pmap: fix bogus {no such process} comm field text

function                                             old     new   delta
read_cmdline                                         246     266     +20
procps_get_maps                                      196     193      -3
packed_usage                                       30413   30404      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/2 up/down: 20/-12)              Total: 8 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/libbb/procps.c b/libbb/procps.c
index 05eefe0da..4edc54d48 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -588,12 +588,14 @@ void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
                                 buf[sz] = ' ';
                         sz--;
                 }
+                if (base[0] == '-') /* "-sh" (login shell)? */
+                        base++;
 
                 /* 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++;
+                if (!comm)
+                        return;
                 comm_len = strlen(comm);
                 /* Why compare up to comm_len, not COMM_LEN-1?
                  * Well, some processes rewrite argv, and use _spaces_ there
@@ -612,7 +614,7 @@ void FAST_FUNC read_cmdline(char *buf, int col, unsigned pid, const char *comm)
                         buf[col - 1] = '\0';
                 }
         } else {
-                snprintf(buf, col, "[%s]", comm);
+                snprintf(buf, col, "[%s]", comm ? comm : "?");
         }
 }