pgrep.c

linux下获取一些环境信息的代码

/* emacs settings:  -*- c-basic-offset: 8 tab-width: 8 -*-
 *
 * pgrep/pkill -- utilities to filter the process table
 *
 * Copyright 2000 Kjetil Torgrim Homme <[e-mail]>
 *
 * May be distributed under the conditions of the
 * GNU General Public License; a copy is in COPYING
 *
 * Changes by Albert Cahalan, 2002,2006.
 * 
 */


#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#include <ctype.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <pwd.h>
#include <grp.h>
#include <regex.h>
#include <errno.h>

#include "proc/readproc.h"
#include "proc/sig.h"
#include "proc/devname.h"
#include "proc/sysinfo.h"
#include "proc/version.h" /* procps_version */

// EXIT_SUCCESS is 0
// EXIT_FAILURE is 1
#define EXIT_USAGE 2
#define EXIT_FATAL 3

static int i_am_pkill = 0;
static const char *progname = "pgrep";

union el {
	long	num;
	char *	str;
};

/* User supplied arguments */

static int opt_full = 0;
static int opt_long = 0;
static int opt_oldest = 0;
static int opt_newest = 0;
static int opt_negate = 0;
static int opt_exact = 0;
static int opt_signal = SIGTERM;
static int opt_lock = 0;
static int opt_case = 0;

static const char *opt_delim = "\n";
static union el *opt_pgrp = NULL;
static union el *opt_rgid = NULL;
static union el *opt_pid = NULL;
static union el *opt_ppid = NULL;
static union el *opt_sid = NULL;
static union el *opt_term = NULL;
static union el *opt_euid = NULL;
static union el *opt_ruid = NULL;
static char *opt_pattern = NULL;
static char *opt_pidfile = NULL;


static int usage (int opt) NORETURN;
static int usage (int opt)
{
	if (i_am_pkill)
		fprintf (stderr, "Usage: pkill [-SIGNAL] [-fvx] ");
	else
		fprintf (stderr, "Usage: pgrep [-flvx] [-d DELIM] ");
	fprintf (stderr, "[-n|-o] [-P PPIDLIST] [-g PGRPLIST] [-s SIDLIST]\n"
		 "\t[-u EUIDLIST] [-U UIDLIST] [-G GIDLIST] [-t TERMLIST] "
		 "[PATTERN]\n");
	exit (opt == '?' ? EXIT_SUCCESS : EXIT_USAGE);
}


static union el *split_list (const char *restrict str, int (*convert)(const char *, union el *))
{
	char *copy = strdup (str);
	char *ptr = copy;
	char *sep_pos;
	int i = 0;
	int size = 0;
	union el *list = NULL;

	do {
		if (i == size) {
			size = size * 5 / 4 + 4;
			// add 1 because slot zero is a count
			list = realloc (list, 1 + size * sizeof *list);
			if (list == NULL)
				exit (EXIT_FATAL);
		}
		sep_pos = strchr (ptr, ',');
		if (sep_pos)
			*sep_pos = 0;
		// Use ++i instead of i++ because slot zero is a count
		if (!convert (ptr, &list[++i]))
			exit (EXIT_USAGE);
		if (sep_pos)
			ptr = sep_pos + 1;
	} while (sep_pos);

	free (copy);
	if (!i) {
		free (list);
		list = NULL;
	} else {
		list[0].num = i;
	}
	return list;
}

// strict_atol returns a Boolean: TRUE if the input string
// contains a plain number, FALSE if there are any non-digits.
static int strict_atol (const char *restrict str, long *restrict value)
{
	int res = 0;
	int sign = 1;

	if (*str == '+')
		++str;
	else if (*str == '-') {
		++str;
		sign = -1;
	}

	for ( ; *str; ++str) {
		if (! isdigit (*str))
			return (0);
		res *= 10;
		res += *str - '0';
	}
	*value = sign * res;
	return 1;
}

#include <sys/file.h>

// Seen non-BSD code do this:
//
//if (fcntl_lock(pid_fd, F_SETLK, F_WRLCK, SEEK_SET, 0, 0) == -1)
//                return -1;
int fcntl_lock(int fd, int cmd, int type, int whence, int start, int len)
{
        struct flock lock[1];

        lock->l_type = type;
        lock->l_whence = whence;
        lock->l_start = start;
        lock->l_len = len;

        return fcntl(fd, cmd, lock);
}
                                                

// We try a read lock. The daemon should have a write lock.
// Seen using flock: FreeBSD code
static int has_flock(int fd)
{
	return flock(fd, LOCK_SH|LOCK_NB)==-1 && errno==EWOULDBLOCK;
}

