Linux-specific support.

scsh/linux/fix_stdio.c

@@ -0,0 +1,79 @@
+#include <stdio.h>
+
+/* The current stdio lib that Linux uses has a problem that screws up
+** scsh's interrupt system: when a stdio function such as getc() or fputs()
+** blocks in an i/o system call, and that system call is interrupted, the
+** stdio function realises this and loops, retrying the the i/o operation.
+** What we need is for the stdio function to return an error, with 
+** errno=EINTR -- i.e., we need for the stdio function to give control back
+** to the caller, telling it that the i/o call was interrupted.
+**
+** The EINTR error return is in fact mandated by Posix. The next release
+** of the GNU libc will provide this functionality. The current release
+** doesn't. So we use the workaround in this file. Calling 
+**	remove_bone_from_head_of_linux_libc()
+** will smash the call tables of the i/o library so that non-retrying
+** functions get called to do the i/o system calls.
+**
+** Why does scsh need non-retry? Because in scsh, Unix signals are *not*
+** handled by the actual Unix signal handler. The signal handler is just
+** a piece of C code that sets a bit, notifying the S48 vm that it needs
+** to service a signal. When the vm gets to a vm instruction boundary,
+** it suspends execution of the program and services the interrupt by
+** invoking a *Scheme* function. In this way, we can interrupt on VM
+** instruction boundaries with VM interrupt handlers.
+**
+** If a C function retries when interrupted, we never return to Scheme,
+** and so the vm never has a chance to service the interrupt. This is bad.
+**
+** This code was contributed by Roland McGrath.
+*/
+
+#ifdef __GLIBC__
+
+/* GNU libc 2.0 needs no fixing. */
+void remove_bone_from_head_of_linux_libc () {}
+
+#else
+
+#include <libio.h>
+
+extern _IO_ssize_t _IO_file_read (_IO_FILE *, void *, _IO_ssize_t);
+_IO_ssize_t
+my_linux_file_read (_IO_FILE *fp, void *buf, _IO_ssize_t size)
+{
+  return read (fp->_fileno, buf, size);
+}
+
+extern _IO_ssize_t _IO_file_write (_IO_FILE *, const void *, _IO_ssize_t);
+_IO_ssize_t
+my_linux_file_write (_IO_FILE *fp, const void *buf, _IO_ssize_t size)
+{
+  return write (fp->_fileno, buf, size);
+}
+
+static void
+debone (_IO_ssize_t (**jumptable) ())
+{
+  _IO_ssize_t (**p) ();
+  int r, w;
+  r = w = 0;
+  for (p = jumptable; !r || !w; ++p)
+    {
+      if (*p == &_IO_file_read)
+	++r, *p = &my_linux_file_read;
+      else if (*p == &_IO_file_write)
+	++w, *p = &my_linux_file_write;
+    }
+}
+
+void
+remove_bone_from_head_of_linux_libc ()
+{
+  extern _IO_ssize_t (*_IO_file_jumps[]) (); /* used for normal fds */
+  extern _IO_ssize_t (*_IO_proc_jumps[]) (); /* used by popen */
+
+  debone (_IO_file_jumps);
+  debone (_IO_proc_jumps);
+}
+#endif

scsh/linux/signals1.c

@@ -0,0 +1,52 @@
+/* This is bogus -- currently unchanged from the bsd file. */
+/* Need to turn off synchronous error signals (SIGPIPE, SIGSYS). */
+
+#include "../scsh_aux.h"
+
+/* Make sure our exports match up w/the implementation: */
+#include "../signals1.h"
+
+/* This table converts Unix signal numbers to S48/scsh interrupt numbers.
+** If the signal doesn't have an interrupt number, the entry is -1.
+** (Only asynchronous signals have interrupt numbers.)
+**
+** Note that we bake into this table the integer values of the signals --
+** i.e., we assume that SIGHUP=1, SIGALRM=15, etc. So this definition is
+** very system-dependent.
+*/
+const int sig2int[] = {
+  	-1,		/* 0 is not a signal */
+	scshint_hup,	/* SIGHUP */
+	scshint_keyboard,	/* SIGINT */
+	scshint_quit,	/* SIGQUIT */
+	-1,		/* SIGILL */
+	-1,		/* SIGTRAP */
+	-1,		/* SIGABRT & SIGIOT */
+	-1,		/* SIGBUS */
+	-1,		/* SIGFPE */
+	-1,		/* SIGKILL */
+	scshint_usr1,	/* SIGUSR1 */
+	-1,		/* SIGSEGV */
+	scshint_usr2,	/* SIGUSR2 */
+	-1,		/* SIGPIPE */
+	scshint_alarm,	/* SIGALRM */
+	scshint_term,	/* SIGTERM */
+	-1,		/* SIGTKFLT (x86 coprocessor stack fault) */
+	scshint_chld,	/* SIGCHLD */
+	scshint_cont,	/* SIGCONT */
+	-1,		/* SIGSTOP */
+	scshint_tstp,	/* SIGTSTP */
+	-1, /*	scshint_ttyin,	/* SIGTTIN */
+	-1, /*	scshint_ttou,	/* SIGTTOU */
+	scshint_urg,	/* SIGURG */
+	scshint_xcpu,	/* SIGXCPU */
+	scshint_xfsz,	/* SIGXFSZ */
+	scshint_vtalrm,	/* SIGVTALRM */
+	scshint_prof,	/* SIGPROF */
+	scshint_winch,	/* SIGWINCH */
+	scshint_io,	/* SIGIO aka SIGPOLL*/
+	scshint_pwr,	/* SIGPWR */
+	-1		/* SIGPWR */
+        };
+
+const int max_sig = 31; /* SIGUNUSED */