libbb/procps.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright 1998 by Albert Cahalan; all rights reserved.
   6  * Copyright (C) 2002 by Vladimir Oleynik <dzo@simtreas.ru>
   7  * SELinux support: (c) 2007 by Yuichi Nakamura <ynakam@hitachisoft.jp>
   8  *
   9  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  10  */
  11
  12 #include "libbb.h"
  13
  14
  15 typedef struct id_to_name_map_t {
  16         uid_t id;
  17         char name[USERNAME_MAX_SIZE];
  18 } id_to_name_map_t;
  19
  20 typedef struct cache_t {
  21         id_to_name_map_t *cache;
  22         int size;
  23 } cache_t;
  24
  25 static cache_t username, groupname;
  26
  27 static void clear_cache(cache_t *cp)
  28 {
  29         free(cp->cache);
  30         cp->cache = NULL;
  31         cp->size = 0;
  32 }
  33 void FAST_FUNC clear_username_cache(void)
  34 {
  35         clear_cache(&username);
  36         clear_cache(&groupname);
  37 }
  38
  39 #if 0 /* more generic, but we don't need that yet */
  40 /* Returns -N-1 if not found. */
  41 /* cp->cache[N] is allocated and must be filled in this case */
  42 static int get_cached(cache_t *cp, uid_t id)
  43 {
  44         int i;
  45         for (i = 0; i < cp->size; i++)
  46                 if (cp->cache[i].id == id)
  47                         return i;
  48         i = cp->size++;
  49         cp->cache = xrealloc_vector(cp->cache, 2, i);
  50         cp->cache[i++].id = id;
  51         return -i;
  52 }
  53 #endif
  54
  55 static char* get_cached(cache_t *cp, uid_t id,
  56                         char* FAST_FUNC x2x_utoa(uid_t id))
  57 {
  58         int i;
  59         for (i = 0; i < cp->size; i++)
  60                 if (cp->cache[i].id == id)
  61                         return cp->cache[i].name;
  62         i = cp->size++;
  63         cp->cache = xrealloc_vector(cp->cache, 2, i);
  64         cp->cache[i].id = id;
  65         /* Never fails. Generates numeric string if name isn't found */
  66         safe_strncpy(cp->cache[i].name, x2x_utoa(id), sizeof(cp->cache[i].name));
  67         return cp->cache[i].name;
  68 }
  69 const char* FAST_FUNC get_cached_username(uid_t uid)
  70 {
  71         return get_cached(&username, uid, uid2uname_utoa);
  72 }
  73 const char* FAST_FUNC get_cached_groupname(gid_t gid)
  74 {
  75         return get_cached(&groupname, gid, gid2group_utoa);
  76 }
  77
  78
  79 #define PROCPS_BUFSIZE 1024
  80
  81 static int read_to_buf(const char *filename, void *buf)
  82 {
  83         int fd;
  84         /* open_read_close() would do two reads, checking for EOF.
  85          * When you have 10000 /proc/$NUM/stat to read, it isn't desirable */
  86         ssize_t ret = -1;
  87         fd = open(filename, O_RDONLY);
  88         if (fd >= 0) {
  89                 ret = read(fd, buf, PROCPS_BUFSIZE-1);
  90                 close(fd);
  91         }
  92         ((char *)buf)[ret > 0 ? ret : 0] = '\0';
  93         return ret;
  94 }
  95
  96 static procps_status_t* FAST_FUNC alloc_procps_scan(void)
  97 {
  98         unsigned n = getpagesize();
  99         procps_status_t* sp = xzalloc(sizeof(procps_status_t));
 100         sp->dir = xopendir("/proc");
 101         while (1) {
 102                 n >>= 1;
 103                 if (!n) break;
 104                 sp->shift_pages_to_bytes++;
 105         }
 106         sp->shift_pages_to_kb = sp->shift_pages_to_bytes - 10;
 107         return sp;
 108 }
 109
 110 void FAST_FUNC free_procps_scan(procps_status_t* sp)
 111 {
 112         closedir(sp->dir);
 113 #if ENABLE_FEATURE_SHOW_THREADS
 114         if (sp->task_dir)
 115                 closedir(sp->task_dir);
 116 #endif
 117         free(sp->argv0);
 118         free(sp->exe);
 119         IF_SELINUX(free(sp->context);)
 120         free(sp);
 121 }
 122
 123 #if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 124 static unsigned long fast_strtoul_16(char **endptr)
 125 {
 126         unsigned char c;
 127         char *str = *endptr;
 128         unsigned long n = 0;
 129
 130         /* Need to stop on both ' ' and '\n' */
 131         while ((c = *str++) > ' ') {
 132                 c = ((c|0x20) - '0');
 133                 if (c > 9)
 134                         /* c = c + '0' - 'a' + 10: */
 135                         c = c - ('a' - '0' - 10);
 136                 n = n*16 + c;
 137         }
 138         *endptr = str; /* We skip trailing space! */
 139         return n;
 140 }
 141 #endif
 142
 143 #if ENABLE_FEATURE_FAST_TOP || ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 144 /* We cut a lot of corners here for speed */
 145 static unsigned long fast_strtoul_10(char **endptr)
 146 {
 147         unsigned char c;
 148         char *str = *endptr;
 149         unsigned long n = *str - '0';
 150
 151         /* Need to stop on both ' ' and '\n' */
 152         while ((c = *++str) > ' ')
 153                 n = n*10 + (c - '0');
 154
 155         *endptr = str + 1; /* We skip trailing space! */
