Collect and report kernel warnings.
A flex-based daemon collects kernel warnings by parsing /var/log/messages
as lines are added to it. For every warning the daemon sends a sample
to a sparse UMA histogram using a hash of the warning as the bucket.
Then, if the warning hasn't been seen before, the daemon invokes the
crash collector to upload the warning stack trace.
BUG=chromium:217382
TEST=manually tested (for now), automated test on its way
CQ-DEPEND=Ic8d5773d05d717a275c4a4b5616e0e4c307337b8
CQ-DEPEND=I6a4010acad0ffe20c702bb0fc455e3da7cdf3ac1
Change-Id: I89090e5c2b61ec46b4e740f0895c591728d70e77
Reviewed-on: https://gerrit.chromium.org/gerrit/48277
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Tested-by: Luigi Semenzato <semenzato@chromium.org>
diff --git a/crash_reporter/Makefile b/crash_reporter/Makefile
index 648308f..4a0f488 100644
--- a/crash_reporter/Makefile
+++ b/crash_reporter/Makefile
@@ -12,6 +12,7 @@
CRASH_OBJS = \
crash_collector.o \
kernel_collector.o \
+ kernel_warning_collector.o \
udev_collector.o \
unclean_shutdown_collector.o \
user_collector.o
@@ -44,6 +45,18 @@
all: CXX_BINARY(list_proxies)
+# -- Executable warn_collector --
+
+CC_BINARY(warn_collector): LDLIBS += -lfl -lmetrics
+CC_BINARY(warn_collector): lex.yy.o
+clean: CLEAN(warn_collector)
+all: CC_BINARY(warn_collector)
+lex.yy.c: $(SRC)/warn_collector.l
+ flex $<
+clean: CLEAN(lex.yy.o)
+$(eval $(call add_object_rules,lex.yy.o,CC,c))
+
+
# -- Unit Tests --
# Uncomment these to just run specific test(s).
@@ -65,8 +78,10 @@
tests: TEST(CXX_BINARY($(1)))
endef
+CC_BINARY(warn_collector_test): warn_collector_test.o
+
# If $(TEST_BINS) is not already set, assume any filename matching *_test.cc
# is a test.
TEST_BINS ?= $(patsubst $(SRC)/%.cc,%,$(wildcard $(SRC)/*_test.cc))
$(foreach prog,$(TEST_BINS),$(eval $(call TEST_RULES_template,$(prog))))
-
+tests: TEST(CC_BINARY(warn_collector_test))
diff --git a/crash_reporter/TEST_WARNING b/crash_reporter/TEST_WARNING
new file mode 100644
index 0000000..64ad2e9
--- /dev/null
+++ b/crash_reporter/TEST_WARNING
@@ -0,0 +1,31 @@
+Apr 31 25:25:25 localhost kernel: [117959.226729] [<ffffffff810e16bf>] do_vfs_ioctl+0x469/0x4b3
+Apr 31 25:25:25 localhost kernel: [117959.226738] [<ffffffff810d3117>] ? fsnotify_access+0x58/0x60
+Apr 31 25:25:25 localhost kernel: [117959.226747] [<ffffffff810d3791>] ? vfs_read+0xad/0xd7
+Apr 31 25:25:25 localhost kernel: [117959.226756] [<ffffffff810e175f>] sys_ioctl+0x56/0x7b
+Apr 31 25:25:25 localhost kernel: [117959.226765] [<ffffffff810d37fe>] ? sys_read+0x43/0x73
+Apr 31 25:25:25 localhost kernel: [117959.226774] [<ffffffff8146b7d2>] system_call_fastpath+0x16/0x1b
+Apr 31 25:25:25 localhost kernel: [117959.226782] ---[ end trace f16822cad7406cec ]---
+Apr 31 25:25:25 localhost kernel: [117959.231085] ------------[ cut here ]------------
+Apr 31 25:25:25 localhost kernel: [117959.231100] WARNING: at /mnt/host/source/src/third_party/kernel/files/drivers/gpu/drm/i915/intel_dp.c:351 intel_dp_check_edp+0x6b/0xb9()
+Apr 31 25:25:25 localhost kernel: [117959.231113] Hardware name: Link
+Apr 31 25:25:25 localhost kernel: [117959.231117] eDP powered off while attempting aux channel communication.
