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 #include "libbb.h"
  12
  13
  14 typedef struct id_to_name_map_t {
  15         uid_t id;
  16         char name[USERNAME_MAX_SIZE];
  17 } id_to_name_map_t;
  18
  19 typedef struct cache_t {
  20         id_to_name_map_t *cache;
  21         int size;
  22 } cache_t;
  23
  24 static cache_t username, groupname;
  25
  26 static void clear_cache(cache_t *cp)
  27 {
  28         free(cp->cache);
  29         cp->cache = NULL;
  30         cp->size = 0;
  31 }
  32 void FAST_FUNC clear_username_cache(void)
  33 {
  34         clear_cache(&username);
  35         clear_cache(&groupname);
  36 }
  37
  38 #if 0 /* more generic, but we don't need that yet */
  39 /* Returns -N-1 if not found. */
  40 /* cp->cache[N] is allocated and must be filled in this case */
  41 static int get_cached(cache_t *cp, uid_t id)
  42 {
  43         int i;
  44         for (i = 0; i < cp->size; i++)
  45                 if (cp->cache[i].id == id)
  46                         return i;
  47         i = cp->size++;
  48         cp->cache = xrealloc_vector(cp->cache, 2, i);
  49         cp->cache[i++].id = id;
  50         return -i;
  51 }
  52 #endif
  53
  54 static char* get_cached(cache_t *cp, uid_t id,
  55                         char* FAST_FUNC x2x_utoa(uid_t id))
  56 {
  57         int i;
  58         for (i = 0; i < cp->size; i++)
  59                 if (cp->cache[i].id == id)
  60                         return cp->cache[i].name;
  61         i = cp->size++;
  62         cp->cache = xrealloc_vector(cp->cache, 2, i);
  63         cp->cache[i].id = id;
  64         /* Never fails. Generates numeric string if name isn't found */
  65         safe_strncpy(cp->cache[i].name, x2x_utoa(id), sizeof(cp->cache[i].name));
  66         return cp->cache[i].name;
  67 }
  68 const char* FAST_FUNC get_cached_username(uid_t uid)
  69 {
  70         return get_cached(&username, uid, uid2uname_utoa);
  71 }
  72 const char* FAST_FUNC get_cached_groupname(gid_t gid)
  73 {
  74         return get_cached(&groupname, gid, gid2group_utoa);
  75 }
  76
  77
  78 #define PROCPS_BUFSIZE 1024
  79
  80 static int read_to_buf(const char *filename, void *buf)
  81 {
  82         int fd;
  83         /* open_read_close() would do two reads, checking for EOF.
  84          * When you have 10000 /proc/$NUM/stat to read, it isn't desirable */
  85         ssize_t ret = -1;
  86         fd = open(filename, O_RDONLY);
  87         if (fd >= 0) {
  88                 ret = read(fd, buf, PROCPS_BUFSIZE-1);
  89                 close(fd);
  90         }
  91         ((char *)buf)[ret > 0 ? ret : 0] = '\0';
  92         return ret;
  93 }
  94
  95 static procps_status_t* FAST_FUNC alloc_procps_scan(void)
  96 {
  97         unsigned n = getpagesize();
  98         procps_status_t* sp = xzalloc(sizeof(procps_status_t));
  99         sp->dir = xopendir("/proc");
 100         while (1) {
 101                 n >>= 1;
 102                 if (!n) break;
 103                 sp->shift_pages_to_bytes++;
 104         }
 105         sp->shift_pages_to_kb = sp->shift_pages_to_bytes - 10;
 106         return sp;
 107 }
 108
 109 void FAST_FUNC free_procps_scan(procps_status_t* sp)
 110 {
 111         closedir(sp->dir);
 112 #if ENABLE_FEATURE_SHOW_THREADS
 113         if (sp->task_dir)
 114                 closedir(sp->task_dir);
 115 #endif
 116         free(sp->argv0);
 117         free(sp->exe);
 118         IF_SELINUX(free(sp->context);)
 119         free(sp);
 120 }
 121
 122 #if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 123 static unsigned long long fast_strtoull_16(char **endptr)
 124 {
 125         unsigned char c;
 126         char *str = *endptr;
 127         unsigned long long n = 0;
 128
 129         /* Need to stop on both ' ' and '\n' */
 130         while ((c = *str++) > ' ') {
 131                 c = ((c|0x20) - '0');
 132                 if (c > 9)
 133                         /* c = c + '0' - 'a' + 10: */
 134                         c = c - ('a' - '0' - 10);
 135                 n = n*16 + c;
 136         }
 137         *endptr = str; /* We skip trailing space! */
 138         return n;
 139 }
 140 #endif
 141
 142 #if ENABLE_FEATURE_FAST_TOP || ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 143 /* We cut a lot of corners here for speed */
 144 static unsigned long fast_strtoul_10(char **endptr)
 145 {
 146         unsigned char c;
 147         char *str = *endptr;
 148         unsigned long n = *str - '0';
 149
 150         /* Need to stop on both ' ' and '\n' */
 151         while ((c = *++str) > ' ')
 152                 n = n*10 + (c - '0');
 153
 154         *endptr = str + 1; /* We skip trailing space! */
 155         return n;
 156 }
 157
 158 # if ENABLE_FEATURE_FAST_TOP
 159 static long fast_strtol_10(char **endptr)
 160 {
 161         if (**endptr != '-')
 162                 return fast_strtoul_10(endptr);
