1 files changed, 54 insertions, 0 deletions
diff --git a/library/wchan.c b/library/wchan.c
new file mode 100644
index 0000000..d342fef
--- /dev/null
+++ b/library/wchan.c
@@ -0,0 +1,54 @@
+/*
+ * wchan.c - kernel symbol handling
+ *
+ * Copyright © 2015-2023 Jim Warner <james.warner@comcast.net>
+ * Copyright © 1998-2003 Albert Cahalan
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "wchan.h"  // to verify prototype
+
+
+const char *lookup_wchan (int pid) {
+   static __thread char buf[64];
+   const char *ret = buf;
+   ssize_t num;
+   int fd;
+
+   snprintf(buf, sizeof buf, "/proc/%d/wchan", pid);
+   fd = open(buf, O_RDONLY);
+   if (fd==-1) return "?";
+
+   num = read(fd, buf, sizeof buf - 1);
+   close(fd);
+
+   if (num<1) return "?"; // allow for "0"
+   buf[num] = '\0';
+
+   if (buf[0]=='0' && buf[1]=='\0') return "-";
+
+   // lame ppc64 has a '.' in front of every name
+   if (*ret=='.') ret++;
+   while(*ret=='_') ret++;
+
+   return ret;
+}