File 0001-Merge-pull-request-7362-from-zyga-feature-... of Package snapd

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File 0001-Merge-pull-request-7362-from-zyga-feature-panic.patch of Package snapd (Revision 1d0989d31c91798a642a4e663b7df4c3)

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From 29bbf34dd35b4f94434383a183066dff3585c80c Mon Sep 17 00:00:00 2001
From: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Date: Thu, 5 Sep 2019 19:44:01 +0200
Subject: [PATCH 1/3] Merge pull request #7362 from zyga/feature/panic

cmd: unify die() across C programs
---
 cmd/Makefile.am                             |  6 ++
 cmd/libsnap-confine-private/panic-test.c    | 88 ++++++++++++++++++++
 cmd/libsnap-confine-private/panic.c         | 67 +++++++++++++++
 cmd/libsnap-confine-private/panic.h         | 91 +++++++++++++++++++++
 cmd/libsnap-confine-private/utils.c         | 19 ++---
 cmd/system-shutdown/system-shutdown-utils.c | 13 ---
 cmd/system-shutdown/system-shutdown.c       | 21 +++++
 7 files changed, 279 insertions(+), 26 deletions(-)
 create mode 100644 cmd/libsnap-confine-private/panic-test.c
 create mode 100644 cmd/libsnap-confine-private/panic.c
 create mode 100644 cmd/libsnap-confine-private/panic.h

