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-rw-r--r--sigchain.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/sigchain.c b/sigchain.c
new file mode 100644
index 000000000..a18d505e5
--- /dev/null
+++ b/sigchain.c
@@ -0,0 +1,43 @@
+#include "sigchain.h"
+#include "cache.h"
+
+#define SIGCHAIN_MAX_SIGNALS 32
+
+struct sigchain_signal {
+ sigchain_fun *old;
+ int n;
+ int alloc;
+};
+static struct sigchain_signal signals[SIGCHAIN_MAX_SIGNALS];
+
+static void check_signum(int sig)
+{
+ if (sig < 1 || sig >= SIGCHAIN_MAX_SIGNALS)
+ die("BUG: signal out of range: %d", sig);
+}
+
+int sigchain_push(int sig, sigchain_fun f)
+{
+ struct sigchain_signal *s = signals + sig;
+ check_signum(sig);
+
+ ALLOC_GROW(s->old, s->n + 1, s->alloc);
+ s->old[s->n] = signal(sig, f);
+ if (s->old[s->n] == SIG_ERR)
+ return -1;
+ s->n++;
+ return 0;
+}
+
+int sigchain_pop(int sig)
+{
+ struct sigchain_signal *s = signals + sig;
+ check_signum(sig);
+ if (s->n < 1)
+ return 0;
+
+ if (signal(sig, s->old[s->n - 1]) == SIG_ERR)
+ return -1;
+ s->n--;
+ return 0;
+}