xl: Add subcommand 'xl dmesg'

[Yu Zhiguo <yuzg@cn.fujitsu.com>]

Can be used to read and/or clear dmesg buffer.

Signed-off-by: Yu Zhiguo <yuzg@cn.fujitsu.com>

diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/libxl.c	Thu May 20 19:52:13 2010 +0800
@@ -2827,6 +2827,18 @@
     return xc_send_debug_keys(ctx->xch, keys);
 }
 
+int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
+                          unsigned int *pnr_chars, int clear,
+                          int incremental, uint32_t *pindex)
+{
+    int ret;
+
+    ret = xc_readconsolering(ctx->xch, pbuffer, pnr_chars, clear,
+                             incremental, pindex);
+
+    return ret;
+}
+
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid)
 {
     char *dompath = libxl_xs_get_dompath(ctx, domid);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/libxl.h	Thu May 20 19:52:13 2010 +0800
@@ -512,6 +512,9 @@
                        char *trigger_name, uint32_t vcpuid);
 int libxl_send_sysrq(struct libxl_ctx *ctx, uint32_t domid, char sysrq);
 int libxl_send_debug_keys(struct libxl_ctx *ctx, char *keys);
+int libxl_readconsolering(struct libxl_ctx *ctx, char **pbuffer,
+                          unsigned int *pnr_chars, int clear,
+                          int incremental, uint32_t *pindex);
 uint32_t libxl_vm_get_start_time(struct libxl_ctx *ctx, uint32_t domid);
 
 char *libxl_tmem_list(struct libxl_ctx *ctx, uint32_t domid, int use_long);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.c	Thu May 20 19:52:13 2010 +0800
@@ -3246,6 +3246,66 @@
     exit(0);
 }
 
+int main_dmesg(int argc, char **argv)
+{
+    unsigned int clear = 0, index = 0, incremental = 0;
+    unsigned int count = 16384 + 1, size = count;
+    char *str, *ptr;
+    int opt, ret;
+
+    while ((opt = getopt(argc, argv, "hc")) != -1) {
+        switch (opt) {
+        case 'c':
+            clear = 1;
+            break;
+        case 'h':
+            help("dmesg");
+            exit(0);
+        default:
+            fprintf(stderr, "option not supported\n");
+            break;
+        }
+    }
+
+    str = malloc(size);
+    memset(str, 0, size);
+    ret = libxl_readconsolering(&ctx, &str, &count, clear,
+                                incremental, &index);
+    if (ret < 0)
+        goto out;
+
+    while (!incremental && count == size) {
+        size += count - 1;
+        if (size < count)
+            break;
+
+        ptr = realloc(str, size);
+        if (!ptr)
+            break;
+
+        str = ptr + count;
+        count = size - count;
+        ret = libxl_readconsolering(&ctx, &str, &count, clear,
+                                    1, &index);
+        if (ret < 0) {
+            str = ptr;
+            break;
+        }
+
+        count += str - ptr;
+        str = ptr;
+    }
+
+out:
+    printf(str);
+    free(str);
+
+    if (ret)
+        exit(1);
+
+    exit(0);
+}
+
 int main_top(int argc, char **argv)
 {
     int opt;
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdimpl.h
--- a/tools/libxl/xl_cmdimpl.h	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.h	Thu May 20 19:52:13 2010 +0800
@@ -45,6 +45,7 @@
 int main_trigger(int argc, char **argv);
 int main_sysrq(int argc, char **argv);
 int main_debug_keys(int argc, char **argv);
+int main_dmesg(int argc, char **argv);
 int main_top(int argc, char **argv);
 int main_networkattach(int argc, char **argv);
 int main_networklist(int argc, char **argv);
diff -r 840f269d95fb -r ab11e3eab7cc tools/libxl/xl_cmdtable.c
--- a/tools/libxl/xl_cmdtable.c	Wed May 19 22:59:52 2010 +0100
+++ b/tools/libxl/xl_cmdtable.c	Thu May 20 19:52:13 2010 +0800
@@ -191,6 +191,12 @@
       "Send debug keys to Xen",
       "<Keys>",
     },
+    { "dmesg",
+      &main_dmesg,
+      "Read and/or clear dmesg buffer",
+      "[-c]",
+      "  -c                        Clear dmesg buffer as well as printing it",
+    },
     { "top",
       &main_top,
       "Monitor a host and the domains in real time",