all: Refactor malloc+memset to use calloc

When a zeroed out allocation is required, use calloc() rather than
malloc() followed by an explicit memset(). The result will be the
same, but using calloc() everywhere increases consistency in the
codebase and avoids the risk of subtle bugs when code is injected
between malloc and memset by accident.

Closes https://github.com/curl/curl/pull/2497

13 files changed, 16 insertions, 46 deletions

diff --git a/docs/examples/evhiperfifo.c b/docs/examples/evhiperfifo.c
index 257c127a7..c0c230b26 100644
--- a/docs/examples/evhiperfifo.c
+++ b/docs/examples/evhiperfifo.c
@@ -336,7 +336,6 @@ static void new_conn(char *url, GlobalInfo *g)
   CURLMcode rc;
 
   conn = calloc(1, sizeof(ConnInfo));
-  memset(conn, 0, sizeof(ConnInfo));
   conn->error[0]='\0';
 
   conn->easy = curl_easy_init();
diff --git a/docs/examples/fopen.c b/docs/examples/fopen.c
index eb27c6ae9..f1706fbe6 100644
--- a/docs/examples/fopen.c
+++ b/docs/examples/fopen.c
@@ -237,12 +237,10 @@ URL_FILE *url_fopen(const char *url, const char *operation)
   URL_FILE *file;
   (void)operation;
 
-  file = malloc(sizeof(URL_FILE));
+  file = calloc(1, sizeof(URL_FILE));
   if(!file)
     return NULL;
 
-  memset(file, 0, sizeof(URL_FILE));
-
   file->handle.file = fopen(url, operation);
   if(file->handle.file)
     file->type = CFTYPE_FILE; /* marked as URL */
diff --git a/docs/examples/hiperfifo.c b/docs/examples/hiperfifo.c
index 7794283c6..fec62b85f 100644
--- a/docs/examples/hiperfifo.c
+++ b/docs/examples/hiperfifo.c
@@ -339,7 +339,6 @@ static void new_conn(char *url, GlobalInfo *g)
   CURLMcode rc;
 
   conn = calloc(1, sizeof(ConnInfo));
-  memset(conn, 0, sizeof(ConnInfo));
   conn->error[0]='\0';
 
   conn->easy = curl_easy_init();
diff --git a/lib/content_encoding.c b/lib/content_encoding.c
index 2b2188b73..7c979efcc 100644
--- a/lib/content_encoding.c
+++ b/lib/content_encoding.c
@@ -873,10 +873,9 @@ static contenc_writer *new_unencoding_writer(struct connectdata *conn,
                                              contenc_writer *downstream)
 {
   size_t sz = offsetof(contenc_writer, params) + handler->paramsize;
-  contenc_writer *writer = (contenc_writer *) malloc(sz);
+  contenc_writer *writer = (contenc_writer *) calloc(1, sz);
 
   if(writer) {
-    memset(writer, 0, sz);
     writer->handler = handler;
     writer->downstream = downstream;
     if(handler->init_writer(conn, writer)) {
diff --git a/lib/curl_ntlm_core.c b/lib/curl_ntlm_core.c
index 72eda34ad..e27cab353 100644
--- a/lib/curl_ntlm_core.c
+++ b/lib/curl_ntlm_core.c
@@ -745,12 +745,10 @@ CURLcode Curl_ntlm_core_mk_ntlmv2_resp(unsigned char *ntlmv2hash,
   len = NTLM_HMAC_MD5_LEN + NTLMv2_BLOB_LEN;
 
   /* Allocate the response */
-  ptr = malloc(len);
+  ptr = calloc(1, len);
   if(!ptr)
     return CURLE_OUT_OF_MEMORY;
 
-  memset(ptr, 0, len);
-
   /* Create the BLOB structure */
   snprintf((char *)ptr + NTLM_HMAC_MD5_LEN, NTLMv2_BLOB_LEN,
            "%c%c%c%c"   /* NTLMv2_BLOB_SIGNATURE */
diff --git a/lib/nwlib.c b/lib/nwlib.c
index 290cbe31f..215d933ac 100644
--- a/lib/nwlib.c
+++ b/lib/nwlib.c
@@ -186,11 +186,9 @@ int GetOrSetUpData(int id, libdata_t **appData,
 
     app_data = (libdata_t *) get_app_data(id);
     if(!app_data) {
-      app_data = malloc(sizeof(libdata_t));
+      app_data = calloc(1, sizeof(libdata_t));
 
       if(app_data) {
-        memset(app_data, 0, sizeof(libdata_t));
-
         app_data->tenbytes = malloc(10);
         app_data->lock     = NXMutexAlloc(0, 0, &liblock);
 
diff --git a/lib/vauth/krb5_sspi.c b/lib/vauth/krb5_sspi.c
index 1b4cef486..196b157d6 100644
--- a/lib/vauth/krb5_sspi.c
+++ b/lib/vauth/krb5_sspi.c
@@ -150,12 +150,10 @@ CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
       krb5->p_identity = NULL;
 
