Command line support for altering the log file location

Add command line support for logging to a location other than /tmp/qemu.log.

With logging enabled (command line option -d), the log is written to
the hard-coded path /tmp/qemu.log. This patch adds support for writing
the log to a different location by passing the -D option.

Signed-off-by: Matthew Fernandez <matthew.fernandez@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/linux-user/main.c b/linux-user/main.c
index 04da0a4..71dd253 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2832,6 +2832,8 @@
 {
     const char *filename;
     const char *cpu_model;
+    const char *log_file = DEBUG_LOGFILE;
+    const char *log_mask = NULL;
     struct target_pt_regs regs1, *regs = &regs1;
     struct image_info info1, *info = &info1;
     struct linux_binprm bprm;
@@ -2853,9 +2855,6 @@
 
     qemu_cache_utils_init(envp);
 
-    /* init debug */
-    cpu_set_log_filename(DEBUG_LOGFILE);
-
     if ((envlist = envlist_create()) == NULL) {
         (void) fprintf(stderr, "Unable to allocate envlist\n");
         exit(1);
@@ -2894,22 +2893,15 @@
         if (!strcmp(r, "-")) {
             break;
         } else if (!strcmp(r, "d")) {
-            int mask;
-            const CPULogItem *item;
-
-	    if (optind >= argc)
+            if (optind >= argc) {
 		break;
-
-	    r = argv[optind++];
-            mask = cpu_str_to_log_mask(r);
-            if (!mask) {
-                printf("Log items (comma separated):\n");
-                for(item = cpu_log_items; item->mask != 0; item++) {
-                    printf("%-10s %s\n", item->name, item->help);
-                }
-                exit(1);
             }
-            cpu_set_log(mask);
+            log_mask = argv[optind++];
+        } else if (!strcmp(r, "D")) {
+            if (optind >= argc) {
+                break;
+            }
+            log_file = argv[optind++];
         } else if (!strcmp(r, "E")) {
             r = argv[optind++];
             if (envlist_setenv(envlist, r) != 0)
@@ -3022,6 +3014,23 @@
     filename = argv[optind];
     exec_path = argv[optind];
 
+    /* init debug */
+    cpu_set_log_filename(log_file);
+    if (log_mask) {
+        int mask;
+        const CPULogItem *item;
+
+        mask = cpu_str_to_log_mask(r);
+        if (!mask) {
+            printf("Log items (comma separated):\n");
+            for (item = cpu_log_items; item->mask != 0; item++) {
+                printf("%-10s %s\n", item->name, item->help);
+            }
+            exit(1);
+        }
+        cpu_set_log(mask);
+    }
+
     /* Zero out regs */
     memset(regs, 0, sizeof(struct target_pt_regs));