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-rw-r--r--wrapper.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/wrapper.c b/wrapper.c
index 6a015de5f0..f92b147598 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -131,6 +131,14 @@ void *xcalloc(size_t nmemb, size_t size)
}
/*
+ * Limit size of IO chunks, because huge chunks only cause pain. OS X
+ * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in
+ * the absense of bugs, large chunks can result in bad latencies when
+ * you decide to kill the process.
+ */
+#define MAX_IO_SIZE (8*1024*1024)
+
+/*
* xread() is the same a read(), but it automatically restarts read()
* operations with a recoverable error (EAGAIN and EINTR). xread()
* DOES NOT GUARANTEE that "len" bytes is read even if the data is available.
@@ -138,6 +146,8 @@ void *xcalloc(size_t nmemb, size_t size)
ssize_t xread(int fd, void *buf, size_t len)
{
ssize_t nr;
+ if (len > MAX_IO_SIZE)
+ len = MAX_IO_SIZE;
while (1) {
nr = read(fd, buf, len);
if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
@@ -154,6 +164,8 @@ ssize_t xread(int fd, void *buf, size_t len)
ssize_t xwrite(int fd, const void *buf, size_t len)
{
ssize_t nr;
+ if (len > MAX_IO_SIZE)
+ len = MAX_IO_SIZE;
while (1) {
nr = write(fd, buf, len);
if ((nr < 0) && (errno == EAGAIN || errno == EINTR))