minimal.c

linux下获取一些环境信息的代码

/*
 * Copyright 1998,2004 by Albert Cahalan; all rights reserved.
 * This file may be used subject to the terms and conditions of the
 * GNU Library General Public License Version 2, or any later version
 * at your option, as published by the Free Software Foundation.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Library General Public License for more details.
 */

/* This is a minimal /bin/ps, designed to be smaller than the old ps
 * while still supporting some of the more important features of the
 * new ps. (for total size, note that this ps does not need libproc)
 * It is suitable for Linux-on-a-floppy systems only.
 *
 * Maintainers: do not compile or install for normal systems.
 * Anyone needing this will want to tweak their compiler anyway.
 */

#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <dirent.h>


#define DEV_ENCODE(M,m) ( \
  ( (M&0xfff) << 8)   |   ( (m&0xfff00) << 12)   |   (m&0xff)   \
)

///////////////////////////////////////////////////////
#ifdef __sun__
#include <sys/mkdev.h>
#define _STRUCTURED_PROC 1
#include <sys/procfs.h>
#define NO_TTY_VALUE DEV_ENCODE(-1,-1)
#define HZ 1    // only bother with seconds
#endif

///////////////////////////////////////////////////////
#ifdef __FreeBSD__
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/user.h>
#define NO_TTY_VALUE DEV_ENCODE(-1,-1)
#define HZ 1    // only bother with seconds
#endif

///////////////////////////////////////////////////////
#ifdef __linux__
#include <asm/param.h>  /* HZ */
#include <asm/page.h>   /* PAGE_SIZE */
#define NO_TTY_VALUE DEV_ENCODE(0,0)
#ifndef HZ
#warning HZ not defined, assuming it is 100
#define HZ 100
#endif
#endif

///////////////////////////////////////////////////////////

#ifndef PAGE_SIZE
#warning PAGE_SIZE not defined, assuming it is 4096
#define PAGE_SIZE 4096
#endif



static char P_tty_text[16];
static char P_cmd[16];
static char P_state;
static int P_euid;
static int P_pid;
static int P_ppid, P_pgrp, P_session, P_tty_num, P_tpgid;
static unsigned long P_flags, P_min_flt, P_cmin_flt, P_maj_flt, P_cmaj_flt, P_utime, P_stime;
static long P_cutime, P_cstime, P_priority, P_nice, P_timeout, P_alarm;
static unsigned long P_start_time, P_vsize;
static long P_rss;
static unsigned long P_rss_rlim, P_start_code, P_end_code, P_start_stack, P_kstk_esp, P_kstk_eip;
static unsigned P_signal, P_blocked, P_sigignore, P_sigcatch;
static unsigned long P_wchan, P_nswap, P_cnswap;



#if 0
static int screen_cols = 80;
static int w_count;
#endif

static int want_one_pid;
static const char *want_one_command;
static int select_notty;
static int select_all;

static int ps_format;
static int old_h_option;

/* we only pretend to support this */
static int show_args;    /* implicit with -f and all BSD options */
static int bsd_c_option; /* this option overrides the above */

static int ps_argc;    /* global argc */
static char **ps_argv; /* global argv */
static int thisarg;    /* index into ps_argv */
static char *flagptr;  /* current location in ps_argv[thisarg] */




static void usage(void){
  fprintf(stderr,
    "-C   select by command name (minimal ps only accepts one)\n"
    "-p   select by process ID (minimal ps only accepts one)\n"
    "-e   all processes (same as ax)\n"
    "a    all processes w/ tty, including other users\n"
    "x    processes w/o controlling ttys\n"
    "-f   full format\n"
    "-j,j job control format\n"
    "v    virtual memory format\n"
    "-l,l long format\n"
    "u    user-oriented format\n"
    "-o   user-defined format (limited support, only \"ps -o pid=\")\n"
    "h    no header\n"
/*
    "-A   all processes (same as ax)\n"
    "c    true command name\n"
    "-w,w wide output\n"
*/
  );
  exit(1);
}

/*
 * Return the next argument, or call the usage function.
 * This handles both:   -oFOO   -o FOO
 */
static const char *get_opt_arg(void){
  const char *ret;
  ret = flagptr+1;    /* assume argument is part of ps_argv[thisarg] */
  if(*ret) return ret;
  if(++thisarg >= ps_argc) usage();   /* there is nothing left */
  /* argument is the new ps_argv[thisarg] */
  ret = ps_argv[thisarg];
  if(!ret || !*ret) usage();
  return ret;
}


/* return the PID, or 0 if nothing good */
static void parse_pid(const char *str){
  char *endp;
  int num;
  if(!str)            goto bad;
  num = strtol(str, &endp, 0);
  if(*endp != '\0')   goto bad;
  if(num<1)           goto bad;
  if(want_one_pid)    goto bad;
  want_one_pid = num;
  return;
bad:
  usage();
}

