signal.c

linux进程跟踪的工具和源代码

/*
 * Copyright (c) 1991, 1992 Paul Kranenburg <[e-mail]>
 * Copyright (c) 1993 Branko Lankester <[e-mail]>
 * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <[e-mail]>
 * Copyright (c) 1996-1999 Wichert Akkerman <[e-mail]>
 * Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *                     Linux for s390 port by D.J. Barrow
 *                    <[e-mail],[e-mail]>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *	$Id: signal.c,v 1.28 2001/03/28 20:29:17 wichert Exp $
 */

#include "defs.h"

#include <signal.h>
#include <sys/user.h>
#include <fcntl.h>

#ifdef SVR4
#include <sys/ucontext.h>
#endif /* SVR4 */

#ifdef HAVE_SYS_REG_H
# include <sys/reg.h>
#ifndef PTRACE_PEEKUSR
# define PTRACE_PEEKUSR PTRACE_PEEKUSER
#endif
#ifndef PTRACE_POKEUSR
# define PTRACE_POKEUSR PTRACE_POKEUSER
#endif
#elif defined(HAVE_LINUX_PTRACE_H)
#undef PTRACE_SYSCALL
#include <linux/ptrace.h>
#endif


#ifdef LINUX

#ifdef IA64
# include <asm/ptrace_offsets.h>
#endif /* !IA64 */

#if HAVE_ASM_REG_H
#ifdef SPARC
#  define fpq kernel_fpq
#  define fq kernel_fq
#  define fpu kernel_fpu
#endif
#include <asm/reg.h>
#ifdef SPARC
#  undef fpq
#  undef fq
#  undef fpu 
#endif

#endif /* HAVE_ASM_REG_H */
#ifdef HAVE_ASM_SIGCONTEXT_H
#ifdef SPARC
typedef struct {
	struct regs		si_regs;
	int			si_mask;
} m_siginfo_t;
#else
#include <asm/sigcontext.h>
#endif /* SPARC */
#else /* !HAVE_ASM_SIGCONTEXT_H */
#ifdef I386
struct sigcontext_struct {
	unsigned short gs, __gsh;
	unsigned short fs, __fsh;
	unsigned short es, __esh;
	unsigned short ds, __dsh;
	unsigned long edi;
	unsigned long esi;
	unsigned long ebp;
	unsigned long esp;
	unsigned long ebx;
	unsigned long edx;
	unsigned long ecx;
	unsigned long eax;
	unsigned long trapno;
	unsigned long err;
	unsigned long eip;
	unsigned short cs, __csh;
	unsigned long eflags;
	unsigned long esp_at_signal;
	unsigned short ss, __ssh;
	unsigned long i387;
	unsigned long oldmask;
	unsigned long cr2;
};
#else /* !I386 */
#ifdef M68K
struct sigcontext
{
	unsigned long sc_mask;
	unsigned long sc_usp;
	unsigned long sc_d0;
	unsigned long sc_d1;
	unsigned long sc_a0;
	unsigned long sc_a1;
	unsigned short sc_sr;
	unsigned long sc_pc;
	unsigned short sc_formatvec;
};
#endif /* M68K */
#endif /* !I386 */
#endif /* !HAVE_ASM_SIGCONTEXT_H */
#ifndef NSIG
#define NSIG 32
#endif
#ifdef ARM
#undef NSIG
#define NSIG 32
#endif
#endif /* LINUX */

char *signalent0[] = {
#include "signalent.h"
};
int nsignals0 = sizeof signalent0 / sizeof signalent0[0];

#if SUPPORTED_PERSONALITIES >= 2
char *signalent1[] = {
#include "signalent1.h"
};
int nsignals1 = sizeof signalent1 / sizeof signalent1[0];
#endif /* SUPPORTED_PERSONALITIES >= 2 */

#if SUPPORTED_PERSONALITIES >= 3
char *signalent2[] = {
#include "signalent2.h"
};
int nsignals2 = sizeof signalent2 / sizeof signalent2[0];
#endif /* SUPPORTED_PERSONALITIES >= 3 */

char **signalent;
int nsignals;

