Hi,
In malloc_conf_init(), readlink(2) is called in order to read
"/etc/malloc.conf". When readlink(2) fail (which is a common case, for
exemple when "/etc/malloc.conf" does not exists) errno is set. This can
lead to unexpected behaviour of malloc(), in my case malloc() set
errno=2 (ENOENT) because "/etc/malloc.conf" does not exist (see test.c
attached).
I wrote a patch that fixed the issue (against the dev branch). At first
I didn't catch the !_WIN32 condition, so review is welcome (I could not
test it under Windows). Also I thought it might be better to save &
restore errno in malloc_init(), because it could catch other function
call modifying errno. Does this make sens ?
Patch attached :)
Regards,
Alex.
>From 9cdc50b39e2b976aa25362cc3a14c6ba839631c3 Mon Sep 17 00:00:00 2001
From: Alexandre Perrin <[email protected]>
Date: Fri, 20 Sep 2013 19:58:11 +0200
Subject: [PATCH] malloc_conf_init: revert errno value when readlink(2) fail.
---
src/jemalloc.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/src/jemalloc.c b/src/jemalloc.c
index bc350ed..e3991da 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -436,8 +436,9 @@ malloc_conf_init(void)
}
break;
case 1: {
+ int linklen = 0;
#ifndef _WIN32
- int linklen;
+ int saved_errno = errno;
const char *linkname =
# ifdef JEMALLOC_PREFIX
"/etc/"JEMALLOC_PREFIX"malloc.conf"
@@ -446,21 +447,20 @@ malloc_conf_init(void)
# endif
;
- if ((linklen = readlink(linkname, buf,
- sizeof(buf) - 1)) != -1) {
- /*
- * Use the contents of the "/etc/malloc.conf"
- * symbolic link's name.
- */
- buf[linklen] = '\0';
- opts = buf;
- } else
-#endif
- {
+ /*
+ * Try to use the contents of the "/etc/malloc.conf"
+ * symbolic link's name.
+ */
+ linklen = readlink(linkname, buf, sizeof(buf) - 1);
+ if (linklen == -1) {
/* No configuration specified. */
- buf[0] = '\0';
- opts = buf;
+ linklen = 0;
+ /* restore errno */
+ set_errno(saved_errno);
}
+#endif
+ buf[linklen] = '\0';
+ opts = buf;
break;
} case 2: {
const char *envname =
--
1.8.3.4
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
int
main(int argc, char *argv[])
{
(void)printf("errno=%d\n", errno);
(void)malloc(42);
(void)printf("errno=%d\n", errno);
return (0);
}
/*
will output the following under FreeBSD:
errno=0
errno=2
*/
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