Bump to version 1.22.1
[platform/upstream/busybox.git] / libbb / procps.c
index be0d61b..5b68d34 100644 (file)
@@ -5,20 +5,20 @@
  * Copyright 1998 by Albert Cahalan; all rights reserved.
  * Copyright (C) 2002 by Vladimir Oleynik <dzo@simtreas.ru>
  * SELinux support: (c) 2007 by Yuichi Nakamura <ynakam@hitachisoft.jp>
- * 
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
 #include "libbb.h"
 
 
-typedef struct unsigned_to_name_map_t {
-       unsigned id;
+typedef struct id_to_name_map_t {
+       uid_t id;
        char name[USERNAME_MAX_SIZE];
-} unsigned_to_name_map_t;
+} id_to_name_map_t;
 
 typedef struct cache_t {
-       unsigned_to_name_map_t *cache;
+       id_to_name_map_t *cache;
        int size;
 } cache_t;
 
@@ -30,7 +30,7 @@ static void clear_cache(cache_t *cp)
        cp->cache = NULL;
        cp->size = 0;
 }
-void clear_username_cache(void)
+void FAST_FUNC clear_username_cache(void)
 {
        clear_cache(&username);
        clear_cache(&groupname);
@@ -39,39 +39,40 @@ void clear_username_cache(void)
 #if 0 /* more generic, but we don't need that yet */
 /* Returns -N-1 if not found. */
 /* cp->cache[N] is allocated and must be filled in this case */
-static int get_cached(cache_t *cp, unsigned id)
+static int get_cached(cache_t *cp, uid_t id)
 {
        int i;
        for (i = 0; i < cp->size; i++)
                if (cp->cache[i].id == id)
                        return i;
        i = cp->size++;
-       cp->cache = xrealloc(cp->cache, cp->size * sizeof(*cp->cache));
+       cp->cache = xrealloc_vector(cp->cache, 2, i);
        cp->cache[i++].id = id;
        return -i;
 }
 #endif
 
-typedef char* ug_func(char *name, long uid, int bufsize);
-static char* get_cached(cache_t *cp, unsigned id, ug_func* fp)
+static char* get_cached(cache_t *cp, uid_t id,
+                       char* FAST_FUNC x2x_utoa(uid_t id))
 {
        int i;
        for (i = 0; i < cp->size; i++)
                if (cp->cache[i].id == id)
                        return cp->cache[i].name;
        i = cp->size++;
-       cp->cache = xrealloc(cp->cache, cp->size * sizeof(*cp->cache));
+       cp->cache = xrealloc_vector(cp->cache, 2, i);
        cp->cache[i].id = id;
-       fp(cp->cache[i].name, id, sizeof(cp->cache[i].name));
+       /* Never fails. Generates numeric string if name isn't found */
+       safe_strncpy(cp->cache[i].name, x2x_utoa(id), sizeof(cp->cache[i].name));
        return cp->cache[i].name;
 }
-const char* get_cached_username(uid_t uid)
+const char* FAST_FUNC get_cached_username(uid_t uid)
 {
-       return get_cached(&username, uid, bb_getpwuid);
+       return get_cached(&username, uid, uid2uname_utoa);
 }
-const char* get_cached_groupname(gid_t gid)
+const char* FAST_FUNC get_cached_groupname(gid_t gid)
 {
-       return get_cached(&groupname, gid, bb_getgrgid);
+       return get_cached(&groupname, gid, gid2group_utoa);
 }
 
 
@@ -79,95 +80,318 @@ const char* get_cached_groupname(gid_t gid)
 
 static int read_to_buf(const char *filename, void *buf)
 {
-       ssize_t ret;
-       ret = open_read_close(filename, buf, PROCPS_BUFSIZE-1);
+       int fd;
+       /* open_read_close() would do two reads, checking for EOF.
+        * When you have 10000 /proc/$NUM/stat to read, it isn't desirable */
+       ssize_t ret = -1;
+       fd = open(filename, O_RDONLY);
+       if (fd >= 0) {
+               ret = read(fd, buf, PROCPS_BUFSIZE-1);
+               close(fd);
+       }
        ((char *)buf)[ret > 0 ? ret : 0] = '\0';
        return ret;
 }
 
