Provide mechanism to set UUID for Dom0

This file gets installed to the host system.

This patch cleans it up: 1. remove things that don't exist anymore; 2. change xm to xl; 3. fix xen-devel list address; 4. add things that are missing.

Signed-off-by Wei Liu <[email protected]>

Quoted 7 lines · Wei Liu

This file gets installed to the host system.

This patch cleans it up: 1. remove things that don't exist anymore; 2. change xm to xl; 3. fix xen-devel list address; 4. add things that are missing.

Signed-off-by Wei Liu <[email protected]>

Is this file actually worth keeping?  Considering how obsolete its information is, I severely doubt anyone uses it.

If we do want to keep it, can you strip trailing whitespace in this patch as well please?

~Andrew

This file gets installed to the host system.

This patch cleans it up: 1. remove things that don't exist anymore; 2. change xm to xl; 3. fix xen-devel list address; 4. add things that are missing.

If that's set, the stub is going to contain that UUID.

No functional change.

Signed-off-by Wei Liu <[email protected]>

---
 tools/helpers/init-dom-json.c        | 5 ++++-
 tools/helpers/init-dom-json.h        | 3 ++-
 tools/helpers/init-xenstore-domain.c | 2 +-
 tools/helpers/xen-init-dom0.c        | 2 +-
 4 files changed, 8 insertions(+), 4 deletions(-)

tools/helpers/init-dom-json.c +1 -1

index 704e7cb4f0..9514b3ceb6 100644
@@ -7,7 +7,7 @@
 #include <xenctrl.h>
 #include <libxl.h>
 
-int gen_stub_json_config(uint32_t domid)
+int gen_stub_json_config(uint32_t domid, libxl_uuid *uuid)
 {
     int rc = 1;
     xentoollog_logger_stdiostream *logger;

If that's set, the stub is going to contain that UUID.

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

tools/helpers/xen-init-dom0.c +45 -1

index 09bc0027f9..2b06610c7c 100644
@@ -2,24 +2,75 @@
 #include <stdint.h>
 #include <string.h>
 #include <stdio.h>
+#include <fcntl.h>
 
+#include <xenctrl.h>
 #include <xenstore.h>
+#include <libxl.h>
 
 #include "init-dom-json.h"
+#include "_paths.h"
 
 #define DOMNAME_PATH   "/local/domain/0/name"
 #define DOMID_PATH     "/local/domain/0/domid"
 
+#define DOM0_UUID_PATH XEN_CONFIG_DIR "/dom0-uuid"
+
+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    int fd = -1;
+    ssize_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];
+
+    libxl_uuid_clear(uuid);
+
+    fd = open(DOM0_UUID_PATH, O_RDONLY);
+    if (fd < 0) {
+        fprintf(stderr, "failed to open %s\n", DOM0_UUID_PATH);
+        goto out;
+    }
+
+    r = read(fd, uuid_buf, LIBXL_UUID_FMTLEN);
+    if (r == -1) {
+        fprintf(stderr, "failed to read %s, errno %d\n", DOM0_UUID_PATH, errno);
+        goto out;
+    }
+
+    if (r != LIBXL_UUID_FMTLEN) {
+        fprintf(stderr, "file too short\n");
+        goto out;
+    }
+
+    uuid_buf[LIBXL_UUID_FMTLEN] = 0;
+
+    if (libxl_uuid_from_string(uuid, uuid_buf)) {
+        fprintf(stderr, "failed to parse UUID\n");
+        libxl_uuid_clear(uuid);
+    }
+
+out:
+    if (fd >= 0) close(fd);
+}
+
 int main(int argc, char **argv)
 {
     int rc;
-    struct xs_handle *xsh;
+    struct xs_handle *xsh = NULL;
+    xc_interface *xch = NULL;
     char *domname_string = NULL, *domid_string = NULL;
+    libxl_uuid uuid;
 
     xsh = xs_open(0);
     if (!xsh) {

tools/helpers/xen-init-dom0.c +11 -2

     }
 
     /* Sanity check: this program can only be run once. */

@@ -31,7 +82,16 @@ int main(int argc, char **argv)
         goto out;
     }
 
-    rc = gen_stub_json_config(0, NULL);
+    get_dom0_uuid(&uuid);
+
+    if (!libxl_uuid_is_nil(&uuid) &&
+        xc_domain_sethandle(xch, 0, libxl_uuid_bytearray(&uuid))) {
+        fprintf(stderr, "failed to set Dom0 UUID\n");
+        rc = 1;
+        goto out;
+    }
+
+    rc = gen_stub_json_config(0, &uuid);
     if (rc)
         goto out;
 

