[mod_webdav] use copy_file_range() if available

SConstruct

@@ -386,6 +386,7 @@ if 1:
 		'arc4random_buf',
 		'chroot',
 		'clock_gettime',
+		'copy_file_range',
 		'dup2',
 		'epoll_ctl',
 		'explicit_bzero',

configure.ac

@@ -1216,6 +1216,7 @@ AC_CHECK_FUNCS([\
   arc4random_buf \
   chroot \
   clock_gettime \
+  copy_file_range \
   epoll_ctl \
   explicit_bzero \
   explicit_memset \

src/CMakeLists.txt

@@ -150,6 +150,7 @@ check_type_size(off_t SIZEOF_OFF_T)
 
 check_function_exists(arc4random_buf HAVE_ARC4RANDOM_BUF)
 check_function_exists(chroot HAVE_CHROOT)
+check_function_exists(copy_file_range HAVE_COPY_FILE_RANGE)
 check_function_exists(epoll_ctl HAVE_EPOLL_CTL)
 check_function_exists(fork HAVE_FORK)
 check_function_exists(getloadavg HAVE_GETLOADAVG)

src/meson.build

@@ -113,6 +113,7 @@ conf_data.set('SIZEOF_OFF_T', compiler.sizeof('off_t', args: defs))
 
 conf_data.set('HAVE_ARC4RANDOM_BUF', compiler.has_function('arc4random_buf', args: defs))
 conf_data.set('HAVE_CHROOT', compiler.has_function('chroot', args: defs))
+conf_data.set('HAVE_COPY_FILE_RANGE', compiler.has_function('copy_file_range', args: defs))
 conf_data.set('HAVE_EPOLL_CTL', compiler.has_function('epoll_ctl', args: defs))
 conf_data.set('HAVE_FORK', compiler.has_function('fork', args: defs))
 conf_data.set('HAVE_GETLOADAVG', compiler.has_function('getloadavg', args: defs))

src/mod_webdav.c

@@ -4369,11 +4369,11 @@ mod_webdav_put_deprecated_unsafe_partial_put_compat (connection * const con,
     const char *num = h->ptr;
     off_t offset;
     char *err;
-    if (0 != strncmp(num, "bytes", sizeof("bytes")-1)) {
+    if (0 != strncmp(num, "bytes ", sizeof("bytes ")-1)) {
         http_status_set_error(con, 501); /* Not Implemented */
         return HANDLER_FINISHED;
     }
-    num += 5; /* +5 for "bytes" */
+    num += sizeof("bytes ")-1; /* +6 for "bytes " */
     offset = strtoll(num, &err, 10); /*(strtoll() ignores leading whitespace)*/
     if (num == err || *err != '-' || offset < 0) {
         http_status_set_error(con, 501); /* Not Implemented */
@@ -4387,6 +4387,27 @@ mod_webdav_put_deprecated_unsafe_partial_put_compat (connection * const con,
         return HANDLER_FINISHED;
     }
 
+  #ifdef HAVE_COPY_FILE_RANGE
+    /* use Linux copy_file_range() if available
+     * (Linux 4.5, but glibc 2.27 provides a user-space emulation)
+     * fd_in and fd_out must be on same mount (handled in mod_webdav_put_prep())
+     * check that reqbody is contained in single tempfile and open fd (expected)
+     * (Note: copying might take some time, temporarily pausing server)
+     */
+    chunkqueue * const cq = con->request_content_queue;
+    chunk *c = cq->first;
+    off_t cqlen = chunkqueue_length(cq);
+    if (c->type == FILE_CHUNK && NULL == c->next && c->file.fd >= 0) {
+        loff_t zoff = 0;
+        loff_t ooff = offset;
+        ssize_t wr;
+        do {
+            wr = copy_file_range(c->file.fd,&zoff,fd,&ooff,(size_t)cqlen, 0);
+        } while (wr >= 0 && (cqlen -= wr));
+    }
+    if (0 != cqlen) /* fallback, retry if copy_file_range() did not finish */
+  #endif
+  {
     if (-1 == lseek(fd, offset, SEEK_SET)) {
         close(fd);
         http_status_set_error(con, 500); /* Internal Server Error */
@@ -4398,6 +4419,7 @@ mod_webdav_put_deprecated_unsafe_partial_put_compat (connection * const con,
      * (Note: copying might take some time, temporarily pausing server)
      * (error status is set if error occurs) */
     mod_webdav_write_cq(con, con->request_content_queue, fd);
+  }
 
     struct stat st;
     if (0 != con->conf.etag_flags && !http_status_is_set(con)) {