diff --git a/cmd/Makefile.am b/cmd/Makefile.am
index 88fa15305e..e10dee262d 100644
--- a/cmd/Makefile.am
+++ b/cmd/Makefile.am
@@ -62,6 +62,9 @@ new_format = \
 	 libsnap-confine-private/infofile-test.c \
 	 libsnap-confine-private/infofile.c \
 	 libsnap-confine-private/infofile.h \
+	 libsnap-confine-private/panic-test.h \
+	 libsnap-confine-private/panic.c \
+	 libsnap-confine-private/panic.h \
 	 snap-confine/seccomp-support-ext.c \
 	 snap-confine/seccomp-support-ext.h \
 	 snap-confine/selinux-support.c \
@@ -129,6 +132,8 @@ libsnap_confine_private_a_SOURCES = \
 	libsnap-confine-private/mount-opt.h \
 	libsnap-confine-private/mountinfo.c \
 	libsnap-confine-private/mountinfo.h \
+	libsnap-confine-private/panic.c \
+	libsnap-confine-private/panic.h \
 	libsnap-confine-private/privs.c \
 	libsnap-confine-private/privs.h \
 	libsnap-confine-private/secure-getenv.c \
@@ -159,6 +164,7 @@ libsnap_confine_private_unit_tests_SOURCES = \
 	libsnap-confine-private/locking-test.c \
 	libsnap-confine-private/mount-opt-test.c \
 	libsnap-confine-private/mountinfo-test.c \
+	libsnap-confine-private/panic-test.c \
 	libsnap-confine-private/privs-test.c \
 	libsnap-confine-private/secure-getenv-test.c \
 	libsnap-confine-private/snap-test.c \
diff --git a/cmd/libsnap-confine-private/panic-test.c b/cmd/libsnap-confine-private/panic-test.c
new file mode 100644
index 0000000000..4e9659ab97
--- /dev/null
+++ b/cmd/libsnap-confine-private/panic-test.c
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2019 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "panic.h"
+#include "panic.c"
+
+#include <glib.h>
+
+static void test_panic(void)
+{
+	if (g_test_subprocess()) {
+		errno = 0;
+		sc_panic("death message");
+		g_test_message("expected die not to return");
+		g_test_fail();
+		return;
+	}
+	g_test_trap_subprocess(NULL, 0, 0);
+	g_test_trap_assert_failed();
+	g_test_trap_assert_stderr("death message\n");
+}
+
+static void test_panic_with_errno(void)
+{
+	if (g_test_subprocess()) {
+		errno = EPERM;
+		sc_panic("death message");
+		g_test_message("expected die not to return");
+		g_test_fail();
+		return;
+	}
+	g_test_trap_subprocess(NULL, 0, 0);
+	g_test_trap_assert_failed();
+	g_test_trap_assert_stderr("death message: Operation not permitted\n");
+}
+
+static void custom_panic_msg(const char *fmt, va_list ap, int errno_copy)
+{
+	fprintf(stderr, "PANIC: ");
+	vfprintf(stderr, fmt, ap);
+	fprintf(stderr, " (errno: %d)", errno_copy);
+	fprintf(stderr, "\n");
+}
+
+static void custom_panic_exit(void)
+{
+	fprintf(stderr, "EXITING\n");
+	exit(2);
+}
+
+static void test_panic_customization(void)
+{
+	if (g_test_subprocess()) {
+		sc_set_panic_msg_fn(custom_panic_msg);
+		sc_set_panic_exit_fn(custom_panic_exit);
+		errno = 123;
+		sc_panic("death message");
+		g_test_message("expected die not to return");
+		g_test_fail();
+		return;
+	}
+	g_test_trap_subprocess(NULL, 0, 0);
+	g_test_trap_assert_failed();
+	g_test_trap_assert_stderr("PANIC: death message (errno: 123)\n"
+				  "EXITING\n");
+	// NOTE: g_test doesn't offer facilities to observe the exit code.
+}
+
+static void __attribute__((constructor)) init(void)
+{
+	g_test_add_func("/panic/panic", test_panic);
+	g_test_add_func("/panic/panic_with_errno", test_panic_with_errno);
+	g_test_add_func("/panic/panic_customization", test_panic_customization);
+}
diff --git a/cmd/libsnap-confine-private/panic.c b/cmd/libsnap-confine-private/panic.c
new file mode 100644
index 0000000000..5a80b89c45
--- /dev/null
+++ b/cmd/libsnap-confine-private/panic.c
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2019 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "panic.h"
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static sc_panic_exit_fn panic_exit_fn = NULL;
+static sc_panic_msg_fn panic_msg_fn = NULL;
+
+void sc_panic(const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    sc_panicv(fmt, ap);
+    va_end(ap);
+}
+
+void sc_panicv(const char *fmt, va_list ap) {
+    int errno_copy = errno;
+
+    if (panic_msg_fn != NULL) {
+        panic_msg_fn(fmt, ap, errno_copy);
+    } else {
+        vfprintf(stderr, fmt, ap);
+        if (errno != 0) {
+            fprintf(stderr, ": %s\n", strerror(errno_copy));
+        } else {
+            fprintf(stderr, "\n");
+        }
+    }
+
+    if (panic_exit_fn != NULL) {
+        panic_exit_fn();
+    }
+    exit(1);
+}
+
+sc_panic_exit_fn sc_set_panic_exit_fn(sc_panic_exit_fn fn) {
+    sc_panic_exit_fn old = panic_exit_fn;
+    panic_exit_fn = fn;
+    return old;
+}
+
+sc_panic_msg_fn sc_set_panic_msg_fn(sc_panic_msg_fn fn) {
+    sc_panic_msg_fn old = panic_msg_fn;
+    panic_msg_fn = fn;
+    return old;
+}
diff --git a/cmd/libsnap-confine-private/panic.h b/cmd/libsnap-confine-private/panic.h
new file mode 100644
index 0000000000..c25fcd78ea
--- /dev/null
+++ b/cmd/libsnap-confine-private/panic.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2019 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef SC_PANIC_H
+#define SC_PANIC_H
+
+#include <stdarg.h>
+
+/**
+ * sc_panic is an exit-with-message utility function.
+ *
+ * The function takes a printf-like format string that is formatted and printed
+ * somehow. The function then terminates the process by calling exit. Both
+ * aspects can be customized.
+ *
+ * The particular nature of the exit can be customized by calling
+ * sc_set_panic_action. The panic action is a function that is called before
+ * attempting to exit.
+ *
+ * The way the error message is formatted and printed can be customized by
+ * calling sc_set_panic_format_fn(). By default the error is printed to
+ * standard error. If the error is related to a system call failure then errno
+ * can be set to a non-zero value just prior to calling sc_panic. The value
+ * will then be used when crafting the error message.
+ **/
+__attribute__((noreturn, format(printf, 1, 2))) void sc_panic(const char *fmt, ...);
+
+/**
+ * sc_panicv is a variant of sc_panic with an argument list.
+ **/
+__attribute__((noreturn)) void sc_panicv(const char *fmt, va_list ap);
+
+/**
+ * sc_panic_exit_fn is the type of the exit function used by sc_panic().
+ **/
+typedef void (*sc_panic_exit_fn)(void);
+
+/**
+ * sc_set_panic_exit_fn sets the panic exit function.
+ *
+ * When sc_panic is called it will eventually exit the running process. Just
+ * prior to that, it will call the panic exit function, if one has been set.
+ *
+ * If exiting the process is undesired, for example while running in intrd as
+ * pid 1, during the system shutdown phase, then a process can set the panic
+ * exit function. Note that if the specified function returns then panic will
+ * proceed to call exit(3) anyway.
+ *
+ * The old exit function, if any, is returned.
+ **/
+sc_panic_exit_fn sc_set_panic_exit_fn(sc_panic_exit_fn fn);
+
+/**
+ * sc_panic_msg_fn is the type of the format function used by sc_panic().
+ **/
+typedef void (*sc_panic_msg_fn)(const char *fmt, va_list ap, int errno_copy);
+
+/**
+ * sc_set_panic_msg_fn sets the panic message function.
+ *
+ * When sc_panic is called it will attempt to print an error message to
+ * standard error. The message includes information provided by the caller: the
+ * format string, the argument vector for a printf-like function as well as a
+ * copy of the system errno value, which may be zero if the error is not
+ * originated by a system call error.
+ *
+ * If custom formatting of the error message is desired, for example while
+ * running in initrd as pid 1, during the system shutdown phase, then a process
+ * can set the panic message function. Once set the function takes over the
+ * responsibility of printing an error message (in whatever form is
+ * appropriate).
+ *
+ * The old message function, if any, is returned.
+ **/
+sc_panic_msg_fn sc_set_panic_msg_fn(sc_panic_msg_fn fn);
+
+#endif
diff --git a/cmd/libsnap-confine-private/utils.c b/cmd/libsnap-confine-private/utils.c
index c3a688d08c..f829f5ef56 100644
--- a/cmd/libsnap-confine-private/utils.c
+++ b/cmd/libsnap-confine-private/utils.c
@@ -23,23 +23,16 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-#include "utils.h"
 #include "cleanup-funcs.h"
+#include "panic.h"
+#include "utils.h"
 
