readproc.c

linux下获取一些环境信息的代码

    if(unlikely(unlikely(!ent) || unlikely(!ent->d_name))) return 0;
    if(likely( likely(*ent->d_name > '0') && likely(*ent->d_name <= '9') )) break;
  }
  p->tgid = strtoul(ent->d_name, NULL, 10);
  p->tid = p->tgid;
  memcpy(path, "/proc/", 6);
  strcpy(path+6, ent->d_name);  // trust /proc to not contain evil top-level entries
  return 1;
}

//////////////////////////////////////////////////////////////////////////////////
// This finds tasks in /proc/*/task/ in the traditional way.
// Return non-zero on success.
static int simple_nexttid(PROCTAB *restrict const PT, const proc_t *restrict const p, proc_t *restrict const t, char *restrict const path) {
  static struct direct *ent;		/* dirent handle */
  if(PT->taskdir_user != p->tgid){
    if(PT->taskdir){
      closedir(PT->taskdir);
    }
    // use "path" as some tmp space
    snprintf(path, PROCPATHLEN, "/proc/%d/task", p->tgid);
    PT->taskdir = opendir(path);
    if(!PT->taskdir) return 0;
    PT->taskdir_user = p->tgid;
  }
  for (;;) {
    ent = readdir(PT->taskdir);
    if(unlikely(unlikely(!ent) || unlikely(!ent->d_name))) return 0;
    if(likely( likely(*ent->d_name > '0') && likely(*ent->d_name <= '9') )) break;
  }
  t->tid = strtoul(ent->d_name, NULL, 10);
  t->tgid = p->tgid;
  t->ppid = p->ppid;  // cover for kernel behavior? we want both actually...?
  snprintf(path, PROCPATHLEN, "/proc/%d/task/%s", p->tgid, ent->d_name);
  return 1;
}

//////////////////////////////////////////////////////////////////////////////////
// This "finds" processes in a list that was given to openproc().
// Return non-zero on success. (tgid was handy)
static int listed_nextpid(PROCTAB *restrict const PT, proc_t *restrict const p) {
  char *restrict const path = PT->path;
  pid_t tgid = *(PT->pids)++;
  if(likely( tgid )){
    snprintf(path, PROCPATHLEN, "/proc/%d", tgid);
    p->tgid = tgid;
    p->tid = tgid;  // they match for leaders
  }
  return tgid;
}

//////////////////////////////////////////////////////////////////////////////////
/* readproc: return a pointer to a proc_t filled with requested info about the
 * next process available matching the restriction set.  If no more such
 * processes are available, return a null pointer (boolean false).  Use the
 * passed buffer instead of allocating space if it is non-NULL.  */

/* This is optimized so that if a PID list is given, only those files are
 * searched for in /proc.  If other lists are given in addition to the PID list,
 * the same logic can follow through as for the no-PID list case.  This is
 * fairly complex, but it does try to not to do any unnecessary work.
 */
proc_t* readproc(PROCTAB *restrict const PT, proc_t *restrict p) {
  proc_t *ret;
  proc_t *saved_p;

  PT->did_fake=0;
//  if (PT->taskdir) {
//    closedir(PT->taskdir);
//    PT->taskdir = NULL;
//    PT->taskdir_user = -1;
//  }

  saved_p = p;
  if(!p) p = xcalloc(p, sizeof *p); /* passed buf or alloced mem */

  for(;;){
    // fills in the path, plus p->tid and p->tgid
    if (unlikely(! PT->finder(PT,p) )) goto out;

    // go read the process data
    ret = PT->reader(PT,p);
    if(ret) return ret;
  }

out:
  if(!saved_p) free(p);
  // FIXME: maybe set tid to -1 here, for "-" in display?
  return NULL;
}

