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[PATCH] Avoid busy loop in wordexp when substituted command closedits stdout
- From: Andreas Schwab <schwab at suse dot de>
- To: libc-alpha at sourceware dot org
- Date: Mon, 21 Jan 2013 11:05:24 +0100
- Subject: [PATCH] Avoid busy loop in wordexp when substituted command closedits stdout
Once we receive EOF from the command no further output is expected, so
just block until the process dies instead of busy looping.
Andreas.
[BZ #15020]
* posix/wordexp.c (exec_comm): Avoid busy loop when command has
closed its stdout.
diff --git a/NEWS b/NEWS
index cf6191b..abbbbae 100644
--- a/NEWS
+++ b/NEWS
@@ -10,7 +10,7 @@ Version 2.18
* The following bugs are resolved with this release:
13951, 14200, 14317, 14327, 14496, 14964, 14981, 14982, 14985, 14994,
- 14996, 15003, 15023.
+ 14996, 15003, 15020, 15023.
Version 2.17
diff --git a/posix/wordexp.c b/posix/wordexp.c
index bf49baa..96ce8a4 100644
--- a/posix/wordexp.c
+++ b/posix/wordexp.c
@@ -953,7 +953,12 @@ exec_comm (char *comm, char **word, size_t *word_length, size_t *max_length,
if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
bufsize))) < 1)
{
- if (TEMP_FAILURE_RETRY (__waitpid (pid, &status, WNOHANG)) == 0)
+ /* If read returned 0 then the process has closed its
+ stdout. Don't use WNOHANG in that case to avoid busy
+ looping until the process eventually exits. */
+ if (TEMP_FAILURE_RETRY (__waitpid (pid, &status,
+ buflen == 0 ? 0 : WNOHANG))
+ == 0)
continue;
if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
bufsize))) < 1)
@@ -983,7 +988,12 @@ exec_comm (char *comm, char **word, size_t *word_length, size_t *max_length,
if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
bufsize))) < 1)
{
- if (TEMP_FAILURE_RETRY (__waitpid (pid, &status, WNOHANG)) == 0)
+ /* If read returned 0 then the process has closed its
+ stdout. Don't use WNOHANG in that case to avoid busy
+ looping until the process eventually exits. */
+ if (TEMP_FAILURE_RETRY (__waitpid (pid, &status,
+ buflen == 0 ? 0 : WNOHANG))
+ == 0)
continue;
if ((buflen = TEMP_FAILURE_RETRY (__read (fildes[0], buffer,
bufsize))) < 1)
--
1.8.1
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."