+Apr 31 25:25:25 localhost kernel: [117959.231240] Pid: 10508, comm: X Tainted: G WC 3.4.0 #1
+Apr 31 25:25:25 localhost kernel: [117959.231247] Call Trace:
+Apr 31 25:25:25 localhost kernel: [117959.231393] [<ffffffff810d3117>] ? fsnotify_access+0x58/0x60
+Apr 31 25:25:25 localhost kernel: [117959.231402] [<ffffffff810d3791>] ? vfs_read+0xad/0xd7
+Apr 31 25:25:25 localhost kernel: [117959.231411] [<ffffffff810e175f>] sys_ioctl+0x56/0x7b
+Apr 31 25:25:25 localhost kernel: [117959.231420] [<ffffffff810d37fe>] ? sys_read+0x43/0x73
+Apr 31 25:25:25 localhost kernel: [117959.231431] [<ffffffff8146b7d2>] system_call_fastpath+0x16/0x1b
+Apr 31 25:25:25 localhost kernel: [117959.231439] ---[ end trace f16822cad7406ced ]---
+Apr 31 25:25:25 localhost kernel: [117959.231450] ------------[ cut here ]------------
+Apr 31 25:25:25 localhost kernel: [117959.231458] BARNING: at /mnt/host/source/src/third_party/kernel/files/drivers/gpu/drm/i915/intel_dp.c:351 intel_dp_check_edp+0x6b/0xb9()
+Apr 31 25:25:25 localhost kernel: [117959.231458] ("BARNING" above is intentional)
+Apr 31 25:25:25 localhost kernel: [117959.231471] Hardware name: Link
+Apr 31 25:25:25 localhost kernel: [117959.231475] eDP powered off while attempting aux channel communication.
+Apr 31 25:25:25 localhost kernel: [117959.231482] Modules linked in: nls_iso8859_1 nls_cp437 vfat fat rfcomm i2c_dev ath9k_btcoex snd_hda_codec_hdmi snd_hda_codec_ca0132 mac80211 snd_hda_intel ath9k_common_btcoex snd_hda_codec ath9k_hw_btcoex aesni_intel cryptd snd_hwdep ath snd_pcm aes_x86_64 isl29018(C) memconsole snd_timer snd_page_alloc industrialio(C) cfg80211 rtc_cmos nm10_gpio zram(C) zsmalloc(C) lzo_decompress lzo_compress fuse nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_mark option usb_wwan cdc_ether usbnet ath3k btusb bluetooth uvcvideo videobuf2_core videodev videobuf2_vmalloc videobuf2_memops joydev
+Apr 31 25:25:25 localhost kernel: [117959.231588] Pid: 10508, comm: X Tainted: G WC 3.4.0 #1
+Apr 31 25:25:25 localhost kernel: [117959.231595] Call Trace:
+Apr 31 25:25:25 localhost kernel: [117959.231601] [<ffffffff8102a931>] warn_slowpath_common+0x83/0x9c
+Apr 31 25:25:25 localhost kernel: [117959.231610] [<ffffffff8102a9ed>] warn_slowpath_fmt+0x46/0x48
+Apr 31 25:25:25 localhost kernel: [117959.231620] [<ffffffff812af495>] intel_dp_check_edp+0x6b/0xb9
+Apr 31 25:25:25 localhost kernel: [117959.231629] [<ffffffff8102a9ed>] ? warn_slowpath_fmt+
diff --git a/crash_reporter/crash_reporter.cc b/crash_reporter/crash_reporter.cc
index e76c5c8..d298108 100644
--- a/crash_reporter/crash_reporter.cc
+++ b/crash_reporter/crash_reporter.cc
@@ -15,6 +15,7 @@
#include "base/stringprintf.h"
#include "chromeos/syslog_logging.h"
#include "crash-reporter/kernel_collector.h"
+#include "crash-reporter/kernel_warning_collector.h"
#include "crash-reporter/udev_collector.h"
#include "crash-reporter/unclean_shutdown_collector.h"
#include "crash-reporter/user_collector.h"
@@ -30,6 +31,7 @@
DEFINE_string(user, "", "User crash info (pid:signal:exec_name)");
DEFINE_bool(unclean_check, true, "Check for unclean shutdown");
DEFINE_string(udev, "", "Udev event description (type:device:subsystem)");
+DEFINE_bool(kernel_warning, false, "Report collected kernel warning");
#pragma GCC diagnostic error "-Wstrict-aliasing"
static const char kCrashCounterHistogram[] = "Logging.CrashCounter";
@@ -47,6 +49,7 @@
kCrashKindUser = 2,
kCrashKindKernel = 3,
kCrashKindUdev = 4,
+ kCrashKindKernelWarning = 5,
kCrashKindMax
};
@@ -176,6 +179,17 @@
return 0;
}
+static int HandleKernelWarning(KernelWarningCollector
+ *kernel_warning_collector) {
+ // Accumulate logs to help in diagnosing failures during collection.
