lib: let the max filesize option stop too big transfers too

Previously it would only stop them from getting started if the size is
known to be too big then.

Update the libcurl and curl docs accordingly.

Fixes #11810
Reported-by: Elliot Killick
Assisted-by: Jay Satiro
Closes #11820

docs/cmdline-opts/max-filesize.d

@@ -18,6 +18,9 @@ A size modifier may be used. For example, Appending 'k' or 'K' counts the
 number as kilobytes, 'm' or 'M' makes it megabytes, while 'g' or 'G' makes it
 gigabytes. Examples: 200K, 3m and 1G. (Added in 7.58.0)
 
-**NOTE**: The file size is not always known prior to download, and for such
-files this option has no effect even if the file transfer ends up being larger
-than this given limit.
+**NOTE**: before curl 8.4.0, when the file size is not known prior to
+download, for such files this option has no effect even if the file transfer
+ends up being larger than this given limit.
+
+Starting with curl 8.4.0, this option aborts the transfer if it reaches the
+threshold during transfer.

docs/libcurl/opts/CURLOPT_MAXFILESIZE.3

@@ -41,6 +41,9 @@ transfers this option has no effect - even if the file transfer eventually
 ends up being larger than this given limit.
 
 If you want a limit above 2GB, use \fICURLOPT_MAXFILESIZE_LARGE(3)\fP.
+
+Since 8.4.0, this option also stops ongoing transfers if they reach this
+threshold.
 .SH DEFAULT
 None
 .SH PROTOCOLS

docs/libcurl/opts/CURLOPT_MAXFILESIZE_LARGE.3

@@ -40,6 +40,9 @@ returned.
 The file size is not always known prior to the download start, and for such
 transfers this option has no effect - even if the file transfer eventually
 ends up being larger than this given limit.
+
+Since 8.4.0, this option also stops ongoing transfers if they reach this
+threshold.
 .SH DEFAULT
 None
 .SH PROTOCOLS

lib/c-hyper.c

@@ -258,7 +258,11 @@ static int hyper_body_chunk(void *userdata, const hyper_buf *chunk)
   }
 
   data->req.bytecount += len;
-  Curl_pgrsSetDownloadCounter(data, data->req.bytecount);
+  result = Curl_pgrsSetDownloadCounter(data, data->req.bytecount);
+  if(result) {
+    data->state.hresult = result;
+    return HYPER_ITER_BREAK;
+  }
   return HYPER_ITER_CONTINUE;
 }
 

lib/file.c

@@ -571,7 +571,9 @@ static CURLcode file_do(struct Curl_easy *data, bool *done)
     if(result)
       return result;
 
-    Curl_pgrsSetDownloadCounter(data, bytecount);
+    result = Curl_pgrsSetDownloadCounter(data, bytecount);
+    if(result)
+      return result;
 
     if(Curl_pgrsUpdate(data))
       result = CURLE_ABORTED_BY_CALLBACK;

lib/ldap.c

@@ -735,7 +735,9 @@ static CURLcode ldap_do(struct Curl_easy *data, bool *done)
       if(result)
         goto quit;
       dlsize++;
-      Curl_pgrsSetDownloadCounter(data, dlsize);
+      result = Curl_pgrsSetDownloadCounter(data, dlsize);
+      if(result)
+        goto quit;
     }
 
     if(ber)

lib/mqtt.c

@@ -668,7 +668,9 @@ MQTT_SUBACK_COMING:
 
     mq->npacket -= nread;
     k->bytecount += nread;
-    Curl_pgrsSetDownloadCounter(data, k->bytecount);
+    result = Curl_pgrsSetDownloadCounter(data, k->bytecount);
+    if(result)
+      goto end;
 
