trace: enable tracing in qemu-img

The command will work this way:
    qemu-img --trace "qcow2*" create -f qcow2 1.img 64G

[Quote "qcow2*" to protect against shell globbing as suggested by Eric
Blake <eblake@redhat.com>.
--Stefan]
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1466174654-30130-8-git-send-email-den@openvz.org
Suggested by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Makefile

@@ -566,7 +566,7 @@ qemu.1: qemu-doc.texi qemu-options.texi qemu-monitor.texi qemu-monitor-info.texi
 	  "  GEN   $@")
 qemu.1: qemu-option-trace.texi
 
-qemu-img.1: qemu-img.texi qemu-img-cmds.texi
+qemu-img.1: qemu-img.texi qemu-option-trace.texi qemu-img-cmds.texi
 	$(call quiet-command, \
 	  perl -Ww -- $(SRC_PATH)/scripts/texi2pod.pl $< qemu-img.pod && \
 	  $(POD2MAN) --section=1 --center=" " --release=" " qemu-img.pod > $@, \

qemu-img.c

@@ -32,6 +32,7 @@
 #include "qemu/config-file.h"
 #include "qemu/option.h"
 #include "qemu/error-report.h"
+#include "qemu/log.h"
 #include "qom/object_interfaces.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/block-backend.h"
@@ -39,6 +40,7 @@
 #include "block/blockjob.h"
 #include "block/qapi.h"
 #include "crypto/init.h"
+#include "trace/control.h"
 #include <getopt.h>
 
 #define QEMU_IMG_VERSION "qemu-img version " QEMU_VERSION QEMU_PKGVERSION \
@@ -96,6 +98,8 @@ static void QEMU_NORETURN help(void)
            "\n"
            "    '-h', '--help'       display this help and exit\n"
            "    '-V', '--version'    output version information and exit\n"
+           "    '-T', '--trace'      [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
+           "                         specify tracing options\n"
            "\n"
            "Command syntax:\n"
 #define DEF(option, callback, arg_string)        \
@@ -3806,10 +3810,12 @@ int main(int argc, char **argv)
     const img_cmd_t *cmd;
     const char *cmdname;
     Error *local_error = NULL;
+    char *trace_file = NULL;
     int c;
     static const struct option long_options[] = {
         {"help", no_argument, 0, 'h'},
         {"version", no_argument, 0, 'V'},
+        {"trace", required_argument, NULL, 'T'},
         {0, 0, 0, 0}
     };
 
@@ -3835,8 +3841,9 @@ int main(int argc, char **argv)
 
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_source_opts);
+    qemu_add_opts(&qemu_trace_opts);
 
-    while ((c = getopt_long(argc, argv, "+hV", long_options, NULL)) != -1) {
+    while ((c = getopt_long(argc, argv, "+hVT:", long_options, NULL)) != -1) {
         switch (c) {
         case 'h':
             help();
@@ -3844,6 +3851,10 @@ int main(int argc, char **argv)
         case 'V':
             printf(QEMU_IMG_VERSION);
             return 0;
+        case 'T':
+            g_free(trace_file);
+            trace_file = trace_opt_parse(optarg);
+            break;
         }
     }
 
@@ -3857,6 +3868,12 @@ int main(int argc, char **argv)
     argv += optind;
     optind = 1;
 
+    if (!trace_init_backends()) {
+        exit(1);
+    }
+    trace_init_file(trace_file);
+    qemu_set_log(LOG_TRACE);
+
     /* find the command */
     for (cmd = img_cmds; cmd->name != NULL; cmd++) {
         if (!strcmp(cmdname, cmd->name)) {

qemu-img.texi

@@ -22,6 +22,9 @@ Standard options:
 Display this help and exit
 @item -V, --version
 Display version information and exit
+@item -T, --trace [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}]
+@findex --trace
+@include qemu-option-trace.texi
 @end table
 
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