/***************** parse SysV options, including Unix98  *****************/
static void parse_sysv_option(void){
  do{
    switch(*flagptr){
    /**** selection ****/
    case 'C': /* end */
      if(want_one_command) usage();
      want_one_command = get_opt_arg();
      return; /* can't have any more options */
    case 'p': /* end */
      parse_pid(get_opt_arg());
      return; /* can't have any more options */
    case 'A':
    case 'e':
      select_all++;
      select_notty++;
case 'w':    /* here for now, since the real one is not used */
      break;
    /**** output format ****/
    case 'f':
      show_args = 1;
      /* FALL THROUGH */
    case 'j':
    case 'l':
      if(ps_format) usage();
      ps_format = *flagptr;
      break;
    case 'o': /* end */
      /* We only support a limited form: "ps -o pid="  (yes, just "pid=") */
      if(strcmp(get_opt_arg(),"pid=")) usage();
      if(ps_format) usage();
      ps_format = 'o';
      old_h_option++;
      return; /* can't have any more options */
    /**** other stuff ****/
#if 0
    case 'w':
      w_count++;
      break;
#endif
    default:
      usage();
    } /* switch */
  }while(*++flagptr);
}

/************************* parse BSD options **********************/
static void parse_bsd_option(void){
  do{
    switch(*flagptr){
    /**** selection ****/
    case 'a':
      select_all++;
      break;
    case 'x':
      select_notty++;
      break;
    case 'p': /* end */
      parse_pid(get_opt_arg());
      return; /* can't have any more options */
    /**** output format ****/
    case 'j':
    case 'l':
    case 'u':
    case 'v':
      if(ps_format) usage();
      ps_format = 0x80 | *flagptr;  /* use 0x80 to tell BSD from SysV */
      break;
    /**** other stuff ****/
    case 'c':
      bsd_c_option++;
#if 0
      break;
#endif
    case 'w':
#if 0
      w_count++;
#endif
      break;
    case 'h':
      old_h_option++;
      break;
    default:
      usage();
    } /* switch */
  }while(*++flagptr);
}

#if 0
#include <termios.h>
/* not used yet */
static void choose_dimensions(void){
  struct winsize ws;
  char *columns;
  /* screen_cols is 80 by default */
  if(ioctl(1, TIOCGWINSZ, &ws) != -1 && ws.ws_col>30) screen_cols = ws.ws_col;
  columns = getenv("COLUMNS");
  if(columns && *columns){
    long t;
    char *endptr;
    t = strtol(columns, &endptr, 0);
    if(!*endptr && (t>30) && (t<(long)999999999)) screen_cols = (int)t;
  }
  if(w_count && (screen_cols<132)) screen_cols=132;
  if(w_count>1) screen_cols=999999999;
}
#endif

static void arg_parse(int argc, char *argv[]){
  int sel = 0;  /* to verify option sanity */
  ps_argc = argc;
  ps_argv = argv;
  thisarg = 0;
  /**** iterate over the args ****/
  while(++thisarg < ps_argc){
    flagptr = ps_argv[thisarg];
    switch(*flagptr){
    case '0' ... '9':
      show_args = 1;
      parse_pid(flagptr);
      break;
    case '-':
      flagptr++;
      parse_sysv_option();
      break;
    default:
      show_args = 1;
      parse_bsd_option();
      break;
    }
  }
  /**** sanity check and clean-up ****/
  if(want_one_pid) sel++;
  if(want_one_command) sel++;
  if(select_notty || select_all) sel++;
  if(sel>1 || select_notty>1 || select_all>1 || bsd_c_option>1 || old_h_option>1) usage();
  if(bsd_c_option) show_args = 0;
}

#ifdef __sun__
/* return 1 if it works, or 0 for failure */
static int stat2proc(int pid) {
    struct psinfo p;  //   /proc/*/psinfo, struct psinfo, psinfo_t
    char buf[32];
    int num;
    int fd;
    int tty_maj, tty_min;
    snprintf(buf, sizeof buf, "/proc/%d/psinfo", pid);
    if ( (fd = open(buf, O_RDONLY, 0) ) == -1 ) return 0;
    num = read(fd, &p, sizeof p);
    close(fd);
    if(num != sizeof p) return 0;

    num = PRFNSZ;
    if (num >= sizeof P_cmd) num = sizeof P_cmd - 1;
    memcpy(P_cmd, p.pr_fname, num);  // p.pr_fname or p.pr_lwp.pr_name
    P_cmd[num] = '\0';

    P_pid     = p.pr_pid;
    P_ppid    = p.pr_ppid;
    P_pgrp    = p.pr_pgid;
    P_session = p.pr_sid;
    P_euid    = p.pr_euid;
    P_rss     = p.pr_rssize;
    P_vsize   = p.pr_size;