ksym.c

linux下获取一些环境信息的代码

/*
 * Copyright 1998-2003 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.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <stdarg.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include "procps.h"
#include "version.h"
#include "sysinfo.h" /* smp_num_cpus */
#include "wchan.h"  // to verify prototypes

#define KSYMS_FILENAME "/proc/ksyms"

#if 0
#undef KSYMS_FILENAME
#define KSYMS_FILENAME  "/would/be/nice/to/have/this/file"
#define SYSMAP_FILENAME "/home/albert/ps/45621/System.map-hacked"
#define linux_version_code 131598 /* ? */
#define smp_num_cpus 2
#endif

#if 0
#undef KSYMS_FILENAME
#define KSYMS_FILENAME  "/home/albert/ps/45621/ksyms-2.3.12"
#define SYSMAP_FILENAME "/home/albert/ps/45621/System.map-2.3.12"
#define linux_version_code 131852 /* 2.3.12 */
#define smp_num_cpus 2
#endif

#if 0
#undef KSYMS_FILENAME
#define KSYMS_FILENAME  "/home/albert/ps/45621/ksyms-2.3.18ac8-MODVERS"
#define SYSMAP_FILENAME "/home/albert/ps/45621/System.map-2.3.18ac8-MODVERS"
#define linux_version_code 131858 /* 2.3.18ac8 */
#define smp_num_cpus 2
#endif

#if 0
#undef KSYMS_FILENAME
#define KSYMS_FILENAME  "/home/albert/ps/45621/ksyms-2.3.18ac8-NOMODVERS"
#define SYSMAP_FILENAME "/home/albert/ps/45621/System.map-2.3.18ac8-NOMODVERS"
#define linux_version_code 131858 /* 2.3.18ac8 */
#define smp_num_cpus 2
#endif

/* These are the symbol types, with relative popularity:
 *     ? w  machine type junk for Alpha -- odd syntax
 *     ? S  not for i386
 *     4 W  not for i386
 *    60 R
 *   100 A
 *   125 r
 *   363 s  not for i386
 *   858 B
 *   905 g  generated by modutils?
 *   929 G  generated by modutils?
 *  1301 b
 *  2750 D
 *  4481 d
 * 11417 ?
 * 13666 t
 * 15442 T
 *
 * For i386, that is: "RArBbDd?tT"
 */

#define SYMBOL_TYPE_CHARS "Tt?dDbBrARGgsWS"

/*
 * '?' is a symbol type
 * '.' is part of a name (versioning?)
 * "\t[]" are for the module name in /proc/ksyms
 */
#define LEGAL_SYSMAP_CHARS "0123456789_ ?.\n\t[]" \
                     "abcdefghijklmnopqrstuvwxyz" \
                     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

/* System.map lines look like:
 * hex num, space, one of SYMBOL_TYPE_CHARS, space, LEGAL_SYSMAP_CHARS, \n
 *
 * Alpha systems can start with a few lines that have the address replaced
 * by space padding and a 'w' for the type. For those lines, the last space
 * is followed by something like: mikasa_primo_mv p2k_mv sable_gamma_mv
 * (just one of those, always with a "_mv", then the newline)
 *
 * The /proc/ksyms lines are like System.map lines w/o the symbol type char.
 * When odd features are used, the name part contains:
 * "(.*)_R(smp_|smp2gig_|2gig_)?[0-9a-fA-F]{8,}"
 * It is likely that more crap will be added...
 */

typedef struct symb {
  unsigned KLONG addr;
  const char *name;
} symb;

/* These mostly rely on POSIX to make them zero. */

static symb hashtable[256];

static char       *sysmap_data;
static unsigned    sysmap_room;
static symb       *sysmap_index;
static unsigned    sysmap_count;

static char       *ksyms_data;
static unsigned    ksyms_room     = 4096;
static symb       *ksyms_index;
static unsigned    ksyms_count;
static unsigned    idx_room;

