tools: warn_unused_result build fixes.

Note that some of the existing error checking for asprintf was wrong
for Linux.  asprintf in glibc returns -1 on error, but leaves the
pointer uninitialized.  Only the BSDs zero out the pointer on error.

Also, while fixing these warnings I saw several error paths that were
incorrect.  This patch minimally fixes the warn_unused_result; more
complete error path cleanup will be a later patch.

Signed-off-by:  Charles Coffing <ccoffing@novell.com>

5 files changed, 49 insertions, 39 deletions

diff --git a/tools/blktap/drivers/blktapctrl.c b/tools/blktap/drivers/blktapctrl.c
index aeec870af2..6613768654 100644
--- a/tools/blktap/drivers/blktapctrl.c
+++ b/tools/blktap/drivers/blktapctrl.c
@@ -143,7 +143,8 @@ static int get_new_dev(int *major, int *minor, blkif_t *blkif)
 		return -1;
 	}
 
-	asprintf(&devname,"%s/%s%d",BLKTAP_DEV_DIR, BLKTAP_DEV_NAME, *minor);
+	if (asprintf(&devname,"%s/%s%d",BLKTAP_DEV_DIR, BLKTAP_DEV_NAME, *minor) == -1)
+		return -1;
 	make_blktap_dev(devname,*major,*minor);	
 	DPRINTF("Received device id %d and major %d, "
 		"sent domid %d and be_id %d\n",
@@ -495,20 +496,27 @@ int blktapctrl_new_blkif(blkif_t *blkif)
 
 		if (!exist) {
 			DPRINTF("Process does not exist:\n");
-			asprintf(&rdctldev, 
-				 "%s/tapctrlread%d", BLKTAP_CTRL_DIR, minor);
-			blkif->fds[READ] = open_ctrl_socket(rdctldev);
-
+			if (asprintf(&rdctldev,
+				     "%s/tapctrlread%d", BLKTAP_CTRL_DIR, minor) == -1)
+				return -1;
+			if (asprintf(&wrctldev,
+				     "%s/tapctrlwrite%d", BLKTAP_CTRL_DIR, minor) == -1) {
+				free(rdctldev);
+				return -1;
+			}
+			if (asprintf(&cmd, "tapdisk %s %s", wrctldev, rdctldev) == -1) {
+				free(rdctldev);
+				free(wrctldev);
+				return -1;
+			}
 
-			asprintf(&wrctldev, 
-				 "%s/tapctrlwrite%d", BLKTAP_CTRL_DIR, minor);
+			blkif->fds[READ] = open_ctrl_socket(rdctldev);
 			blkif->fds[WRITE] = open_ctrl_socket(wrctldev);
 			
 			if (blkif->fds[READ] == -1 || blkif->fds[WRITE] == -1) 
 				goto fail;
 
 			/*launch the new process*/
-			asprintf(&cmd, "tapdisk %s %s", wrctldev, rdctldev);
 			DPRINTF("Launching process, CMDLINE [%s]\n",cmd);
 			if (system(cmd) == -1) {
 				DPRINTF("Unable to fork, cmdline: [%s]\n",cmd);
@@ -692,7 +700,8 @@ int main(int argc, char *argv[])
 	register_new_unmap_hook(unmap_blktapctrl);
 
 	/* Attach to blktap0 */
-	asprintf(&devname,"%s/%s0", BLKTAP_DEV_DIR, BLKTAP_DEV_NAME);
+	if (asprintf(&devname,"%s/%s0", BLKTAP_DEV_DIR, BLKTAP_DEV_NAME) == -1)
+                goto open_failed;
 	if ((ret = xc_find_device_number("blktap0")) < 0) {
 		DPRINTF("couldn't find device number for 'blktap0'\n");
 		goto open_failed;
diff --git a/tools/blktap/drivers/block-qcow.c b/tools/blktap/drivers/block-qcow.c
index a1fab17c55..928e517ef5 100644
--- a/tools/blktap/drivers/block-qcow.c
+++ b/tools/blktap/drivers/block-qcow.c
@@ -871,7 +871,10 @@ int tdqcow_open (struct disk_driver *dd, const char *name, td_flag_t flags)
 	}
 
 	s->fd = fd;
-	asprintf(&s->name,"%s", name);
+	if (asprintf(&s->name,"%s", name) == -1) {
+		close(fd);
+		return -1;
+	}
 
 	ASSERT(sizeof(QCowHeader) + sizeof(QCowHeader_ext) < 512);
 
@@ -1165,7 +1168,7 @@ int tdqcow_close(struct disk_driver *dd)
 		offset = sizeof(QCowHeader) + sizeof(uint32_t);
 		lseek(fd, offset, SEEK_SET);
 		out = cpu_to_be32(cksum);
-		write(fd, &out, sizeof(uint32_t));
+		if (write(fd, &out, sizeof(uint32_t))) ;
 		close(fd);
 	}
 
diff --git a/tools/blktap/drivers/tapdisk.c b/tools/blktap/drivers/tapdisk.c
index 954901b2a8..94a4e48c30 100644
--- a/tools/blktap/drivers/tapdisk.c
+++ b/tools/blktap/drivers/tapdisk.c
@@ -220,7 +220,8 @@ static int map_new_dev(struct td_state *s, int minor)
 	fd_list_entry_t *ptr;
 	int page_size;
 
