procs-need-restart: Ignore EACCESS if not running as root

man/procs-need-restart.1.adoc

@@ -22,6 +22,7 @@ It reports processes that use (maps into memory) files that have been deleted or
 
 The command accepts one or more PID of processes to scan.
 If no positional argument is given, all processes running on the system (except kernel processes) are scanned.
+But if user`'s effective UID is not 0 (i.e. not running as root), processes the user has no permissions to examine are ignored.
 
 This program is part of *apk-autoupdate* package.
 

src/procs-need-restart.c

@@ -60,6 +60,7 @@
 #define RET_ERROR              -1
 
 #define FLAG_VERBOSE           0x0001
+#define FLAG_IGNORE_EACCES     0x0002
 
 // Length of highest pid_t (int) value encoded as a decimal number.
 #define PID_STR_MAX            10
@@ -83,7 +84,8 @@ static const char *HELP_MSG =
 	"\n"
 	"Find processes that use (maps into memory) files which have been deleted\n"
 	"or replaced on disk (and the new files are not identical to the mapped ones).\n"
-	"If no PID is specified, scan all processes.\n"
+	"If no PID is specified, scan all processes.  But if user's effective UID is\n"
+	"not 0 (i.e. not root), ignore processes we don't have permissions to examine.\n"
 	"\n"
 	"This program is part of apk-autoupdate.\n"
 	"\n"
@@ -274,6 +276,9 @@ static int proc_maps_replaced_files (pid_t pid, const char **file_patterns) {
 		if ((maps_fp = fopen(maps_path, "r")) == NULL) {
 			int fopen_err = errno;
 
+			if (fopen_err == EACCES && flags & FLAG_IGNORE_EACCES) {
+				return 1;  //  no
+			}
 			// If process does not exist anymore, then it's not an error.
 			if (proc_exists(pid) == 1) {
 				return 1;  // no
@@ -348,6 +353,9 @@ static int proc_has_replaced_exe (pid_t pid, const char **file_patterns) {
 	if (resolve_link(exe_path, link_path, sizeof(link_path)) < 0) {
 		int link_err = errno;
 
+		if (link_err == EACCES && flags & FLAG_IGNORE_EACCES) {
+			return 1;  //  no
+		}
 		// If process does not exist anymore, then it's not an error.
 		if (proc_exists(pid) == 1) {
 			return 1;  // no
@@ -489,6 +497,9 @@ int main (int argc, char **argv) {
 		return scan_procs(pids, file_patterns);
 
 	} else {
+		if (geteuid() != 0) {
+			flags |= FLAG_IGNORE_EACCES;
+		}
 		return scan_all_procs(file_patterns);
 	}
 }