 163
 164         (*endptr)++;
 165         return - (long)fast_strtoul_10(endptr);
 166 }
 167 # endif
 168
 169 static char *skip_fields(char *str, int count)
 170 {
 171         do {
 172                 while (*str++ != ' ')
 173                         continue;
 174                 /* we found a space char, str points after it */
 175         } while (--count);
 176         return str;
 177 }
 178 #endif
 179
 180 #if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
 181 int FAST_FUNC procps_read_smaps(pid_t pid, struct smaprec *total,
 182                 void (*cb)(struct smaprec *, void *), void *data)
 183 {
 184         FILE *file;
 185         struct smaprec currec;
 186         char filename[sizeof("/proc/%u/smaps") + sizeof(int)*3];
 187         char buf[PROCPS_BUFSIZE];
 188 #if !ENABLE_PMAP
 189         void (*cb)(struct smaprec *, void *) = NULL;
 190         void *data = NULL;
 191 #endif
 192
 193         sprintf(filename, "/proc/%u/smaps", (int)pid);
 194
 195         file = fopen_for_read(filename);
 196         if (!file)
 197                 return 1;
 198
 199         memset(&currec, 0, sizeof(currec));
 200         while (fgets(buf, PROCPS_BUFSIZE, file)) {
 201                 // Each mapping datum has this form:
 202                 // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
 203                 // Size:                nnn kB
 204                 // Rss:                 nnn kB
 205                 // .....
 206
 207                 char *tp, *p;
 208
 209 #define SCAN(S, X) \
 210                 if ((tp = is_prefixed_with(buf, S)) != NULL) {       \
 211                         tp = skip_whitespace(tp);                    \
 212                         total->X += currec.X = fast_strtoul_10(&tp); \
 213                         continue;                                    \
 214                 }
 215                 if (cb) {
 216                         SCAN("Pss:"  , smap_pss     );
 217                         SCAN("Swap:" , smap_swap    );
 218                 }
 219                 SCAN("Private_Dirty:", private_dirty);
 220                 SCAN("Private_Clean:", private_clean);
 221                 SCAN("Shared_Dirty:" , shared_dirty );
 222                 SCAN("Shared_Clean:" , shared_clean );
 223 #undef SCAN
 224                 tp = strchr(buf, '-');
 225                 if (tp) {
 226                         // We reached next mapping - the line of this form:
 227                         // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
 228
 229                         if (cb) {
 230                                 /* If we have a previous record, there's nothing more
 231                                  * for it, call the callback and clear currec
 232                                  */
 233                                 if (currec.smap_size)
 234                                         cb(&currec, data);
 235                                 free(currec.smap_name);
 236                         }
 237                         memset(&currec, 0, sizeof(currec));
 238
 239                         *tp = ' ';
 240                         tp = buf;
 241                         currec.smap_start = fast_strtoull_16(&tp);
 242                         currec.smap_size = (fast_strtoull_16(&tp) - currec.smap_start) >> 10;
 243
 244                         strncpy(currec.smap_mode, tp, sizeof(currec.smap_mode)-1);
 245
 246                         // skipping "rw-s FILEOFS M:m INODE "
 247                         tp = skip_whitespace(skip_fields(tp, 4));
 248                         // filter out /dev/something (something != zero)
 249                         if (!is_prefixed_with(tp, "/dev/") || strcmp(tp, "/dev/zero\n") == 0) {
 250                                 if (currec.smap_mode[1] == 'w') {
 251                                         currec.mapped_rw = currec.smap_size;
 252                                         total->mapped_rw += currec.smap_size;
 253                                 } else if (currec.smap_mode[1] == '-') {
 254                                         currec.mapped_ro = currec.smap_size;
 255                                         total->mapped_ro += currec.smap_size;
 256                                 }
 257                         }
 258
 259                         if (strcmp(tp, "[stack]\n") == 0)
 260                                 total->stack += currec.smap_size;
 261                         if (cb) {
 262                                 p = skip_non_whitespace(tp);
 263                                 if (p == tp) {
 264                                         currec.smap_name = xstrdup("  [ anon ]");
 265                                 } else {
 266                                         *p = '\0';
 267                                         currec.smap_name = xstrdup(tp);
 268                                 }