     /* Allocate our credentials handle */
-    krb5->credentials = malloc(sizeof(CredHandle));
+    krb5->credentials = calloc(1, sizeof(CredHandle));
     if(!krb5->credentials)
       return CURLE_OUT_OF_MEMORY;
 
-    memset(krb5->credentials, 0, sizeof(CredHandle));
-
     /* Acquire our credentials handle */
     status = s_pSecFn->AcquireCredentialsHandle(NULL,
                                                 (TCHAR *)
@@ -167,11 +165,9 @@ CURLcode Curl_auth_create_gssapi_user_message(struct Curl_easy *data,
       return CURLE_LOGIN_DENIED;
 
     /* Allocate our new context handle */
-    krb5->context = malloc(sizeof(CtxtHandle));
+    krb5->context = calloc(1, sizeof(CtxtHandle));
     if(!krb5->context)
       return CURLE_OUT_OF_MEMORY;
-
-    memset(krb5->context, 0, sizeof(CtxtHandle));
   }
 
   if(chlg64 && *chlg64) {
diff --git a/lib/vauth/ntlm_sspi.c b/lib/vauth/ntlm_sspi.c
index e748ce3b6..921524618 100644
--- a/lib/vauth/ntlm_sspi.c
+++ b/lib/vauth/ntlm_sspi.c
@@ -125,12 +125,10 @@ CURLcode Curl_auth_create_ntlm_type1_message(struct Curl_easy *data,
     ntlm->p_identity = NULL;
 
   /* Allocate our credentials handle */
-  ntlm->credentials = malloc(sizeof(CredHandle));
+  ntlm->credentials = calloc(1, sizeof(CredHandle));
   if(!ntlm->credentials)
     return CURLE_OUT_OF_MEMORY;
 
-  memset(ntlm->credentials, 0, sizeof(CredHandle));
-
   /* Acquire our credentials handle */
   status = s_pSecFn->AcquireCredentialsHandle(NULL,
                                               (TCHAR *) TEXT(SP_NAME_NTLM),
@@ -141,12 +139,10 @@ CURLcode Curl_auth_create_ntlm_type1_message(struct Curl_easy *data,
     return CURLE_LOGIN_DENIED;
 
   /* Allocate our new context handle */
-  ntlm->context = malloc(sizeof(CtxtHandle));
+  ntlm->context = calloc(1, sizeof(CtxtHandle));
   if(!ntlm->context)
     return CURLE_OUT_OF_MEMORY;
 
-  memset(ntlm->context, 0, sizeof(CtxtHandle));
-
   /* Setup the type-1 "output" security buffer */
   type_1_desc.ulVersion = SECBUFFER_VERSION;
   type_1_desc.cBuffers  = 1;
diff --git a/lib/vauth/spnego_sspi.c b/lib/vauth/spnego_sspi.c
index a6797cdaf..c8ecacff6 100644
--- a/lib/vauth/spnego_sspi.c
+++ b/lib/vauth/spnego_sspi.c
@@ -153,12 +153,10 @@ CURLcode Curl_auth_decode_spnego_message(struct Curl_easy *data,
       nego->p_identity = NULL;
 
     /* Allocate our credentials handle */
-    nego->credentials = malloc(sizeof(CredHandle));
+    nego->credentials = calloc(1, sizeof(CredHandle));
     if(!nego->credentials)
       return CURLE_OUT_OF_MEMORY;
 
-    memset(nego->credentials, 0, sizeof(CredHandle));
-
     /* Acquire our credentials handle */
     nego->status =
       s_pSecFn->AcquireCredentialsHandle(NULL,
@@ -170,11 +168,9 @@ CURLcode Curl_auth_decode_spnego_message(struct Curl_easy *data,
       return CURLE_LOGIN_DENIED;
 