+ chromeos::LogToString(true);
+ bool handled = kernel_warning_collector->Collect();
+ chromeos::LogToString(false);
+ if (!handled)
+ return 1;
+ return 0;
+}
+
// Interactive/diagnostics mode for generating kernel crash signatures.
static int GenerateKernelSignature(KernelCollector *kernel_collector) {
std::string kcrash_contents;
@@ -238,6 +252,9 @@
UdevCollector udev_collector;
udev_collector.Initialize(CountUdevCrash, IsFeedbackAllowed);
+ KernelWarningCollector kernel_warning_collector;
+ udev_collector.Initialize(CountUdevCrash, IsFeedbackAllowed);
+
if (FLAGS_init) {
return Initialize(&kernel_collector,
&user_collector,
@@ -258,5 +275,9 @@
return HandleUdevCrash(&udev_collector);
}
+ if (FLAGS_kernel_warning) {
+ return HandleKernelWarning(&kernel_warning_collector);
+ }
+
return HandleUserCrash(&user_collector);
}
diff --git a/crash_reporter/kernel_warning_collector.cc b/crash_reporter/kernel_warning_collector.cc
new file mode 100644
index 0000000..b504f49
--- /dev/null
+++ b/crash_reporter/kernel_warning_collector.cc
@@ -0,0 +1,97 @@
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crash-reporter/kernel_warning_collector.h"
+
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "base/stringprintf.h"
+
+namespace {
+const char kExecName[] = "kernel-warning";
+const char kKernelWarningSignatureKey[] = "sig";
+const char kKernelWarningPath[] = "/var/run/kwarn/warning";
+const pid_t kKernelPid = 0;
+const uid_t kRootUid = 0;
+} // namespace
+
+KernelWarningCollector::KernelWarningCollector() {
+}
+
+KernelWarningCollector::~KernelWarningCollector() {
+}
+
+bool KernelWarningCollector::LoadKernelWarning(std::string *content,
+ std::string *hash_string) {
+ FilePath kernel_warning_path(kKernelWarningPath);
+ if (!file_util::ReadFileToString(kernel_warning_path, content)) {
+ LOG(ERROR) << "Could not open " << kKernelWarningPath;
+ return false;
+ }
+ /* Verify that the first line contains an 8-digit hex hash. */
+ *hash_string = content->substr(0, 8);
+ std::vector<uint8> output;
+ if (!base::HexStringToBytes(*hash_string, &output)) {
+ LOG(ERROR) << "Bad hash " << *hash_string << " in " << kKernelWarningPath;
+ return false;
+ }
+ return true;
+}
+
+bool KernelWarningCollector::Collect() {
+ std::string reason = "normal collection";
+ bool feedback = true;
+ if (IsDeveloperImage()) {
+ reason = "always collect from developer builds";
+ feedback = true;
+ } else if (!is_feedback_allowed_function_()) {
+ reason = "no user consent";
+ feedback = false;
+ }
+
+ LOG(INFO) << "Processing kernel warning: " << reason;
+
+ if (!feedback) {
+ return true;
+ }
+
+ std::string kernel_warning;
+ std::string warning_hash;
+ if (!LoadKernelWarning(&kernel_warning, &warning_hash)) {
+ return true;
+ }
+
+ FilePath root_crash_directory;
+ if (!GetCreatedCrashDirectoryByEuid(kRootUid, &root_crash_directory, NULL)) {
+ return true;
+ }
+
+ std::string dump_basename =
+ FormatDumpBasename(kExecName, time(NULL), kKernelPid);
+ FilePath kernel_crash_path = root_crash_directory.Append(
+ StringPrintf("%s.kcrash", dump_basename.c_str()));
+
+ // We must use WriteNewFile instead of file_util::WriteFile as we
+ // do not want to write with root access to a symlink that an attacker
+ // might have created.
