)
+    return gpg_error (GPG_ERR_INV_VALUE);
   
   err = vfs_start (ctx, 1, command, data_cb, data_cb_value,
 		   inq_cb, inq_cb_value, status_cb, status_cb_value);
@@ -232,6 +235,10 @@ gpgme_op_vfs_mount (gpgme_ctx_t ctx, const char *container_file,
   TRACE_BEG4 (DEBUG_CTX, "gpgme_op_vfs_mount", ctx,
 	      "container=%s, mount_dir=%s, flags=0x%x, op_err=%p",
 	      container_file, mount_dir, flags, op_err);
+
+  if (!ctx)
+    return TRACE_ERR (gpg_error (GPG_ERR_INV_VALUE));
+
   err = _gpgme_op_vfs_mount (ctx, container_file, mount_dir, flags, op_err);
   return TRACE_ERR (err);
 }