mimepost: allocate main struct on-demand

This makes the easy handle 432 bytes smaller (totally 5352 bytes on my
rather maximized Linux 64 bit build). The 440 byte mimepost struct is
now allocated only when needed.

Closes #20260

lib/easy.c

@@ -891,7 +891,7 @@ static CURLcode dupset(struct Curl_easy *dst, struct Curl_easy *src)
   /* Copy src->set into dst->set first, then deal with the strings
      afterwards */
   dst->set = src->set;
-  Curl_mime_initpart(&dst->set.mimepost);
+  dst->set.mimepostp = NULL;
 
   /* clear all dest string and blob pointers first, in case we error out
      mid-function */
@@ -927,8 +927,17 @@ static CURLcode dupset(struct Curl_easy *dst, struct Curl_easy *src)
     dst->set.postfields = dst->set.str[i];
   }
 
-  /* Duplicate mime data. */
-  result = Curl_mime_duppart(dst, &dst->set.mimepost, &src->set.mimepost);
+  if(src->set.mimepostp) {
+    /* Duplicate mime data. Get a mimepost struct for the clone as well */
+    dst->set.mimepostp = curlx_malloc(sizeof(*dst->set.mimepostp));
+    if(!dst->set.mimepostp)
+      return CURLE_OUT_OF_MEMORY;
+
+    Curl_mime_initpart(dst->set.mimepostp);
+    result = Curl_mime_duppart(dst, dst->set.mimepostp, src->set.mimepostp);
+    if(result)
+      return result;
+  }
 
   if(src->set.resolve)
     dst->state.resolve = dst->set.resolve;

lib/http.c

@@ -2117,7 +2117,7 @@ static CURLcode set_post_reader(struct Curl_easy *data, Curl_HttpReq httpreq)
   switch(httpreq) {
 #ifndef CURL_DISABLE_MIME
   case HTTPREQ_POST_MIME:
-    data->state.mimepost = &data->set.mimepost;
+    data->state.mimepost = data->set.mimepostp;
     break;
 #endif
 #ifndef CURL_DISABLE_FORM_API

lib/imap.c

@@ -859,22 +859,23 @@ static CURLcode imap_perform_append(struct Curl_easy *data,
 
 #ifndef CURL_DISABLE_MIME
   /* Prepare the mime data if some. */
-  if(data->set.mimepost.kind != MIMEKIND_NONE) {
+  if(IS_MIME_POST(data)) {
+    curl_mimepart *postp = data->set.mimepostp;
     /* Use the whole structure as data. */
-    data->set.mimepost.flags &= ~(unsigned int)MIME_BODY_ONLY;
+    postp->flags &= ~(unsigned int)MIME_BODY_ONLY;
 
     /* Add external headers and mime version. */
-    curl_mime_headers(&data->set.mimepost, data->set.headers, 0);
-    result = Curl_mime_prepare_headers(data, &data->set.mimepost, NULL,
+    curl_mime_headers(postp, data->set.headers, 0);
+    result = Curl_mime_prepare_headers(data, postp, NULL,
                                        NULL, MIMESTRATEGY_MAIL);
 
     if(!result)
       if(!Curl_checkheaders(data, STRCONST("Mime-Version")))
-        result = Curl_mime_add_header(&data->set.mimepost.curlheaders,
+        result = Curl_mime_add_header(&postp->curlheaders,
                                       "Mime-Version: 1.0");
 
     if(!result)
-      result = Curl_creader_set_mime(data, &data->set.mimepost);
+      result = Curl_creader_set_mime(data, postp);
     if(result)
       return result;
     data->state.infilesize = Curl_creader_client_length(data);

lib/setopt.c

@@ -1383,6 +1383,38 @@ static CURLcode setopt_slist(struct Curl_easy *data, CURLoption option,
   return result;
 }
 