-	asprintf(&devname,"%s/%s%d", BLKTAP_DEV_DIR, BLKTAP_DEV_NAME, minor);
+	if (asprintf(&devname,"%s/%s%d", BLKTAP_DEV_DIR, BLKTAP_DEV_NAME, minor) == -1)
+		return -1;
 	tap_fd = open(devname, O_RDWR);
 	if (tap_fd == -1) 
 	{
diff --git a/tools/blktap/lib/xenbus.c b/tools/blktap/lib/xenbus.c
index fb36e748fe..53a3338f1e 100644
--- a/tools/blktap/lib/xenbus.c
+++ b/tools/blktap/lib/xenbus.c
@@ -360,8 +360,7 @@ int add_blockdevice_probe_watch(struct xs_handle *h, const char *domid)
 	char *path;
 	struct xenbus_watch *vbd_watch;
 	
-	asprintf(&path, "/local/domain/%s/backend/tap", domid);
-	if (path == NULL) 
+	if (asprintf(&path, "/local/domain/%s/backend/tap", domid) == -1)
 		return -ENOMEM;
 	
 	vbd_watch = (struct xenbus_watch *)malloc(sizeof(struct xenbus_watch));
@@ -399,8 +398,7 @@ int watch_for_domid(struct xs_handle *h)
 	struct xenbus_watch *domid_watch;
 	char *path = NULL;
 
-	asprintf(&path, "/local/domain");
-	if (path == NULL) 
+	if (asprintf(&path, "/local/domain") == -1)
 		return -ENOMEM;
 
 	domid_watch = malloc(sizeof(struct xenbus_watch));
diff --git a/tools/blktap/lib/xs_api.c b/tools/blktap/lib/xs_api.c
index 539d0e3c51..783b4ce3b3 100644
--- a/tools/blktap/lib/xs_api.c
+++ b/tools/blktap/lib/xs_api.c
@@ -126,10 +126,12 @@ int xs_printf(struct xs_handle *h, const char *dir, const char *node,
 	ret = vasprintf(&buf, fmt, ap);
 	va_end(ap);
 	
-	asprintf(&path, "%s/%s", dir, node);
-	
-	if ((path == NULL) || (buf == NULL))
-		return 0;
+	if (ret == -1)
+		return ENOMEM;
+	if (asprintf(&path, "%s/%s", dir, node) == -1) {
+		free(buf);
+		return ENOMEM;
+	}
 
 	ret = xs_write(h, XBT_NULL, path, buf, strlen(buf)+1);
 	
@@ -180,10 +182,11 @@ char *get_dom_domid(struct xs_handle *h)
 	
 	e = xs_directory(h, xth, "/local/domain", &num);
 	if (e == NULL)
-		return NULL;
+		goto done;
 
 	for (i = 0; (i < num) && (domid == NULL); i++) {
-		asprintf(&path, "/local/domain/%s/name", e[i]);
+		if (asprintf(&path, "/local/domain/%s/name", e[i]) == -1)
+			break;
 		val = xs_read(h, xth, path, &len);
 		free(path);
 		if (val == NULL)
@@ -191,29 +194,31 @@ char *get_dom_domid(struct xs_handle *h)
 		
 		if (strcmp(val, DOMNAME) == 0) {
 			/* match! */
-			asprintf(&path, "/local/domain/%s/domid", e[i]);
+			if (asprintf(&path, "/local/domain/%s/domid", e[i]) == -1) {
+				free(val);
+				break;
+			}
 			domid = xs_read(h, xth, path, &len);
 			free(path);
 		}
 		free(val);
 	}
+done:
 	xs_transaction_end(h, xth, 0);
-	
-	free(e);
+	if (e)
+		free(e);
 	return domid;
 }
 
 int convert_dev_name_to_num(char *name) {
-	char *p_sd, *p_hd, *p_xvd, *p_plx, *p, *alpha,*ptr;
+	char *p, *ptr;
 	int majors[10] = {3,22,33,34,56,57,88,89,90,91};
 	int maj,i,ret = 0;
-
-	asprintf(&p_sd,"/dev/sd");
-	asprintf(&p_hd,"/dev/hd");
-	asprintf(&p_xvd,"/dev/xvd");
-	asprintf(&p_plx,"plx");
-	asprintf(&alpha,"abcdefghijklmnop");
-	
+	char *p_sd = "/dev/sd";
+	char *p_hd = "/dev/hd";
+	char *p_xvd = "/dev/xvd";
+	char *p_plx = "plx";
+	char *alpha = "abcdefghijklmnop";
 
 	if (strstr(name, p_sd) != NULL) {
 		p = name + strlen(p_sd);
@@ -251,12 +256,6 @@ int convert_dev_name_to_num(char *name) {
 		ret = BASE_DEV_VAL;
 	}
 
-	free(p_sd);
-	free(p_hd);
-	free(p_xvd);
-	free(p_plx);
-	free(alpha);
-
 	return ret;
 }