-procps_status_t* alloc_procps_scan(int flags)
+static procps_status_t* FAST_FUNC alloc_procps_scan(void)
 {
+       unsigned n = getpagesize();
        procps_status_t* sp = xzalloc(sizeof(procps_status_t));
        sp->dir = xopendir("/proc");
+       while (1) {
+               n >>= 1;
+               if (!n) break;
+               sp->shift_pages_to_bytes++;
+       }
+       sp->shift_pages_to_kb = sp->shift_pages_to_bytes - 10;
        return sp;
 }
 
-void free_procps_scan(procps_status_t* sp)
+void FAST_FUNC free_procps_scan(procps_status_t* sp)
 {
        closedir(sp->dir);
-       free(sp->cmd);
-       USE_SELINUX(free(sp->context);)
+#if ENABLE_FEATURE_SHOW_THREADS
+       if (sp->task_dir)
+               closedir(sp->task_dir);
+#endif
+       free(sp->argv0);
+       free(sp->exe);
+       IF_SELINUX(free(sp->context);)
        free(sp);
 }
 
-void BUG_comm_size(void);
-procps_status_t* procps_scan(procps_status_t* sp, int flags)
+#if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
+static unsigned long fast_strtoul_16(char **endptr)
+{
+       unsigned char c;
+       char *str = *endptr;
+       unsigned long n = 0;
+
+       /* Need to stop on both ' ' and '\n' */
+       while ((c = *str++) > ' ') {
+               c = ((c|0x20) - '0');
+               if (c > 9)
+                       /* c = c + '0' - 'a' + 10: */
+                       c = c - ('a' - '0' - 10);
+               n = n*16 + c;
+       }
+       *endptr = str; /* We skip trailing space! */
+       return n;
+}
+#endif
+
+#if ENABLE_FEATURE_FAST_TOP || ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
+/* We cut a lot of corners here for speed */
+static unsigned long fast_strtoul_10(char **endptr)
+{
+       unsigned char c;
+       char *str = *endptr;
+       unsigned long n = *str - '0';
+
+       /* Need to stop on both ' ' and '\n' */
+       while ((c = *++str) > ' ')
+               n = n*10 + (c - '0');
+
+       *endptr = str + 1; /* We skip trailing space! */
+       return n;
+}
+
+# if ENABLE_FEATURE_FAST_TOP
+static long fast_strtol_10(char **endptr)
+{
+       if (**endptr != '-')
+               return fast_strtoul_10(endptr);
+
+       (*endptr)++;
+       return - (long)fast_strtoul_10(endptr);
+}
+# endif
+
+static char *skip_fields(char *str, int count)
+{
+       do {
+               while (*str++ != ' ')
+                       continue;
+               /* we found a space char, str points after it */
+       } while (--count);
+       return str;
+}
+#endif
+
+#if ENABLE_FEATURE_TOPMEM || ENABLE_PMAP
+int FAST_FUNC procps_read_smaps(pid_t pid, struct smaprec *total,
+               void (*cb)(struct smaprec *, void *), void *data)
 {
-       struct dirent *entry;
+       FILE *file;
+       struct smaprec currec;
+       char filename[sizeof("/proc/%u/smaps") + sizeof(int)*3];
        char buf[PROCPS_BUFSIZE];
-       char filename[sizeof("/proc//cmdline") + sizeof(int)*3];
-       char *filename_tail;
-       long tasknice;
-       unsigned pid;
-       int n;
-       struct stat sb;
+#if !ENABLE_PMAP
+       void (*cb)(struct smaprec *, void *) = NULL;
+       void *data = NULL;
+#endif
+
+       sprintf(filename, "/proc/%u/smaps", (int)pid);
+
+       file = fopen_for_read(filename);
+       if (!file)
+               return 1;
+
+       memset(&currec, 0, sizeof(currec));
+       while (fgets(buf, PROCPS_BUFSIZE, file)) {
+               // Each mapping datum has this form:
+               // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
+               // Size:                nnn kB
+               // Rss:                 nnn kB
+               // .....
+
+               char *tp = buf, *p;
+
+#define SCAN(S, X) \
+               if (strncmp(tp, S, sizeof(S)-1) == 0) {              \
+                       tp = skip_whitespace(tp + sizeof(S)-1);      \
+                       total->X += currec.X = fast_strtoul_10(&tp); \
+                       continue;                                    \
+               }
+               if (cb) {
+                       SCAN("Pss:"  , smap_pss     );
+                       SCAN("Swap:" , smap_swap    );
+               }
+               SCAN("Private_Dirty:", private_dirty);
+               SCAN("Private_Clean:", private_clean);
+               SCAN("Shared_Dirty:" , shared_dirty );
+               SCAN("Shared_Clean:" , shared_clean );
+#undef SCAN
+               tp = strchr(buf, '-');
+               if (tp) {
+                       // We reached next mapping - the line of this form:
+                       // f7d29000-f7d39000 rw-s FILEOFS M:m INODE FILENAME
+
+                       if (cb) {
+                               /* If we have a previous record, there's nothing more
+                                * for it, call the callback and clear currec
+                                */
+                               if (currec.smap_size)
+                                       cb(&currec, data);
+                               free(currec.smap_name);
+                       }
+                       memset(&currec, 0, sizeof(currec));
+
+                       *tp = ' ';
+                       tp = buf;
+                       currec.smap_start = fast_strtoul_16(&tp);
+                       currec.smap_size = (fast_strtoul_16(&tp) - currec.smap_start) >> 10;
+
+                       strncpy(currec.smap_mode, tp, sizeof(currec.smap_mode)-1);
 