//////////////////////////////////////////////////////////////////////////////////
// readtask: return a pointer to a proc_t filled with requested info about the
// next task available.  If no more such tasks are available, return a null
// pointer (boolean false).  Use the passed buffer instead of allocating
// space if it is non-NULL.
proc_t* readtask(PROCTAB *restrict const PT, const proc_t *restrict const p, proc_t *restrict t) {
  static char path[PROCPATHLEN];       // must hold /proc/2000222000/task/2000222000/cmdline
  proc_t *ret;
  proc_t *saved_t;

  saved_t = t;
  if(!t) t = xcalloc(t, sizeof *t); /* passed buf or alloced mem */

  // 1. got to fake a thread for old kernels
  // 2. for single-threaded processes, this is faster (but must patch up stuff that differs!)
  if(task_dir_missing || p->nlwp < 2){
    if(PT->did_fake) goto out;
    PT->did_fake=1;
    memcpy(t,p,sizeof(proc_t));
    // use the per-task pending, not per-tgid pending
#ifdef SIGNAL_STRING
	memcpy(&t->signal, &t->_sigpnd, sizeof t->signal);
#else
	t->signal = t->_sigpnd;
#endif
    return t;
  }

  for(;;){
    // fills in the path, plus t->tid and t->tgid
    if (unlikely(! PT->taskfinder(PT,p,t,path) )) goto out;  // simple_nexttid

    // go read the task data
    ret = PT->taskreader(PT,p,t,path);          // simple_readtask
    if(ret) return ret;
  }

out:
  if(!saved_t) free(t);
  return NULL;
}

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

// initiate a process table scan
PROCTAB* openproc(int flags, ...) {
    va_list ap;
    struct stat sbuf;
    static int did_stat;
    PROCTAB* PT = xmalloc(sizeof(PROCTAB));

    if(!did_stat){
      task_dir_missing = stat("/proc/self/task", &sbuf);
      did_stat = 1;
    }
    PT->taskdir = NULL;
    PT->taskdir_user = -1;
    PT->taskfinder = simple_nexttid;
    PT->taskreader = simple_readtask;

    PT->reader = simple_readproc;
    if (flags & PROC_PID){
      PT->procfs = NULL;
      PT->finder = listed_nextpid;
    }else{
      PT->procfs = opendir("/proc");
      if(!PT->procfs) return NULL;
      PT->finder = simple_nextpid;
    }
    PT->flags = flags;

    va_start(ap, flags);		/*  Init args list */
    if (flags & PROC_PID)
    	PT->pids = va_arg(ap, pid_t*);
    else if (flags & PROC_UID) {
    	PT->uids = va_arg(ap, uid_t*);
	PT->nuid = va_arg(ap, int);
    }
    va_end(ap);				/*  Clean up args list */

    return PT;
}

// terminate a process table scan
void closeproc(PROCTAB* PT) {
    if (PT){
        if (PT->procfs) closedir(PT->procfs);
        if (PT->taskdir) closedir(PT->taskdir);
        memset(PT,'#',sizeof(PROCTAB));
        free(PT);
    }
}

// deallocate the space allocated by readproc if the passed rbuf was NULL
void freeproc(proc_t* p) {
    if (!p)	/* in case p is NULL */
	return;
    /* ptrs are after strings to avoid copying memory when building them. */
    /* so free is called on the address of the address of strvec[0]. */
    if (p->cmdline)
	free((void*)*p->cmdline);
    if (p->environ)
	free((void*)*p->environ);
    free(p);
}


//////////////////////////////////////////////////////////////////////////////////
void look_up_our_self(proc_t *p) {
    char sbuf[1024];

    if(file2str("/proc/self", "stat", sbuf, sizeof sbuf) == -1){
        fprintf(stderr, "Error, do this: mount -t proc none /proc\n");
        _exit(47);
    }
    stat2proc(sbuf, p);    // parse /proc/self/stat
}

HIDDEN_ALIAS(readproc);
HIDDEN_ALIAS(readtask);

/* Convenient wrapper around openproc and readproc to slurp in the whole process
 * table subset satisfying the constraints of flags and the optional PID list.
 * Free allocated memory with exit().  Access via tab[N]->member.  The pointer
 * list is NULL terminated.
 */
proc_t** readproctab(int flags, ...) {
    PROCTAB* PT = NULL;
    proc_t** tab = NULL;
    int n = 0;
    va_list ap;

    va_start(ap, flags);		/* pass through args to openproc */
    if (flags & PROC_UID) {
	/* temporary variables to ensure that va_arg() instances
	 * are called in the right order
	 */
	uid_t* u;
	int i;

	u = va_arg(ap, uid_t*);
	i = va_arg(ap, int);
	PT = openproc(flags, u, i);
    }
    else if (flags & PROC_PID)
	PT = openproc(flags, va_arg(ap, void*)); /* assume ptr sizes same */
    else
	PT = openproc(flags);
    va_end(ap);
    do {					/* read table: */
	tab = xrealloc(tab, (n+1)*sizeof(proc_t*));/* realloc as we go, using */
	tab[n] = readproc_direct(PT, NULL);     /* final null to terminate */
    } while (tab[n++]);				  /* stop when NULL reached */
    closeproc(PT);
    return tab;
}

