Fix for #22721 (poor file() performance on systems without mmap)

diff --git a/main/streams/streams.c b/main/streams/streams.c
index 68ed1104512f7dbf53a9cf085b4b581c20f2d486..72d75c40195c75ca252e9804767543fb703b53cc 100755 (executable)
--- a/main/streams/streams.c
+++ b/main/streams/streams.c
@@ -1100,6 +1100,7 @@ PHPAPI size_t _php_stream_copy_to_mem(php_stream *src, char **buf, size_t maxlen
        size_t len = 0, max_len;
        int step = CHUNK_SIZE;
        int min_room = CHUNK_SIZE / 4;
+       php_stream_statbuf ssbuf;
 
        if (buf)
                *buf = NULL;
@@ -1129,9 +1130,20 @@ PHPAPI size_t _php_stream_copy_to_mem(php_stream *src, char **buf, size_t maxlen
                        return mapped;
                }
        }
+       
+       /* avoid many reallocs by allocating a good sized chunk to begin with, if we can.
+        * Note that the stream may be filtered, in which case the stat result may be inaccurate,
+        * as the filter may inflate or deflate the number of bytes that we can read.
+        * In order to avoid an upsize followed by a downsize of the buffer, overestimate by the
+        * step size (which is 2K).
+        * */
+       if (php_stream_stat(src, &ssbuf) == 0 && ssbuf.sb.st_size > 0) {
+               max_len = ssbuf.sb.st_size + step;
+       } else {
+               max_len = step;
+       }
 
-       ptr = *buf = pemalloc_rel_orig(step, persistent);
-       max_len = step;
+       ptr = *buf = pemalloc_rel_orig(max_len, persistent);
 
        while((ret = php_stream_read(src, ptr, max_len - len))) {
                len += ret;