+ if (WriteNewFile(kernel_crash_path,
+ kernel_warning.data(),
+ kernel_warning.length()) !=
+ static_cast<int>(kernel_warning.length())) {
+ LOG(INFO) << "Failed to write kernel warning to "
+ << kernel_crash_path.value().c_str();
+ return true;
+ }
+
+ AddCrashMetaData(kKernelWarningSignatureKey, warning_hash);
+ WriteCrashMetaData(
+ root_crash_directory.Append(
+ StringPrintf("%s.meta", dump_basename.c_str())),
+ kExecName, kernel_crash_path.value());
+
+ LOG(INFO) << "Stored kernel warning into " << kernel_crash_path.value();
+ return true;
+}
diff --git a/crash_reporter/kernel_warning_collector.h b/crash_reporter/kernel_warning_collector.h
new file mode 100644
index 0000000..2f8c793
--- /dev/null
+++ b/crash_reporter/kernel_warning_collector.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef _CRASH_REPORTER_KERNEL_WARNING_COLLECTOR_H_
+#define _CRASH_REPORTER_KERNEL_WARNING_COLLECTOR_H_
+
+#include <gtest/gtest_prod.h> // for FRIEND_TEST
+#include <string>
+
+#include "crash-reporter/crash_collector.h"
+
+// Kernel warning collector.
+class KernelWarningCollector : public CrashCollector {
+ public:
+ KernelWarningCollector();
+
+ virtual ~KernelWarningCollector();
+
+ // Collects warning.
+ bool Collect();
+
+ private:
+ friend class KernelWarningCollectorTest;
+ FRIEND_TEST(KernelWarningCollectorTest, CollectOK);
+
+ // Reads the full content of the kernel warn dump and the warning hash.
+ bool LoadKernelWarning(std::string *hash, std::string *content);
+};
+
+#endif // _CRASH_REPORTER_KERNEL_WARNING_COLLECTOR_H_
diff --git a/crash_reporter/warn_collector.l b/crash_reporter/warn_collector.l
new file mode 100644
index 0000000..d0977dc
--- /dev/null
+++ b/crash_reporter/warn_collector.l
@@ -0,0 +1,300 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * This flex program reads /var/log/messages as it grows and saves kernel
+ * warnings to files. It keeps track of warnings it has seen (based on
+ * file/line only, ignoring differences in the stack trace), and reports only
+ * the first warning of each kind, but maintains a count of all warnings by
+ * using their hashes as buckets in a UMA sparse histogram. It also invokes
+ * the crash collector, which collects the warnings and prepares them for later
+ * shipment to the crash server.