 156         return n;
 157 }
 158
 159 # if ENABLE_FEATURE_FAST_TOP
 160 static long fast_strtol_10(char **endptr)
 161 {
 162         if (**endptr != '-')
 163                 return fast_strtoul_10(endptr);
 164
 165         (*endptr)++;
 166         return - (long)fast_strtoul_10(endptr);
 167 }
 168 # endif
 169
 170 static char *skip_fields(char *str, int count)
 171 {
 172         do {
 173                 while (*str++ != ' ')
 174                         continue;
 175                 /* we found a space char, str points after it */
 176         } while (--count);
 177         return str;
 178 }
 179 #endif
 180
 181 #if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 182 int FAST_FUNC procps_read_smaps(pid_t pid, struct smaprec *total,
 183                 void (*cb)(struct smaprec *, void *), void *data)
 184 {
 185         FILE *file;
 186         struct smaprec currec;
 187         char filename[sizeof("/proc/%u/smaps") + sizeof(int)*3];
 188         char buf[PROCPS_BUFSIZE];
 189 #if !ENABLE_PMAP
 190         void (*cb)(struct smaprec *, void *) = NULL;
 191         void *data = NULL;
 192 #endif
 193
 194         sprintf(filename, "/proc/%u/smaps", (int)pid);
 195
 196         file = fopen_for_read(filename);
 197         if (!file)
 198                 return 1;
 199
 200         memset(&currec, 0, sizeof(currec));
 201         while (fgets(buf, PROCPS_BUFSIZE, file)) {
 202                 // Each mapping datum has this form:
 203                 // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
 204                 // Size:                nnn kB
 205                 // Rss:                 nnn kB
 206                 // .....
 207
 208                 char *tp, *p;
 209
 210 #define SCAN(S, X) \
 211                 if ((tp = is_prefixed_with(buf, S)) != NULL) {       \
 212                         tp = skip_whitespace(tp);                    \
 213                         total->X += currec.X = fast_strtoul_10(&tp); \
 214                         continue;                                    \
 215                 }
 216                 if (cb) {
 217                         SCAN("Pss:"  , smap_pss     );
 218                         SCAN("Swap:" , smap_swap    );
 219                 }
 220                 SCAN("Private_Dirty:", private_dirty);
 221                 SCAN("Private_Clean:", private_clean);
 222                 SCAN("Shared_Dirty:" , shared_dirty );
 223                 SCAN("Shared_Clean:" , shared_clean );
 224 #undef SCAN
 225                 tp = strchr(buf, '-');
 226                 if (tp) {
 227                         // We reached next mapping - the line of this form:
 228                         // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
 229
 230                         if (cb) {
 231                                 /* If we have a previous record, there's nothing more
 232                                  * for it, call the callback and clear currec
 233                                  */
 234                                 if (currec.smap_size)
 235                                         cb(&currec, data);
 236                                 free(currec.smap_name);
 237                         }
 238                         memset(&currec, 0, sizeof(currec));
 239
 240                         *tp = ' ';
 241                         tp = buf;
 242                         currec.smap_start = fast_strtoul_16(&tp);
 243                         currec.smap_size = (fast_strtoul_16(&tp) - currec.smap_start) >> 10;
 244
 245                         strncpy(currec.smap_mode, tp, sizeof(currec.smap_mode)-1);
 246
 247                         // skipping "rw-s FILEOFS M:m INODE "
 248                         tp = skip_whitespace(skip_fields(tp, 4));
 249                         // filter out /dev/something (something != zero)
 250                         if (!is_prefixed_with(tp, "/dev/") || strcmp(tp, "/dev/zero\n") == 0) {
 251                                 if (currec.smap_mode[1] == 'w') {
 252                                         currec.mapped_rw = currec.smap_size;
 253                                         total->mapped_rw += currec.smap_size;
 254                                 } else if (currec.smap_mode[1] == '-') {
 255                                         currec.mapped_ro = currec.smap_size;
 256                                         total->mapped_ro += currec.smap_size;
 257                                 }
 258                         }
 259
 260                         if (strcmp(tp, "[stack]\n") == 0)
 261                                 total->stack += currec.smap_size;
 262                         if (cb) {
 263                                 p = skip_non_whitespace(tp);
 264                                 if (p == tp) {
 265                                         currec.smap_name = xstrdup("  [ anon ]");
 266                                 } else {
 267                                         *p = '\0';
