/* * The main module for truss. Suprisingly simple, but, then, the other * files handle the bulk of the work. And, of course, the kernel has to * do a lot of the work :). */ /* * $Id: main.c,v 1.2 1997/12/06 14:39:30 peter Exp $ */ #include #include #include #include #include #include #include #include #include #include extern int setup_and_wait(char **); extern int start_tracing(int, int); extern void i386_syscall_entry(int, int); extern void i386_syscall_exit(int, int); extern void i386_linux_syscall_entry(int, int); extern void i386_linux_syscall_exit(int, int); /* * These should really be parameterized -- I don't like having globals, * but this is the easiest way, right now, to deal with them. */ int pid = 0; int nosigs = 0; FILE *outfile = stderr; char *prog; int Procfd; char progtype[50]; /* OS and type of executable */ static inline void usage(void) { fprintf(stderr, "usage: %s [-o ] [-S] { [-p ] | " "[ ] }\n", prog); exit(1); } struct ex_types { char *type; void (*enter_syscall)(int, int); void (*exit_syscall)(int, int); } ex_types[] = { { "FreeBSD a.out", i386_syscall_entry, i386_syscall_exit }, { "FreeBSD ELF", i386_syscall_entry, i386_syscall_exit }, { "Linux ELF", i386_linux_syscall_entry, i386_linux_syscall_exit }, { 0, 0, 0 }, }; /* * Set the execution type. This is called after every exec, and when * a process is first monitored. The procfs pseudo-file "etype" has * the execution module type -- see /proc/curproc/etype for an example. */ static struct ex_types * set_etype() { struct ex_types *funcs; char etype[24]; char progtype[32]; int fd; sprintf(etype, "/proc/%d/etype", pid); if ((fd = open(etype, O_RDONLY)) == -1) { strcpy(progtype, "FreeBSD a.out"); } else { int len = read(fd, progtype, sizeof(progtype)); progtype[len-1] = '\0'; close(fd); } for (funcs = ex_types; funcs->type; funcs++) if (!strcmp(funcs->type, progtype)) break; return funcs; } main(int ac, char **av) { int mask; int c; int i; char **command; struct procfs_status pfs; char etype[25]; struct ex_types *funcs; int fd; int in_exec = 0; prog = av[0]; while ((c = getopt(ac, av, "p:o:S")) != EOF) { switch (c) { case 'p': /* specified pid */ pid = atoi(optarg); break; case 'o': /* Specified output file */ if ((outfile = fopen(optarg, "w")) == NULL) { fprintf (stderr, "%s: cannot open %s\n", av[0], optarg); exit(1); } break; case 'S': /* Don't trace signals */ nosigs = 1; break; default: usage(); } } ac -= optind; av += optind; if (ac && pid != 0) usage(); /* * If truss starts the process itself, it will ignore some signals -- * they should be passed off to the process, which may or may not * exit. If, however, we are examining an already-running process, * then we restore the event mask on these same signals. */ if (pid == 0) { /* Start a command ourselves */ command = av; pid = setup_and_wait(command); signal(SIGINT, SIG_IGN); signal(SIGTERM, SIG_IGN); signal(SIGQUIT, SIG_IGN); } else { extern void restore_proc(int); signal(SIGINT, restore_proc); signal(SIGTERM, restore_proc); signal(SIGQUIT, restore_proc); } /* * At this point, if we started the process, it is stopped waiting to * be woken up, either in exit() or in execve(). */ Procfd = start_tracing(pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT | (nosigs ? 0 : S_SIG)); pfs.why = 0; funcs = set_etype(); /* * At this point, it's a simple loop, waiting for the process to * stop, finding out why, printing out why, and then continuing it. * All of the grunt work is done in the support routines. */ do { int val = 0; if (ioctl(Procfd, PIOCWAIT, &pfs) == -1) perror("PIOCWAIT top of loop"); else { switch(i = pfs.why) { case S_SCE: funcs->enter_syscall(pid, pfs.val); break; case S_SCX: /* * This is so we don't get two messages for an exec -- one * for the S_EXEC, and one for the syscall exit. It also, * conveniently, ensures that the first message printed out * isn't the return-from-syscall used to create the process. */ if (in_exec) { in_exec = 0; break; } funcs->exit_syscall(pid, pfs.val); break; case S_SIG: fprintf(outfile, "SIGNAL %d\n", pfs.val); break; case S_EXIT: fprintf (outfile, "process exit, rval = %d\n", pfs.val); break; case S_EXEC: funcs = set_etype(); in_exec = 1; break; default: fprintf (outfile, "Process stopped because of: %d\n", i); break; } } if (ioctl(Procfd, PIOCCONT, &val) == -1) perror("PIOCCONT"); } while (pfs.why != S_EXIT); return 0; }