Optionally return bytes received from http_file_get()

`http_dl->bytes_received` was already free'd when it was accessed inside
`aesgcm_file_get()`.

Change `http_file_get()` to optionally return the number of bytes received
so we know how much data we have to decrypt.

This fixes #1994

Signed-off-by: Steffen Jaeckel <s@jaeckel.eu>

src/tools/aesgcm_download.c

@@ -109,9 +109,15 @@ aesgcm_file_get(void* userdata)
     http_dl->filename = strdup(tmpname);
     http_dl->cmd_template = NULL;
     http_dl->silent = FALSE;
+    http_dl->return_bytes_received = TRUE;
     aesgcm_dl->http_dl = http_dl;
 
-    http_file_get(http_dl); // TODO(wstrm): Verify result.
+    ssize_t* p_bytes_received = http_file_get(http_dl);
+    if (!p_bytes_received) {
+        return NULL;
+    }
+    ssize_t bytes_received = *p_bytes_received;
+    free(p_bytes_received);
 
     auto_FILE FILE* tmpfh = fopen(tmpname, "rb");
     if (tmpfh == NULL) {
@@ -125,7 +131,7 @@ aesgcm_file_get(void* userdata)
 
     gcry_error_t crypt_res;
     crypt_res = omemo_decrypt_file(tmpfh, outfh,
-                                   http_dl->bytes_received, fragment);
+                                   bytes_received, fragment);
 
     remove(tmpname);
 

src/tools/http_download.c

@@ -105,6 +105,7 @@ void*
 http_file_get(void* userdata)
 {
     HTTPDownload* download = (HTTPDownload*)userdata;
+    ssize_t* ret = NULL;
 
     char* err = NULL;
 
@@ -208,6 +209,10 @@ http_file_get(void* userdata)
                                        "Downloading '%s': done\nSaved to '%s'",
                                        download->url, download->filename);
             win_mark_received(download->window, download->id);
+            if (download->return_bytes_received) {
+                ret = malloc(sizeof(*ret));
+                *ret = download->bytes_received;
+            }
         }
     }
 
@@ -241,7 +246,7 @@ out:
     free(download->id);
     free(download);
 
-    return NULL;
+    return ret;
 }
 
 void

src/tools/http_download.h

@@ -58,6 +58,7 @@ typedef struct http_download_t
     pthread_t worker;
     int cancel;
     gboolean silent;
+    gboolean return_bytes_received;
 } HTTPDownload;
 
 void* http_file_get(void* userdata);