// Try again, this time with threads and selection.
proc_data_t *readproctab2(int(*want_proc)(proc_t *buf), int(*want_task)(proc_t *buf), PROCTAB *restrict const PT) {
    proc_t** ptab = NULL;
    unsigned n_proc_alloc = 0;
    unsigned n_proc = 0;

    proc_t** ttab = NULL;
    unsigned n_task_alloc = 0;
    unsigned n_task = 0;

    proc_t*  data = NULL;
    unsigned n_alloc = 0;
    unsigned long n_used = 0;

    proc_data_t *pd;

    for(;;){
        proc_t *tmp;
        if(n_alloc == n_used){
          //proc_t *old = data;
          n_alloc = n_alloc*5/4+30;  // grow by over 25%
          data = realloc(data,sizeof(proc_t)*n_alloc);
          //if(!data) return NULL;
        }
        if(n_proc_alloc == n_proc){
          //proc_t **old = ptab;
          n_proc_alloc = n_proc_alloc*5/4+30;  // grow by over 25%
          ptab = realloc(ptab,sizeof(proc_t*)*n_proc_alloc);
          //if(!ptab) return NULL;
        }
        tmp = readproc_direct(PT, data+n_used);
        if(!tmp) break;
        if(!want_proc(tmp)) continue;
        ptab[n_proc++] = (proc_t*)(n_used++);
        if(!(  PT->flags & PROC_LOOSE_TASKS  )) continue;
        for(;;){
          proc_t *t;
          if(n_alloc == n_used){
            proc_t *old = data;
            n_alloc = n_alloc*5/4+30;  // grow by over 25%
            data = realloc(data,sizeof(proc_t)*n_alloc);
	    // have to move tmp too
	    tmp = data+(tmp-old);
            //if(!data) return NULL;
          }
          if(n_task_alloc == n_task){
            //proc_t **old = ttab;
            n_task_alloc = n_task_alloc*5/4+1;  // grow by over 25%
            ttab = realloc(ttab,sizeof(proc_t*)*n_task_alloc);
            //if(!ttab) return NULL;
          }
          t = readtask_direct(PT, tmp, data+n_used);
          if(!t) break;
          if(!want_task(t)) continue;
          ttab[n_task++] = (proc_t*)(n_used++);
        }
    }

    pd = malloc(sizeof(proc_data_t));
    pd->proc = ptab;
    pd->task = ttab;
    pd->nproc = n_proc;
    pd->ntask = n_task;
    if(PT->flags & PROC_LOOSE_TASKS){
      pd->tab = ttab;
      pd->n   = n_task;
    }else{
      pd->tab = ptab;
      pd->n   = n_proc;
    }
    // change array indexes to pointers
    while(n_proc--) ptab[n_proc] = data+(long)(ptab[n_proc]);
    while(n_task--) ttab[n_task] = data+(long)(ttab[n_task]);

    return pd;
}

/*
 * get_proc_stats - lookup a single tasks information and fill out a proc_t
 *
 * On failure, returns NULL.  On success, returns 'p' and 'p' is a valid
 * and filled out proc_t structure.
 */
proc_t * get_proc_stats(pid_t pid, proc_t *p) {
	static char path[PATH_MAX], sbuf[1024];
	struct stat statbuf;

	sprintf(path, "/proc/%d", pid);
	if (stat(path, &statbuf)) {
		perror("stat");
		return NULL;
	}

	if (file2str(path, "stat", sbuf, sizeof sbuf) >= 0)
		stat2proc(sbuf, p);	/* parse /proc/#/stat */
	if (file2str(path, "statm", sbuf, sizeof sbuf) >= 0)
		statm2proc(sbuf, p);	/* ignore statm errors here */
	if (file2str(path, "status", sbuf, sizeof sbuf) >= 0)
		status2proc(sbuf, p, 0 /*FIXME*/);

	return p;
}