#if defined(SUNOS4) || defined(FREEBSD)

static struct xlat sigvec_flags[] = {
	{ SV_ONSTACK,	"SV_ONSTACK"	},
	{ SV_INTERRUPT,	"SV_INTERRUPT"	},
	{ SV_RESETHAND,	"SV_RESETHAND"	},
	{ SA_NOCLDSTOP,	"SA_NOCLDSTOP"	},
	{ 0,		NULL		},
};

#endif /* SUNOS4 || FREEBSD */

#ifdef HAVE_SIGACTION

static struct xlat sigact_flags[] = {
#ifdef SA_RESTORER
	{ SA_RESTORER,	"SA_RESTORER"	},
#endif
#ifdef SA_STACK
	{ SA_STACK,	"SA_STACK"	},
#endif
#ifdef SA_RESTART
	{ SA_RESTART,	"SA_RESTART"	},
#endif
#ifdef SA_INTERRUPT
	{ SA_INTERRUPT,	"SA_INTERRUPT"	},
#endif
#ifdef SA_NOMASK
	{ SA_NOMASK,	"SA_NOMASK"	},
#endif
#ifdef SA_ONESHOT
	{ SA_ONESHOT,	"SA_ONESHOT"	},
#endif
#ifdef SA_SIGINFO
	{ SA_SIGINFO,	"SA_SIGINFO"	},
#endif
#ifdef SA_RESETHAND
	{ SA_RESETHAND,	"SA_RESETHAND"	},
#endif
#ifdef SA_ONSTACK
	{ SA_ONSTACK,	"SA_ONSTACK"	},
#endif
#ifdef SA_NODEFER
	{ SA_NODEFER,	"SA_NODEFER"	},
#endif
#ifdef SA_NOCLDSTOP
	{ SA_NOCLDSTOP,	"SA_NOCLDSTOP"	},
#endif
#ifdef SA_NOCLDWAIT
	{ SA_NOCLDWAIT,	"SA_NOCLDWAIT"	},
#endif
#ifdef _SA_BSDCALL
	{ _SA_BSDCALL,	"_SA_BSDCALL"	},
#endif
	{ 0,		NULL		},
};

static struct xlat sigprocmaskcmds[] = {
	{ SIG_BLOCK,	"SIG_BLOCK"	},
	{ SIG_UNBLOCK,	"SIG_UNBLOCK"	},
	{ SIG_SETMASK,	"SIG_SETMASK"	},
#ifdef SIG_SETMASK32
	{ SIG_SETMASK32,"SIG_SETMASK32"	},
#endif
	{ 0,		NULL		},
};

#endif /* HAVE_SIGACTION */

/* Anonymous realtime signals. */
/* Under glibc 2.1, SIGRTMIN et al are functions, but __SIGRTMIN is a
   constant.  This is what we want.  Otherwise, just use SIGRTMIN. */
#ifdef SIGRTMIN
#ifndef __SIGRTMIN
#define __SIGRTMIN SIGRTMIN
#define __SIGRTMAX SIGRTMAX /* likewise */
#endif
#endif

char *
signame(sig)
int sig;
{
	static char buf[30];
	if (sig < nsignals) {
		return signalent[sig];
#ifdef SIGRTMIN
	} else if (sig >= __SIGRTMIN && sig <= __SIGRTMAX) {
		sprintf(buf, "SIGRT_%ld", (long)(sig - __SIGRTMIN));
		return buf;
#endif /* SIGRTMIN */
	} else {
		sprintf(buf, "%d", sig);
		return buf;
	}
}

#ifndef UNIXWARE
static void
long_to_sigset(l, s)
long l;
sigset_t *s;
{
	sigemptyset(s);
	*(long *)s = l;
}
#endif

static int
copy_sigset_len(tcp, addr, s, len)
struct tcb *tcp;
long addr;
sigset_t *s;
int len;
{
	if (len > sizeof(*s))
		len = sizeof(*s);
	sigemptyset(s);
	if (umoven(tcp, addr, len, (char *)s) < 0)
		return -1;
	return 0;
}