 268                                         currec.smap_name = xstrdup(tp);
 269                                 }
 270                         }
 271                         total->smap_size += currec.smap_size;
 272                 }
 273         }
 274         fclose(file);
 275
 276         if (cb) {
 277                 if (currec.smap_size)
 278                         cb(&currec, data);
 279                 free(currec.smap_name);
 280         }
 281
 282         return 0;
 283 }
 284 #endif
 285
 286 procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 287 {
 288         if (!sp)
 289                 sp = alloc_procps_scan();
 290
 291         for (;;) {
 292                 struct dirent *entry;
 293                 char buf[PROCPS_BUFSIZE];
 294                 long tasknice;
 295                 unsigned pid;
 296                 int n;
 297                 char filename[sizeof("/proc/%u/task/%u/cmdline") + sizeof(int)*3 * 2];
 298                 char *filename_tail;
 299
 300 #if ENABLE_FEATURE_SHOW_THREADS
 301                 if (sp->task_dir) {
 302                         entry = readdir(sp->task_dir);
 303                         if (entry)
 304                                 goto got_entry;
 305                         closedir(sp->task_dir);
 306                         sp->task_dir = NULL;
 307                 }
 308 #endif
 309                 entry = readdir(sp->dir);
 310                 if (entry == NULL) {
 311                         free_procps_scan(sp);
 312                         return NULL;
 313                 }
 314  IF_FEATURE_SHOW_THREADS(got_entry:)
 315                 pid = bb_strtou(entry->d_name, NULL, 10);
 316                 if (errno)
 317                         continue;
 318 #if ENABLE_FEATURE_SHOW_THREADS
 319                 if ((flags & PSSCAN_TASKS) && !sp->task_dir) {
 320                         /* We found another /proc/PID. Do not use it,
 321                          * there will be /proc/PID/task/PID (same PID!),
 322                          * so just go ahead and dive into /proc/PID/task. */
 323                         sprintf(filename, "/proc/%u/task", pid);
 324                         /* Note: if opendir fails, we just go to next /proc/XXX */
 325                         sp->task_dir = opendir(filename);
 326                         sp->main_thread_pid = pid;
 327                         continue;
 328                 }
 329 #endif
 330
 331                 /* After this point we can:
 332                  * "break": stop parsing, return the data
 333                  * "continue": try next /proc/XXX
 334                  */
 335
 336                 memset(&sp->vsz, 0, sizeof(*sp) - offsetof(procps_status_t, vsz));
 337
 338                 sp->pid = pid;
 339                 if (!(flags & ~PSSCAN_PID))
 340                         break; /* we needed only pid, we got it */
 341
 342 #if ENABLE_SELINUX
 343                 if (flags & PSSCAN_CONTEXT) {
 344                         if (getpidcon(sp->pid, &sp->context) < 0)
 345                                 sp->context = NULL;
 346                 }
 347 #endif
 348
 349 #if ENABLE_FEATURE_SHOW_THREADS
 350                 if (sp->task_dir)
 351                         filename_tail = filename + sprintf(filename, "/proc/%u/task/%u/", sp->main_thread_pid, pid);
 352                 else
 353 #endif
 354                         filename_tail = filename + sprintf(filename, "/proc/%u/", pid);
 355
 356                 if (flags & PSSCAN_UIDGID) {
 357                         struct stat sb;
 358                         if (stat(filename, &sb))
 359                                 continue; /* process probably exited */
 360                         /* Effective UID/GID, not real */
 361                         sp->uid = sb.st_uid;
 362                         sp->gid = sb.st_gid;
 363                 }
 364
 365                 /* These are all retrieved from proc/NN/stat in one go: */
 366                 if (flags & (PSSCAN_PPID | PSSCAN_PGID | PSSCAN_SID
 367                         | PSSCAN_COMM | PSSCAN_STATE
 368                         | PSSCAN_VSZ | PSSCAN_RSS
 369                         | PSSCAN_STIME | PSSCAN_UTIME | PSSCAN_START_TIME
 370                         | PSSCAN_TTY | PSSCAN_NICE
 371                         | PSSCAN_CPU)
 372                 ) {
 373                         int s_idx;
 374                         char *cp, *comm1;
 375                         int tty;
 376 #if !ENABLE_FEATURE_FAST_TOP
 377                         unsigned long vsz, rss;
 378 #endif
 379                         /* see proc(5) for some details on this */
 380                         strcpy(filename_tail, "stat");
 381                         n = read_to_buf(filename, buf);
 382                         if (n < 0)
 383                                 continue; /* process probably exited */
 384                         cp = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