 void die(const char *msg, ...)
 {
-	int saved_errno = errno;
-	va_list va;
-	va_start(va, msg);
-	vfprintf(stderr, msg, va);
-	va_end(va);
-
-	if (errno != 0) {
-		fprintf(stderr, ": %s\n", strerror(saved_errno));
-	} else {
-		fprintf(stderr, "\n");
-	}
-	exit(1);
+	va_list ap;
+	va_start(ap, msg);
+	sc_panicv(msg, ap);
+	va_end(ap);
 }
 
 struct sc_bool_name {
diff --git a/cmd/system-shutdown/system-shutdown-utils.c b/cmd/system-shutdown/system-shutdown-utils.c
index 136b87769c..8256f6ba12 100644
--- a/cmd/system-shutdown/system-shutdown-utils.c
+++ b/cmd/system-shutdown/system-shutdown-utils.c
@@ -53,19 +53,6 @@ void kmsg(const char *fmt, ...)
 	va_end(va);
 }
 
-__attribute__((noreturn))
-void die(const char *msg)
-{
-	if (errno == 0) {
-		kmsg("*** %s", msg);
-	} else {
-		kmsg("*** %s: %s", msg, strerror(errno));
-	}
-	sync();
-	reboot(RB_HALT_SYSTEM);
-	exit(1);
-}
-
 int sc_read_reboot_arg(char *arg, size_t max_size)
 {
 	FILE *f;
diff --git a/cmd/system-shutdown/system-shutdown.c b/cmd/system-shutdown/system-shutdown.c
index 0202721ba4..714fbdded0 100644
--- a/cmd/system-shutdown/system-shutdown.c
+++ b/cmd/system-shutdown/system-shutdown.c
@@ -33,9 +33,30 @@
 
 #include "system-shutdown-utils.h"
 #include "../libsnap-confine-private/string-utils.h"
+#include "../libsnap-confine-private/panic.h"
+
+static void show_error(const char *fmt, va_list ap, int errno_copy)
+{
+	fprintf(stderr, "snapd system-shutdown helper: ");
+	fprintf(stderr, "*** ");
+	vfprintf(stderr, fmt, ap);
+	if (errno_copy != 0) {
+		fprintf(stderr, ": %s", strerror(errno_copy));
+	}
+	fprintf(stderr, "\n");
+}
+
+static void sync_and_halt(void)
+{
+	sync();
+	reboot(RB_HALT_SYSTEM);
+}
 
 int main(int argc, char *argv[])
 {
+	sc_set_panic_msg_fn(show_error);
+	sc_set_panic_exit_fn(sync_and_halt);
+
 	// 256 should be more than enough...
 	char reboot_arg[256] = { 0 };
 
-- 
2.23.0

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File 0001-Merge-pull-request-7362-from-zyga-feature-panic.patch of Package snapd (Revision 1d0989d31c91798a642a4e663b7df4c3)

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