#ifdef LINUX
/* Original sigset is unsigned long */
#define copy_sigset(tcp, addr, s) copy_sigset_len(tcp, addr, s, sizeof(long))
#else
#define copy_sigset(tcp, addr, s) copy_sigset_len(tcp, addr, s, sizeof(sigset_t))
#endif

static char *
sprintsigmask(s, mask, rt)
char *s;
sigset_t *mask;
int rt; /* set might include realtime sigs */
{
	int i, nsigs;
	int maxsigs;
	char *format;
	static char outstr[256];

	strcpy(outstr, s);
	s = outstr + strlen(outstr);
	nsigs = 0;
	maxsigs = nsignals;
#ifdef __SIGRTMAX
	if (rt)
		maxsigs = __SIGRTMAX; /* instead */
#endif
	for (i = 1; i < maxsigs; i++) {
		if (sigismember(mask, i) == 1)
			nsigs++;
	}
	if (nsigs >= nsignals * 2 / 3) {
		*s++ = '~';
		for (i = 1; i < maxsigs; i++) {
			switch (sigismember(mask, i)) {
			case 1:
				sigdelset(mask, i);
				break;
			case 0:
				sigaddset(mask, i);
				break;
			}
		}
	}
	format = "%s";
	*s++ = '[';
	for (i = 1; i < maxsigs; i++) {
		if (sigismember(mask, i) == 1) {
			/* real-time signals on solaris don't have
			 * signalent entries
			 */
			if (i < nsignals) {
				sprintf(s, format, signalent[i] + 3);
			}
			else {
				char tsig[32];
				sprintf(tsig, "%u", i);
				sprintf(s, format, tsig);
			}
			s += strlen(s);
			format = " %s";
		}
	}
	*s++ = ']';
	*s = '\0';
	return outstr;
}

static void
printsigmask(mask, rt)
sigset_t *mask;
int rt;
{
	tprintf("%s", sprintsigmask("", mask, rt));
}

void
printsignal(nr)
int nr;
{
	tprintf(signame(nr));
}

/*
 * Check process TCP for the disposition of signal SIG.
 * Return 1 if the process would somehow manage to  survive signal SIG,
 * else return 0.  This routine will never be called with SIGKILL.
 */
int
sigishandled(tcp, sig)
struct tcb *tcp;
int sig;
{
#ifdef LINUX
	int sfd;
	char sname[32];
	char buf[1024];
	char *s;
	int i;
	unsigned int signalled, blocked, ignored, caught;

	/* This is incredibly costly but it's worth it. */
	sprintf(sname, "/proc/%d/stat", tcp->pid);
	if ((sfd = open(sname, O_RDONLY)) == -1) {
		perror(sname);
		return 1;
	}
	i = read(sfd, buf, 1024);
	buf[i] = '\0';
	close(sfd);
	/*
	 * Skip the extraneous fields. This loses if the
	 * command name has any spaces in it.  So be it.
	 */
	for (i = 0, s = buf; i < 30; i++) {
		while (*++s != ' ') {
			if (!*s)
				break;
		}
	}
	if (sscanf(s, "%u%u%u%u",
		   &signalled, &blocked, &ignored, &caught) != 4) {
		fprintf(stderr, "/proc/pid/stat format error\n");
		return 1;
	}
#ifdef DEBUG
	fprintf(stderr, "sigs: %08x %08x %08x %08x\n",
		signalled, blocked, ignored, caught);
#endif
	if ((ignored & sigmask(sig)) || (caught & sigmask(sig)))
		return 1;
#endif /* LINUX */

#ifdef SUNOS4
	void (*u_signal)();

	if (upeek(tcp->pid, uoff(u_signal[0]) + sig*sizeof(u_signal),
	    (long *) &u_signal) < 0) {
		return 0;
	}
	if (u_signal != SIG_DFL)
		return 1;
#endif /* SUNOS4 */