 269                         }
 270                         total->smap_size += currec.smap_size;
 271                 }
 272         }
 273         fclose(file);
 274
 275         if (cb) {
 276                 if (currec.smap_size)
 277                         cb(&currec, data);
 278                 free(currec.smap_name);
 279         }
 280
 281         return 0;
 282 }
 283 #endif
 284
 285 procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 286 {
 287         if (!sp)
 288                 sp = alloc_procps_scan();
 289
 290         for (;;) {
 291                 struct dirent *entry;
 292                 char buf[PROCPS_BUFSIZE];
 293                 long tasknice;
 294                 unsigned pid;
 295                 int n;
 296                 char filename[sizeof("/proc/%u/task/%u/cmdline") + sizeof(int)*3 * 2];
 297                 char *filename_tail;
 298
 299 #if ENABLE_FEATURE_SHOW_THREADS
 300                 if (sp->task_dir) {
 301                         entry = readdir(sp->task_dir);
 302                         if (entry)
 303                                 goto got_entry;
 304                         closedir(sp->task_dir);
 305                         sp->task_dir = NULL;
 306                 }
 307 #endif
 308                 entry = readdir(sp->dir);
 309                 if (entry == NULL) {
 310                         free_procps_scan(sp);
 311                         return NULL;
 312                 }
 313  IF_FEATURE_SHOW_THREADS(got_entry:)
 314                 pid = bb_strtou(entry->d_name, NULL, 10);
 315                 if (errno)
 316                         continue;
 317 #if ENABLE_FEATURE_SHOW_THREADS
 318                 if ((flags & PSSCAN_TASKS) && !sp->task_dir) {
 319                         /* We found another /proc/PID. Do not use it,
 320                          * there will be /proc/PID/task/PID (same PID!),
 321                          * so just go ahead and dive into /proc/PID/task. */
 322                         sprintf(filename, "/proc/%u/task", pid);
 323                         /* Note: if opendir fails, we just go to next /proc/XXX */
 324                         sp->task_dir = opendir(filename);
 325                         sp->main_thread_pid = pid;
 326                         continue;
 327                 }
 328 #endif
 329
 330                 /* After this point we can:
 331                  * "break": stop parsing, return the data
 332                  * "continue": try next /proc/XXX
 333                  */
 334
 335                 memset(&sp->vsz, 0, sizeof(*sp) - offsetof(procps_status_t, vsz));
 336
 337                 sp->pid = pid;
 338                 if (!(flags & ~PSSCAN_PID))
 339                         break; /* we needed only pid, we got it */
 340
 341 #if ENABLE_SELINUX
 342                 if (flags & PSSCAN_CONTEXT) {
 343                         if (getpidcon(sp->pid, &sp->context) < 0)
 344                                 sp->context = NULL;
 345                 }
 346 #endif
 347
 348 #if ENABLE_FEATURE_SHOW_THREADS
 349                 if (sp->task_dir)
 350                         filename_tail = filename + sprintf(filename, "/proc/%u/task/%u/", sp->main_thread_pid, pid);
 351                 else
 352 #endif
 353                         filename_tail = filename + sprintf(filename, "/proc/%u/", pid);
 354
 355                 if (flags & PSSCAN_UIDGID) {
 356                         struct stat sb;
 357                         if (stat(filename, &sb))
 358                                 continue; /* process probably exited */
 359                         /* Effective UID/GID, not real */
 360                         sp->uid = sb.st_uid;
 361                         sp->gid = sb.st_gid;
 362                 }
 363
 364                 /* These are all retrieved from proc/NN/stat in one go: */
 365                 if (flags & (PSSCAN_PPID | PSSCAN_PGID | PSSCAN_SID
 366                         | PSSCAN_COMM | PSSCAN_STATE
 367                         | PSSCAN_VSZ | PSSCAN_RSS
 368                         | PSSCAN_STIME | PSSCAN_UTIME | PSSCAN_START_TIME
 369                         | PSSCAN_TTY | PSSCAN_NICE
 370                         | PSSCAN_CPU)
 371                 ) {
 372                         int s_idx;
 373                         char *cp, *comm1;
 374                         int tty;
 375 #if !ENABLE_FEATURE_FAST_TOP
 376                         unsigned long vsz, rss;
 377 #endif
 378                         /* see proc(5) for some details on this */
 379                         strcpy(filename_tail, "stat");
 380                         n = read_to_buf(filename, buf);
 381                         if (n < 0)
 382                                 continue; /* process probably exited */
 383                         cp = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
 384                         /*if (!cp || cp[1] != ' ')
