From c094f988454a6a51c34db4ec478d221ee15519bf Mon Sep 17 00:00:00 2001
From: Fredrik Tolf <fredrik@dolda2000.com>
Date: Sun, 19 Feb 2017 19:32:03 +0100
Subject: [PATCH] Added pstack program.

---
 pstack.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 pstack.c

diff --git a/pstack.c b/pstack.c
new file mode 100644
index 0000000..055bcf4
--- /dev/null
+++ b/pstack.c
@@ -0,0 +1,89 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+#include <libunwind.h>
+#include <libunwind-ptrace.h>
+
+static void usage(FILE *out)
+{
+    fprintf(out, "usage: pstack [-h] PID\n");
+}
+
+static int dumpstack(pid_t pid)
+{
+    int rv, s;
+    unw_addr_space_t rps;
+    unw_cursor_t uw;
+    unw_word_t reg, pcoff;
+    void *ptd;
+    char pnm[64];
+    
+    rps = unw_create_addr_space(&_UPT_accessors, 0);
+    ptd = _UPT_create(pid);
+    rv = 0;
+    if((s = unw_init_remote(&uw, rps, ptd)) != 0) {
+	fprintf(stderr, "pstack: init_remote: %i\n", s);
+	rv = 1;
+	goto out;
+    }
+    do {
+	if(!(s = unw_get_proc_name(&uw, pnm, sizeof(pnm), &pcoff)) || (s == -UNW_ENOMEM)) {
+	    pnm[sizeof(pnm) - 1] = 0;
+	    printf("%s+%jx\n", pnm, (intmax_t)pcoff);
+	} else {
+	    unw_get_reg(&uw, UNW_REG_IP, &reg);
+	    printf("%jx\n", (intmax_t)reg);
+	}
+    } while((s = unw_step(&uw)) > 0);
+    if(s < 0) {
+	fprintf(stderr, "pstack: step: %i\n", s);
+    }
+out:
+    _UPT_destroy(ptd);
+    unw_destroy_addr_space(rps);
+    return(rv);
+}
+
+int main(int argc, char **argv)
+{
+    int c, s;
+    pid_t pid;
+    
+    while((c = getopt(argc, argv, "h")) != -1) {
+	switch(c) {
+	case 'h':
+	    usage(stdout);
+	    exit(0);
+	default:
+	    usage(stderr);
+	    exit(1);
+	}
+    }
+    if(argc - optind < 1) {
+	usage(stderr);
+	exit(1);
+    }
+    pid = atoi(argv[optind]);
+    if(ptrace(PTRACE_ATTACH, pid, NULL, NULL)) {
+	fprintf(stderr, "pstack: attach %i: %s\n", pid, strerror(errno));
+	exit(1);
+    }
+    while(1) {
+	if(waitpid(pid, &s, 0) < 0) {
+	    fprintf(stderr, "pstack: wait: %s\n", strerror(errno));
+	    exit(1);
+	}
+	if(WIFSTOPPED(s))
+	    break;
+    }
+    dumpstack(pid);
+    if(ptrace(PTRACE_DETACH, pid, NULL, NULL)) {
+	fprintf(stderr, "pstack: detach: %s\n", strerror(errno));
+    }
+    return(0);
+}
-- 
2.11.0