+#if !defined(CURL_DISABLE_HTTP) || !defined(CURL_DISABLE_SMTP) ||       \
+  !defined(CURL_DISABLE_IMAP)
+# ifndef CURL_DISABLE_MIME
+static CURLcode setopt_mimepost(struct Curl_easy *data, curl_mime *mimep)
+{
+  /*
+   * Set to make us do MIME POST
+   */
+  CURLcode result;
+  struct UserDefined *s = &data->set;
+  if(!s->mimepostp) {
+    s->mimepostp = curlx_malloc(sizeof(*s->mimepostp));
+    if(!s->mimepostp)
+      return CURLE_OUT_OF_MEMORY;
+    Curl_mime_initpart(s->mimepostp);
+  }
+
+  result = Curl_mime_set_subparts(s->mimepostp, mimep, FALSE);
+  if(!result) {
+    s->method = HTTPREQ_POST_MIME;
+    s->opt_no_body = FALSE; /* this is implied */
+#ifndef CURL_DISABLE_FORM_API
+    Curl_mime_cleanpart(data->state.formp);
+    Curl_safefree(data->state.formp);
+    data->state.mimepost = NULL;
+#endif
+  }
+  return result;
+}
+#endif /* !CURL_DISABLE_MIME */
+#endif /* !CURL_DISABLE_HTTP || !CURL_DISABLE_SMTP || !CURL_DISABLE_IMAP */
+
 /* assorted pointer type arguments */
 static CURLcode setopt_pointers(struct Curl_easy *data, CURLoption option,
                                 va_list param)
@@ -1405,25 +1437,11 @@ static CURLcode setopt_pointers(struct Curl_easy *data, CURLoption option,
     break;
 #endif /* !CURL_DISABLE_FORM_API */
 #endif /* !CURL_DISABLE_HTTP */
-#if !defined(CURL_DISABLE_HTTP) || !defined(CURL_DISABLE_SMTP) || \
+#if !defined(CURL_DISABLE_HTTP) || !defined(CURL_DISABLE_SMTP) ||       \
   !defined(CURL_DISABLE_IMAP)
 # ifndef CURL_DISABLE_MIME
   case CURLOPT_MIMEPOST:
-    /*
-     * Set to make us do MIME POST
-     */
-    result = Curl_mime_set_subparts(&s->mimepost,
-                                    va_arg(param, curl_mime *),
-                                    FALSE);
-    if(!result) {
-      s->method = HTTPREQ_POST_MIME;
-      s->opt_no_body = FALSE; /* this is implied */
-#ifndef CURL_DISABLE_FORM_API
-      Curl_mime_cleanpart(data->state.formp);
-      Curl_safefree(data->state.formp);
-      data->state.mimepost = NULL;
-#endif
-    }
+    result = setopt_mimepost(data, va_arg(param, curl_mime *));
     break;
 #endif /* !CURL_DISABLE_MIME */
 #endif /* !CURL_DISABLE_HTTP || !CURL_DISABLE_SMTP || !CURL_DISABLE_IMAP */

lib/smtp.c

@@ -766,22 +766,24 @@ static CURLcode smtp_perform_mail(struct Curl_easy *data,
 
 #ifndef CURL_DISABLE_MIME
   /* Prepare the mime data if some. */
-  if(data->set.mimepost.kind != MIMEKIND_NONE) {
+  if(IS_MIME_POST(data)) {
+    curl_mimepart *postp = data->set.mimepostp;
+
     /* Use the whole structure as data. */
-    data->set.mimepost.flags &= ~(unsigned int)MIME_BODY_ONLY;
+    postp->flags &= ~(unsigned int)MIME_BODY_ONLY;
 
     /* Add external headers and mime version. */
-    curl_mime_headers(&data->set.mimepost, data->set.headers, 0);
-    result = Curl_mime_prepare_headers(data, &data->set.mimepost, NULL,
+    curl_mime_headers(postp, data->set.headers, 0);
+    result = Curl_mime_prepare_headers(data, postp, NULL,
                                        NULL, MIMESTRATEGY_MAIL);
 
     if(!result)
       if(!Curl_checkheaders(data, STRCONST("Mime-Version")))
-        result = Curl_mime_add_header(&data->set.mimepost.curlheaders,
+        result = Curl_mime_add_header(&postp->curlheaders,
                                       "Mime-Version: 1.0");
 
     if(!result)
-      result = Curl_creader_set_mime(data, &data->set.mimepost);
+      result = Curl_creader_set_mime(data, postp);
     if(result)
       goto out;
     data->state.infilesize = Curl_creader_total_length(data);

lib/url.c

@@ -175,7 +175,8 @@ void Curl_freeset(struct Curl_easy *data)
   Curl_bufref_free(&data->state.referer);
   Curl_bufref_free(&data->state.url);
 
