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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/Assertions.h>
28#include <AK/LogStream.h>
29#include <AK/Types.h>
30#include <Kernel/Syscall.h>
31#include <LibC/sys/arch/i386/regs.h>
32#include <signal.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <sys/ptrace.h>
37#include <sys/wait.h>
38#include <unistd.h>
39
40static int usage()
41{
42 printf("usage: strace [-p pid] [command...]\n");
43 return 1;
44}
45
46static int g_pid = -1;
47
48static void handle_sigint(int)
49{
50 if (g_pid == -1)
51 return;
52
53 if (ptrace(PT_DETACH, g_pid, 0, 0) == -1) {
54 perror("detach");
55 }
56}
57
58int main(int argc, char** argv)
59{
60 if (argc == 1)
61 return usage();
62
63 if (!strcmp(argv[1], "-p")) {
64 if (argc != 3)
65 return usage();
66 g_pid = atoi(argv[2]);
67 } else {
68 int pid = fork();
69 if (!pid) {
70 if (ptrace(PT_TRACE_ME, 0, 0, 0) == -1) {
71 perror("traceme");
72 return 1;
73 }
74 int rc = execvp(argv[1], &argv[1]);
75 if (rc < 0) {
76 perror("execvp");
77 exit(1);
78 }
79 ASSERT_NOT_REACHED();
80 }
81 if (waitpid(pid, nullptr, WSTOPPED) != pid) {
82 perror("waitpid");
83 return 1;
84 }
85 g_pid = pid;
86 }
87
88 struct sigaction sa;
89 memset(&sa, 0, sizeof(struct sigaction));
90 sa.sa_handler = handle_sigint;
91 sigaction(SIGINT, &sa, nullptr);
92
93 if (ptrace(PT_ATTACH, g_pid, 0, 0) == -1) {
94 perror("attach");
95 return 1;
96 }
97
98 if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
99 perror("waitpid");
100 return 1;
101 }
102
103 for (;;) {
104 if (ptrace(PT_SYSCALL, g_pid, 0, 0) == -1) {
105 if (errno == ESRCH)
106 return 0;
107 perror("syscall");
108 return 1;
109 }
110 if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
111 perror("wait_pid");
112 return 1;
113 }
114
115 PtraceRegisters regs = {};
116 if (ptrace(PT_GETREGS, g_pid, ®s, 0) == -1) {
117 perror("getregs");
118 return 1;
119 }
120
121 u32 syscall_index = regs.eax;
122 u32 arg1 = regs.edx;
123 u32 arg2 = regs.ecx;
124 u32 arg3 = regs.ebx;
125
126 // skip syscall exit
127 if (ptrace(PT_SYSCALL, g_pid, 0, 0) == -1) {
128 if (errno == ESRCH)
129 return 0;
130 perror("syscall");
131 return 1;
132 }
133 if (waitpid(g_pid, nullptr, WSTOPPED) != g_pid) {
134 perror("wait_pid");
135 return 1;
136 }
137
138 if (ptrace(PT_GETREGS, g_pid, ®s, 0) == -1) {
139 if (errno == ESRCH && syscall_index == SC_exit) {
140 regs.eax = 0;
141 } else {
142 perror("getregs");
143 return 1;
144 }
145 }
146
147 u32 res = regs.eax;
148
149 fprintf(stderr, "%s(0x%x, 0x%x, 0x%x)\t=%d\n",
150 Syscall::to_string(
151 (Syscall::Function)syscall_index),
152 arg1,
153 arg2,
154 arg3,
155 res);
156 }
157
158 return 0;
159
160 return 0;
161}