+ */
+
+%{
+#include <fcntl.h>
+#include <inttypes.h>
+#include <pwd.h>
+#include <stdarg.h>
+#include <sys/inotify.h>
+#include <sys/select.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "metrics/c_metrics_library.h"
+
+int WarnStart(void);
+void WarnEnd(void);
+void WarnInput(char *buf, int *result, size_t max_size);
+
+#define YY_INPUT(buf, result, max_size) WarnInput(buf, &result, max_size)
+
+%}
+
+/* Define a few useful regular expressions. */
+
+D [0-9]
+PREFIX .*" kernel: [ "*{D}+"."{D}+"]"
+CUT_HERE {PREFIX}" ------------[ cut here".*
+WARNING {PREFIX}" WARNING: at "
+END_TRACE {PREFIX}" ---[ end trace".*
+
+/* Use exclusive start conditions. */
+%x PRE_WARN WARN
+
+%%
+ /* The scanner itself. */
+
+^{CUT_HERE}\n{WARNING} BEGIN(PRE_WARN);
+.|\n /* ignore all other input in state 0 */
+<PRE_WARN>.*\n if (WarnStart()) {
+ BEGIN(WARN); ECHO;
+ } else {
+ BEGIN(0);
+ }
+
+ /* Assume the warning ends at the "end trace" line */
+<WARN>^{END_TRACE}\n ECHO; BEGIN(0); WarnEnd();
+<WARN>^.*\n ECHO;
+
+%%
+
+#define HASH_BITMAP_SIZE (1 << 15) /* size in bits */
+#define HASH_BITMAP_MASK (HASH_BITMAP_SIZE - 1)
+
+const char warn_hist_name[] = "Platform.KernelWarningHashes";
+uint32_t hash_bitmap[HASH_BITMAP_SIZE / 32];
+CMetricsLibrary metrics_library;
+
+const char *prog_name; /* the name of this program */
+int yyin_fd; /* instead of FILE *yyin to avoid buffering */
+int i_fd; /* for inotify, to detect file changes */
+int testing; /* 1 if running test */
+int filter; /* 1 when using as filter (for development) */
+int fifo; /* 1 when reading from fifo (for devel) */
+int draining; /* 1 when draining renamed log file */
+
+const char *msg_path = "/var/log/messages";
+const char warn_dump_dir[] = "/var/run/kwarn";
+const char *warn_dump_path = "/var/run/kwarn/warning";
+const char *crash_reporter_command;
+
+static void Die(const char *format, ...) {
+ va_list ap;
+ va_start(ap, format);
+ fprintf(stderr, "%s: ", prog_name);
+ vfprintf(stderr, format, ap);
+ exit(1);
+}
+
+static void RunCrashReporter(void) {
+ int status = system(crash_reporter_command);
+ if (status != 0)
+ Die("%s exited with status %d\n", crash_reporter_command, status);
+}
+
+static uint32_t StringHash(const char *string) {
+ uint32_t hash = 0;
+ while (*string != '\0') {
+ hash = (hash << 5) + hash + *string++;
+ }
+ return hash;
+}
+
+/* We expect only a handful of different warnings per boot session, so the
+ * probability of a collision is very low, and statistically it won't matter
+ * (unless warnings with the same hash also happens in tandem, which is even
+ * rarer).
+ */
+static int HashSeen(uint32_t hash) {
+ int word_index = (hash & HASH_BITMAP_MASK) / 32;
+ int bit_index = (hash & HASH_BITMAP_MASK) % 32;
+ return hash_bitmap[word_index] & 1 << bit_index;
+}
+
+static void SetHashSeen(uint32_t hash) {
+ int word_index = (hash & HASH_BITMAP_MASK) / 32;
+ int bit_index = (hash & HASH_BITMAP_MASK) % 32;
+ hash_bitmap[word_index] |= 1 << bit_index;
+}
+
+int WarnStart(void) {
+ uint32_t hash;
+
+ if (filter)
+ return 1;
+
+ hash = StringHash(yytext);
+ if (!(testing || fifo || filter)) {
+ CMetricsLibrarySendSparseToUMA(metrics_library, warn_hist_name, (int) hash);
+ }
+ if (HashSeen(hash))
+ return 0;
+ SetHashSeen(hash);
+
+ yyout = fopen(warn_dump_path, "w");
+ if (yyout == NULL)
+ Die("fopen %s failed: %s\n", warn_dump_path, strerror(errno));
+ fprintf(yyout, "%08x\n", hash);
+ return 1;
+}
+
+void WarnEnd(void) {
+ if (filter)
+ return;
+ fclose(yyout);
+ yyout = stdout; /* for debugging */
+ RunCrashReporter();
+}
+
+static void WarnOpenInput(const char *path) {
+ yyin_fd = open(path, O_RDONLY);
+ if (yyin_fd < 0)
+ Die("could not open %s: %s\n", path, strerror(errno));
+ if (!fifo) {
+ /* Set up notification of file growth and rename. */
+ i_fd = inotify_init();
+ if (i_fd < 0)
+ Die("inotify_init: %s\n", strerror(errno));
+ if (inotify_add_watch(i_fd, path, IN_MODIFY | IN_MOVE_SELF) < 0)
+ Die("inotify_add_watch: %s\n", strerror(errno));
+ }
+}
+
+/* We replace the default YY_INPUT() for the following reasons:
+ *
+ * 1. We want to read data as soon as it becomes available, but the default
+ * YY_INPUT() uses buffered I/O.
