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[xen-4.0-testing] blktap2: Fix naked unchecked uses of read/write/chdir.

 

 

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patchbot at xen

May 16, 2012, 6:22 PM

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[xen-4.0-testing] blktap2: Fix naked unchecked uses of read/write/chdir.

# HG changeset patch
# User Keir Fraser <keir [at] xen>
# Date 1337011336 -3600
# Node ID c6eb61ed6f04b4079525c3944b5a55268e1db4f1
# Parent c68a5b43fb44ac83f340c3c2c69b7495af1d6f2d
blktap2: Fix naked unchecked uses of read/write/chdir.

These cause warnings under warn_unused_result, and for read/write we
ought to deal with partial io results.

Signed-off-by: Keir Fraser <keir [at] xen>
xen-unstable changeset: 25299:01d64a3dea71
xen-unstable date: Fri May 11 18:30:29 2012 +0100

blktap2: Fix another uninitialised value error

gcc -O1 -fno-omit-frame-pointer -m32 -march=i686 -g
-fno-strict-aliasing -std=gnu99 -Wall -Wstrict-prototypes
-Wdeclaration-after-statement -D__XEN_TOOLS__ -MMD -MF
.block-remus.o.d -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -fno-optimize-sibling-calls
-mno-tls-direct-seg-refs -Werror -g -Wno-unused -fno-strict-aliasing
-I../include -I../drivers
-I/home/osstest/build.12828.build-i386/xen-unstable/tools/blktap2/drivers/../../../tools/libxc
-I/home/osstest/build.12828.build-i386/xen-unstable/tools/blktap2/drivers/../../../tools/include
-D_GNU_SOURCE -DUSE_NFS_LOCKS -c -o block-remus.o block-remus.c

block-remus.c: In function 'ramdisk_flush':
block-remus.c:508: error: 'buf' may be used uninitialized in this
function
make[5]: *** [block-remus.o] Error 1

This is because gcc can see that merge_requests doesn't always set
*mergedbuf but gcc isn't able to prove that it always does so if
merge_requests returns 0 and that in that case the value of
ramdisk_flush::buf isn't used.

This is too useful a warning to disable, despite the occasional false
positive of this form. The conventional approach is to suppress the
warning by explicitly initialising the variable to 0.

This has just come to light because 25275:27d63b9f111a reenabled
optimisation for this area of code, and gcc's data flow analysis
(which is required to trigger the uninitialised variable warning) only
occurs when optimisation is turned on.

Signed-off-by: Ian Jackson <ian.jackson [at] eu>
xen-unstable changeset: 25281:60064411a8a9
xen-unstable date: Thu May 10 14:26:14 2012 +0100

blktap2: Do not build with -O0

Signed-off-by: Keir Fraser <keir [at] xen>
xen-unstable changeset: 25275:27d63b9f111a
xen-unstable date: Thu May 10 11:22:18 2012 +0100

blktap2: Fix uninitialised value error.

Signed-off-by: Keir Fraser <keir [at] xen>
xen-unstable changeset: 25274:cb82b5aa73bd
xen-unstable date: Thu May 10 11:21:59 2012 +0100

tools/blktap2: fix out of bounds access in block-log.c

block-log.c: In function 'ctl_close_sock':
block-log.c:363:23: warning: array subscript is above array bounds
[-Warray-bounds]

Adjust loop condition in ctl_close_sock() to fix warning.
Adjust array acccess in ctl_close() to actually access the array
member.

Signed-off-by: Olaf Hering <olaf [at] aepfle>
Acked-by: Ian Jackson <ian.jackson [at] eu>
Committed-by: Keir Fraser <keir [at] xen>
xen-unstable changeset: 25273:83a02f225bde
xen-unstable date: Thu May 10 11:20:04 2012 +0100

tools/blktap2: fix build errors caused by Werror in
vhd_journal_write_entry

-O2 -Wall -Werror triggers these warnings:

libvhd-journal.c: In function 'vhd_journal_write_entry':
libvhd-journal.c:335: warning: statement with no effect

Really return the error from vhd_journal_write() to caller.

