1 files changed, 184 insertions, 0 deletions
diff --git a/src/libstddjb/selfpipe.c b/src/libstddjb/selfpipe.c
new file mode 100644
index 0000000..c4609c8
--- /dev/null
+++ b/src/libstddjb/selfpipe.c
@@ -0,0 +1,184 @@
+/* ISC license. */
+
+/* MT-unsafe */
+
+#include <skalibs/sysdeps.h>
+
+#ifdef SKALIBS_HASSIGNALFD
+
+#include <errno.h>
+#include <signal.h>
+#include <sys/signalfd.h>
+
+#include <skalibs/allreadwrite.h>
+#include <skalibs/sig.h>
+#include <skalibs/djbunix.h>
+
+struct selfpipe_s
+{
+  sigset_t caught ;
+  int fd ;
+} ;
+
+static struct selfpipe_s sp = { .fd = -1 } ;
+
+int selfpipe_fd ()
+{
+  return sp.fd ;
+}
+
+int selfpipe_read ()
+{
+  struct signalfd_siginfo buf ;
+  ssize_t r = sanitize_read(fd_read(sp.fd, (char *)&buf, sizeof(struct signalfd_siginfo))) ;
+  return (r <= 0) ? r : buf.ssi_signo ;
+}
+
+int selfpipe_trap (int sig)
+{
+  sigset_t set = sp.caught ;
+  sigset_t old ;
+  if (sp.fd == -1) return (errno = EBADF, 0) ;
+  if (sigaddset(&set, sig) == -1 || sigprocmask(SIG_BLOCK, &set, &old) == -1) return 0 ;
+  if (signalfd(sp.fd, &set, SFD_NONBLOCK | SFD_CLOEXEC) == -1)
+  {
+    int e = errno ;
+    sigprocmask(SIG_SETMASK, &old, 0) ;
+    errno = e ;
+    return 0 ;
+  }
+  sp.caught = set ;
+  return 1 ;
+}
+
+int selfpipe_trapset (sigset_t const *set)
+{
+  sigset_t old ;
+  if (sp.fd == -1) return (errno = EBADF, 0) ;
+  if (sigprocmask(SIG_SETMASK, set, &old) == -1) return 0 ;
+  if (signalfd(sp.fd, set, SFD_NONBLOCK | SFD_CLOEXEC) == -1)
+  {
+    int e = errno ;
+    sigprocmask(SIG_SETMASK, &old, 0) ;
+    errno = e ;
+    return 0 ;
+  }
+  sp.caught = *set ;
+  return 1 ;
+}
+
+void selfpipe_finish ()
+{
+  int e = errno ;
+  fd_close(sp.fd) ; sp.fd = -1 ;
+  sigprocmask(SIG_UNBLOCK, &sp.caught, 0) ;
+  sigemptyset(&sp.caught) ;
+  errno = e ;
+}
+
+int selfpipe_init ()
+{
+  sigemptyset(&sp.caught) ;
+  sig_blocknone() ;
+  sp.fd = signalfd(sp.fd, &sp.caught, SFD_NONBLOCK | SFD_CLOEXEC) ;
+  return sp.fd ;
+}
+
+#else
+
+#include <skalibs/nonposix.h>
+
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+
+#include <skalibs/nsig.h>
+#include <skalibs/sig.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/djbunix.h>
+
+struct selfpipe_s
+{
+  sigset_t caught ;
+  int fd[2] ;
+} ;
+
+static struct selfpipe_s sp = { .fd = { -1, -1 } } ;
+
+static void selfpipe_tophalf (int s)
+{
+  int e = errno ;
+  unsigned char c = (unsigned char)s ;
+  write(sp.fd[1], (char *)&c, 1) ;
+  errno = e ;
+}
+
+int selfpipe_fd ()
+{
+  return sp.fd[0] ;
+}
+
+int selfpipe_read ()
+{
+  char c ;
+  ssize_t r = sanitize_read((fd_read(sp.fd[0], &c, 1))) ;
+  return (r <= 0) ? r : c ;
+}
+
+int selfpipe_trap (int sig)
+{
+  if (sp.fd[0] == -1) return (errno = EBADF, 0) ;
+  if (!sig_catch(sig, &selfpipe_tophalf)) return 0 ;
+  sigaddset(&sp.caught, sig) ;
+  sig_unblock(sig) ;
+  return 1 ;
+}
+
+int selfpipe_trapset (sigset_t const *set)
+{
+  unsigned int i = 1 ;
+  if (sp.fd[0] == -1) return (errno = EBADF, 0) ;
+  for (; i < SKALIBS_NSIG ; i++)
+  {
+    int h = sigismember(set, i) ;
+    if (h < 0) continue ;
+    if (h)
+    {
+      if (!sig_catch(i, &selfpipe_tophalf)) goto err ;
+    }
+    else if (sigismember(&sp.caught, i))
+    {
+      if (!sig_restore(i)) goto err ;
+    }
+  }
+  sig_blocknone() ;
+  sp.caught = *set ;
+  return 1 ;
+
+ err:
+  sig_restoreto(set, i) ;
+  return 0 ;
+}
+
+void selfpipe_finish ()
+{
+  int e = errno ;
+  sigprocmask(SIG_BLOCK, &sp.caught, 0) ;
+  sig_restoreto(&sp.caught, SKALIBS_NSIG) ;
+  fd_close(sp.fd[1]) ;
+  fd_close(sp.fd[0]) ;
+  sigprocmask(SIG_UNBLOCK, &sp.caught, 0) ;
+  sigemptyset(&sp.caught) ;
+  sp.fd[0] = sp.fd[1] = -1 ;
+  errno = e ;
+}
+
+int selfpipe_init ()
+{
+  if (sp.fd[0] >= 0) selfpipe_finish() ;
+  else sigemptyset(&sp.caught) ;
+  sig_blocknone() ;
+  return pipenbcoe(sp.fd) < 0 ? -1 : sp.fd[0] ;
+}
+
+#endif