On Jun 8, 2009, at 2:00 PM, Jeff Layton wrote:
Several of the routines in nfssvc.c declare a buffer for strings.
Use a
shared static buffer instead to keep it off of the stack. Also, the
buffer allocated in some places is *really* large. BUFSIZ is generally
8k. These routines don't need nearly that much.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
utils/nfsd/nfssvc.c | 28 +++++++++++++++++-----------
1 files changed, 17 insertions(+), 11 deletions(-)
diff --git a/utils/nfsd/nfssvc.c b/utils/nfsd/nfssvc.c
index 0a7546a..025554d 100644
--- a/utils/nfsd/nfssvc.c
+++ b/utils/nfsd/nfssvc.c
@@ -24,18 +24,25 @@
#define NFSD_VERS_FILE "/proc/fs/nfsd/versions"
#define NFSD_THREAD_FILE "/proc/fs/nfsd/threads"
+/*
+ * declaring a common static scratch buffer here keeps us from
having to
+ * continually thrash the stack. The value of 128 bytes here is
really just a
+ * SWAG and can be increased if necessary. It ought to be enough
for the
+ * routines below however.
+ */
+char buf[128];
+
static void
nfssvc_setfds(int port, unsigned int ctlbits, char *haddr)
{
int fd, n, on=1;
- char buf[BUFSIZ];
int udpfd = -1, tcpfd = -1;
struct sockaddr_in sin;
fd = open(NFSD_PORTS_FILE, O_RDONLY);
if (fd < 0)
return;
- n = read(fd, buf, BUFSIZ);
+ n = read(fd, buf, sizeof(buf));
close(fd);
if (n != 0)
return;
@@ -91,7 +98,7 @@ nfssvc_setfds(int port, unsigned int ctlbits, char
*haddr)
}
}
if (udpfd >= 0) {
- snprintf(buf, BUFSIZ,"%d\n", udpfd);
+ snprintf(buf, sizeof(buf), "%d\n", udpfd);
Since sizeof(buf) is a SWAG, maybe we should have some way of finding
out if the buffer is ever overflowed. Just a thought.
if (write(fd, buf, strlen(buf)) != strlen(buf)) {
xlog(L_ERROR,
"writing fds to kernel failed: errno %d (%m)",
@@ -103,7 +110,7 @@ nfssvc_setfds(int port, unsigned int ctlbits,
char *haddr)
if (tcpfd >= 0) {
if (fd < 0)
fd = open(NFSD_PORTS_FILE, O_WRONLY);
- snprintf(buf, BUFSIZ,"%d\n", tcpfd);
+ snprintf(buf, sizeof(buf), "%d\n", tcpfd);
if (write(fd, buf, strlen(buf)) != strlen(buf)) {
xlog(L_ERROR,
"writing fds to kernel failed: errno %d (%m)",
@@ -118,7 +125,7 @@ static void
nfssvc_versbits(unsigned int ctlbits, int minorvers4)
{
int fd, n, off;
- char buf[BUFSIZ], *ptr;
+ char *ptr;
ptr = buf;
off = 0;
@@ -128,17 +135,17 @@ nfssvc_versbits(unsigned int ctlbits, int
minorvers4)
for (n = NFSD_MINVERS; n <= NFSD_MAXVERS; n++) {
if (NFSCTL_VERISSET(ctlbits, n))
- off += snprintf(ptr+off, BUFSIZ - off, "+%d ", n);
+ off += snprintf(ptr+off, sizeof(buf) - off, "+%d ", n);
else
- off += snprintf(ptr+off, BUFSIZ - off, "-%d ", n);
+ off += snprintf(ptr+off, sizeof(buf) - off, "-%d ", n);
}
n = minorvers4 >= 0 ? minorvers4 : -minorvers4;
if (n >= NFSD_MINMINORVERS4 && n <= NFSD_MAXMINORVERS4)
- off += snprintf(ptr+off, BUFSIZ - off, "%c4.%d",
+ off += snprintf(ptr+off, sizeof(buf) - off, "%c4.%d",
minorvers4 > 0 ? '+' : '-',
n);
xlog(D_GENERAL, "Writing version string to kernel: %s", buf);
- snprintf(ptr+off, BUFSIZ - off, "\n");
+ snprintf(ptr+off, sizeof(buf) - off, "\n");
if (write(fd, buf, strlen(buf)) != strlen(buf))
xlog(L_ERROR, "Setting version failed: errno %d (%m)", errno);
@@ -168,9 +175,8 @@ nfssvc(int port, int nrservs, unsigned int
versbits, int minorvers4,
* Just write the number in.
* Cannot handle port number yet, but does anyone care?
*/
- char buf[20];
int n;
- snprintf(buf, 20,"%d\n", nrservs);
+ snprintf(buf, sizeof(buf), "%d\n", nrservs);
n = write(fd, buf, strlen(buf));
close(fd);
if (n != strlen(buf))
--
1.6.0.6
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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