+ *
+ * 2. We want to block on end of input and wait for the file to grow.
+ *
+ * 3. We want to detect log rotation, and reopen the input file as needed.
+ */
+void WarnInput(char *buf, int *result, size_t max_size) {
+ while (1) {
+ *result = read(yyin_fd, buf, max_size);
+ if (*result < 0)
+ Die("read: %s", strerror(errno));
+ if (*result > 0 || fifo || filter)
+ return;
+ if (draining) {
+ /* Assume we're done with this log, and move to next
+ * log. Rsyslogd may keep writing to the old log file
+ * for a while, but we don't care since we don't have
+ * to be exact.
+ */
+ close(yyin_fd);
+ if (YYSTATE == WARN) {
+ /* Be conservative in case we lose the warn
+ * terminator during the switch---or we may
+ * collect personally identifiable information.
+ */
+ WarnEnd();
+ }
+ BEGIN(0); /* see above comment */
+ sleep(1); /* avoid race with log rotator */
+ WarnOpenInput(msg_path);
+ draining = 0;
+ continue;
+ }
+ /* Nothing left to read, so we must wait. */
+ struct inotify_event event;
+ int n = read(i_fd, &event, sizeof(event));
+ if (n <= 0)
+ Die("inotify: %s\n", strerror(errno));
+ if (event.mask & IN_MOVE_SELF) {
+ /* The file has been renamed. Before switching
+ * to the new one, we process any remaining
+ * content of this file.
+ */
+ draining = 1;
+ }
+ }
+}
+
+int main(int argc, char **argv) {
+ int result;
+ struct passwd *user;
+ prog_name = argv[0];
+
+ if (argc == 2 && strcmp(argv[1], "--test") == 0)
+ testing = 1;
+ else if (argc == 2 && strcmp(argv[1], "--filter") == 0)
+ filter = 1;
+ else if (argc == 2 && strcmp(argv[1], "--fifo") == 0) {
+ fifo = 1;
+ } else if (argc != 1) {
+ fprintf(stderr,
+ "usage: %s [single-flag]\n"
+ "flags (for testing only):\n"
+ "--fifo\tinput is fifo \"fifo\", output is stdout\n"
+ "--filter\tinput is stdin, output is stdout\n"
+ "--test\trun self-test\n",
+ prog_name);
+ exit(1);
+ }
+
+ metrics_library = CMetricsLibraryNew();
+ CMetricsLibraryInit(metrics_library);
+
+ crash_reporter_command = testing ?
+ "./warn_collector_test_reporter.sh" :
+ "/sbin/crash_reporter --kernel_warning";
+
+ /* When filtering with --filter (for development) use stdin for input.
+ * Otherwise read input from a file or a fifo.
+ */
+ yyin_fd = fileno(stdin);
+ if (testing) {
+ msg_path = "messages";
+ warn_dump_path = "warning";
+ }
+ if (fifo) {
+ msg_path = "fifo";
+ }
+ if (!filter) {
+ WarnOpenInput(msg_path);
+ }
+
+ /* Create directory for dump file. Still need to be root here. */
+ unlink(warn_dump_path);
+ if (!testing && !fifo && !filter) {
+ rmdir(warn_dump_dir);
+ result = mkdir(warn_dump_dir, 0755);
+ if (result < 0)
+ Die("could not create %s: %s\n",
+ warn_dump_dir, strerror(errno));
+ }
+
+ if (0) {
+ /* TODO(semenzato): put this back in once we decide it's safe
+ * to make /var/spool/crash rwxrwxrwx root, or use a different
+ * owner and setuid for the crash reporter as well.
