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From c443b67561891ae68d688daf5f8ce37820cdba2b Mon Sep 17 00:00:00 2001
From: Jason Evans <jasone@canonware.com>
Date: Sat, 29 Oct 2016 22:41:04 -0700
Subject: [PATCH] Use syscall(2) rather than {open,read,close}(2) during boot.
Some applications wrap various system calls, and if they call the
allocator in their wrappers, unexpected reentry can result. This is not
a general solution (many other syscalls are spread throughout the code),
but this resolves a bootstrapping issue that is apparently common.
This resolves #443.
---
src/pages.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/src/pages.c b/src/pages.c
index 05b0d69..84e2216 100644
--- a/src/pages.c
+++ b/src/pages.c
@@ -207,6 +207,11 @@ os_overcommits_sysctl(void)
#endif
#ifdef JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY
+/*
+ * Use syscall(2) rather than {open,read,close}(2) when possible to avoid
+ * reentry during bootstrapping if another library has interposed system call
+ * wrappers.
+ */
static bool
os_overcommits_proc(void)
{
@@ -214,12 +219,26 @@ os_overcommits_proc(void)
char buf[1];
ssize_t nread;
+#ifdef SYS_open
+ fd = (int)syscall(SYS_open, "/proc/sys/vm/overcommit_memory", O_RDONLY);
+#else
fd = open("/proc/sys/vm/overcommit_memory", O_RDONLY);
+#endif
if (fd == -1)
return (false); /* Error. */
+#ifdef SYS_read
+ nread = (ssize_t)syscall(SYS_read, fd, &buf, sizeof(buf));
+#else
nread = read(fd, &buf, sizeof(buf));
+#endif
+
+#ifdef SYS_close
+ syscall(SYS_close, fd);
+#else
close(fd);
+#endif
+
if (nread < 1)
return (false); /* Error. */
/*
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