From 0e2ffa3632d3fd481c75a36cc176ddb1614f8107 Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Tue, 13 Feb 2024 11:39:06 +0100
Subject: [PATCH] file: use xfer buf for file:// transfers

- For file:// transfers use the multi handle's transfer buffer for
  up- and downloads.

Prior to this change a6c9a33 (precedes 8.6.0) changed the file://
transfers to use a smaller stack based buffer, and that caused a
significant performance decrease in Windows.

Bug: https://github.com/curl/curl/issues/12750#issuecomment-1920103086
Reported-by: edmcln@users.noreply.github.com

Closes https://github.com/curl/curl/pull/12932
---
 lib/file.c | 48 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 34 insertions(+), 14 deletions(-)

diff --git a/lib/file.c b/lib/file.c
index b7ce3a8eda..63089e0f2a 100644
--- a/lib/file.c
+++ b/lib/file.c
@@ -59,6 +59,7 @@
 #include "file.h"
 #include "speedcheck.h"
 #include "getinfo.h"
+#include "multiif.h"
 #include "transfer.h"
 #include "url.h"
 #include "parsedate.h" /* for the week day and month names */
@@ -290,7 +291,9 @@ static CURLcode file_upload(struct Curl_easy *data)
   int fd;
   int mode;
   CURLcode result = CURLE_OK;
-  char buffer[8*1024], *uphere_save;
+  char *xfer_buf;
+  size_t xfer_blen;
+  char *uphere_save;
   curl_off_t bytecount = 0;
   struct_stat file_stat;
   const char *sendbuf;
@@ -340,12 +343,18 @@ static CURLcode file_upload(struct Curl_easy *data)
   /* Yikes! Curl_fillreadbuffer uses data->req.upload_fromhere to READ
    * client data to! Please, someone fix... */
   uphere_save = data->req.upload_fromhere;
+
+  result = Curl_multi_xfer_buf_borrow(data, &xfer_buf, &xfer_blen);
+  if(result)
+    goto out;
+
   while(!result) {
     size_t nread;
     ssize_t nwrite;
     size_t readcount;
-    data->req.upload_fromhere = buffer;
-    result = Curl_fillreadbuffer(data, sizeof(buffer), &readcount);
+
+    data->req.upload_fromhere = xfer_buf;
+    result = Curl_fillreadbuffer(data, xfer_blen, &readcount);
     if(result)
       break;
 
@@ -359,16 +368,16 @@ static CURLcode file_upload(struct Curl_easy *data)
       if((curl_off_t)nread <= data->state.resume_from) {
         data->state.resume_from -= nread;
         nread = 0;
-        sendbuf = buffer;
+        sendbuf = xfer_buf;
       }
       else {
-        sendbuf = buffer + data->state.resume_from;
+        sendbuf = xfer_buf + data->state.resume_from;
         nread -= (size_t)data->state.resume_from;
         data->state.resume_from = 0;
       }
     }
     else
-      sendbuf = buffer;
+      sendbuf = xfer_buf;
 
     /* write the data to the target */
     nwrite = write(fd, sendbuf, nread);
@@ -389,7 +398,9 @@ static CURLcode file_upload(struct Curl_easy *data)
   if(!result && Curl_pgrsUpdate(data))
     result = CURLE_ABORTED_BY_CALLBACK;
 
+out:
   close(fd);
+  Curl_multi_xfer_buf_release(data, xfer_buf);
   data->req.upload_fromhere = uphere_save;
 
   return result;
@@ -419,6 +430,8 @@ static CURLcode file_do(struct Curl_easy *data, bool *done)
   bool fstated = FALSE;
   int fd;
   struct FILEPROTO *file;
+  char *xfer_buf;
+  size_t xfer_blen;
 
   *done = TRUE; /* unconditionally */
 
@@ -543,23 +556,26 @@ static CURLcode file_do(struct Curl_easy *data, bool *done)
 
   Curl_pgrsTime(data, TIMER_STARTTRANSFER);
 
+  result = Curl_multi_xfer_buf_borrow(data, &xfer_buf, &xfer_blen);
+  if(result)
+    goto out;
+
   while(!result) {
-    char tmpbuf[8*1024];
     ssize_t nread;
     /* Don't fill a whole buffer if we want less than all data */
     size_t bytestoread;
 
     if(size_known) {
-      bytestoread = (expected_size < (curl_off_t)(sizeof(tmpbuf)-1)) ?
-        curlx_sotouz(expected_size) : (sizeof(tmpbuf)-1);
+      bytestoread = (expected_size < (curl_off_t)(xfer_blen-1)) ?
+        curlx_sotouz(expected_size) : (xfer_blen-1);
     }
     else
-      bytestoread = sizeof(tmpbuf)-1;
+      bytestoread = xfer_blen-1;
 
-    nread = read(fd, tmpbuf, bytestoread);
+    nread = read(fd, xfer_buf, bytestoread);
 
     if(nread > 0)
-      tmpbuf[nread] = 0;
+      xfer_buf[nread] = 0;
 
     if(nread <= 0 || (size_known && (expected_size == 0)))
       break;
@@ -567,18 +583,22 @@ static CURLcode file_do(struct Curl_easy *data, bool *done)
     if(size_known)
       expected_size -= nread;
 
-    result = Curl_client_write(data, CLIENTWRITE_BODY, tmpbuf, nread);
+    result = Curl_client_write(data, CLIENTWRITE_BODY, xfer_buf, nread);
     if(result)
-      return result;
+      goto out;
 
     if(Curl_pgrsUpdate(data))
       result = CURLE_ABORTED_BY_CALLBACK;
     else
       result = Curl_speedcheck(data, Curl_now());
+    if(result)
+      goto out;
   }
   if(Curl_pgrsUpdate(data))
     result = CURLE_ABORTED_BY_CALLBACK;
 
+out:
+  Curl_multi_xfer_buf_release(data, xfer_buf);
   return result;
 }