 385                                 continue;*/
 386                         cp[0] = '\0';
 387                         BUILD_BUG_ON(sizeof(sp->comm) < 16);
 388                         comm1 = strchr(buf, '(');
 389                         /*if (comm1)*/
 390                                 safe_strncpy(sp->comm, comm1 + 1, sizeof(sp->comm));
 391
 392 #if !ENABLE_FEATURE_FAST_TOP
 393                         n = sscanf(cp+2,
 394                                 "%c %u "               /* state, ppid */
 395                                 "%u %u %d %*s "        /* pgid, sid, tty, tpgid */
 396                                 "%*s %*s %*s %*s %*s " /* flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
 397                                 "%lu %lu "             /* utime, stime */
 398                                 "%*s %*s %*s "         /* cutime, cstime, priority */
 399                                 "%ld "                 /* nice */
 400                                 "%*s %*s "             /* timeout, it_real_value */
 401                                 "%lu "                 /* start_time */
 402                                 "%lu "                 /* vsize */
 403                                 "%lu "                 /* rss */
 404 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 405                                 "%*s %*s %*s %*s %*s %*s " /*rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
 406                                 "%*s %*s %*s %*s "         /*signal, blocked, sigignore, sigcatch */
 407                                 "%*s %*s %*s %*s "         /*wchan, nswap, cnswap, exit_signal */
 408                                 "%d"                       /*cpu last seen on*/
 409 # endif
 410                                 ,
 411                                 sp->state, &sp->ppid,
 412                                 &sp->pgid, &sp->sid, &tty,
 413                                 &sp->utime, &sp->stime,
 414                                 &tasknice,
 415                                 &sp->start_time,
 416                                 &vsz,
 417                                 &rss
 418 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 419                                 , &sp->last_seen_on_cpu
 420 # endif
 421                                 );
 422
 423                         if (n < 11)
 424                                 continue; /* bogus data, get next /proc/XXX */
 425 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 426                         if (n == 11)
 427                                 sp->last_seen_on_cpu = 0;
 428 # endif
 429
 430                         /* vsz is in bytes and we want kb */
 431                         sp->vsz = vsz >> 10;
 432                         /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
 433                         sp->rss = rss << sp->shift_pages_to_kb;
 434                         sp->tty_major = (tty >> 8) & 0xfff;
 435                         sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
 436 #else
 437 /* This costs ~100 bytes more but makes top faster by 20%
 438  * If you run 10000 processes, this may be important for you */
 439                         sp->state[0] = cp[2];
 440                         cp += 4;
 441                         sp->ppid = fast_strtoul_10(&cp);
 442                         sp->pgid = fast_strtoul_10(&cp);
 443                         sp->sid = fast_strtoul_10(&cp);
 444                         tty = fast_strtoul_10(&cp);
 445                         sp->tty_major = (tty >> 8) & 0xfff;
 446                         sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
 447                         cp = skip_fields(cp, 6); /* tpgid, flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
 448                         sp->utime = fast_strtoul_10(&cp);
 449                         sp->stime = fast_strtoul_10(&cp);
 450                         cp = skip_fields(cp, 3); /* cutime, cstime, priority */
 451                         tasknice = fast_strtol_10(&cp);
 452                         cp = skip_fields(cp, 2); /* timeout, it_real_value */
 453                         sp->start_time = fast_strtoul_10(&cp);
 454                         /* vsz is in bytes and we want kb */
 455                         sp->vsz = fast_strtoul_10(&cp) >> 10;
 456                         /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
 457                         sp->rss = fast_strtoul_10(&cp) << sp->shift_pages_to_kb;
 458 # if ENABLE_FEATURE_TOP_SMP_PROCESS
 459                         /* (6): rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
 460                         /* (4): signal, blocked, sigignore, sigcatch */
 461                         /* (4): wchan, nswap, cnswap, exit_signal */
 462                         cp = skip_fields(cp, 14);
 463 //FIXME: is it safe to assume this field exists?
