annotate some functions as non-returning (#3574)

src/firejail/arp.c

@@ -239,9 +239,7 @@ int arp_check(const char *dev, uint32_t destaddr) {
  }
  }
 
- // it will never get here!
- close(sock);
- return -1;
+ __builtin_unreachable();
 }
 
 // assign a random IP address and check it

src/firejail/firejail.h

@@ -371,14 +371,14 @@ char *guess_shell(void);
 
 // sandbox.c
 int sandbox(void* sandbox_arg);
-void start_application(int no_sandbox, FILE *fp);
+void start_application(int no_sandbox, FILE *fp) __attribute__((noreturn));
 void set_apparmor(void);
 
 // network_main.c
 void net_configure_sandbox_ip(Bridge *br);
 void net_configure_veth_pair(Bridge *br, const char *ifname, pid_t child);
 void net_check_cfg(void);
-void net_dns_print(pid_t pid);
+void net_dns_print(pid_t pid) __attribute__((noreturn));
 void network_main(pid_t child);
 void net_print(pid_t pid);
 
@@ -453,13 +453,12 @@ void profile_add_ignore(const char *str);
 void list(void);
 void tree(void);
 void top(void);
-void netstats(void);
 
 // usage.c
 void usage(void);
 
 // join.c
-void join(pid_t pid, int argc, char **argv, int index);
+void join(pid_t pid, int argc, char **argv, int index) __attribute__((noreturn));
 bool is_ready_for_join(const pid_t pid);
 void check_join_permission(pid_t pid);
 pid_t switch_to_child(pid_t pid);
@@ -486,7 +485,7 @@ int macro_id(const char *name);
 
 
 // util.c
-void errLogExit(char* fmt, ...);
+void errLogExit(char* fmt, ...) __attribute__((noreturn));
 void fwarning(char* fmt, ...);
 void fmessage(char* fmt, ...);
 void drop_privs(int nogroups);
@@ -584,7 +583,7 @@ int seccomp_load(const char *fname);
 int seccomp_filter_drop(bool native);
 int seccomp_filter_keep(bool native);
 int seccomp_filter_mdwx(bool native);
-void seccomp_print_filter(pid_t pid);
+void seccomp_print_filter(pid_t pid) __attribute__((noreturn));
 
 // caps.c
 void seccomp_load_file_list(void);
@@ -595,7 +594,7 @@ void caps_set(uint64_t caps);
 void caps_check_list(const char *clist, void (*callback)(int));
 void caps_drop_list(const char *clist);
 void caps_keep_list(const char *clist);
-void caps_print_filter(pid_t pid);
+void caps_print_filter(pid_t pid) __attribute__((noreturn));
 void caps_drop_dac_override(void);
 
 // fs_trace.c
@@ -618,7 +617,7 @@ void read_cpu_list(const char *str);
 void set_cpu_affinity(void);
 void load_cpu(const char *fname);
 void save_cpu(void);
-void cpu_print_filter(pid_t pid);
+void cpu_print_filter(pid_t pid) __attribute__((noreturn));
 
 // cgroup.c
 void save_cgroup(void);
@@ -640,7 +639,7 @@ void netns(const char *nsname);
 void netns_mounts(const char *nsname);
 
 // bandwidth.c
-void bandwidth_pid(pid_t pid, const char *command, const char *dev, int down, int up);
+void bandwidth_pid(pid_t pid, const char *command, const char *dev, int down, int up) __attribute__((noreturn));
 void network_set_run_file(pid_t pid);
 
 // fs_etc.c
@@ -650,7 +649,7 @@ void fs_private_dir_list(const char *private_dir, const char *private_run_dir, c
 // no_sandbox.c
 int check_namespace_virt(void);
 int check_kernel_procs(void);
-void run_no_sandbox(int argc, char **argv);
+void run_no_sandbox(int argc, char **argv) __attribute__((noreturn));
 
