joshenders

Importing Hand-Rolled C Header Files in LLDB

Scenario

• We're debugging a dylib, libhello.dylib
• The dylib is linked from hello
• The exported function is helloworld()
• We do not have source, but have reversed a struct from the library and created a hand-crafted header file

Header File

joshenders

Getting started with Nintendo Switch Development using devkitpro on macOS

Prerequsite: Ensure Xcode command line tools are installed

xcode-select --install

Install the devkitpro Package Manager

joshenders

Making a UEFI bootable iPXE USB drive

Build the UEFI executable for iPXE

# First we'll clone iPXE
$ git clone git://git.ipxe.org/ipxe.git
# Go into the src directory of the cloned git repo
$ cd ipxe/src
# Compile the UEFI iPXE executable

joshenders

--- debian/varnish.init	2016-12-13 01:13:34.465123880 +0000
+++ debian/varnish.init.new	2016-12-13 01:18:50.215749771 +0000
@@ -88,8 +88,10 @@
     log_daemon_msg "Reloading $DESC" "$NAME"
     if /usr/share/varnish/reload-vcl -q; then
         log_end_msg 0
+        return 0
     else
         log_end_msg 1
+        return 1

joshenders

Background

The current verison of NodeJS hardcodes the path where perf data is written when the --perf-basic-prof flag is used.

https://github.com/v8/v8/blob/061c2ab23a1d4cd192b935e7912e7dfb1fed845d/src/log.cc#L236

At Pinterest, /tmp has limited capacity and so we weren't able to utilize perf data to troubleshoot NodeJS without filling the disk and crashing the running system.

How to patch

First I'll copy the system node binary to my local directory so this set of actions isn't destructive to the running system:

joshenders

--- rules	2016-11-25 23:23:25.924313744 +0000
+++ rules.new	2016-11-25 23:23:17.788331016 +0000
@@ -15,7 +15,7 @@
 DEB_HOST_ARCH ?= $(shell dpkg-architecture -qDEB_HOST_ARCH)

 # Set local state dir for FHS
-LOCAL_CONFIGURE_FLAGS = --localstatedir=/var/lib
+LOCAL_CONFIGURE_FLAGS = --localstatedir=/var/lib --enable-debugging-symbols

 ifneq ($(filter $(DEB_HOST_ARCH),$(DISABLE_JEMALLOC_ARCH_LIST)),)

joshenders

--- debian/control	2012-06-18 18:59:16.000000000 +0000
+++ debian/control 	2016-11-03 07:10:00.536388796 +0000
@@ -36,13 +36,6 @@
   * URL rewriting
   * Graceful handling of "dead" backends

-Package: varnish-doc
-Architecture: all
-Section: doc
-Depends: ${misc:Depends}, libjs-jquery, libjs-underscore

joshenders

--- reload-vcl	2011-10-29 13:24:10.000000000 +0000
+++ /usr/share/varnish/reload-vcl	2016-12-11 09:51:08.696300339 +0000
@@ -1,9 +1,13 @@
 #!/bin/sh
-
+#
 # reload-varnish: Script to reload varnishd from VCL defined in
 # /etc/default/varnish.
 #
 # Stig Sandbeck Mathisen <ssm@debian.org>

joshenders

--- a/bin/varnishd/cache_gzip.c
+++ b/bin/varnishd/cache_gzip.c
@@ -646,9 +646,6 @@
		bytes -= w;
		VGZ_Ibuf(vg, st->ptr + st->len, w);
		st->len += w;
-		sp->obj->len += w;
-		if (sp->wrk->do_stream)
-			RES_StreamPoll(sp);

joshenders

diff --git a/bin/varnishncsa/varnishncsa.c b/bin/varnishncsa/varnishncsa.c
index ff07ed5..3af1367 100644
--- a/bin/varnishncsa/varnishncsa.c
+++ b/bin/varnishncsa/varnishncsa.c
@@ -98,6 +98,7 @@ static struct logline {
	struct tm df_t;			/* %t, Date and time */
	char *df_u;			/* %u, Remote user */
	char *df_ttfb;			/* Time to first byte */
+	char *df_ttlb;			/* Time to last byte */
	const char *df_hitmiss;		/* Whether this is a hit or miss */