From 45face3ba147a4c5f4f7e09cf10c95986b915002 Mon Sep 17 00:00:00 2001 From: Gary Benson Date: Wed, 19 Aug 2015 13:53:24 +0100 Subject: [PATCH] Prelimit number of bytes to read in "vFile:pread:" While handling "vFile:pread:" packets, gdbserver would read the number of bytes requested regardless of whether this would fit into the reply packet. gdbserver would then return a packet's worth of data and discard the remainder. When accessing large binaries GDB (via BFD) routinely makes large "vFile:pread:" requests, resulting in gdbserver allocating large unnecessary buffers and reading some portions of the file many times over. This commit causes gdbserver to limit the number of bytes to be read to a sensible maximum prior to allocating buffers and reading data. gdb/gdbserver/ChangeLog: * hostio.c (handle_pread): Do not attempt to read more data than hostio_reply_with_data can fit in a packet. --- gdb/gdbserver/ChangeLog | 5 +++++ gdb/gdbserver/hostio.c | 12 ++++++++++++ 2 files changed, 17 insertions(+) diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 2764d28f59..ef497492d9 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,8 @@ +2015-08-19 Gary Benson + + * hostio.c (handle_pread): Do not attempt to read more data + than hostio_reply_with_data can fit in a packet. + 2015-08-18 Joel Brobecker * linux-aarch32-low.c (NT_ARM_VFP): Define if not already defined. diff --git a/gdb/gdbserver/hostio.c b/gdb/gdbserver/hostio.c index b38a6bd056..8788f07391 100644 --- a/gdb/gdbserver/hostio.c +++ b/gdb/gdbserver/hostio.c @@ -344,6 +344,7 @@ handle_pread (char *own_buf, int *new_packet_len) { int fd, ret, len, offset, bytes_sent; char *p, *data; + static int max_reply_size = -1; p = own_buf + strlen ("vFile:pread:"); @@ -359,6 +360,17 @@ handle_pread (char *own_buf, int *new_packet_len) return; } + /* Do not attempt to read more than the maximum number of bytes + hostio_reply_with_data can fit in a packet. We may still read + too much because of escaping, but this is handled below. */ + if (max_reply_size == -1) + { + sprintf (own_buf, "F%x;", PBUFSIZ); + max_reply_size = PBUFSIZ - strlen (own_buf); + } + if (len > max_reply_size) + len = max_reply_size; + data = xmalloc (len); #ifdef HAVE_PREAD ret = pread (fd, data, len, offset);