 #define MAX_ENVS 256 // some sane maximum number of environment variables
 #define MAX_ENV_LEN (PATH_MAX + 32) // FOOBAR=SOME_PATH
@@ -681,7 +680,7 @@ void fs_private_lib(void);
 // protocol.c
 void protocol_filter_save(void);
 void protocol_filter_load(const char *fname);
-void protocol_print_filter(pid_t pid);
+void protocol_print_filter(pid_t pid) __attribute__((noreturn));
 
 // restrict_users.c
 void restrict_users(void);
@@ -693,7 +692,7 @@ void fs_logger2int(const char *msg1, int d);
 void fs_logger3(const char *msg1, const char *msg2, const char *msg3);
 void fs_logger_print(void);
 void fs_logger_change_owner(void);
-void fs_logger_print_log(pid_t pid);
+void fs_logger_print_log(pid_t pid) __attribute__((noreturn));
 
 // run_symlink.c
 void run_symlink(int argc, char **argv, int run_as_is);
@@ -719,11 +718,11 @@ void fs_mkfile(const char *name);
 
 void fs_x11(void);
 int x11_display(void);
-void x11_start(int argc, char **argv);
-void x11_start_xpra(int argc, char **argv);
-void x11_start_xephyr(int argc, char **argv);
+void x11_start(int argc, char **argv) __attribute__((noreturn));
+void x11_start_xpra(int argc, char **argv) __attribute__((noreturn));
+void x11_start_xephyr(int argc, char **argv) __attribute__((noreturn));
 void x11_block(void);
-void x11_start_xvfb(int argc, char **argv);
+void x11_start_xvfb(int argc, char **argv) __attribute__((noreturn));
 void x11_xorg(void);
 
 // ls.c
@@ -733,7 +732,7 @@ enum {
  SANDBOX_FS_PUT,
  SANDBOX_FS_MAX // this should always be the last entry
 };
-void sandboxfs(int op, pid_t pid, const char *path1, const char *path2);
+void sandboxfs(int op, pid_t pid, const char *path1, const char *path2) __attribute__((noreturn));
 
 // checkcfg.c
 #define DEFAULT_ARP_PROBES 2
@@ -839,7 +838,7 @@ void build_appimage_cmdline(char **command_line, char **window_title, int argc,
 // run sbox
 int sbox_run(unsigned filter, int num, ...);
 int sbox_run_v(unsigned filter, char * const arg[]);
-void sbox_exec_v(unsigned filter, char * const arg[]);
+void sbox_exec_v(unsigned filter, char * const arg[]) __attribute__((noreturn));
 
 // run_files.c
 void delete_run_files(pid_t pid);

src/firejail/join.c

@@ -588,7 +588,7 @@ void join(pid_t pid, int argc, char **argv, int index) {
 
  start_application(0, NULL);
 
- // it will never get here!!!
+ __builtin_unreachable();
  }
  EUID_USER();
 

src/firejail/main.c

@@ -1159,8 +1159,7 @@ int main(int argc, char **argv, char **envp) {
 
  // start the program directly without sandboxing
  run_no_sandbox(argc, argv);
- // it will never get here!
- assert(0);
+ __builtin_unreachable();
  }
  }
  EUID_ASSERT();

src/firejail/protocol.c

@@ -90,7 +90,7 @@ void protocol_print_filter(pid_t pid) {
  exit(0);
 #else
  fwarning("--protocol not supported on this platform\n");
- return;
+ exit(1);
 #endif
 }
 

src/firejail/sbox.c

@@ -31,7 +31,7 @@
 #define O_PATH 010000000
 #endif
 
-static int sbox_do_exec_v(unsigned filtermask, char * const arg[]) {
+static int __attribute__((noreturn)) sbox_do_exec_v(unsigned filtermask, char * const arg[]) {
  // build a new, clean environment
  int env_index = 0;
  char *new_environment[256] = { NULL };

src/firejail/x11.c

@@ -682,7 +682,7 @@ static char * get_title_arg_str() {
 }
 
 
-void x11_start_xpra_old(int argc, char **argv, int display, char *display_str) {
+static void __attribute__((noreturn)) x11_start_xpra_old(int argc, char **argv, int display, char *display_str) {
  EUID_ASSERT();
  int i;
  struct stat s;
@@ -921,7 +921,7 @@ void x11_start_xpra_old(int argc, char **argv, int display, char *display_str) {
 }
 