v2:
- simplify the patch by just adding the missing return statement

Signed-off-by: Olaf Hering <olaf [at] aepfle>
Committed-by: Keir Fraser <keir [at] xen>
xen-unstable changeset: 25272:ca02580986d2
xen-unstable date: Thu May 10 11:19:05 2012 +0100
---


diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/Makefile
--- a/tools/blktap2/drivers/Makefile Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/Makefile Mon May 14 17:02:16 2012 +0100
@@ -9,7 +9,7 @@ QCOW_UTIL = img2qcow qcow-create qcow2r
LOCK_UTIL = lock-util
INST_DIR = $(SBINDIR)

-CFLAGS += -Werror -g -O0
+CFLAGS += -Werror -g
CFLAGS += -Wno-unused
CFLAGS += -fno-strict-aliasing
CFLAGS += -I../lib -I../../libxc
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/block-log.c
--- a/tools/blktap2/drivers/block-log.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/block-log.c Mon May 14 17:02:16 2012 +0100
@@ -347,11 +347,11 @@ static int ctl_open(struct tdlog_state*
static int ctl_close(struct tdlog_state* s)
{
while (s->connected) {
+ s->connected--;
tapdisk_server_unregister_event(s->connections[s->connected].id);
close(s->connections[s->connected].fd);
s->connections[s->connected].fd = -1;
s->connections[s->connected].id = 0;
- s->connected--;
}

if (s->ctl.fd >= 0) {
@@ -382,7 +382,7 @@ static int ctl_close_sock(struct tdlog_s
{
int i;

- for (i = 0; i <= s->connected; i++) {
+ for (i = 0; i < s->connected; i++) {
if (s->connections[i].fd == fd) {
tapdisk_server_unregister_event(s->connections[i].id);
close(s->connections[i].fd);
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/block-qcow.c
--- a/tools/blktap2/drivers/block-qcow.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/block-qcow.c Mon May 14 17:02:16 2012 +0100
@@ -1457,7 +1457,7 @@ int tdqcow_get_parent_id(td_driver_t *dr
{
off_t off;
char *buf, *filename;
- int len, secs, type, err = -EINVAL;
+ int len, secs, type = 0, err = -EINVAL;
struct tdqcow_state *child = (struct tdqcow_state *)driver->data;

if (!child->backing_file_offset)
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/block-remus.c
--- a/tools/blktap2/drivers/block-remus.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/block-remus.c Mon May 14 17:02:16 2012 +0100
@@ -481,7 +481,7 @@ static char* merge_requests(struct ramdi
static int ramdisk_flush(td_driver_t *driver, struct tdremus_state* s)
{
uint64_t* sectors;
- char* buf;
+ char* buf = NULL;
uint64_t base, batchlen;
int i, j, count = 0;

diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-diff.c
--- a/tools/blktap2/drivers/tapdisk-diff.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-diff.c Mon May 14 17:02:16 2012 +0100
@@ -169,7 +169,7 @@ tapdisk_stream_poll_clear(struct tapdisk
{
int dummy;

- read(p->pipe[POLL_READ], &dummy, sizeof(dummy));
+ read_exact(p->pipe[POLL_READ], &dummy, sizeof(dummy));
p->set = 0;
}

@@ -179,7 +179,7 @@ tapdisk_stream_poll_set(struct tapdisk_s
int dummy = 0;

if (!p->set) {
- write(p->pipe[POLL_WRITE], &dummy, sizeof(dummy));
+ write_exact(p->pipe[POLL_WRITE], &dummy, sizeof(dummy));
p->set = 1;
}
}
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-log.c
--- a/tools/blktap2/drivers/tapdisk-log.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-log.c Mon May 14 17:02:16 2012 +0100
@@ -37,6 +37,7 @@
#include <sys/time.h>

#include "tapdisk-log.h"
+#include "tapdisk-utils.h"

#define MAX_ENTRY_LEN 512
#define MAX_ERROR_MESSAGES 16
@@ -247,7 +248,7 @@ tlog_flush(void)
wsize = ((size + 511) & (~511));

memset(tapdisk_log.buf + size, '\n', wsize - size);
- write(fd, tapdisk_log.buf, wsize);
+ write_exact(fd, tapdisk_log.buf, wsize);

tapdisk_log.p = tapdisk_log.buf;

diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-queue.c
--- a/tools/blktap2/drivers/tapdisk-queue.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-queue.c Mon May 14 17:02:16 2012 +0100
@@ -435,7 +435,7 @@ tapdisk_lio_ack_event(struct tqueue *que
uint64_t val;

if (lio->flags & LIO_FLAG_EVENTFD)
- read(lio->event_fd, &val, sizeof(val));
+ read_exact(lio->event_fd, &val, sizeof(val));
}

static void
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-stream.c
--- a/tools/blktap2/drivers/tapdisk-stream.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-stream.c Mon May 14 17:02:16 2012 +0100
@@ -144,7 +144,7 @@ tapdisk_stream_poll_clear(struct tapdisk
{
int dummy;