@@ -55,6 +115,7 @@ out:
     free(domid_string);
     free(domname_string);
     xs_close(xsh);
+    xc_interface_close(xch);
     return rc;
 }
 
--

2.11.0

_______________________________________________
Xen-devel mailing list
[email protected]
https://lists.xenproject.org/mailman/listinfo/xen-devel

Quoted 11 lines

int main(int argc, char **argv)

 {
     int rc;

tools/helpers/xen-init-dom0.c +3 -1

-    struct xs_handle *xsh;
+    struct xs_handle *xsh = NULL;
+    xc_interface *xch = NULL;
     char *domname_string = NULL, *domid_string = NULL;
+    libxl_uuid uuid;
 
     xsh = xs_open(0);
     if (!xsh) {

tools/helpers/xen-init-dom0.c line 73

Quoted 10 lines

tools/helpers/xen-init-dom0.c +8 -1

         fprintf(stderr, "cannot open xenstore connection\n");
-        exit(1);
+        rc = 1;
+        goto out;
+    }
+
+    xch = xc_interface_open(NULL, NULL, 0);
+    if (!xch) {
+        fprintf(stderr, "xc_interface_open() failed\n");
+        rc = 1;

Do you want a goto out here?

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

tools/helpers/xen-init-dom0.c +5 -0

+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    int fd = -1;
+    ssize_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];

tools/helpers/xen-init-dom0.c +18 -2

+        libxl_uuid_clear(uuid);
+    }
+
+out:
+    if (fd >= 0) close(fd);
+}
+
 int main(int argc, char **argv)
 {
     int rc;
-    struct xs_handle *xsh;
+    struct xs_handle *xsh = NULL;
+    xc_interface *xch = NULL;
     char *domname_string = NULL, *domid_string = NULL;
+    libxl_uuid uuid;
 
     xsh = xs_open(0);
     if (!xsh) {
         fprintf(stderr, "cannot open xenstore connection\n");
-        exit(1);
+        rc = 1;
+        goto out;
+    }
+
+    xch = xc_interface_open(NULL, NULL, 0);
+    if (!xch) {
+        fprintf(stderr, "xc_interface_open() failed\n");
+        rc = 1;
     }
 
     /* Sanity check: this program can only be run once. */

Quoted 4 lines · Wei Liu

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

[snip]
In general this looks good, however I am not familiar with libxl conventions, so just some generic comments below.

Quoted 11 lines

tools/helpers/xen-init-dom0.c +11 -0

+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    int fd = -1;
+    ssize_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];
+
+    libxl_uuid_clear(uuid);
+
+    fd = open(DOM0_UUID_PATH, O_RDONLY);
+    if (fd < 0) {
+        fprintf(stderr, "failed to open %s\n", DOM0_UUID_PATH);

tools/helpers/xen-init-dom0.c line 33

Quoted 4 lines

tools/helpers/xen-init-dom0.c +4 -0

+        goto out;
+    }
+
+    r = read(fd, uuid_buf, LIBXL_UUID_FMTLEN);

Could this be a short read? I'm not familiar with libxl conventions, but would there be a utility function that repeats the read if it is short, or would fread be better?

tools/helpers/xen-init-dom0.c line 40

Quoted 8 lines

tools/helpers/xen-init-dom0.c +7 -0

+    if (r == -1) {
+        fprintf(stderr, "failed to read %s, errno %d\n", DOM0_UUID_PATH, errno);
+        goto out;
+    }
+
+    if (r != LIBXL_UUID_FMTLEN) {
+        fprintf(stderr, "file too short\n");

Would be nice to print which file is too short.

tools/helpers/xen-init-dom0.c line 47

Quoted 8 lines

tools/helpers/xen-init-dom0.c +7 -0

+        goto out;
+    }
+
+    uuid_buf[LIBXL_UUID_FMTLEN] = 0;
+
+    if (libxl_uuid_from_string(uuid, uuid_buf)) {
+        fprintf(stderr, "failed to parse UUID\n");

As above, would be nice to print which file this error is from.

