killall, pidof: use argv0 for process matching too

top: show cmdline, not comm field
(fixes problems with re-execed applets showing as processes with name "exe",
and not being found by pidof/killall by applet name)

function                                             old     new   delta
find_pid_by_name                                      98     156     +58
procps_scan                                          692     732     +40
top_main                                            2724    2762     +38
find_pair                                            164     180     +16
collect_int                                          114     123      +9
cmp_main                                             547     555      +8
collect_fork                                         112     119      +7
collect_ctx                                          112     119      +7
read_package_field                                   253     257      +4
passwd_main                                         1983    1985      +2
process_stdin                                        435     433      -2
xstrtoul_range_sfx                                   229     226      -3
get_next_block                                      1852    1849      -3
arith                                               2042    2033      -9
sv_main                                             1236    1226     -10
singlemount                                         4690    4672     -18
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 10/6 up/down: 189/-45)          Total: 144 bytes
   text    data     bss     dec     hex filename
 734789    3028   14400  752217   b7a59 busybox_old
 734933    3028   14400  752361   b7ae9 busybox_unstripped

include/libbb.h

@@ -836,6 +836,8 @@ typedef struct {
 	DIR *dir;
 /* Fields are set to 0/NULL if failed to determine (or not requested) */
 	char *cmd;
+	char *argv0;
+	/*char *exe;*/
 	USE_SELINUX(char *context;)
 	/* Everything below must contain no ptrs to malloc'ed data:
 	 * it is memset(0) for each process in procps_scan() */
@@ -861,13 +863,15 @@ enum {
 	PSSCAN_UIDGID   = 1 << 4,
 	PSSCAN_COMM     = 1 << 5,
 	PSSCAN_CMD      = 1 << 6,
-	PSSCAN_STATE    = 1 << 7,
+	PSSCAN_ARGV0    = 1 << 7,
-	PSSCAN_VSZ      = 1 << 8,
+	PSSCAN_EXE      = 1 << 8, /* not implemented yet */
-	PSSCAN_RSS      = 1 << 9,
+	PSSCAN_STATE    = 1 << 9,
-	PSSCAN_STIME    = 1 << 10,
+	PSSCAN_VSZ      = 1 << 10,
-	PSSCAN_UTIME    = 1 << 11,
+	PSSCAN_RSS      = 1 << 11,
-	PSSCAN_TTY      = 1 << 12,
+	PSSCAN_STIME    = 1 << 12,
-	USE_SELINUX(PSSCAN_CONTEXT  = 1 << 13,)
+	PSSCAN_UTIME    = 1 << 13,
+	PSSCAN_TTY      = 1 << 14,
+	USE_SELINUX(PSSCAN_CONTEXT  = 1 << 15,)
 	/* These are all retrieved from proc/NN/stat in one go: */
 	PSSCAN_STAT     = PSSCAN_PPID | PSSCAN_PGID | PSSCAN_SID
 	                | PSSCAN_COMM | PSSCAN_STATE

libbb/find_pid_by_name.c

@@ -38,6 +38,14 @@ execXXX("/proc/self/exe", applet_name, params....)
 and therefore comm field contains "exe".
 */
 
+static const char *bb_basename(const char *name)
+{
+	const char *cp = strrchr(name, '/');
+	if (cp)
+		return cp + 1;
+	return name;
+}
+
 /* find_pid_by_name()
  *
  *  Modified by Vladimir Oleynik for use with libbb/procps.c
@@ -55,8 +63,16 @@ pid_t* find_pid_by_name(const char* procName)
 	procps_status_t* p = NULL;
 
 	pidList = xmalloc(sizeof(*pidList));
-	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM))) {
+	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGV0))) {
-		if (strncmp(p->comm, procName, sizeof(p->comm)-1) == 0) {
+		if (
+		/* we require comm to match and to not be truncated */
+		/* in Linux, if comm is 15 chars, it may be a truncated
+		 * name, so we don't allow that to match */
+		    (!p->comm[sizeof(p->comm)-2] && strcmp(p->comm, procName) == 0)
+		/* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
+		 || (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
+		/* TOOD: we can also try exe, do we want that? */
+		) {
 			pidList = xrealloc(pidList, sizeof(*pidList) * (i+2));
 			pidList[i++] = p->pid;
 		}

libbb/procps.c

@@ -266,18 +266,24 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags)
 
 		}
 
-		if (flags & PSSCAN_CMD) {
+		if (flags & (PSSCAN_CMD|PSSCAN_ARGV0)) {
+			if (sp->argv0) {
+				free(sp->argv0);
+				sp->argv0 = NULL;
+			}
+			if (sp->cmd) {
 				free(sp->cmd);
 				sp->cmd = NULL;
+			}
 			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 (buf[n-1] == '\n') {
+			if (flags & PSSCAN_ARGV0)
-				if (!--n)
+				sp->argv0 = xstrdup(buf);
-					break;
+			if (flags & PSSCAN_CMD) {
-				buf[n] = '\0';
-			}
 				do {
 					n--;
 					if ((unsigned char)(buf[n]) < ' ')
@@ -285,6 +291,7 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags)
 				} while (n);
 				sp->cmd = xstrdup(buf);
 			}
+		}
 		break;
 	}
 	return sp;

procps/top.c

@@ -40,7 +40,8 @@ typedef struct top_status_t {
 	unsigned pid, ppid;
 	unsigned uid;
 	char state[4];
-	char comm[COMM_LEN];
+/* TODO: read /proc/$PID/cmdline only for processes which are displayed */
+	char cmd[64];
 } top_status_t;
 
 typedef struct jiffy_counts_t{
@@ -444,7 +445,7 @@ static void display_status(int count, int scr_width)
 #endif
 		);
 		if (col > 0)
-			printf("%.*s", col, s->comm);
+			printf("%.*s", col, s->cmd);
 		/* printf(" %d/%d %lld/%lld", s->pcpu, total_pcpu,
 			jif.busy - prev_jif.busy, jif.total - prev_jif.total); */
 		s++;
@@ -559,6 +560,7 @@ int top_main(int argc, char **argv)
 				| PSSCAN_UTIME
 				| PSSCAN_STATE
 				| PSSCAN_COMM
+				| PSSCAN_CMD
 				| PSSCAN_SID
 				| PSSCAN_UIDGID
 		))) {
@@ -572,7 +574,10 @@ int top_main(int argc, char **argv)
 #endif
 			top[n].uid = p->uid;
 			strcpy(top[n].state, p->state);
-			strcpy(top[n].comm, p->comm);
+			if (p->cmd)
+				safe_strncpy(top[n].cmd, p->cmd, sizeof(top[n].cmd));
+			else /* mimic ps */
+				sprintf(top[n].cmd, "[%s]", p->comm);
 		}
 		if (ntop == 0) {
 			bb_error_msg_and_die("no process info in /proc");
@@ -585,6 +590,7 @@ int top_main(int argc, char **argv)
 			continue;
 		}
 		do_stats();
+/* TODO: we don't need to sort all 10000 processes, we need to find top 24! */
 		qsort(top, ntop, sizeof(top_status_t), (void*)mult_lvl_cmp);
 #else
 		qsort(top, ntop, sizeof(top_status_t), (void*)sort_function);