1 /* 2 * Copryight 1997 Sean Eric Fagan 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. All advertising materials mentioning features or use of this software 13 * must display the following acknowledgement: 14 * This product includes software developed by Sean Eric Fagan 15 * 4. Neither the name of the author may be used to endorse or promote 16 * products derived from this software without specific prior written 17 * permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 /* 36 * Various setup functions for truss. Not the cleanest-written code, 37 * I'm afraid. 38 */ 39 40 #include <sys/param.h> 41 #include <sys/types.h> 42 #include <sys/ptrace.h> 43 #include <sys/wait.h> 44 45 #include <err.h> 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <signal.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <time.h> 53 #include <unistd.h> 54 55 #include <machine/reg.h> 56 57 #include "truss.h" 58 #include "extern.h" 59 60 static int child_pid; 61 62 /* 63 * setup_and_wait() is called to start a process. All it really does 64 * is fork(), set itself up to stop on exec or exit, and then exec 65 * the given command. At that point, the child process stops, and 66 * the parent can wake up and deal with it. 67 */ 68 69 int 70 setup_and_wait(char *command[]) 71 { 72 int pid; 73 int waitval; 74 75 pid = vfork(); 76 if (pid == -1) { 77 err(1, "fork failed"); 78 } 79 if (pid == 0) { /* Child */ 80 ptrace(PT_TRACE_ME, 0, 0, 0); 81 setpgid (0, 0); 82 execvp(command[0], command); 83 err(1, "execvp %s", command[0]); 84 } 85 86 /* Only in the parent here */ 87 if (waitpid(pid, &waitval, 0) < -1) { 88 err(1, "unexpect stop in waitpid"); 89 return 0; 90 } 91 92 child_pid = pid; 93 94 return (pid); 95 } 96 97 /* 98 * start_tracing picks up where setup_and_wait() dropped off -- namely, 99 * it sets the event mask for the given process id. Called for both 100 * monitoring an existing process and when we create our own. 101 */ 102 103 int 104 start_tracing(int pid) 105 { 106 int waitval; 107 int ret; 108 int retry = 10; 109 110 do { 111 ret = ptrace(PT_ATTACH, pid, NULL, 0); 112 usleep(200); 113 } while(ret && retry-- > 0); 114 if (ret) 115 err(1, "can not attach to target process"); 116 117 child_pid = pid; 118 if (waitpid(pid, &waitval, 0) < -1) 119 err(1, "Unexpect stop in waitpid"); 120 121 return (0); 122 } 123 124 /* 125 * Restore a process back to it's pre-truss state. 126 * Called for SIGINT, SIGTERM, SIGQUIT. This only 127 * applies if truss was told to monitor an already-existing 128 * process. 129 */ 130 void 131 restore_proc(int signo __unused) 132 { 133 int waitval; 134 135 /* stop the child so that we can detach */ 136 kill(child_pid, SIGSTOP); 137 if (waitpid(child_pid, &waitval, 0) < -1) 138 err(1, "Unexpected stop in waitpid"); 139 140 if (ptrace(PT_DETACH, child_pid, (caddr_t)1, 0) < 0) 141 err(1, "Can not detach the process"); 142 143 kill(child_pid, SIGCONT); 144 exit(0); 145 } 146 147 /* 148 * Change curthread member based on lwpid. 149 * If it is a new thread, create a threadinfo structure 150 */ 151 static void 152 find_thread(struct trussinfo *info, lwpid_t lwpid) 153 { 154 info->curthread = NULL; 155 struct threadinfo *np; 156 SLIST_FOREACH(np, &info->threadlist, entries) { 157 if (np->tid == lwpid) { 158 info->curthread = np; 159 return; 160 } 161 } 162 163 np = (struct threadinfo *)malloc(sizeof(struct threadinfo)); 164 if (np == NULL) 165 errx(1, "malloc() failed"); 166 np->tid = lwpid; 167 np->in_fork = 0; 168 np->in_syscall = 0; 169 SLIST_INSERT_HEAD(&info->threadlist, np, entries); 170 info->curthread = np; 171 } 172 173 /* 174 * Start the traced process and wait until it stoped. 175 * Fill trussinfo structure. 176 * When this even returns, the traced process is in stop state. 177 */ 178 void 179 waitevent(struct trussinfo *info) 180 { 181 int waitval; 182 static int pending_signal = 0; 183 184 ptrace(PT_SYSCALL, info->pid, (caddr_t)1, pending_signal); 185 pending_signal = 0; 186 187 if (waitpid(info->pid, &waitval, 0) < -1) { 188 err(1, "Unexpected stop in waitpid"); 189 } 190 191 if (WIFCONTINUED(waitval)) { 192 info->pr_why = S_NONE; 193 return; 194 } 195 if (WIFEXITED(waitval)) { 196 info->pr_why = S_EXIT; 197 info->pr_data = WEXITSTATUS(waitval); 198 return; 199 } 200 if (WIFSTOPPED(waitval)) { 201 struct ptrace_lwpinfo lwpinfo; 202 ptrace(PT_LWPINFO, info->pid, (caddr_t)&lwpinfo, sizeof(lwpinfo)); 203 find_thread(info, lwpinfo.pl_lwpid); 204 switch(WSTOPSIG(waitval)) { 205 case SIGTRAP: 206 info->pr_why = info->curthread->in_syscall?S_SCX:S_SCE; 207 info->curthread->in_syscall = 1 - info->curthread->in_syscall; 208 break; 209 default: 210 info->pr_why = S_SIG; 211 info->pr_data = WSTOPSIG(waitval); 212 pending_signal = info->pr_data; 213 break; 214 } 215 } 216 if (WIFSIGNALED(waitval)) { 217 info->pr_why = S_EXIT; 218 info->pr_why = 0; 219 return; 220 } 221 } 222