     /* if QoS is set, message contains packet id */
 

lib/progress.c

@@ -317,9 +317,16 @@ timediff_t Curl_pgrsLimitWaitTime(curl_off_t cursize,
 /*
  * Set the number of downloaded bytes so far.
  */
-void Curl_pgrsSetDownloadCounter(struct Curl_easy *data, curl_off_t size)
+CURLcode Curl_pgrsSetDownloadCounter(struct Curl_easy *data, curl_off_t size)
 {
+  if(data->set.max_filesize && (size > data->set.max_filesize)) {
+    failf(data, "Exceeded the maximum allowed file size "
+          "(%" CURL_FORMAT_CURL_OFF_T ")",
+          data->set.max_filesize);
+    return CURLE_FILESIZE_EXCEEDED;
+  }
   data->progress.downloaded = size;
+  return CURLE_OK;
 }
 
 /*

lib/progress.h

@@ -46,7 +46,10 @@ int Curl_pgrsDone(struct Curl_easy *data);
 void Curl_pgrsStartNow(struct Curl_easy *data);
 void Curl_pgrsSetDownloadSize(struct Curl_easy *data, curl_off_t size);
 void Curl_pgrsSetUploadSize(struct Curl_easy *data, curl_off_t size);
-void Curl_pgrsSetDownloadCounter(struct Curl_easy *data, curl_off_t size);
+
+/* It is fine to not check the return code if 'size' is set to 0 */
+CURLcode Curl_pgrsSetDownloadCounter(struct Curl_easy *data, curl_off_t size);
+
 void Curl_pgrsSetUploadCounter(struct Curl_easy *data, curl_off_t size);
 void Curl_ratelimit(struct Curl_easy *data, struct curltime now);
 int Curl_pgrsUpdate(struct Curl_easy *data);

lib/smb.c

@@ -1049,7 +1049,12 @@ static CURLcode smb_request_state(struct Curl_easy *data, bool *done)
     }
     data->req.bytecount += len;
     data->req.offset += len;
-    Curl_pgrsSetDownloadCounter(data, data->req.bytecount);
+    result = Curl_pgrsSetDownloadCounter(data, data->req.bytecount);
+    if(result) {
+      req->result = result;
+      next_state = SMB_CLOSE;
+      break;
+    }
     next_state = (len < MAX_PAYLOAD_SIZE) ? SMB_CLOSE : SMB_DOWNLOAD;
     break;
 

lib/telnet.c

@@ -1570,8 +1570,9 @@ static CURLcode telnet_do(struct Curl_easy *data, bool *done)
         }
 
         total_dl += nread;
-        Curl_pgrsSetDownloadCounter(data, total_dl);
-        result = telrcv(data, (unsigned char *)buf, nread);
+        result = Curl_pgrsSetDownloadCounter(data, total_dl);
+        if(!result)
+          result = telrcv(data, (unsigned char *)buf, nread);
         if(result) {
           keepon = FALSE;
           break;

lib/tftp.c

@@ -1141,12 +1141,15 @@ static CURLcode tftp_receive_packet(struct Curl_easy *data)
         result = Curl_client_write(data, CLIENTWRITE_BODY,
                                    (char *)state->rpacket.data + 4,
                                    state->rbytes-4);
+        if(!result) {
+          k->bytecount += state->rbytes-4;
+          result = Curl_pgrsSetDownloadCounter(data,
+                                               (curl_off_t) k->bytecount);
+        }
         if(result) {
           tftp_state_machine(state, TFTP_EVENT_ERROR);
           return result;
         }
-        k->bytecount += state->rbytes-4;
-        Curl_pgrsSetDownloadCounter(data, (curl_off_t) k->bytecount);
       }
       break;
     case TFTP_EVENT_ERROR:

lib/transfer.c

@@ -671,7 +671,9 @@ static CURLcode readwrite_data(struct Curl_easy *data,
       k->bytecount += nread;
       max_recv -= nread;
 
-      Curl_pgrsSetDownloadCounter(data, k->bytecount);
+      result = Curl_pgrsSetDownloadCounter(data, k->bytecount);
+      if(result)
+        goto out;
 
       if(!k->chunk && (nread || k->badheader || is_empty_data)) {
         /* If this is chunky transfer, it was already written */