+                       // skipping "rw-s FILEOFS M:m INODE "
+                       tp = skip_whitespace(skip_fields(tp, 4));
+                       // filter out /dev/something (something != zero)
+                       if (strncmp(tp, "/dev/", 5) != 0 || strcmp(tp, "/dev/zero\n") == 0) {
+                               if (currec.smap_mode[1] == 'w') {
+                                       currec.mapped_rw = currec.smap_size;
+                                       total->mapped_rw += currec.smap_size;
+                               } else if (currec.smap_mode[1] == '-') {
+                                       currec.mapped_ro = currec.smap_size;
+                                       total->mapped_ro += currec.smap_size;
+                               }
+                       }
+
+                       if (strcmp(tp, "[stack]\n") == 0)
+                               total->stack += currec.smap_size;
+                       if (cb) {
+                               p = skip_non_whitespace(tp);
+                               if (p == tp) {
+                                       currec.smap_name = xstrdup("  [ anon ]");
+                               } else {
+                                       *p = '\0';
+                                       currec.smap_name = xstrdup(tp);
+                               }
+                       }
+                       total->smap_size += currec.smap_size;
+               }
+       }
+       fclose(file);
+
+       if (cb) {
+               if (currec.smap_size)
+                       cb(&currec, data);
+               free(currec.smap_name);
+       }
+
+       return 0;
+}
+#endif
+
+void BUG_comm_size(void);
+procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
+{
        if (!sp)
-               sp = alloc_procps_scan(flags);
+               sp = alloc_procps_scan();
 