 385                         /*if (!cp || cp[1] != ' ')
 386                                 continue;*/
 387                         cp[0] = '\0';
 388                         BUILD_BUG_ON(sizeof(sp->comm) < 16);
 389                         comm1 = strchr(buf, '(');
 390                         /*if (comm1)*/
 391                                 safe_strncpy(sp->comm, comm1 + 1, sizeof(sp->comm));
 392
 393 #if !ENABLE_FEATURE_FAST_TOP
 394                         n = sscanf(cp+2,
 395                                 "%c %u "               /* state, ppid */
 396                                 "%u %u %d %*s "        /* pgid, sid, tty, tpgid */
 397                                 "%*s %*s %*s %*s %*s " /* flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
 398                                 "%lu %lu "             /* utime, stime */
 399                                 "%*s %*s %*s "         /* cutime, cstime, priority */
 400                                 "%ld "                 /* nice */
 401                                 "%*s %*s "             /* timeout, it_real_value */
 402                                 "%lu "                 /* start_time */
 403                                 "%lu "                 /* vsize */
 404                                 "%lu "                 /* rss */
 405 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 406                                 "%*s %*s %*s %*s %*s %*s " /*rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
 407                                 "%*s %*s %*s %*s "         /*signal, blocked, sigignore, sigcatch */
 408                                 "%*s %*s %*s %*s "         /*wchan, nswap, cnswap, exit_signal */
 409                                 "%d"                       /*cpu last seen on*/
 410 # endif
 411                                 ,
 412                                 sp->state, &sp->ppid,
 413                                 &sp->pgid, &sp->sid, &tty,
 414                                 &sp->utime, &sp->stime,
 415                                 &tasknice,
 416                                 &sp->start_time,
 417                                 &vsz,
 418                                 &rss
 419 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 420                                 , &sp->last_seen_on_cpu
 421 # endif
 422                                 );
 423
 424                         if (n < 11)
 425                                 continue; /* bogus data, get next /proc/XXX */
 426 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 427                         if (n == 11)
 428                                 sp->last_seen_on_cpu = 0;
 429 # endif
 430
 431                         /* vsz is in bytes and we want kb */
 432                         sp->vsz = vsz >> 10;
 433                         /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
 434                         sp->rss = rss << sp->shift_pages_to_kb;
 435                         sp->tty_major = (tty >> 8) & 0xfff;
 436                         sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
 437 #else
 438 /* This costs ~100 bytes more but makes top faster by 20%
 439  * If you run 10000 processes, this may be important for you */
 440                         sp->state[0] = cp[2];
 441                         cp += 4;
 442                         sp->ppid = fast_strtoul_10(&cp);
 443                         sp->pgid = fast_strtoul_10(&cp);
 444                         sp->sid = fast_strtoul_10(&cp);
 445                         tty = fast_strtoul_10(&cp);
 446                         sp->tty_major = (tty >> 8) & 0xfff;
 447                         sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
 448                         cp = skip_fields(cp, 6); /* tpgid, flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
 449                         sp->utime = fast_strtoul_10(&cp);
 450                         sp->stime = fast_strtoul_10(&cp);
 451                         cp = skip_fields(cp, 3); /* cutime, cstime, priority */
 452                         tasknice = fast_strtol_10(&cp);
 453                         cp = skip_fields(cp, 2); /* timeout, it_real_value */
 454                         sp->start_time = fast_strtoul_10(&cp);
 455                         /* vsz is in bytes and we want kb */
 456                         sp->vsz = fast_strtoul_10(&cp) >> 10;
 457                         /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
 458                         sp->rss = fast_strtoul_10(&cp) << sp->shift_pages_to_kb;
 459 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 460                         /* (6): rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
 461                         /* (4): signal, blocked, sigignore, sigcatch */
 462                         /* (4): wchan, nswap, cnswap, exit_signal */
 463                         cp = skip_fields(cp, 14);
 464 //FIXME: is it safe to assume this field exists?
