Improve toolbox SIGPIPE behavior.

None of our tools -- except for top, which I'd fixed previously --
handles SIGPIE correctly. Let's just handle SIGPIPE in the driver.

Bug: https://code.google.com/p/android/issues/detail?id=157920
Change-Id: I322ea411f53c71585a64118c217d54389f675d4e

2 files changed, 15 insertions, 6 deletions

diff --git a/toolbox/toolbox.c b/toolbox/toolbox.c
index 0eac390e4..915da440c 100644
--- a/toolbox/toolbox.c
+++ b/toolbox/toolbox.c
@@ -1,6 +1,8 @@
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 int main(int, char **);
 
@@ -31,11 +33,24 @@ static struct
     { 0, 0 },
 };
 
+static void SIGPIPE_handler(int signal) {
+    // Those desktop Linux tools that catch SIGPIPE seem to agree that it's
+    // a successful way to exit, not a failure. (Which makes sense --- we were
+    // told to stop by a reader, rather than failing to continue ourselves.)
+    _exit(0);
+}
+
 int main(int argc, char **argv)
 {
     int i;
     char *name = argv[0];
 
+    // Let's assume that none of this code handles broken pipes. At least ls,
+    // ps, and top were broken (though I'd previously added this fix locally
+    // to top). We exit rather than use SIG_IGN because tools like top will
+    // just keep on writing to nowhere forever if we don't stop them.
+    signal(SIGPIPE, SIGPIPE_handler);
+
     if((argc > 1) && (argv[1][0] == '@')) {
         name = argv[1] + 1;
         argc--;
diff --git a/toolbox/top.c b/toolbox/top.c
index b1a275c16..1e99d4cc0 100644
--- a/toolbox/top.c
+++ b/toolbox/top.c
@@ -109,15 +109,9 @@ static int proc_thr_cmp(const void *a, const void *b);
 static int numcmp(long long a, long long b);
 static void usage(char *cmd);
 
-static void exit_top(int signal) {
-  exit(EXIT_FAILURE);
-}
-
 int top_main(int argc, char *argv[]) {
     num_used_procs = num_free_procs = 0;
 
-    signal(SIGPIPE, exit_top);
-
     max_procs = 0;
     delay = 3;
     iterations = -1;