        for (;;) {
+               struct dirent *entry;
+               char buf[PROCPS_BUFSIZE];
+               long tasknice;
+               unsigned pid;
+               int n;
+               char filename[sizeof("/proc/%u/task/%u/cmdline") + sizeof(int)*3 * 2];
+               char *filename_tail;
+
+#if ENABLE_FEATURE_SHOW_THREADS
+               if (sp->task_dir) {
+                       entry = readdir(sp->task_dir);
+                       if (entry)
+                               goto got_entry;
+                       closedir(sp->task_dir);
+                       sp->task_dir = NULL;
+               }
+#endif
                entry = readdir(sp->dir);
                if (entry == NULL) {
                        free_procps_scan(sp);
                        return NULL;
                }
+ IF_FEATURE_SHOW_THREADS(got_entry:)
                pid = bb_strtou(entry->d_name, NULL, 10);
                if (errno)
                        continue;
+#if ENABLE_FEATURE_SHOW_THREADS
+               if ((flags & PSSCAN_TASKS) && !sp->task_dir) {
+                       /* We found another /proc/PID. Do not use it,
+                        * there will be /proc/PID/task/PID (same PID!),
+                        * so just go ahead and dive into /proc/PID/task. */
+                       sprintf(filename, "/proc/%u/task", pid);
+                       /* Note: if opendir fails, we just go to next /proc/XXX */
+                       sp->task_dir = opendir(filename);
+                       sp->main_thread_pid = pid;
+                       continue;
+               }
+#endif
 
-               /* After this point we have to break, not continue
-                * ("continue" would mean that current /proc/NNN
-                * is not a valid process info) */
+               /* After this point we can:
+                * "break": stop parsing, return the data
+                * "continue": try next /proc/XXX
+                */
 
                memset(&sp->vsz, 0, sizeof(*sp) - offsetof(procps_status_t, vsz));
 
                sp->pid = pid;
-               if (!(flags & ~PSSCAN_PID)) break;
+               if (!(flags & ~PSSCAN_PID))
+                       break; /* we needed only pid, we got it */
 
 #if ENABLE_SELINUX
                if (flags & PSSCAN_CONTEXT) {
                        if (getpidcon(sp->pid, &sp->context) < 0)
                                sp->context = NULL;
-               }       
-#endif 
+               }
+#endif
 
-               filename_tail = filename + sprintf(filename, "/proc/%d", pid);
+#if ENABLE_FEATURE_SHOW_THREADS
+               if (sp->task_dir)
+                       filename_tail = filename + sprintf(filename, "/proc/%u/task/%u/", sp->main_thread_pid, pid);
+               else
+#endif
+                       filename_tail = filename + sprintf(filename, "/proc/%u/", pid);
 
                if (flags & PSSCAN_UIDGID) {
+                       struct stat sb;
                        if (stat(filename, &sb))
-                               break;
-                       /* Need comment - is this effective or real UID/GID? */
+                               continue; /* process probably exited */
+                       /* Effective UID/GID, not real */
                        sp->uid = sb.st_uid;
                        sp->gid = sb.st_gid;
                }
 
