readproc.c

linux下获取一些环境信息的代码

    if(unlikely(num >= sizeof P->cmd)) num = sizeof P->cmd - 1;
    memcpy(P->cmd, S, num);
    P->cmd[num] = '\0';
    S = tmp + 2;                 // skip ") "

    num = sscanf(S,
       "%c "
       "%d %d %d %d %d "
       "%lu %lu %lu %lu %lu "
       "%Lu %Lu %Lu %Lu "  /* utime stime cutime cstime */
       "%ld %ld "
       "%d "
       "%ld "
       "%Lu "  /* start_time */
       "%lu "
       "%ld "
       "%lu %"KLF"u %"KLF"u %"KLF"u %"KLF"u %"KLF"u "
       "%*s %*s %*s %*s " /* discard, no RT signals & Linux 2.1 used hex */
       "%"KLF"u %*lu %*lu "
       "%d %d "
       "%lu %lu",
       &P->state,
       &P->ppid, &P->pgrp, &P->session, &P->tty, &P->tpgid,
       &P->flags, &P->min_flt, &P->cmin_flt, &P->maj_flt, &P->cmaj_flt,
       &P->utime, &P->stime, &P->cutime, &P->cstime,
       &P->priority, &P->nice,
       &P->nlwp,
       &P->alarm,
       &P->start_time,
       &P->vsize,
       &P->rss,
       &P->rss_rlim, &P->start_code, &P->end_code, &P->start_stack, &P->kstk_esp, &P->kstk_eip,
/*     P->signal, P->blocked, P->sigignore, P->sigcatch,   */ /* can't use */
       &P->wchan, /* &P->nswap, &P->cnswap, */  /* nswap and cnswap dead for 2.4.xx and up */
/* -- Linux 2.0.35 ends here -- */
       &P->exit_signal, &P->processor,  /* 2.2.1 ends with "exit_signal" */
/* -- Linux 2.2.8 to 2.5.17 end here -- */
       &P->rtprio, &P->sched  /* both added to 2.5.18 */
    );

    if(!P->nlwp){
      P->nlwp = 1;
    }

LEAVE(0x160);
}

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

static void statm2proc(const char* s, proc_t *restrict P) {
    int num;
    num = sscanf(s, "%ld %ld %ld %ld %ld %ld %ld",
	   &P->size, &P->resident, &P->share,
	   &P->trs, &P->lrs, &P->drs, &P->dt);
/*    fprintf(stderr, "statm2proc converted %d fields.\n",num); */
}

static int file2str(const char *directory, const char *what, char *ret, int cap) {
    static char filename[80];
    int fd, num_read;

    sprintf(filename, "%s/%s", directory, what);
    fd = open(filename, O_RDONLY, 0);
    if(unlikely(fd==-1)) return -1;
    num_read = read(fd, ret, cap - 1);
    close(fd);
    if(unlikely(num_read<=0)) return -1;
    ret[num_read] = '\0';
    return num_read;
}

static char** file2strvec(const char* directory, const char* what) {
    char buf[2048];	/* read buf bytes at a time */
    char *p, *rbuf = 0, *endbuf, **q, **ret;
    int fd, tot = 0, n, c, end_of_file = 0;
    int align;

    sprintf(buf, "%s/%s", directory, what);
    fd = open(buf, O_RDONLY, 0);
    if(fd==-1) return NULL;

    /* read whole file into a memory buffer, allocating as we go */
    while ((n = read(fd, buf, sizeof buf - 1)) > 0) {
	if (n < (int)(sizeof buf - 1))
	    end_of_file = 1;
	if (n == 0 && rbuf == 0)
	    return NULL;	/* process died between our open and read */
	if (n < 0) {
	    if (rbuf)
		free(rbuf);
	    return NULL;	/* read error */
	}
	if (end_of_file && buf[n-1])		/* last read char not null */
	    buf[n++] = '\0';			/* so append null-terminator */
	rbuf = xrealloc(rbuf, tot + n);		/* allocate more memory */
	memcpy(rbuf + tot, buf, n);		/* copy buffer into it */
	tot += n;				/* increment total byte ctr */
	if (end_of_file)
	    break;
    }
    close(fd);
    if (n <= 0 && !end_of_file) {
	if (rbuf) free(rbuf);
	return NULL;		/* read error */
    }
    endbuf = rbuf + tot;			/* count space for pointers */
    align = (sizeof(char*)-1) - ((tot + sizeof(char*)-1) & (sizeof(char*)-1));
    for (c = 0, p = rbuf; p < endbuf; p++)
    	if (!*p)
	    c += sizeof(char*);
    c += sizeof(char*);				/* one extra for NULL term */

    rbuf = xrealloc(rbuf, tot + c + align);	/* make room for ptrs AT END */
    endbuf = rbuf + tot;			/* addr just past data buf */
    q = ret = (char**) (endbuf+align);		/* ==> free(*ret) to dealloc */
    *q++ = p = rbuf;				/* point ptrs to the strings */
    endbuf--;					/* do not traverse final NUL */
    while (++p < endbuf) 
    	if (!*p)				/* NUL char implies that */
	    *q++ = p+1;				/* next string -> next char */

