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1 files changed, 168 insertions, 0 deletions

diff --git a/coro.c b/coro.c
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index 0000000..eb95aa8
--- /dev/null
+++ b/coro.c
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+/*
+ * Copyright (c) 2001 Marc Alexander Lehmann <pcg@goof.com>
+ * 
+ * Redistribution and use in source and binary forms, with or without modifica-
+ * tion, are permitted provided that the following conditions are met:
+ * 
+ *   1.  Redistributions of source code must retain the above copyright notice,
+ *       this list of conditions and the following disclaimer.
+ * 
+ *   2.  Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ * 
+ *   3.  The name of the author may not be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
+ * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
+ * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
+ * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
+ * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This library is modelled strictly after Ralf S. Engelschalls article at
+ * http://www.gnu.org/software/pth/rse-pmt.ps.  So most of the credit must
+ * go to Ralf S. Engelschall <rse@engelschall.com>.
+ */
+
+#include "coro.h"
+
+#if CORO_LOOSE || CORO_SJLJ
+
+#include <signal.h>
+
+static volatile coro_func coro_init_func;
+static volatile void *coro_init_arg;
+static volatile coro_context *new_coro, *create_coro;
+
+static void
+coro_init (void)
+{
+  volatile coro_func func = coro_init_func;
+  volatile void *arg = coro_init_arg;
+
+  coro_transfer (new_coro, create_coro);
+
+  func (arg);
+
+  /* the new coro returned. bad. just abort() for now */
+  abort ();
+}
+
+# if CORO_SJLJ
+# define coro_save(ctx)     (void)setjmp((ctx)->env)
+
+static volatile int trampoline_count;
+
+/* trampoline signal handler */
+static void
+trampoline(int sig)
+{
+  if (setjmp (&(new_coro->env)))
+    coro_init (); /* start it */
+  else
+    trampoline_count++;
+}
+
+# endif
+
+#elif CORO_UCONTEXT
+# define coro_save(ctx)     getcontext(&((ctx)->uc))
+#endif
+
+/* initialize a machine state */
+void coro_create(coro_context *ctx,
+                 coro_func coro, void *arg,
+                 void *sptr, long ssize)
+{
+#if CORO_UCONTEXT
+
+  getcontext (&(ctx->uc));
+
+  ctx->uc.uc_link          =  0;
+  ctx->uc.uc_stack.ss_sp    = sptr;
+  ctx->uc.uc_stack.ss_size  = (size_t) ssize;
+  ctx->uc.uc_stack.ss_flags = 0;
+
+  makecontext (&(ctx->uc), (void (*)()) coro, 1, arg);
+
+#elif CORO_SJLJ || CORO_LOOSE
+
+# if CORO_SJLJ
+  stack_t ostk, nstk;
+  struct sigaction osa, nsa;
+  sigset_t nsig, osig;
+# endif
+  coro_context nctx;
+
+  coro_init_func = coro;
+  coro_init_arg  = arg;
+
+  new_coro    = ctx;
+  create_coro = &nctx;
+
+# if CORO_SJLJ
+  /* we use SIGUSR2. first block it, then fiddle with it. */
+
+  sigemptyset (&nsig);
+  sigaddset (&nsig, SIGUSR2);
+  sigprocmask (SIG_BLOCK, &nsig, &osig);
+
+  nsa.sa_handler = trampoline;
+  sigemptyset (&nsa.sa_mask);
+  nsa.sa_flags = SA_ONSTACK;
+
+  if (sigaction (SIGUSR2, &nsa, &osa))
+    perror ("sigaction");
+
+  /* set the new stack */
+  nstk.ss_sp    = sptr;
+  nstk.ss_size  = ssize;
+  nstk.ss_flags = 0;
+
+  if (sigaltstack (&nstk, &ostk) < 0)
+    perror ("sigaltstack");
+
+  trampoline_count = 0;
+  kill (getpid (), SIGUSR2);
+  sigfillset (&nsig); sigdelset (&nsig, SIGUSR2);
+
+  while (!trampoline_count)
+    sigsuspend (&nsig);
+
+  sigaltstack (0, &nstk);
+  nstk.ss_flags = SS_DISABLE;
+  if (sigaltstack (&nstk, 0) < 0)
+    perror ("sigaltstack");
+
+  sigaltstack (0, &nstk);
+  if (~nstk.ss_flags & SS_DISABLE)
+    abort ();
+
+  if (~ostk.ss_flags & SS_DISABLE)
+    sigaltstack (&ostk, 0);
+
+  sigaction (SIGUSR1, &osa, 0);
+
+  sigprocmask (SIG_SETMASK, &osig, 0);
+
+# elif MS_LOOSE
+
+  coro_save (ctx);
+  ctx->env[7] = (int)((char *)sptr + ssize);
+  ctx->env[8] = (int)coro;
+
+# endif
+
+  coro_transfer (create_coro, new_coro);
+
+#else
+error unsupported architecture
+#endif
+}
+