 
-void x11_start_xpra_new(int argc, char **argv, char *display_str) {
+static void __attribute__((noreturn)) x11_start_xpra_new(int argc, char **argv, char *display_str) {
  EUID_ASSERT();
  int i;
  pid_t server = 0;

src/firemon/firemon.h

@@ -46,13 +46,13 @@ void firemon_sleep(int st);
 
 
 // procevent.c
-void procevent(pid_t pid);
+void procevent(pid_t pid) __attribute__((noreturn));
 
 // usage.c
 void usage(void);
 
 // top.c
-void top(void);
+void top(void) __attribute__((noreturn));
 
 // list.c
 void list(void);
@@ -82,7 +82,7 @@ void cgroup(pid_t pid, int print_procs);
 void tree(pid_t pid);
 
 // netstats.c
-void netstats(void);
+void netstats(void) __attribute__((noreturn));
 
 // x11.c
 void x11(pid_t pid, int print_procs);

src/firemon/procevent.c

@@ -220,7 +220,7 @@ static int procevent_netlink_setup(void) {
 }
 
 
-static int procevent_monitor(const int sock, pid_t mypid) {
+static void __attribute__((noreturn)) procevent_monitor(const int sock, pid_t mypid) {
  ssize_t len;
  struct nlmsghdr *nlmsghdr;
 
@@ -246,8 +246,7 @@ static int procevent_monitor(const int sock, pid_t mypid) {
 
  int rv = select(max, &readfds, NULL, NULL, &tv);
  if (rv == -1) {
- fprintf(stderr, "recv: %s\n", strerror(errno));
- return -1;
+ errExit("recv");
  }
 
  // timeout
@@ -259,7 +258,7 @@ static int procevent_monitor(const int sock, pid_t mypid) {
 
 
  if ((len = recv(sock, buf, sizeof(buf), 0)) == 0)
- return 0;
+ exit(0);
  if (len == -1) {
  if (errno == EINTR)
  continue;
@@ -271,7 +270,7 @@ static int procevent_monitor(const int sock, pid_t mypid) {
  }
  else {
  fprintf(stderr,"Error: rx socket recv call, errno %d, %s\n", errno, strerror(errno));
- return -1;
+ exit(1);
  }
  }
 
@@ -497,7 +496,7 @@ static int procevent_monitor(const int sock, pid_t mypid) {
  exit(0);
  }
  }
- return 0;
+ __builtin_unreachable();
 }
 
 void procevent(pid_t pid) {
@@ -515,6 +514,4 @@ void procevent(pid_t pid) {
  }
 
  procevent_monitor(sock, pid); // it will never return from here
- assert(0);
- close(sock); // quiet static analyzers
 }

src/include/syscall.h

@@ -32,7 +32,7 @@ void filter_add_blacklist_override(int fd, int syscall, int arg, void *ptrarg, b
 // errno.c
 void errno_print(void);
 int errno_find_name(const char *name);
-char *errno_find_nr(int nr);
+const char *errno_find_nr(int nr);
 
 // syscall.c
 void syscall_print(void);

src/lib/errno.c

@@ -183,7 +183,7 @@ int errno_find_name(const char *name) {
  return -1;
 }
 
-char *errno_find_nr(int nr) {
+const char *errno_find_nr(int nr) {
  int i;
  int elems = sizeof(errnolist) / sizeof(errnolist[0]);
  for (i = 0; i < elems; i++) {