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/*
* 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;
}
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