+ */
+
+ /* Get low privilege uid, gid. */
+ user = getpwnam("chronos");
+ if (user == NULL)
+ Die("getpwnam failed\n");
+
+ /* Change dump directory ownership. */
+ if (chown(warn_dump_dir, user->pw_uid, user->pw_gid) < 0)
+ Die("chown: %s\n", strerror(errno));
+
+ /* Drop privileges. */
+ if (setuid(user->pw_uid) < 0) {
+ Die("setuid: %s\n", strerror(errno));
+ }
+ }
+
+ /* Go! */
+ return yylex();
+}
+
+/* Flex should really know not to generate these functions.
+ */
+void UnusedFunctionWarningSuppressor(void) {
+ yyunput(0, 0);
+ (void) input();
+}
diff --git a/crash_reporter/warn_collector_test.c b/crash_reporter/warn_collector_test.c
new file mode 100644
index 0000000..67f3455
--- /dev/null
+++ b/crash_reporter/warn_collector_test.c
@@ -0,0 +1,14 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/*
+ * Test driver for the warn_collector daemon.
+ */
+#include <stdlib.h>
+
+int main(int ac, char **av)
+{
+ return system("$SRC/warn_collector_test.sh");
+}
diff --git a/crash_reporter/warn_collector_test.sh b/crash_reporter/warn_collector_test.sh
new file mode 100755
index 0000000..e1f8a29
--- /dev/null
+++ b/crash_reporter/warn_collector_test.sh
@@ -0,0 +1,73 @@
+#! /bin/bash
+# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Test for warn_collector. Run the warn collector in the background, emulate
+# the kernel by appending lines to the log file "messages", and observe the log
+# of the (fake) crash reporter each time is run by the warn collector daemon.
+
+set -e
+
+SYSROOT=/build/link
+LD_LIBRARY_PATH=$SYSROOT/lib64:$SYSROOT/usr/lib64
+PATH=.:$SYSROOT/bin:$SYSROOT/usr/bin:$PATH
+TESTLOG=warn-test-log
+
+trap cleanup EXIT
+
+cleanup() {
+ # Kill daemon (if started) on exit
+ kill %
+}
+
+check_log() {
+ n_expected=$1
+ if [ ! -f $TESTLOG ]; then
+ echo $TESTLOG was not created
+ exit 1
+ fi
+ if [ "$(wc -l < $TESTLOG)" -ne $n_expected ]; then
+ echo expected $n_expected lines in $TESTLOG, found this:
+ cat $TESTLOG
+ exit 1
+ fi
+ if egrep -qv '^[0-9a-f]{8}$' $TESTLOG; then
+ echo found bad lines in $TESTLOG:
+ cat $TESTLOG
+ exit 1
+ fi
+}
+
+rm -f warn-test-log
+cp $SRC/warn_collector_test_reporter.sh .
+cp $SRC/TEST_WARNING .
+cp TEST_WARNING messages
+
+# Start the collector daemon. With the --test option, the daemon reads input
+# from ./messages, writes the warning into ./warning, and invokes
+# ./warn_collector_test_reporter.sh to report the warning.
+warn_collector --test &
+
+# After a while, check that the first warning has been collected.
+sleep 1
+check_log 1
+
+# Add the same warning to messages, verify that it is NOT collected
+cat TEST_WARNING >> messages
+sleep 1
+check_log 1
+
+# Add a slightly different warning to messages, check that it is collected.
+sed s/intel_dp.c/intel_xx.c/ < TEST_WARNING >> messages
+sleep 1
+check_log 2
+
+# Emulate log rotation, add a warning, and check.
+mv messages messages.1
+sed s/intel_dp.c/intel_xy.c/ < TEST_WARNING > messages
+sleep 2
+check_log 3
+
+# Success!
+exit 0
diff --git a/crash_reporter/warn_collector_test_reporter.sh b/crash_reporter/warn_collector_test_reporter.sh
new file mode 100755
index 0000000..d8f3fad
--- /dev/null
+++ b/crash_reporter/warn_collector_test_reporter.sh
@@ -0,0 +1,16 @@
+#! /bin/sh
+# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Replacement for the crash reporter, for testing. Log the first line of the
+# "warning" file, which by convention contains the warning hash, and remove the
+# file.
+
+set -e
+
+exec 1>> warn-test-log
+exec 2>> warn-test-log
+
+head -1 warning
+rm warning