-  Curl_mime_cleanpart(&data->set.mimepost);
+  Curl_mime_cleanpart(data->set.mimepostp);
+  Curl_safefree(data->set.mimepostp);
 
 #ifndef CURL_DISABLE_COOKIES
   curl_slist_free_all(data->state.cookielist);
@@ -385,8 +386,6 @@ void Curl_init_userdefined(struct Curl_easy *data)
   set->socks5auth = CURLAUTH_BASIC | CURLAUTH_GSSAPI;
 #endif
 
-  Curl_mime_initpart(&set->mimepost);
-
   Curl_ssl_easy_config_init(data);
 #ifndef CURL_DISABLE_DOH
   set->doh_verifyhost = TRUE;

lib/urldata.h

@@ -1341,7 +1341,7 @@ struct UserDefined {
   struct curl_slist *headers; /* linked list of extra headers */
   struct curl_httppost *httppost;  /* linked list of old POST data */
 #if !defined(CURL_DISABLE_MIME) || !defined(CURL_DISABLE_FORM_API)
-  curl_mimepart mimepost;  /* MIME/POST data. */
+  curl_mimepart *mimepostp;  /* MIME/POST data. */
 #endif
 #ifndef CURL_DISABLE_TELNET
   struct curl_slist *telnet_options; /* linked list of telnet options */
@@ -1591,7 +1591,8 @@ struct UserDefined {
 };
 
 #ifndef CURL_DISABLE_MIME
-#define IS_MIME_POST(a) ((a)->set.mimepost.kind != MIMEKIND_NONE)
+#define IS_MIME_POST(a)                                                 \
+  ((a)->set.mimepostp && ((a)->set.mimepostp->kind != MIMEKIND_NONE))
 #else
 #define IS_MIME_POST(a) FALSE
 #endif

tests/libtest/lib589.c

@@ -27,6 +27,8 @@ static CURLcode test_lib589(const char *URL)
 {
   CURL *curl;
   CURLcode result = CURLE_OK;
+  curl_mime *mime = NULL;
+  curl_mimepart *part;
 
   if(curl_global_init(CURL_GLOBAL_ALL) != CURLE_OK) {
     curl_mfprintf(stderr, "curl_global_init() failed\n");
@@ -46,13 +48,14 @@ static CURLcode test_lib589(const char *URL)
   test_setopt(curl, CURLOPT_HEADER, 1L); /* include header */
 
   if(testnum == 584) {
-    curl_mime *mime = curl_mime_init(curl);
-    curl_mimepart *part = curl_mime_addpart(mime);
-    curl_mime_name(part, "fake");
-    curl_mime_data(part, "party", 5);
-    test_setopt(curl, CURLOPT_MIMEPOST, mime);
-    result = curl_easy_perform(curl);
-    curl_mime_free(mime);
+    mime = curl_mime_init(curl);
+    part = curl_mime_addpart(mime);
+    if(mime && part) {
+      curl_mime_name(part, "fake");
+      curl_mime_data(part, "party", 5);
+      test_setopt(curl, CURLOPT_MIMEPOST, mime);
+      result = curl_easy_perform(curl);
+    }
     if(result)
       goto test_cleanup;
   }
@@ -65,6 +68,7 @@ static CURLcode test_lib589(const char *URL)
 test_cleanup:
 
   /* always cleanup */
+  curl_mime_free(mime);
   curl_easy_cleanup(curl);
   curl_global_cleanup();
 

tests/unit/unit3214.c

@@ -41,7 +41,7 @@ static void checksize(const char *name, size_t size, size_t allowed)
 }
 
 /* the maximum sizes we allow specific structs to grow to */
-#define MAX_CURL_EASY           5850
+#define MAX_CURL_EASY           5370
 #define MAX_CONNECTDATA         1300
 #define MAX_CURL_MULTI          850
 #define MAX_CURL_HTTPPOST       112