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 * $FreeBSD: src/usr.bin/truss/setup.c,v 1.10.2.2 2002/02/15 11:43:51 des Exp $ 32 * $DragonFly: src/usr.bin/truss/setup.c,v 1.2 2003/06/17 04:29:33 dillon Exp $ 33 */ 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/ioctl.h> 42 #include <sys/pioctl.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 <unistd.h> 53 54 #include "extern.h" 55 56 static int evflags = 0; 57 58 /* 59 * setup_and_wait() is called to start a process. All it really does 60 * is fork(), set itself up to stop on exec or exit, and then exec 61 * the given command. At that point, the child process stops, and 62 * the parent can wake up and deal with it. 63 */ 64 65 int 66 setup_and_wait(char *command[]) { 67 struct procfs_status pfs; 68 char buf[32]; 69 int fd; 70 int pid; 71 int flags; 72 73 pid = fork(); 74 if (pid == -1) { 75 err(1, "fork failed"); 76 } 77 if (pid == 0) { /* Child */ 78 int mask = S_EXEC | S_EXIT; 79 fd = open("/proc/curproc/mem", O_WRONLY); 80 if (fd == -1) 81 err(2, "cannot open /proc/curproc/mem"); 82 fcntl(fd, F_SETFD, 1); 83 if (ioctl(fd, PIOCBIS, mask) == -1) 84 err(3, "PIOCBIS"); 85 flags = PF_LINGER; 86 /* 87 * The PF_LINGER flag tells procfs not to wake up the 88 * process on last close; normally, this is the behaviour 89 * we want. 90 */ 91 if (ioctl(fd, PIOCSFL, flags) == -1) 92 warn("cannot set PF_LINGER"); 93 execvp(command[0], command); 94 mask = ~0; 95 ioctl(fd, PIOCBIC, ~0); 96 err(4, "execvp %s", command[0]); 97 } 98 /* Only in the parent here */ 99 100 if (waitpid(pid, NULL, WNOHANG) != 0) { 101 /* 102 * Process exited before it got to us -- meaning the exec failed 103 * miserably -- so we just quietly exit. 104 */ 105 exit(1); 106 } 107 108 sprintf(buf, "/proc/%d/mem", pid); 109 if ((fd = open(buf, O_RDWR)) == -1) 110 err(5, "cannot open %s", buf); 111 if (ioctl(fd, PIOCWAIT, &pfs) == -1) 112 err(6, "PIOCWAIT"); 113 if (pfs.why == S_EXIT) { 114 fprintf(stderr, "process exited before exec'ing\n"); 115 ioctl(fd, PIOCCONT, 0); 116 wait(0); 117 exit(7); 118 } 119 close(fd); 120 return pid; 121 } 122 123 /* 124 * start_tracing picks up where setup_and_wait() dropped off -- namely, 125 * it sets the event mask for the given process id. Called for both 126 * monitoring an existing process and when we create our own. 127 */ 128 129 int 130 start_tracing(int pid, int flags) { 131 int fd; 132 char buf[32]; 133 struct procfs_status tmp; 134 sprintf(buf, "/proc/%d/mem", pid); 135 136 fd = open(buf, O_RDWR); 137 if (fd == -1) { 138 /* 139 * The process may have run away before we could start -- this 140 * happens with SUGID programs. So we need to see if it still 141 * exists before we complain bitterly. 142 */ 143 if (kill(pid, 0) == -1) 144 return -1; 145 err(8, "cannot open %s", buf); 146 } 147 148 if (ioctl(fd, PIOCSTATUS, &tmp) == -1) { 149 err(10, "cannot get procfs status struct"); 150 } 151 evflags = tmp.events; 152 153 if (ioctl(fd, PIOCBIS, flags) == -1) 154 err(9, "cannot set procfs event bit mask"); 155 156 /* 157 * This clears the PF_LINGER set above in setup_and_wait(); 158 * if truss happens to die before this, then the process 159 * needs to be woken up via procctl. 160 */ 161 162 if (ioctl(fd, PIOCSFL, 0) == -1) 163 warn("cannot clear PF_LINGER"); 164 165 return fd; 166 } 167 168 /* 169 * Restore a process back to it's pre-truss state. 170 * Called for SIGINT, SIGTERM, SIGQUIT. This only 171 * applies if truss was told to monitor an already-existing 172 * process. 173 */ 174 void 175 restore_proc(int signo __unused) { 176 extern int Procfd; 177 178 ioctl(Procfd, PIOCBIC, ~0); 179 if (evflags) 180 ioctl(Procfd, PIOCBIS, evflags); 181 exit(0); 182 } 183