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 1.3 2003/11/04 15:34:41 eirikn 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; 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 asprintf(&buf, "%s/curproc/mem", procfs_path); 80 if (buf == NULL) 81 err(1, "Out of memory"); 82 fd = open(buf, O_WRONLY); 83 free(buf); 84 if (fd == -1) 85 err(2, "cannot open %s", buf); 86 fcntl(fd, F_SETFD, 1); 87 if (ioctl(fd, PIOCBIS, mask) == -1) 88 err(3, "PIOCBIS"); 89 flags = PF_LINGER; 90 /* 91 * The PF_LINGER flag tells procfs not to wake up the 92 * process on last close; normally, this is the behaviour 93 * we want. 94 */ 95 if (ioctl(fd, PIOCSFL, flags) == -1) 96 warn("cannot set PF_LINGER"); 97 execvp(command[0], command); 98 mask = ~0; 99 ioctl(fd, PIOCBIC, ~0); 100 err(4, "execvp %s", command[0]); 101 } 102 /* Only in the parent here */ 103 104 if (waitpid(pid, NULL, WNOHANG) != 0) { 105 /* 106 * Process exited before it got to us -- meaning the exec failed 107 * miserably -- so we just quietly exit. 108 */ 109 exit(1); 110 } 111 112 asprintf(&buf, "%s/%d/mem", procfs_path, pid); 113 if (buf == NULL) 114 err(1, "Out of memory"); 115 fd = open(buf, O_RDWR); 116 free(buf); 117 if (fd == -1) 118 err(5, "cannot open %s", buf); 119 if (ioctl(fd, PIOCWAIT, &pfs) == -1) 120 err(6, "PIOCWAIT"); 121 if (pfs.why == S_EXIT) { 122 fprintf(stderr, "process exited before exec'ing\n"); 123 ioctl(fd, PIOCCONT, 0); 124 wait(0); 125 exit(7); 126 } 127 close(fd); 128 return pid; 129 } 130 131 /* 132 * start_tracing picks up where setup_and_wait() dropped off -- namely, 133 * it sets the event mask for the given process id. Called for both 134 * monitoring an existing process and when we create our own. 135 */ 136 137 int 138 start_tracing(int pid, int flags) { 139 int fd; 140 char *buf; 141 struct procfs_status tmp; 142 143 asprintf(&buf, "%s/%d/mem", procfs_path, pid); 144 if (buf == NULL) 145 err(1, "Out of memory"); 146 fd = open(buf, O_RDWR); 147 free(buf); 148 if (fd == -1) { 149 /* 150 * The process may have run away before we could start -- this 151 * happens with SUGID programs. So we need to see if it still 152 * exists before we complain bitterly. 153 */ 154 if (kill(pid, 0) == -1) 155 return -1; 156 err(8, "cannot open %s", buf); 157 } 158 159 if (ioctl(fd, PIOCSTATUS, &tmp) == -1) { 160 err(10, "cannot get procfs status struct"); 161 } 162 evflags = tmp.events; 163 164 if (ioctl(fd, PIOCBIS, flags) == -1) 165 err(9, "cannot set procfs event bit mask"); 166 167 /* 168 * This clears the PF_LINGER set above in setup_and_wait(); 169 * if truss happens to die before this, then the process 170 * needs to be woken up via procctl. 171 */ 172 173 if (ioctl(fd, PIOCSFL, 0) == -1) 174 warn("cannot clear PF_LINGER"); 175 176 return fd; 177 } 178 179 /* 180 * Restore a process back to it's pre-truss state. 181 * Called for SIGINT, SIGTERM, SIGQUIT. This only 182 * applies if truss was told to monitor an already-existing 183 * process. 184 */ 185 void 186 restore_proc(int signo __unused) { 187 ioctl(Procfd, PIOCBIC, ~0); 188 if (evflags) 189 ioctl(Procfd, PIOCBIS, evflags); 190 exit(0); 191 } 192