-               if (flags & PSSCAN_STAT) {
-                       char *cp;
-                       unsigned long vsz, rss;
+               /* These are all retrieved from proc/NN/stat in one go: */
+               if (flags & (PSSCAN_PPID | PSSCAN_PGID | PSSCAN_SID
+                       | PSSCAN_COMM | PSSCAN_STATE
+                       | PSSCAN_VSZ | PSSCAN_RSS
+                       | PSSCAN_STIME | PSSCAN_UTIME | PSSCAN_START_TIME
+                       | PSSCAN_TTY | PSSCAN_NICE
+                       | PSSCAN_CPU)
+               ) {
+                       char *cp, *comm1;
                        int tty;
-
+#if !ENABLE_FEATURE_FAST_TOP
+                       unsigned long vsz, rss;
+#endif
                        /* see proc(5) for some details on this */
-                       strcpy(filename_tail, "/stat");
+                       strcpy(filename_tail, "stat");
                        n = read_to_buf(filename, buf);
                        if (n < 0)
-                               break;
+                               continue; /* process probably exited */
                        cp = strrchr(buf, ')'); /* split into "PID (cmd" and "<rest>" */
-                       if (!cp || cp[1] != ' ')
-                               break;
+                       /*if (!cp || cp[1] != ' ')
+                               continue;*/
                        cp[0] = '\0';
                        if (sizeof(sp->comm) < 16)
                                BUG_comm_size();
-                       sscanf(buf, "%*s (%15c", sp->comm);
+                       comm1 = strchr(buf, '(');
+                       /*if (comm1)*/
+                               safe_strncpy(sp->comm, comm1 + 1, sizeof(sp->comm));
+
+#if !ENABLE_FEATURE_FAST_TOP
                        n = sscanf(cp+2,
                                "%c %u "               /* state, ppid */
                                "%u %u %d %*s "        /* pgid, sid, tty, tpgid */
@@ -175,28 +399,78 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags)
                                "%lu %lu "             /* utime, stime */
                                "%*s %*s %*s "         /* cutime, cstime, priority */
                                "%ld "                 /* nice */
-                               "%*s %*s %*s "         /* timeout, it_real_value, start_time */
+                               "%*s %*s "             /* timeout, it_real_value */
+                               "%lu "                 /* start_time */
                                "%lu "                 /* vsize */
                                "%lu "                 /* rss */
-                       /*      "%lu %lu %lu %lu %lu %lu " rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
-                       /*      "%u %u %u %u "         signal, blocked, sigignore, sigcatch */
-                       /*      "%lu %lu %lu"          wchan, nswap, cnswap */
+# if ENABLE_FEATURE_TOP_SMP_PROCESS
+                               "%*s %*s %*s %*s %*s %*s " /*rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
+                               "%*s %*s %*s %*s "         /*signal, blocked, sigignore, sigcatch */
+                               "%*s %*s %*s %*s "         /*wchan, nswap, cnswap, exit_signal */
+                               "%d"                       /*cpu last seen on*/
+# endif
                                ,
                                sp->state, &sp->ppid,
                                &sp->pgid, &sp->sid, &tty,
                                &sp->utime, &sp->stime,
                                &tasknice,
+                               &sp->start_time,
                                &vsz,
-                               &rss);
-                       if (n != 10)
-                               break;
+                               &rss
+# if ENABLE_FEATURE_TOP_SMP_PROCESS
+                               , &sp->last_seen_on_cpu
+# endif
+                               );
+
+                       if (n < 11)
+                               continue; /* bogus data, get next /proc/XXX */
+# if ENABLE_FEATURE_TOP_SMP_PROCESS
+                       if (n == 11)
+                               sp->last_seen_on_cpu = 0;
+# endif
+
+                       /* vsz is in bytes and we want kb */
+                       sp->vsz = vsz >> 10;
+                       /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
+                       sp->rss = rss << sp->shift_pages_to_kb;
+                       sp->tty_major = (tty >> 8) & 0xfff;
+                       sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
+#else
+/* This costs ~100 bytes more but makes top faster by 20%
+ * If you run 10000 processes, this may be important for you */
+                       sp->state[0] = cp[2];
+                       cp += 4;
+                       sp->ppid = fast_strtoul_10(&cp);
+                       sp->pgid = fast_strtoul_10(&cp);
+                       sp->sid = fast_strtoul_10(&cp);
+                       tty = fast_strtoul_10(&cp);
+                       sp->tty_major = (tty >> 8) & 0xfff;
+                       sp->tty_minor = (tty & 0xff) | ((tty >> 12) & 0xfff00);
+                       cp = skip_fields(cp, 6); /* tpgid, flags, min_flt, cmin_flt, maj_flt, cmaj_flt */
+                       sp->utime = fast_strtoul_10(&cp);
+                       sp->stime = fast_strtoul_10(&cp);
+                       cp = skip_fields(cp, 3); /* cutime, cstime, priority */
+                       tasknice = fast_strtol_10(&cp);
+                       cp = skip_fields(cp, 2); /* timeout, it_real_value */
+                       sp->start_time = fast_strtoul_10(&cp);
+                       /* vsz is in bytes and we want kb */
+                       sp->vsz = fast_strtoul_10(&cp) >> 10;
+                       /* vsz is in bytes but rss is in *PAGES*! Can you believe that? */
+                       sp->rss = fast_strtoul_10(&cp) << sp->shift_pages_to_kb;
+# if ENABLE_FEATURE_TOP_SMP_PROCESS
+                       /* (6): rss_rlim, start_code, end_code, start_stack, kstk_esp, kstk_eip */
+                       /* (4): signal, blocked, sigignore, sigcatch */
+                       /* (4): wchan, nswap, cnswap, exit_signal */
+                       cp = skip_fields(cp, 14);
+//FIXME: is it safe to assume this field exists?
+                       sp->last_seen_on_cpu = fast_strtoul_10(&cp);
+# endif
+#endif /* FEATURE_FAST_TOP */
+
+#if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
+                       sp->niceness = tasknice;
+#endif
 