- read(p->pipe[POLL_READ], &dummy, sizeof(dummy));
+ read_exact(p->pipe[POLL_READ], &dummy, sizeof(dummy));
p->set = 0;
}

@@ -154,7 +154,7 @@ tapdisk_stream_poll_set(struct tapdisk_s
int dummy = 0;

if (!p->set) {
- write(p->pipe[POLL_WRITE], &dummy, sizeof(dummy));
+ write_exact(p->pipe[POLL_WRITE], &dummy, sizeof(dummy));
p->set = 1;
}
}
@@ -202,7 +202,7 @@ tapdisk_stream_print_request(struct tapd
{
unsigned long idx = (unsigned long)tapdisk_stream_request_idx(s, sreq);
char *buf = (char *)MMAP_VADDR(s->vbd->ring.vstart, idx, 0);
- write(s->out_fd, buf, sreq->secs << SECTOR_SHIFT);
+ write_exact(s->out_fd, buf, sreq->secs << SECTOR_SHIFT);
}

static void
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-utils.c
--- a/tools/blktap2/drivers/tapdisk-utils.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-utils.c Mon May 14 17:02:16 2012 +0100
@@ -215,3 +215,40 @@ int tapdisk_linux_version(void)
}

#endif
+int read_exact(int fd, void *data, size_t size)
+{
+ size_t offset = 0;
+ ssize_t len;
+
+ while ( offset < size )
+ {
+ len = read(fd, (char *)data + offset, size - offset);
+ if ( (len == -1) && (errno == EINTR) )
+ continue;
+ if ( len == 0 )
+ errno = 0;
+ if ( len <= 0 )
+ return -1;
+ offset += len;
+ }
+
+ return 0;
+}
+
+int write_exact(int fd, const void *data, size_t size)
+{
+ size_t offset = 0;
+ ssize_t len;
+
+ while ( offset < size )
+ {
+ len = write(fd, (const char *)data + offset, size - offset);
+ if ( (len == -1) && (errno == EINTR) )
+ continue;
+ if ( len <= 0 )
+ return -1;
+ offset += len;
+ }
+
+ return 0;
+}
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk-utils.h
--- a/tools/blktap2/drivers/tapdisk-utils.h Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk-utils.h Mon May 14 17:02:16 2012 +0100
@@ -40,4 +40,7 @@ int tapdisk_parse_disk_type(const char *
int tapdisk_get_image_size(int, uint64_t *, uint32_t *);
int tapdisk_linux_version(void);

+int read_exact(int fd, void *data, size_t size); /* EOF => -1, errno=0 */
+int write_exact(int fd, const void *data, size_t size);
+
#endif
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/drivers/tapdisk2.c
--- a/tools/blktap2/drivers/tapdisk2.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/drivers/tapdisk2.c Mon May 14 17:02:16 2012 +0100
@@ -330,7 +330,12 @@ tapdisk2_create_device(const char *param
char *path;
int err, type;

- chdir("/");
+ if (chdir("/")) {
+ DPRINTF("failed to chdir(/): %d\n", errno);
+ err = 1;
+ goto out;
+ }
+
tapdisk_start_logging("tapdisk2");

err = tapdisk2_set_child_fds();
diff -r c68a5b43fb44 -r c6eb61ed6f04 tools/blktap2/vhd/lib/libvhd-journal.c
--- a/tools/blktap2/vhd/lib/libvhd-journal.c Mon May 14 17:01:51 2012 +0100
+++ b/tools/blktap2/vhd/lib/libvhd-journal.c Mon May 14 17:02:16 2012 +0100
@@ -332,7 +332,7 @@ vhd_journal_write_entry(vhd_journal_t *j

err = vhd_journal_write(j, &e, sizeof(vhd_journal_entry_t));
if (err)
- err;
+ return err;

return 0;
}

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