    *q = 0;					/* null ptr list terminator */
    return ret;
}

// warning: interface may change
int read_cmdline(char *restrict const dst, unsigned sz, unsigned pid){
    char name[32];
    int fd;
    unsigned n = 0;
    dst[0] = '\0';
    snprintf(name, sizeof name, "/proc/%u/cmdline", pid);
    fd = open(name, O_RDONLY);
    if(fd==-1) return 0;
    for(;;){
        ssize_t r = read(fd,dst+n,sz-n);
        if(r==-1){
            if(errno==EINTR) continue;
            break;
        }
        n += r;
        if(n==sz) break; // filled the buffer
        if(r==0) break;  // EOF
    }
    close(fd);
    if(n){
        int i;
        if(n==sz) n--;
        dst[n] = '\0';
        i=n;
        while(i--){
            int c = dst[i];
            if(c<' ' || c>'~') dst[i]=' ';
        }
    }
    return n;
}

/* These are some nice GNU C expression subscope "inline" functions.
 * The can be used with arbitrary types and evaluate their arguments
 * exactly once.
 */

/* Test if item X of type T is present in the 0 terminated list L */
#   define XinL(T, X, L) ( {			\
	    T  x = (X), *l = (L);		\
	    while (*l && *l != x) l++;		\
	    *l == x;				\
	} )

/* Test if item X of type T is present in the list L of length N */
#   define XinLN(T, X, L, N) ( {		\
	    T x = (X), *l = (L);		\
	    int i = 0, n = (N);			\
	    while (i < n && l[i] != x) i++;	\
	    i < n && l[i] == x;			\
	} )

//////////////////////////////////////////////////////////////////////////////////
// This reads process info from /proc in the traditional way, for one process.
// The pid (tgid? tid?) is already in p, and a path to it in path, with some
// room to spare.
static proc_t* simple_readproc(PROCTAB *restrict const PT, proc_t *restrict const p) {
    static struct stat sb;		// stat() buffer
    static char sbuf[1024];	// buffer for stat,statm
    char *restrict const path = PT->path;
    unsigned flags = PT->flags;

    if (unlikely(stat(path, &sb) == -1))	/* no such dirent (anymore) */
	goto next_proc;

    if ((flags & PROC_UID) && !XinLN(uid_t, sb.st_uid, PT->uids, PT->nuid))
	goto next_proc;			/* not one of the requested uids */

    p->euid = sb.st_uid;			/* need a way to get real uid */
    p->egid = sb.st_gid;			/* need a way to get real gid */

    if (flags & PROC_FILLSTAT) {         /* read, parse /proc/#/stat */
	if (unlikely( file2str(path, "stat", sbuf, sizeof sbuf) == -1 ))
	    goto next_proc;			/* error reading /proc/#/stat */
	stat2proc(sbuf, p);				/* parse /proc/#/stat */
    }

    if (unlikely(flags & PROC_FILLMEM)) {	/* read, parse /proc/#/statm */
	if (likely( file2str(path, "statm", sbuf, sizeof sbuf) != -1 ))
	    statm2proc(sbuf, p);		/* ignore statm errors here */
    }						/* statm fields just zero */

    if (flags & PROC_FILLSTATUS) {         /* read, parse /proc/#/status */
       if (likely( file2str(path, "status", sbuf, sizeof sbuf) != -1 )){
           status2proc(sbuf, p, 1);
       }
    }

    // if multithreaded, some values are crap
    if(p->nlwp > 1){
      p->wchan = (KLONG)~0ull;
    }

    /* some number->text resolving which is time consuming and kind of insane */
    if (flags & PROC_FILLUSR){
	memcpy(p->euser,   user_from_uid(p->euid), sizeof p->euser);
        if(flags & PROC_FILLSTATUS) {
            memcpy(p->ruser,   user_from_uid(p->ruid), sizeof p->ruser);
            memcpy(p->suser,   user_from_uid(p->suid), sizeof p->suser);
            memcpy(p->fuser,   user_from_uid(p->fuid), sizeof p->fuser);
        }
    }