 465                         sp->last_seen_on_cpu = fast_strtoul_10(&cp);
 466 # endif
 467 #endif /* FEATURE_FAST_TOP */
 468
 469 #if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
 470                         sp->niceness = tasknice;
 471 #endif
 472                         sp->state[1] = ' ';
 473                         sp->state[2] = ' ';
 474                         s_idx = 1;
 475                         if (sp->vsz == 0 && sp->state[0] != 'Z') {
 476                                 /* not sure what the purpose of this flag */
 477                                 sp->state[1] = 'W';
 478                                 s_idx = 2;
 479                         }
 480                         if (tasknice != 0) {
 481                                 if (tasknice < 0)
 482                                         sp->state[s_idx] = '<';
 483                                 else /* > 0 */
 484                                         sp->state[s_idx] = 'N';
 485                         }
 486                 }
 487
 488 #if ENABLE_FEATURE_TOPMEM
 489                 if (flags & PSSCAN_SMAPS)
 490                         procps_read_smaps(pid, &sp->smaps, NULL, NULL);
 491 #endif /* TOPMEM */
 492 #if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
 493                 if (flags & PSSCAN_RUIDGID) {
 494                         FILE *file;
 495
 496                         strcpy(filename_tail, "status");
 497                         file = fopen_for_read(filename);
 498                         if (file) {
 499                                 while (fgets(buf, sizeof(buf), file)) {
 500                                         char *tp;
 501 #define SCAN_TWO(str, name, statement) \
 502         if ((tp = is_prefixed_with(buf, str)) != NULL) { \
 503                 tp = skip_whitespace(tp); \
 504                 sscanf(tp, "%u", &sp->name); \
 505                 statement; \
 506         }
 507                                         SCAN_TWO("Uid:", ruid, continue);
 508                                         SCAN_TWO("Gid:", rgid, break);
 509 #undef SCAN_TWO
 510                                 }
 511                                 fclose(file);
 512                         }
 513                 }
 514 #endif /* PS_ADDITIONAL_COLUMNS */
 515                 if (flags & PSSCAN_EXE) {
 516                         strcpy(filename_tail, "exe");
 517                         free(sp->exe);
 518                         sp->exe = xmalloc_readlink(filename);
 519                 }
 520                 /* Note: if /proc/PID/cmdline is empty,
 521                  * code below "breaks". Therefore it must be
 522                  * the last code to parse /proc/PID/xxx data
 523                  * (we used to have /proc/PID/exe parsing after it
 524                  * and were getting stale sp->exe).