 464                         sp->last_seen_on_cpu = fast_strtoul_10(&cp);
 465 # endif
 466 #endif /* FEATURE_FAST_TOP */
 467
 468 #if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
 469                         sp->niceness = tasknice;
 470 #endif
 471                         sp->state[1] = ' ';
 472                         sp->state[2] = ' ';
 473                         s_idx = 1;
 474                         if (sp->vsz == 0 && sp->state[0] != 'Z') {
 475                                 /* not sure what the purpose of this flag */
 476                                 sp->state[1] = 'W';
 477                                 s_idx = 2;
 478                         }
 479                         if (tasknice != 0) {
 480                                 if (tasknice < 0)
 481                                         sp->state[s_idx] = '<';
 482                                 else /* > 0 */
 483                                         sp->state[s_idx] = 'N';
 484                         }
 485                 }
 486
 487 #if ENABLE_FEATURE_TOPMEM
 488                 if (flags & PSSCAN_SMAPS)
 489                         procps_read_smaps(pid, &sp->smaps, NULL, NULL);
 490 #endif /* TOPMEM */
 491 #if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
 492                 if (flags & PSSCAN_RUIDGID) {
 493                         FILE *file;
 494
 495                         strcpy(filename_tail, "status");
 496                         file = fopen_for_read(filename);
 497                         if (file) {
 498                                 while (fgets(buf, sizeof(buf), file)) {
 499                                         char *tp;
 500 #define SCAN_TWO(str, name, statement) \
 501         if ((tp = is_prefixed_with(buf, str)) != NULL) { \
 502                 tp = skip_whitespace(tp); \
 503                 sscanf(tp, "%u", &sp->name); \
 504                 statement; \
 505         }
 506                                         SCAN_TWO("Uid:", ruid, continue);
 507                                         SCAN_TWO("Gid:", rgid, break);
 508 #undef SCAN_TWO
 509                                 }
 510                                 fclose(file);
 511                         }
 512                 }
 513 #endif /* PS_ADDITIONAL_COLUMNS */
 514                 if (flags & PSSCAN_EXE) {
 515                         strcpy(filename_tail, "exe");
 516                         free(sp->exe);
 517                         sp->exe = xmalloc_readlink(filename);
 518                 }
 519                 /* Note: if /proc/PID/cmdline is empty,
 520                  * code below "breaks". Therefore it must be
 521                  * the last code to parse /proc/PID/xxx data
 522                  * (we used to have /proc/PID/exe parsing after it
 523                  * and were getting stale sp->exe).