#ifdef SVR4
	/*
	 * Since procfs doesn't interfere with wait I think it is safe
	 * to punt on this question.  If not, the information is there.
	 */
	return 1;
#else /* !SVR4 */
	switch (sig) {
	case SIGCONT:
	case SIGSTOP:
	case SIGTSTP:
	case SIGTTIN:
	case SIGTTOU:
	case SIGCHLD:
	case SIGIO:
#if defined(SIGURG) && SIGURG != SIGIO
	case SIGURG:
#endif
	case SIGWINCH:
		/* Gloria Gaynor says ... */
		return 1;
	default:
		break;
	}
	return 0;
#endif /* !SVR4 */
}

#if defined(SUNOS4) || defined(FREEBSD)

int
sys_sigvec(tcp)
struct tcb *tcp;
{
	struct sigvec sv;
	long addr;

	if (entering(tcp)) {
		printsignal(tcp->u_arg[0]);
		tprintf(", ");
		addr = tcp->u_arg[1];
	} else {
		addr = tcp->u_arg[2];
	}
	if (addr == 0)
		tprintf("NULL");
	else if (!verbose(tcp))
		tprintf("%#lx", addr);
	else if (umove(tcp, addr, &sv) < 0)
		tprintf("{...}");
	else {
		switch ((int) sv.sv_handler) {
		case (int) SIG_ERR:
			tprintf("{SIG_ERR}");
			break;
		case (int) SIG_DFL:
			tprintf("{SIG_DFL}");
			break;
		case (int) SIG_IGN:
			if (tcp->u_arg[0] == SIGTRAP) {
				tcp->flags |= TCB_SIGTRAPPED;
				kill(tcp->pid, SIGSTOP);
			}
			tprintf("{SIG_IGN}");
			break;
		case (int) SIG_HOLD:
			if (tcp->u_arg[0] == SIGTRAP) {
				tcp->flags |= TCB_SIGTRAPPED;
				kill(tcp->pid, SIGSTOP);
			}
			tprintf("SIG_HOLD");
			break;
		default:
			if (tcp->u_arg[0] == SIGTRAP) {
				tcp->flags |= TCB_SIGTRAPPED;
				kill(tcp->pid, SIGSTOP);
			}
			tprintf("{%#lx, ", (unsigned long) sv.sv_handler);
			printsigmask(&sv.sv_mask, 0);
			tprintf(", ");
			if (!printflags(sigvec_flags, sv.sv_flags))
				tprintf("0");
			tprintf("}");
		}
	}
	if (entering(tcp))
		tprintf(", ");
	return 0;
}

int
sys_sigpause(tcp)
struct tcb *tcp;
{
	if (entering(tcp)) {	/* WTA: UD had a bug here: he forgot the braces */
		sigset_t sigm;
		long_to_sigset(tcp->u_arg[0], &sigm);
		printsigmask(&sigm, 0);
	}
	return 0;
}

int
sys_sigstack(tcp)
struct tcb *tcp;
{
	struct sigstack ss;
	long addr;

	if (entering(tcp))
		addr = tcp->u_arg[0];
	else
		addr = tcp->u_arg[1];
	if (addr == 0)
		tprintf("NULL");
	else if (umove(tcp, addr, &ss) < 0)
		tprintf("%#lx", addr);
	else {
		tprintf("{ss_sp %#lx ", (unsigned long) ss.ss_sp);
		tprintf("ss_onstack %s}", ss.ss_onstack ? "YES" : "NO");
	}
	if (entering(tcp))
		tprintf(", ");
	return 0;
}

int
sys_sigcleanup(tcp)
struct tcb *tcp;
{
	return 0;
}

#endif /* SUNOS4 || FREEBSD */

#ifndef SVR4

int
sys_sigsetmask(tcp)
struct tcb *tcp;
{
	if (entering(tcp)) {
		sigset_t sigm;
		long_to_sigset(tcp->u_arg[0], &sigm);