make find_pid_by_name look at /proc/PID/exe too

function                                             old     new   delta
procps_scan                                         1642    1709     +67
find_pid_by_name                                     193     223     +30
free_procps_scan                                      29      37      +8

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 27 insertions, 16 deletions

diff --git a/include/libbb.h b/include/libbb.h
index c7b4de13c..51ac69ed5 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1280,6 +1280,7 @@ typedef struct procps_status_t {
 /* Fields are set to 0/NULL if failed to determine (or not requested) */
 	uint16_t argv_len;
 	char *argv0;
+	char *exe;
 	IF_SELINUX(char *context;)
 	/* Everything below must contain no ptrs to malloc'ed data:
 	 * it is memset(0) for each process in procps_scan() */
@@ -1327,7 +1328,7 @@ enum {
 	PSSCAN_COMM     = 1 << 5,
 	/* PSSCAN_CMD      = 1 << 6, - use read_cmdline instead */
 	PSSCAN_ARGV0    = 1 << 7,
-	/* PSSCAN_EXE      = 1 << 8, - not implemented */
+	PSSCAN_EXE      = 1 << 8,
 	PSSCAN_STATE    = 1 << 9,
 	PSSCAN_VSZ      = 1 << 10,
 	PSSCAN_RSS      = 1 << 11,
diff --git a/libbb/find_pid_by_name.c b/libbb/find_pid_by_name.c
index 600d4e1a8..52a0c6dab 100644
--- a/libbb/find_pid_by_name.c
+++ b/libbb/find_pid_by_name.c
@@ -41,18 +41,20 @@ and therefore comm field contains "exe".
 static int comm_match(procps_status_t *p, const char *procName)
 {
 	int argv1idx;
+	const char *argv1;
 
-	/* comm does not match */
 	if (strncmp(p->comm, procName, 15) != 0)
-		return 0;
+		return 0; /* comm does not match */
 
-	/* in Linux, if comm is 15 chars, it may be a truncated */
-	if (p->comm[14] == '\0') /* comm is not truncated - match */
-		return 1;
+	/* In Linux, if comm is 15 chars, it is truncated.
+	 * (or maybe the name was exactly 15 chars, but there is
+	 * no way to know that) */
+	if (p->comm[14] == '\0')
+		return 1; /* comm is not truncated - matches */
 
 	/* comm is truncated, but first 15 chars match.
 	 * This can be crazily_long_script_name.sh!
-	 * The telltale sign is basename(argv[1]) == procName. */
+	 * The telltale sign is basename(argv[1]) == procName */
 
 	if (!p->argv0)
 		return 0;
@@ -60,8 +62,9 @@ static int comm_match(procps_status_t *p, const char *procName)
 	argv1idx = strlen(p->argv0) + 1;
 	if (argv1idx >= p->argv_len)
 		return 0;
+	argv1 = p->argv0 + argv1idx;
 
-	if (strcmp(bb_basename(p->argv0 + argv1idx), procName) != 0)
+	if (strcmp(bb_basename(argv1), procName) != 0)
 		return 0;
 
 	return 1;
@@ -83,11 +86,12 @@ pid_t* FAST_FUNC find_pid_by_name(const char *procName)
 	procps_status_t* p = NULL;
 
 	pidList = xzalloc(sizeof(*pidList));
-	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGVN))) {
+	while ((p = procps_scan(p, PSSCAN_PID|PSSCAN_COMM|PSSCAN_ARGVN|PSSCAN_EXE))) {
 		if (comm_match(p, procName)
 		/* or we require argv0 to match (essential for matching reexeced /proc/self/exe)*/
 		 || (p->argv0 && strcmp(bb_basename(p->argv0), procName) == 0)
-		/* TODO: we can also try /proc/NUM/exe link, do we want that? */
+		/* or we require /proc/PID/exe link to match */
+		 || (p->exe && strcmp(bb_basename(p->exe), procName) == 0)
 		) {
 			pidList = xrealloc_vector(pidList, 2, i);
 			pidList[i++] = p->pid;
diff --git a/libbb/procps.c b/libbb/procps.c
index 6e122c4d5..307d8d622 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -111,6 +111,7 @@ void FAST_FUNC free_procps_scan(procps_status_t* sp)
 {
 	closedir(sp->dir);
 	free(sp->argv0);
+	free(sp->exe);
 	IF_SELINUX(free(sp->context);)
 	free(sp);
 }
@@ -213,7 +214,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 		}
 #endif
 
-		filename_tail = filename + sprintf(filename, "/proc/%d", pid);
+		filename_tail = filename + sprintf(filename, "/proc/%u/", pid);
 
 		if (flags & PSSCAN_UIDGID) {
 			if (stat(filename, &sb))
@@ -230,7 +231,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 			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;
@@ -340,7 +341,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 		if (flags & (PSSCAN_SMAPS)) {
 			FILE *file;
 
-			strcpy(filename_tail, "/smaps");
+			strcpy(filename_tail, "smaps");
 			file = fopen_for_read(filename);
 			if (!file)
 				break;
@@ -390,7 +391,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 		if (flags & PSSCAN_RUIDGID) {
 			FILE *file;
 
-			strcpy(filename_tail, "/status");
+			strcpy(filename_tail, "status");
 			file = fopen_for_read(filename);
 			if (!file)
 				break;
@@ -415,7 +416,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 			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);
@@ -436,7 +437,7 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 		if (flags & (PSSCAN_ARGV0|PSSCAN_ARGVN)) {
 			free(sp->argv0);
 			sp->argv0 = NULL;
-			strcpy(filename_tail, "/cmdline");
+			strcpy(filename_tail, "cmdline");
 			n = read_to_buf(filename, buf);
 			if (n <= 0)
 				break;
@@ -451,6 +452,11 @@ procps_status_t* FAST_FUNC procps_scan(procps_status_t* sp, int flags)
 			}
 		}
 #endif
+		if (flags & PSSCAN_EXE) {
+			strcpy(filename_tail, "exe");
+			free(sp->exe);
+			sp->exe = xmalloc_readlink(filename);
+		}
 		break;
 	}
 	return sp;