 525                  */
 526 #if 0 /* PSSCAN_CMD is not used */
 527                 if (flags & (PSSCAN_CMD|PSSCAN_ARGV0)) {
 528                         free(sp->argv0);
 529                         sp->argv0 = NULL;
 530                         free(sp->cmd);
 531                         sp->cmd = NULL;
 532                         strcpy(filename_tail, "cmdline");
 533                         /* TODO: to get rid of size limits, read into malloc buf,
 534                          * then realloc it down to real size. */
 535                         n = read_to_buf(filename, buf);
 536                         if (n <= 0)
 537                                 break;
 538                         if (flags & PSSCAN_ARGV0)
 539                                 sp->argv0 = xstrdup(buf);
 540                         if (flags & PSSCAN_CMD) {
 541                                 do {
 542                                         n--;
 543                                         if ((unsigned char)(buf[n]) < ' ')
 544                                                 buf[n] = ' ';
 545                                 } while (n);
 546                                 sp->cmd = xstrdup(buf);
 547                         }
 548                 }
 549 #else
 550                 if (flags & (PSSCAN_ARGV0|PSSCAN_ARGVN)) {
 551                         free(sp->argv0);
 552                         sp->argv0 = NULL;
 553                         strcpy(filename_tail, "cmdline");
 554                         n = read_to_buf(filename, buf);
 555                         if (n <= 0)
 556                                 break;
 557                         if (flags & PSSCAN_ARGVN) {
 558                                 sp->argv_len = n;
 559                                 sp->argv0 = xmemdup(buf, n + 1);
 560                                 /* sp->argv0[n] = '\0'; - buf has it */
 561                         } else {
 562                                 sp->argv_len = 0;
 563                                 sp->argv0 = xstrdup(buf);
 564                         }
 565                 }
 566 #endif
 567                 break;
 568         } /* for (;;) */
 569
 570         return sp;
 571 }
 572
 573 void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
 574 {
 575         int sz;
 576         char filename[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
 577
 578         sprintf(filename, "/proc/%u/cmdline", pid);
 579         sz = open_read_close(filename, buf, col - 1);
 580         if (sz > 0) {
 581                 const char *base;
 582                 int comm_len;
 583
 584                 buf[sz] = '\0';
 585                 while (--sz >= 0 && buf[sz] == '\0')
 586                         continue;
 587                 /* Prevent basename("process foo/bar") = "bar" */
 588                 strchrnul(buf, ' ')[0] = '\0';
 589                 base = bb_basename(buf); /* before we replace argv0's NUL with space */
 590                 while (sz >= 0) {
 591                         if ((unsigned char)(buf[sz]) < ' ')
 592                                 buf[sz] = ' ';
 593                         sz--;
 594                 }
 595                 if (base[0] == '-') /* "-sh" (login shell)? */
 596                         base++;
 597
 598                 /* If comm differs from argv0, prepend "{comm} ".
 599                  * It allows to see thread names set by prctl(PR_SET_NAME).
 600                  */
 601                 if (!comm)
 602                         return;
 603                 comm_len = strlen(comm);
 604                 /* Why compare up to comm_len, not COMM_LEN-1?
 605                  * Well, some processes rewrite argv, and use _spaces_ there
 606                  * while rewriting. (KDE is observed to do it).
 607                  * I prefer to still treat argv0 "process foo bar"
 608                  * as 'equal' to comm "process".
 609                  */
 610                 if (strncmp(base, comm, comm_len) != 0) {
 611                         comm_len += 3;
 612                         if (col > comm_len)
 613                                 memmove(buf + comm_len, buf, col - comm_len);
 614                         snprintf(buf, col, "{%s}", comm);
 615                         if (col <= comm_len)
 616                                 return;
 617                         buf[comm_len - 1] = ' ';
 618                         buf[col - 1] = '\0';
 619                 }
 620         } else {
 621                 snprintf(buf, col, "[%s]", comm ? comm : "?");
 622         }
 623 }
 624
 625 /* from kernel:
 626         //             pid comm S ppid pgid sid tty_nr tty_pgrp flg
 627         sprintf(buffer,"%d (%s) %c %d  %d   %d  %d     %d       %lu %lu \
 628 %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
 629 %lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %llu\n",
 630                 task->pid,
 631                 tcomm,
 632                 state,
 633                 ppid,
 634                 pgid,
 635                 sid,
 636                 tty_nr,
 637                 tty_pgrp,
 638                 task->flags,
 639                 min_flt,
 640                 cmin_flt,
 641                 maj_flt,
 642                 cmaj_flt,
 643                 cputime_to_clock_t(utime),
 644                 cputime_to_clock_t(stime),
 645                 cputime_to_clock_t(cutime),
 646                 cputime_to_clock_t(cstime),
 647                 priority,
 648                 nice,
 649                 num_threads,
 650                 // 0,
 651                 start_time,
 652                 vsize,
 653                 mm ? get_mm_rss(mm) : 0,
 654                 rsslim,
 655                 mm ? mm->start_code : 0,
 656                 mm ? mm->end_code : 0,
 657                 mm ? mm->start_stack : 0,
 658                 esp,
 659                 eip,
 660 the rest is some obsolete cruft
 661 */