-                       sp->tty_str[0] = '?';
-                       /* sp->tty_str[1] = '\0'; - done by memset */
-                       if (tty) /* tty field of "0" means "no tty" */
-                               snprintf(sp->tty_str, sizeof(sp->tty_str), "%u,%u",
-                                       (tty >> 8) & 0xfff, /* major */
-                                       (tty & 0xff) | ((tty >> 12) & 0xfff00));
                        if (sp->vsz == 0 && sp->state[0] != 'Z')
                                sp->state[1] = 'W';
                        else
@@ -207,34 +481,145 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags)
                                sp->state[2] = 'N';
                        else
                                sp->state[2] = ' ';
-
-                       sp->vsz = vsz >> 10; /* vsize is in bytes and we want kb */
-                       sp->rss = rss >> 10;
                }
 
-               if (flags & PSSCAN_CMD) {
+#if ENABLE_FEATURE_TOPMEM
+               if (flags & PSSCAN_SMAPS)
+                       procps_read_smaps(pid, &sp->smaps, NULL, NULL);
+#endif /* TOPMEM */
+#if ENABLE_FEATURE_PS_ADDITIONAL_COLUMNS
+               if (flags & PSSCAN_RUIDGID) {
+                       FILE *file;
+
+                       strcpy(filename_tail, "status");
+                       file = fopen_for_read(filename);
+                       if (file) {
+                               while (fgets(buf, sizeof(buf), file)) {
+                                       char *tp;
+#define SCAN_TWO(str, name, statement) \
+       if (strncmp(buf, str, sizeof(str)-1) == 0) { \
+               tp = skip_whitespace(buf + sizeof(str)-1); \
+               sscanf(tp, "%u", &sp->name); \
+               statement; \
+       }
+                                       SCAN_TWO("Uid:", ruid, continue);
+                                       SCAN_TWO("Gid:", rgid, break);
+#undef SCAN_TWO
+                               }
+                               fclose(file);
+                       }
+               }
+#endif /* PS_ADDITIONAL_COLUMNS */
+               if (flags & PSSCAN_EXE) {
+                       strcpy(filename_tail, "exe");
+                       free(sp->exe);
+                       sp->exe = xmalloc_readlink(filename);
+               }
+               /* Note: if /proc/PID/cmdline is empty,
+                * code below "breaks". Therefore it must be
+                * the last code to parse /proc/PID/xxx data
+                * (we used to have /proc/PID/exe parsing after it
+                * and were getting stale sp->exe).
+                */
+#if 0 /* PSSCAN_CMD is not used */
+               if (flags & (PSSCAN_CMD|PSSCAN_ARGV0)) {
+                       free(sp->argv0);
+                       sp->argv0 = NULL;
                        free(sp->cmd);
                        sp->cmd = NULL;
-                       strcpy(filename_tail, "/cmdline");
+                       strcpy(filename_tail, "cmdline");
+                       /* TODO: to get rid of size limits, read into malloc buf,
+                        * then realloc it down to real size. */
+                       n = read_to_buf(filename, buf);
+                       if (n <= 0)
+                               break;
+                       if (flags & PSSCAN_ARGV0)
+                               sp->argv0 = xstrdup(buf);
+                       if (flags & PSSCAN_CMD) {
+                               do {
+                                       n--;
+                                       if ((unsigned char)(buf[n]) < ' ')
+                                               buf[n] = ' ';
+                               } while (n);
