toolchain/newlib: configure to use our own POSIX signal implementation

Also implement BSD's killpg() which is defined but not implemented by newlib.

Author: d4ilyrun

toolchain/newlib/port/newlib/configure.host

@@ -614,6 +614,7 @@ case "${host}" in
 	;;
   *-*-dailyrun*)
     syscall_dir=syscalls
+	newlib_cflags="${newlib_cflags} -DSIGNAL_PROVIDED"
     ;;
 # RTEMS supplies its own versions of some routines:
 #       malloc()            (reentrant version)

toolchain/newlib/port/newlib/libc/sys/dailyrun/Makefile.inc

@@ -1,2 +1,3 @@
 libc_a_SOURCES += %D%/syscalls.c
 libc_a_SOURCES += %D%/isatty.c
+libc_a_SOURCES += %D%/killpg.c

toolchain/newlib/port/newlib/libc/sys/dailyrun/crt0.c

@@ -1,10 +1,32 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/signal.h>
 #include <unistd.h>
 
 extern int main(int argc, char **argv, char **envp);
 
 extern char _edata;
 extern char _end;
 
+/*
+ * Signal handler trampoline.
+ *
+ * This function calls the actual signal handler and makes sure
+ * the process exits from the signal correctly.
+ *
+ * Must be installed using sigsethandler() first before installing
+ * custom signal handlers.
+ */
+static void handle_signal(int signal, siginfo_t *info, void *data)
+{
+    ucontext_t *ucontext = data;
+    sig_sa_sigaction_t handler = ucontext->sa_handler;
+
+    handler(signal, info, ucontext);
+    sigreturn(ucontext);
+}
+
 void _start(int argc, char **argv, char **envp)
 {
     char *bss;
@@ -15,6 +37,15 @@ void _start(int argc, char **argv, char **envp)
     while (bss < &_end)
         *bss++ = 0;
 
+    /* Install signal handler trampoline. */
+    ret = sigsethandler(handle_signal);
+    if (ret) {
+        fprintf(stderr, "crt0: sigsethandler failed: %s\n", strerror(errno));
+        goto out;
+    }
+
     ret = main(argc, argv, envp);
+
+out:
     _exit(ret);
 }

toolchain/newlib/port/newlib/libc/sys/dailyrun/killpg.c

@@ -0,0 +1,7 @@
+#include <sys/signal.h>
+#include <sys/types.h>
+
+int killpg(pid_t pid, int signal)
+{
+    return kill(-pid, signal);
+}

toolchain/newlib/port/newlib/libc/sys/dailyrun/syscalls.c

@@ -17,6 +17,7 @@
 #include <sys/time.h>
 #include <sys/times.h>
 #include <sys/types.h>
+#include <sys/signal.h>
 
 char **environ; /* pointer to array of char * strings that define the current
                    environment variables */
@@ -85,6 +86,24 @@ char **environ; /* pointer to array of char * strings that define the current
         return ret;                                                        \
     }
 
+#define DEFINE_SYSCALL_4_default(_ret_type, _syscall, _nr, _type1, _type2,    \
+                                 _type3, _type4, ...)                         \
+    _ret_type _##_syscall(_type1 arg1, _type2 arg2, _type3 arg3, _type4 arg4, \
+                          ##__VA_ARGS__)                                      \
+    {                                                                         \
+        _ret_type ret;                                                        \
+        __asm__ volatile("int $0x80"                                          \
+                         : "=a"(ret)                                          \
+                         : "a"(_nr), "b"(arg1), "c"(arg2), "d"(arg3),         \
+                           "S"(arg4)                                          \
+                         : "memory");                                         \
+        if (ret < 0) {                                                        \
+            errno = (int)ret;                                                 \
+            ret = (_ret_type) - 1;                                            \
+        }                                                                     \
+        return ret;                                                           \
+    }
+
 /*
  * Noreturn syscalls (exit)
  */
@@ -113,6 +132,24 @@ pid_t _wait(int *status)
     return _waitpid(-1, status, 0);
 }
 
+/*
+ * signal() should not be used for anything else than setting the handler
+ * to SIGDFL or SIGIGN. For other values follow the BSD semantics: the signal
+ * is masked until delivered and handler (also the same as glibc).
+ */
+int _signal(int signo, sig_sa_handler_t handler)
+{
+    struct sigaction sigaction = {
+        .sa_handler = handler,
+        .sa_flags = 0,
+    };
+
+    sigemptyset(&sigaction.sa_mask);
+    sigaddset(&sigaction.sa_mask, signo);
+
+    return _sigaction(signo, &sigaction, NULL);
+}
+
 /*
  * Unimplemented syscalls
  */