    /* some number->text resolving which is time consuming and kind of insane */
    if (flags & PROC_FILLGRP){
        memcpy(p->egroup, group_from_gid(p->egid), sizeof p->egroup);
        if(flags & PROC_FILLSTATUS) {
            memcpy(p->rgroup, group_from_gid(p->rgid), sizeof p->rgroup);
            memcpy(p->sgroup, group_from_gid(p->sgid), sizeof p->sgroup);
            memcpy(p->fgroup, group_from_gid(p->fgid), sizeof p->fgroup);
        }
    }

    if ((flags & PROC_FILLCOM) || (flags & PROC_FILLARG))	/* read+parse /proc/#/cmdline */
	p->cmdline = file2strvec(path, "cmdline");
    else
        p->cmdline = NULL;

    if (unlikely(flags & PROC_FILLENV))			/* read+parse /proc/#/environ */
	p->environ = file2strvec(path, "environ");
    else
        p->environ = NULL;
    
    return p;
next_proc:
    return NULL;
}

//////////////////////////////////////////////////////////////////////////////////
// This reads /proc/*/task/* data, for one task.
// p is the POSIX process (task group summary) (not needed by THIS implementation)
// t is the POSIX thread (task group member, generally not the leader)
// path is a path to the task, with some room to spare.
static proc_t* simple_readtask(PROCTAB *restrict const PT, const proc_t *restrict const p, proc_t *restrict const t, char *restrict const path) {
    static struct stat sb;		// stat() buffer
    static char sbuf[1024];	// buffer for stat,statm
    unsigned flags = PT->flags;

//printf("hhh\n");
    if (unlikely(stat(path, &sb) == -1))	/* no such dirent (anymore) */
	goto next_task;

//    if ((flags & PROC_UID) && !XinLN(uid_t, sb.st_uid, PT->uids, PT->nuid))
//	goto next_task;			/* not one of the requested uids */

    t->euid = sb.st_uid;			/* need a way to get real uid */
    t->egid = sb.st_gid;			/* need a way to get real gid */

//printf("iii\n");
    if (flags & PROC_FILLSTAT) {         /* read, parse /proc/#/stat */
	if (unlikely( file2str(path, "stat", sbuf, sizeof sbuf) == -1 ))
	    goto next_task;			/* error reading /proc/#/stat */
	stat2proc(sbuf, t);				/* parse /proc/#/stat */
    }

    if (unlikely(flags & PROC_FILLMEM)) {	/* read, parse /proc/#/statm */
#if 0
	if (likely( file2str(path, "statm", sbuf, sizeof sbuf) != -1 ))
	    statm2proc(sbuf, t);		/* ignore statm errors here */
#else
	t->size     = p->size;
	t->resident = p->resident;
	t->share    = p->share;
	t->trs      = p->trs;
	t->lrs      = p->lrs;
	t->drs      = p->drs;
	t->dt       = p->dt;
#endif
    }						/* statm fields just zero */

    if (flags & PROC_FILLSTATUS) {         /* read, parse /proc/#/status */
       if (likely( file2str(path, "status", sbuf, sizeof sbuf) != -1 )){
           status2proc(sbuf, t, 0);
       }
    }

    /* some number->text resolving which is time consuming */
    if (flags & PROC_FILLUSR){
	memcpy(t->euser,   user_from_uid(t->euid), sizeof t->euser);
        if(flags & PROC_FILLSTATUS) {
            memcpy(t->ruser,   user_from_uid(t->ruid), sizeof t->ruser);
            memcpy(t->suser,   user_from_uid(t->suid), sizeof t->suser);
            memcpy(t->fuser,   user_from_uid(t->fuid), sizeof t->fuser);
        }
    }

    /* some number->text resolving which is time consuming */
    if (flags & PROC_FILLGRP){
        memcpy(t->egroup, group_from_gid(t->egid), sizeof t->egroup);
        if(flags & PROC_FILLSTATUS) {
            memcpy(t->rgroup, group_from_gid(t->rgid), sizeof t->rgroup);
            memcpy(t->sgroup, group_from_gid(t->sgid), sizeof t->sgroup);
            memcpy(t->fgroup, group_from_gid(t->fgid), sizeof t->fgroup);
        }
    }

#if 0
    if ((flags & PROC_FILLCOM) || (flags & PROC_FILLARG))	/* read+parse /proc/#/cmdline */
	t->cmdline = file2strvec(path, "cmdline");
    else
        t->cmdline = NULL;

    if (unlikely(flags & PROC_FILLENV))			/* read+parse /proc/#/environ */
	t->environ = file2strvec(path, "environ");
    else
        t->environ = NULL;
#else
    t->cmdline = p->cmdline;  // better not free these until done with all threads!
    t->environ = p->environ;
#endif

    t->ppid = p->ppid;  // ought to put the per-task ppid somewhere

    return t;
next_task:
    return NULL;
}

//////////////////////////////////////////////////////////////////////////////////
// This finds processes in /proc in the traditional way.
// Return non-zero on success.
static int simple_nextpid(PROCTAB *restrict const PT, proc_t *restrict const p) {
  static struct direct *ent;		/* dirent handle */
  char *restrict const path = PT->path;
  for (;;) {
    ent = readdir(PT->procfs);