// We try a read lock. The daemon should have a write lock.
// Seen using fcntl: libslack
static int has_fcntl(int fd)
{
	struct flock f;  // seriously, struct flock is for a fnctl lock!
	f.l_type = F_RDLCK;
	f.l_whence = SEEK_SET;
	f.l_start = 0;
	f.l_len = 0;
	return fcntl(fd,F_SETLK,&f)==-1 && (errno==EACCES || errno==EAGAIN);
}

static union el *read_pidfile(void)
{
	char buf[12];
	int fd;
	struct stat sbuf;
	char *endp;
	int pid;
	union el *list = NULL;

	fd = open(opt_pidfile, O_RDONLY|O_NOCTTY|O_NONBLOCK);
	if(fd<0)
		goto out;
	if(fstat(fd,&sbuf) || !S_ISREG(sbuf.st_mode) || sbuf.st_size<1)
		goto out;
	// type of lock, if any, is not standardized on Linux
	if(opt_lock && !has_flock(fd) && !has_fcntl(fd))
			goto out;
	memset(buf,'\0',sizeof buf);
	buf[read(fd,buf+1,sizeof buf-2)] = '\0';
	pid = strtoul(buf+1,&endp,10);
	if(endp<=buf+1 || pid<1 || pid>0x7fffffff)
		goto out;
	if(*endp && !isspace(*endp))
		goto out;
	list = malloc(2 * sizeof *list);
	list[0].num = 1;
	list[1].num = pid;
out:
	close(fd);
	return list;
}

static int conv_uid (const char *restrict name, union el *restrict e)
{
	struct passwd *pwd;

	if (strict_atol (name, &e->num))
		return (1);

	pwd = getpwnam (name);
	if (pwd == NULL) {
		fprintf (stderr, "%s: invalid user name: %s\n",
			 progname, name);
		return 0;
	}
	e->num = pwd->pw_uid;
	return 1;
}


static int conv_gid (const char *restrict name, union el *restrict e)
{
	struct group *grp;

	if (strict_atol (name, &e->num))
		return 1;

	grp = getgrnam (name);
	if (grp == NULL) {
		fprintf (stderr, "%s: invalid group name: %s\n",
			 progname, name);
		return 0;
	}
	e->num = grp->gr_gid;
	return 1;
}


static int conv_pgrp (const char *restrict name, union el *restrict e)
{
	if (! strict_atol (name, &e->num)) {
		fprintf (stderr, "%s: invalid process group: %s\n",
			 progname, name);
		return 0;
	}
	if (e->num == 0)
		e->num = getpgrp ();
	return 1;
}


static int conv_sid (const char *restrict name, union el *restrict e)
{
	if (! strict_atol (name, &e->num)) {
		fprintf (stderr, "%s: invalid session id: %s\n",
			 progname, name);
		return 0;
	}
	if (e->num == 0)
		e->num = getsid (0);
	return 1;
}


static int conv_num (const char *restrict name, union el *restrict e)
{
	if (! strict_atol (name, &e->num)) {
		fprintf (stderr, "%s: not a number: %s\n",
			 progname, name);
		return 0;
	}
	return 1;
}


static int conv_str (const char *restrict name, union el *restrict e)
{
	e->str = strdup (name);
	return 1;
}


static int match_numlist (long value, const union el *restrict list)
{
	int found = 0;
	if (list == NULL)
		found = 0;
	else {
		int i;
		for (i = list[0].num; i > 0; i--) {
			if (list[i].num == value)
				found = 1;
		}
	}
	return found;
}

static int match_strlist (const char *restrict value, const union el *restrict list)
{
	int found = 0;
	if (list == NULL)
		found = 0;
	else {
		int i;
		for (i = list[0].num; i > 0; i--) {
			if (! strcmp (list[i].str, value))
				found = 1;
		}
	}
	return found;
}

static void output_numlist (const union el *restrict list, int num)
{
	int i;
	const char *delim = opt_delim;
	for (i = 0; i < num; i++) {
		if(i+1==num)
			delim = "\n";
		printf ("%ld%s", list[i].num, delim);
	}
}

static void output_strlist (const union el *restrict list, int num)
{
// FIXME: escape codes
	int i;
	const char *delim = opt_delim;
	for (i = 0; i < num; i++) {
		if(i+1==num)
			delim = "\n";
		printf ("%s%s", list[i].str, delim);
	}
}

static PROCTAB *do_openproc (void)
{
	PROCTAB *ptp;
	int flags = 0;

	if (opt_pattern || opt_full)
		flags |= PROC_FILLCOM;
	if (opt_ruid || opt_rgid)
		flags |= PROC_FILLSTATUS;
	if (opt_oldest || opt_newest || opt_pgrp || opt_sid || opt_term)
		flags |= PROC_FILLSTAT;
	if (!(flags & PROC_FILLSTAT))
		flags |= PROC_FILLSTATUS;  // FIXME: need one, and PROC_FILLANY broken
	if (opt_euid && !opt_negate) {