Quoted 35 lines

tools/helpers/xen-init-dom0.c +18 -2

+        libxl_uuid_clear(uuid);
+    }
+
+out:
+    if (fd >= 0) close(fd);
+}
+
 int main(int argc, char **argv)
 {
     int rc;
-    struct xs_handle *xsh;
+    struct xs_handle *xsh = NULL;
+    xc_interface *xch = NULL;
     char *domname_string = NULL, *domid_string = NULL;
+    libxl_uuid uuid;
 
     xsh = xs_open(0);
     if (!xsh) {
         fprintf(stderr, "cannot open xenstore connection\n");
-        exit(1);
+        rc = 1;
+        goto out;
+    }
+
+    xch = xc_interface_open(NULL, NULL, 0);
+    if (!xch) {
+        fprintf(stderr, "xc_interface_open() failed\n");
+        rc = 1;
     }
 
     /* Sanity check: this program can only be run once. */

@@ -31,7 +82,16 @@ int main(int argc, char **argv)
         goto out;
     }
 

tools/helpers/xen-init-dom0.c int main(int argc, char **argv) · line 89

Quoted 6 lines

tools/helpers/xen-init-dom0.c +5 -1

-    rc = gen_stub_json_config(0, NULL);
+    get_dom0_uuid(&uuid);
+
+    if (!libxl_uuid_is_nil(&uuid) &&
+        xc_domain_sethandle(xch, 0, libxl_uuid_bytearray(&uuid))) {
+        fprintf(stderr, "failed to set Dom0 UUID\n");

Can xc_domain_sethandle tell us why it failed?

Quoted 8 lines

tools/helpers/xen-init-dom0.c +5 -0

+        rc = 1;
+        goto out;
+    }
+
+    rc = gen_stub_json_config(0, &uuid);
     if (rc)
         goto out;
 

tools/helpers/xen-init-dom0.c out: · line 118

Quoted 5 lines

tools/helpers/xen-init-dom0.c +1 -0

@@ -55,6 +115,7 @@ out:
     free(domid_string);
     free(domname_string);
     xs_close(xsh);
+    xc_interface_close(xch);

I assume this function doesn't mind getting called with NULL, right?

Best regards,
--Edwin

Quoted 21 lines · Edwin Török

Quoted 4 lines · Wei Liu

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

[snip]
In general this looks good, however I am not familiar with libxl conventions, so just some generic comments below.

Quoted 11 lines

tools/helpers/xen-init-dom0.c +11 -0

+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    int fd = -1;
+    ssize_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];
+
+    libxl_uuid_clear(uuid);
+
+    fd = open(DOM0_UUID_PATH, O_RDONLY);
+    if (fd < 0) {
+        fprintf(stderr, "failed to open %s\n", DOM0_UUID_PATH);

Quoted 8 lines

tools/helpers/xen-init-dom0.c line 33

Quoted 4 lines

tools/helpers/xen-init-dom0.c +4 -0

+        goto out;
+    }
+
+    r = read(fd, uuid_buf, LIBXL_UUID_FMTLEN);

Could this be a short read? I'm not familiar with libxl conventions, but would there be a utility function that repeats the read if it is short, or would fread be better?

I can use libxl_read_exactly instead. That saves me from writing some code to handle every corner case.

Quoted 28 lines · Wei Liu

Quoted 27 lines · Edwin Török

Quoted 4 lines · Wei Liu

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

[snip]
In general this looks good, however I am not familiar with libxl conventions, so just some generic comments below.

Quoted 5 lines

tools/helpers/xen-init-dom0.c +5 -0

+static void get_dom0_uuid(libxl_uuid *uuid)
+{
+    int fd = -1;
+    ssize_t r;
+    char uuid_buf[LIBXL_UUID_FMTLEN+1];

tools/helpers/xen-init-dom0.c line 33

Quoted 10 lines

tools/helpers/xen-init-dom0.c +10 -0

+
+    libxl_uuid_clear(uuid);
+
+    fd = open(DOM0_UUID_PATH, O_RDONLY);
+    if (fd < 0) {
+        fprintf(stderr, "failed to open %s\n", DOM0_UUID_PATH);
+        goto out;
+    }
+
+    r = read(fd, uuid_buf, LIBXL_UUID_FMTLEN);

Could this be a short read? I'm not familiar with libxl conventions, but would there be a utility function that repeats the read if it is short, or would fread be better?

Quoted 3 lines

I can use libxl_read_exactly instead. That saves me from writing some code to handle every corner case.

On second thought, this requires code to allocating and destroying libxl ctx. I will write a loop here to handle short-read instead.

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.

Signed-off-by Wei Liu <[email protected]>

---
v2:
1. add missing "goto out"
2. print file names more
3. also print errno in xc_interface_open error message
4. take care of short-read

---
 tools/examples/Makefile       |  1 +
 tools/examples/README         |  2 ++
 tools/examples/dom0-uuid      |  0
 tools/helpers/Makefile        |  3 +-
 tools/helpers/xen-init-dom0.c | 65 +++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 67 insertions(+), 4 deletions(-)
 create mode 100644 tools/examples/dom0-uuid

Read from XEN_CONFIG_DIR/dom0-uuid. If it contains a valid UUID, set it for Dom0.