+                               sp->cmd = xstrdup(buf);
+                       }
+               }
+#else
+               if (flags & (PSSCAN_ARGV0|PSSCAN_ARGVN)) {
+                       free(sp->argv0);
+                       sp->argv0 = NULL;
+                       strcpy(filename_tail, "cmdline");
                        n = read_to_buf(filename, buf);
                        if (n <= 0)
                                break;
-                       if (buf[n-1] == '\n') {
-                               if (!--n)
-                                       break;
-                               buf[n] = '\0';
+                       if (flags & PSSCAN_ARGVN) {
+                               sp->argv_len = n;
+                               sp->argv0 = xmalloc(n + 1);
+                               memcpy(sp->argv0, buf, n + 1);
+                               /* sp->argv0[n] = '\0'; - buf has it */
+                       } else {
+                               sp->argv_len = 0;
+                               sp->argv0 = xstrdup(buf);
                        }
-                       do {
-                               n--;
-                               if ((unsigned char)(buf[n]) < ' ')
-                                       buf[n] = ' ';
-                       } while (n);
-                       sp->cmd = xstrdup(buf);
                }
+#endif
                break;
-       }
+       } /* for (;;) */
+
        return sp;
 }
+
+void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
+{
+       int sz;
+       char filename[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
+
+       sprintf(filename, "/proc/%u/cmdline", pid);
+       sz = open_read_close(filename, buf, col - 1);
+       if (sz > 0) {
+               const char *base;
+               int comm_len;
+
+               buf[sz] = '\0';
+               while (--sz >= 0 && buf[sz] == '\0')
+                       continue;
+               /* Prevent basename("process foo/bar") = "bar" */
+               strchrnul(buf, ' ')[0] = '\0';
+               base = bb_basename(buf); /* before we replace argv0's NUL with space */
+               while (sz >= 0) {
+                       if ((unsigned char)(buf[sz]) < ' ')
+                               buf[sz] = ' ';
+                       sz--;
+               }
+
+               /* If comm differs from argv0, prepend "{comm} ".
+                * It allows to see thread names set by prctl(PR_SET_NAME).
+                */
+               if (base[0] == '-') /* "-sh" (login shell)? */
+                       base++;
+               comm_len = strlen(comm);
+               /* Why compare up to comm_len, not COMM_LEN-1?
+                * Well, some processes rewrite argv, and use _spaces_ there
+                * while rewriting. (KDE is observed to do it).
+                * I prefer to still treat argv0 "process foo bar"
+                * as 'equal' to comm "process".
+                */
+               if (strncmp(base, comm, comm_len) != 0) {
+                       comm_len += 3;
+                       if (col > comm_len)
+                               memmove(buf + comm_len, buf, col - comm_len);
+                       snprintf(buf, col, "{%s}", comm);
+                       if (col <= comm_len)
+                               return;
+                       buf[comm_len - 1] = ' ';
+                       buf[col - 1] = '\0';
+               }
+
+       } else {
+               snprintf(buf, col, "[%s]", comm);
+       }
+}
+
 /* from kernel:
        //             pid comm S ppid pgid sid tty_nr tty_pgrp flg
        sprintf(buffer,"%d (%s) %c %d  %d   %d  %d     %d       %lu %lu \