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

2 files changed, 40 insertions, 17 deletions

diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
index 13ccb545d..cfc5b3468 100644
--- a/libbb/find_pid_by_name.c
+++ b/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))) {
-		if (strncmp(p->comm, procName, sizeof(p->comm)-1) == 0) {
+	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGV0))) {
+		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;
 		}
diff --git a/libbb/procps.c b/libbb/procps.c
index 5924d60a8..8413ce8a1 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -92,7 +92,7 @@ static int read_to_buf(const char *filename, void *buf)
 	return ret;
 }
 
-procps_status_t* alloc_procps_scan(int flags)
+procps_status_t *alloc_procps_scan(int flags)
 {
 	procps_status_t* sp = xzalloc(sizeof(procps_status_t));
 	sp->dir = xopendir("/proc");
@@ -133,7 +133,7 @@ static char *skip_fields(char *str, int count)
 #endif
 
 void BUG_comm_size(void);
-procps_status_t* procps_scan(procps_status_t* sp, int flags)
+procps_status_t *procps_scan(procps_status_t* sp, int flags)
 {
 	struct dirent *entry;
 	char buf[PROCPS_BUFSIZE];
@@ -266,24 +266,31 @@ procps_status_t* procps_scan(procps_status_t* sp, int flags)
 
 		}
 
-		if (flags & PSSCAN_CMD) {
-			free(sp->cmd);
-			sp->cmd = NULL;
+		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 (!--n)
-					break;
-				buf[n] = '\0';
+			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);
 			}
-			do {
-				n--;
-				if ((unsigned char)(buf[n]) < ' ')
-					buf[n] = ' ';
-			} while (n);
-			sp->cmd = xstrdup(buf);
 		}
 		break;
 	}