Replace popen() with fork() to kill after timeout

1 files changed, 33 insertions, 7 deletions

diff --git a/wmsl.c b/wmsl.c
index 631044c..88c2fb5 100644
--- a/wmsl.c
+++ b/wmsl.c
@@ -1,6 +1,7 @@
 #include <X11/Xlib.h>
 
 #include <unistd.h>
+#include <err.h>
 #include <signal.h>
 #include <time.h>
 #include <math.h>
@@ -92,6 +93,31 @@ concat_status(const char *text, size_t len)
 	status_text[status_len] = '\0';
 }
 
+int
+run_block(const char *cmd, pid_t *pid)
+{
+	int input[2];
+
+	if (pipe(input) == -1)
+		err(EXIT_FAILURE, "pipe");
+
+	*pid = fork();
+	if (*pid < 0) err(EXIT_FAILURE, "fork");
+
+	if (*pid != 0) {
+		close(input[0]);
+	} else {
+		dup2(input[0], 0);
+		close(input[0]);
+		close(input[1]);
+		close(0);
+		close(1);
+		exit(system(cmd));
+	}
+
+	return input[1];
+}
+
 bool
 read_statusline(int fd, char *buf, size_t size)
 {
@@ -122,9 +148,9 @@ read_statusline(int fd, char *buf, size_t size)
 void
 update_blocks(void)
 {
-	FILE *cmd;
-	int i, output_len, update;
+	int i, fd, output_len, update;
 	char tmp_output[OUTPUTMAX];
+	pid_t child;
 
 	debug("checking block output..\n");
 
@@ -139,17 +165,14 @@ update_blocks(void)
 			blocks[i].flags = IDLE;
 
 			/* get command output */
-			cmd = popen(blocks[i].command, "r");
-			if (!cmd) continue;
+			fd = run_block(blocks[i].command, &child);
 
-			if (!read_statusline(fileno(cmd), tmp_output, OUTPUTMAX)) {
+			if (!read_statusline(fd, tmp_output, OUTPUTMAX)) {
 				output_len = 0;
 			} else {
 				output_len = strlen(tmp_output);
 			}
 
-			pclose(cmd);
-
 			if (output_len != strlen(blocks[i].output)
 					|| strncmp(tmp_output, blocks[i].output, output_len)) {
 				memcpy(blocks[i].output, tmp_output, output_len);
@@ -157,6 +180,9 @@ update_blocks(void)
 				debug("new output from cmd: %s\n", blocks[i].command);
 				update = 1;
 			}
+
+			kill(child, SIGKILL);
+			close(fd);
 		} else {
 			output_len = strlen(blocks[i].output);
 		}