     /* Allocate our new context handle */
-    nego->context = malloc(sizeof(CtxtHandle));
+    nego->context = calloc(1, sizeof(CtxtHandle));
     if(!nego->context)
       return CURLE_OUT_OF_MEMORY;
-
-    memset(nego->context, 0, sizeof(CtxtHandle));
   }
 
   if(chlg64 && *chlg64) {
diff --git a/lib/vtls/polarssl.c b/lib/vtls/polarssl.c
index d36cc70ee..811cdc2fb 100644
--- a/lib/vtls/polarssl.c
+++ b/lib/vtls/polarssl.c
@@ -620,12 +620,10 @@ polarssl_connect_step3(struct connectdata *conn,
     ssl_session *our_ssl_sessionid;
     void *old_ssl_sessionid = NULL;
 
-    our_ssl_sessionid = malloc(sizeof(ssl_session));
+    our_ssl_sessionid = calloc(1, sizeof(ssl_session));
     if(!our_ssl_sessionid)
       return CURLE_OUT_OF_MEMORY;
 
-    memset(our_ssl_sessionid, 0, sizeof(ssl_session));
-
     ret = ssl_get_session(&BACKEND->ssl, our_ssl_sessionid);
     if(ret) {
       failf(data, "ssl_get_session returned -0x%x", -ret);
diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c
index 76392a1fd..11fc401f9 100644
--- a/lib/vtls/schannel.c
+++ b/lib/vtls/schannel.c
@@ -363,12 +363,11 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
 
     /* allocate memory for the re-usable credential handle */
     BACKEND->cred = (struct curl_schannel_cred *)
-      malloc(sizeof(struct curl_schannel_cred));
+      calloc(1, sizeof(struct curl_schannel_cred));
     if(!BACKEND->cred) {
       failf(data, "schannel: unable to allocate memory");
       return CURLE_OUT_OF_MEMORY;
     }
-    memset(BACKEND->cred, 0, sizeof(struct curl_schannel_cred));
     BACKEND->cred->refcount = 1;
 
     /* https://msdn.microsoft.com/en-us/library/windows/desktop/aa374716.aspx
@@ -466,12 +465,11 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
 
   /* allocate memory for the security context handle */
   BACKEND->ctxt = (struct curl_schannel_ctxt *)
-    malloc(sizeof(struct curl_schannel_ctxt));
+    calloc(1, sizeof(struct curl_schannel_ctxt));
   if(!BACKEND->ctxt) {
     failf(data, "schannel: unable to allocate memory");
     return CURLE_OUT_OF_MEMORY;
   }
-  memset(BACKEND->ctxt, 0, sizeof(struct curl_schannel_ctxt));
 
   host_name = Curl_convert_UTF8_to_tchar(hostname);
   if(!host_name)
diff --git a/src/tool_formparse.c b/src/tool_formparse.c
index 719e3413f..5313b3441 100644
--- a/src/tool_formparse.c
+++ b/src/tool_formparse.c
@@ -451,11 +451,10 @@ static CURLcode file_or_stdin(curl_mimepart *part, const char *file)
   if(strcmp(file, "-"))
     return curl_mime_filedata(part, file);
 
-  sip = (standard_input *) malloc(sizeof *sip);
+  sip = (standard_input *) calloc(1, sizeof *sip);
   if(!sip)
     return CURLE_OUT_OF_MEMORY;
 
-  memset((char *) sip, 0, sizeof *sip);
   set_binmode(stdin);
 
   /* If stdin is a regular file, do not buffer data but read it when needed. */
diff --git a/tests/server/sockfilt.c b/tests/server/sockfilt.c
index 40f5bdb48..844d35a4e 100644
--- a/tests/server/sockfilt.c
+++ b/tests/server/sockfilt.c
@@ -727,24 +727,20 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
   }
 
   /* allocate internal array for the internal data */
-  data = malloc(nfds * sizeof(struct select_ws_data));
+  data = calloc(nfds, sizeof(struct select_ws_data));
   if(data == NULL) {
     errno = ENOMEM;
     return -1;
   }
 
   /* allocate internal array for the internal event handles */
-  handles = malloc(nfds * sizeof(HANDLE));
+  handles = calloc(nfds, sizeof(HANDLE));
   if(handles == NULL) {
     free(data);
     errno = ENOMEM;
     return -1;
   }
 
-  /* clear internal arrays */
-  memset(data, 0, nfds * sizeof(struct select_ws_data));
-  memset(handles, 0, nfds * sizeof(HANDLE));
-
   /* loop over the handles in the input descriptor sets */
   for(fds = 0; fds < nfds; fds++) {
     networkevents = 0;