/*********************************/

/* Kill this:  _R(smp_?|smp2gig_?|2gig_?)?[0-9a-f]{8,}$
 * We kill:    (_R[^A-Z]*[0-9a-f]{8,})+$
 *
 * The loop should almost never be taken, but it has to be there.
 * It gets rid of anything that _looks_ like a version code, even
 * if a real version code has already been found. This is because
 * the inability to perfectly recognize a version code may lead to
 * symbol mangling, which in turn leads to mismatches between the
 * /proc/ksyms and System.map data files.
 */
#if 0
static char *chop_version(char *arg){
  char *cp;
  cp = strchr(arg,'\t');
  if(cp) *cp = '\0';  /* kill trailing module name first */
  for(;;){
    char *p;
    int len = 0;
    cp = strrchr(arg, 'R');
    if(!cp || cp<=arg+1 || cp[-1]!='_') break;
    for(p=cp; *++p; ){
      switch(*p){
      default:
        goto out;
      case '0' ... '9':
      case 'a' ... 'f':
        len++;
        continue;
      case 'g' ... 'z':
      case '_':
        len=0;
        continue;
      }
    }
    if(len<8) break;
    cp[-1] = '\0';
  }
out:
  if(*arg=='G'){
    int len = strlen(arg);
    while( len>8 && !memcmp(arg,"GPLONLY_",8) ){
      arg += 8;
      len -= 8;
    }
  }
  return arg;
}
#endif
static char *chop_version(char *arg){
  char *cp;
  cp = strchr(arg,'\t');
  if(cp) *cp = '\0';  /* kill trailing module name first */
  for(;;){
    int len;
    cp = strrchr(arg, 'R');
    if(!cp || cp<=arg+1 || cp[-1]!='_') break;
    len=strlen(cp);
    if(len<9) break;
    if(strpbrk(cp+1,"ABCDEFGHIJKLMNOPQRSTUVWXYZ")) break;
    if(strspn(cp+len-8,"0123456789abcdef")!=8) break;
    cp[-1] = '\0';
  }
  if(*arg=='G'){
    int len = strlen(arg);
    while( len>8 && !memcmp(arg,"GPLONLY_",8) ){
      arg += 8;
      len -= 8;
    }
  }
  return arg;
}

/***********************************/

static const symb *search(unsigned KLONG address, symb *idx, unsigned count){
  unsigned left;
  unsigned mid;
  unsigned right;
  if(!idx) return NULL;   /* maybe not allocated */
  if(address < idx[0].addr) return NULL;
  if(address >= idx[count-1].addr) return idx+count-1;
  left  = 0;
  right = count-1;
  for(;;){
    mid = (left + right) / 2;
    if(address >= idx[mid].addr) left  = mid;
    if(address <= idx[mid].addr) right = mid;
    if(right-left <= 1) break;
  }
  if(address == idx[right].addr) return idx+right;
  return idx+left;
}

/*********************************/

/* allocate if needed, read, and return buffer size */
static void read_file(const char *restrict filename, char **bufp, unsigned *restrict roomp) {
  int fd = 0;
  ssize_t done;
  char *buf = *bufp;
  ssize_t total = 0;
  unsigned room = *roomp;

  if(!room) goto hell;     /* failed before */
  if(!buf) buf = malloc(room);
  if(!buf) goto hell;
open_again:
  fd = open(filename, O_RDONLY|O_NOCTTY|O_NONBLOCK);
  if(fd<0){
    switch(errno){
    case EINTR:  goto open_again;
    default:     _exit(101);
    case EACCES:   /* somebody screwing around? */
      /* FIXME: set a flag to disable symbol lookup? */
    case ENOENT:;  /* no module support */
    }
    goto hell;
  }
  for(;;){
    done = read(fd, buf+total, room-total-1);
    if(done==0) break;  /* nothing left */
    if(done==-1){
      if(errno==EINTR) continue;  /* try again */
      perror("");
      goto hell;
    }
    if(done==(ssize_t)room-total-1){
      char *tmp;
      total += done;
      /* more to go, but no room in buffer */
      room *= 2;
      tmp = realloc(buf, room);
      if(!tmp) goto hell;
      buf = tmp;
      continue;
    }
    if(done>0 && done<(ssize_t)room-total-1){
      total += done; 
      continue;   /* OK, we read some. Go do more. */
    }
    fprintf(stderr,"%ld can't happen\n", (long)done);
    /* FIXME: memory leak */
    _exit(42);
  }
  buf[total] = '\0';   // parse_ksyms() expects NUL-terminated file
  *bufp = buf;
  *roomp = room;
  close(fd);
  return;
hell:
  if(buf) free(buf);
  *bufp = NULL;
  *roomp = 0;   /* this function will never work again */
  total = 0;
  if(fd>0) close(fd);
  return;
}

/*********************************/

static int parse_ksyms(void) {
  char *endp;
  if(!ksyms_room || !ksyms_data) goto quiet_goodbye;
  endp = ksyms_data;
  ksyms_count = 0;
  if(idx_room) goto bypass;  /* some space already allocated */
  idx_room = 512;
  for(;;){
    void *vp;
    idx_room *= 2;
    vp = realloc(ksyms_index, sizeof(symb)*idx_room);
    if(!vp) goto bad_alloc;
    ksyms_index = vp;
bypass:
    for(;;){
      char *saved;
      if(!*endp) return 1;
      saved = endp;
      ksyms_index[ksyms_count].addr = STRTOUKL(endp, &endp, 16);
      if(endp==saved || *endp != ' ') goto bad_parse;
      endp++;
      saved = endp;
      endp = strchr(endp,'\n');
      if(!endp) goto bad_parse;   /* no newline */
      *endp = '\0';
      ksyms_index[ksyms_count].name = chop_version(saved);
      ++endp;
      if(++ksyms_count >= idx_room) break;  /* need more space */