 524                  */
 525 #if 0 /* PSSCAN_CMD is not used */
 526                 if (flags & (PSSCAN_CMD|PSSCAN_ARGV0)) {
 527                         free(sp->argv0);
 528                         sp->argv0 = NULL;
 529                         free(sp->cmd);
 530                         sp->cmd = NULL;
 531                         strcpy(filename_tail, "cmdline");
 532                         /* TODO: to get rid of size limits, read into malloc buf,
 533                          * then realloc it down to real size. */
 534                         n = read_to_buf(filename, buf);
 535                         if (n <= 0)
 536                                 break;
 537                         if (flags & PSSCAN_ARGV0)
 538                                 sp->argv0 = xstrdup(buf);
 539                         if (flags & PSSCAN_CMD) {
 540                                 do {
 541                                         n--;
 542                                         if ((unsigned char)(buf[n]) < ' ')
 543                                                 buf[n] = ' ';
 544                                 } while (n);
 545                                 sp->cmd = xstrdup(buf);
 546                         }
 547                 }
 548 #else
 549                 if (flags & (PSSCAN_ARGV0|PSSCAN_ARGVN)) {
 550                         free(sp->argv0);
 551                         sp->argv0 = NULL;
 552                         strcpy(filename_tail, "cmdline");
 553                         n = read_to_buf(filename, buf);
 554                         if (n <= 0)
 555                                 break;
 556                         if (flags & PSSCAN_ARGVN) {
 557                                 sp->argv_len = n;
 558                                 sp->argv0 = xmemdup(buf, n + 1);
 559                                 /* sp->argv0[n] = '\0'; - buf has it */
 560                         } else {
 561                                 sp->argv_len = 0;
 562                                 sp->argv0 = xstrdup(buf);
 563                         }
 564                 }
 565 #endif
 566                 break;
 567         } /* for (;;) */
 568
 569         return sp;
 570 }
 571
 572 void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
 573 {
 574         int sz;
 575         char filename[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
 576
 577         sprintf(filename, "/proc/%u/cmdline", pid);
 578         sz = open_read_close(filename, buf, col - 1);
 579         if (sz > 0) {
 580                 const char *base;
 581                 int comm_len;
 582
 583                 buf[sz] = '\0';
 584                 while (--sz >= 0 && buf[sz] == '\0')
 585                         continue;
 586                 /* Prevent basename("process foo/bar") = "bar" */
 587                 strchrnul(buf, ' ')[0] = '\0';
 588                 base = bb_basename(buf); /* before we replace argv0's NUL with space */
 589                 while (sz >= 0) {
 590                         if ((unsigned char)(buf[sz]) < ' ')
 591                                 buf[sz] = ' ';
 592                         sz--;
 593                 }
 594                 if (base[0] == '-') /* "-sh" (login shell)? */
 595                         base++;
 596
 597                 /* If comm differs from argv0, prepend "{comm} ".
 598                  * It allows to see thread names set by prctl(PR_SET_NAME).
 599                  */
 600                 if (!comm)
 601                         return;
 602                 comm_len = strlen(comm);
 603                 /* Why compare up to comm_len, not COMM_LEN-1?
 604                  * Well, some processes rewrite argv, and use _spaces_ there
 605                  * while rewriting. (KDE is observed to do it).
 606                  * I prefer to still treat argv0 "process foo bar"
 607                  * as 'equal' to comm "process".
 608                  */
 609                 if (strncmp(base, comm, comm_len) != 0) {
 610                         comm_len += 3;
 611                         if (col > comm_len)
 612                                 memmove(buf + comm_len, buf, col - comm_len);
 613                         snprintf(buf, col, "{%s}", comm);
 614                         if (col <= comm_len)
 615                                 return;
 616                         buf[comm_len - 1] = ' ';
 617                         buf[col - 1] = '\0';
 618                 }
 619         } else {
 620                 snprintf(buf, col, "[%s]", comm ? comm : "?");
 621         }
 622 }
 623
 624 /* from kernel:
 625         //             pid comm S ppid pgid sid tty_nr tty_pgrp flg
 626         sprintf(buffer,"%d (%s) %c %d  %d   %d  %d     %d       %lu %lu \
 627 %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
 628 %lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu %llu\n",
 629                 task->pid,
 630                 tcomm,
 631                 state,
 632                 ppid,
 633                 pgid,
 634                 sid,
 635                 tty_nr,
 636                 tty_pgrp,
 637                 task->flags,
 638                 min_flt,
 639                 cmin_flt,
 640                 maj_flt,
 641                 cmaj_flt,
 642                 cputime_to_clock_t(utime),
 643                 cputime_to_clock_t(stime),
 644                 cputime_to_clock_t(cutime),
 645                 cputime_to_clock_t(cstime),
 646                 priority,
 647                 nice,
 648                 num_threads,
 649                 // 0,
 650                 start_time,
 651                 vsize,
 652                 mm ? get_mm_rss(mm) : 0,
 653                 rsslim,
 654                 mm ? mm->start_code : 0,
 655                 mm ? mm->end_code : 0,
 656                 mm ? mm->start_stack : 0,
 657                 esp,
 658                 eip,
 659 the rest is some obsolete cruft
 660 */