[Qemu-devel] [PATCH] Add search path support for qemu data files.

[Gerd Hoffmann <kraxel@redhat.com>]

This patch allows to specify multiple directories where qemu should look
for data files.  To implement that the behavior of the -L switch is
slightly different now:  Instead of replacing the data directory the
path specified will be appended to the data directory list.  So when
specifiying -L multiple times all directories specified will be checked,
in the order they are specified on the command line, instead of just the
last one.

Additionally the default paths are always appended to the directory
data list.  This allows to specify a incomplete directory (such as the
seabios out/ directory) via -L.  Anything not found there will be loaded
from the default paths, so you don't have to create a symlink farm for
all the rom blobs.

For trouble-shooting a tracepoint has been added, logging which blob
has been loaded from which location.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 trace-events |    1 +
 vl.c         |   36 +++++++++++++++++++++++-------------
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/trace-events b/trace-events
index a27ae43..402504f 100644
--- a/trace-events
+++ b/trace-events
@@ -472,6 +472,7 @@ scsi_request_sense(int target, int lun, int tag) "target %d lun %d tag %d"
 
 # vl.c
 vm_state_notify(int running, int reason) "running %d reason %d"
+load_file(const char *name, const char *path) "name %s location %s"
 
 # block/qcow2.c
 qcow2_writev_start_req(void *co, int64_t sector, int nb_sectors) "co %p sector %" PRIx64 " nb_sectors %d"
diff --git a/vl.c b/vl.c
index c03edf1..d94c3fa 100644
--- a/vl.c
+++ b/vl.c
@@ -178,7 +178,8 @@ int main(int argc, char **argv)
 #define MAX_VIRTIO_CONSOLES 1
 #define MAX_SCLP_CONSOLES 1
 
-static const char *data_dir;
+static const char *data_dir[16];
+static int data_dir_idx;
 const char *bios_name = NULL;
 enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
 DisplayType display_type = DT_DEFAULT;
@@ -2251,14 +2252,16 @@ static int balloon_parse(const char *arg)
 
 char *qemu_find_file(int type, const char *name)
 {
-    int len;
+    int i;
     const char *subdir;
     char *buf;
 
     /* Try the name as a straight path first */
     if (access(name, R_OK) == 0) {
+        trace_load_file(name, name);
         return g_strdup(name);
     }
+
     switch (type) {
     case QEMU_FILE_TYPE_BIOS:
         subdir = "";
@@ -2269,14 +2272,16 @@ char *qemu_find_file(int type, const char *name)
     default:
         abort();
     }
-    len = strlen(data_dir) + strlen(name) + strlen(subdir) + 2;
-    buf = g_malloc0(len);
-    snprintf(buf, len, "%s/%s%s", data_dir, subdir, name);
-    if (access(buf, R_OK)) {
+
+    for (i = 0; i < data_dir_idx; i++) {
+        buf = g_strdup_printf("%s/%s%s", data_dir[i], subdir, name);
+        if (access(buf, R_OK) == 0) {
+            trace_load_file(name, buf);
+            return buf;
+        }
         g_free(buf);
-        return NULL;
     }
-    return buf;
+    return NULL;
 }
 
 static int device_help_func(QemuOpts *opts, void *opaque)
@@ -3252,7 +3257,9 @@ int main(int argc, char **argv, char **envp)
                 add_device_config(DEV_GDB, optarg);
                 break;
             case QEMU_OPTION_L:
-                data_dir = optarg;
+                if (data_dir_idx < ARRAY_SIZE(data_dir)) {
+                    data_dir[data_dir_idx++] = optarg;
+                }
                 break;
             case QEMU_OPTION_bios:
                 bios_name = optarg;
@@ -3892,12 +3899,15 @@ int main(int argc, char **argv, char **envp)
 
     /* If no data_dir is specified then try to find it relative to the
        executable path.  */
-    if (!data_dir) {
-        data_dir = os_find_datadir(argv[0]);
+    if (data_dir_idx < ARRAY_SIZE(data_dir)) {
+        data_dir[data_dir_idx] = os_find_datadir(argv[0]);
+        if (data_dir[data_dir_idx] != NULL) {
+            data_dir_idx++;
+        }
     }
     /* If all else fails use the install path specified when building. */
-    if (!data_dir) {
-        data_dir = CONFIG_QEMU_DATADIR;
+    if (data_dir_idx < ARRAY_SIZE(data_dir)) {
+        data_dir[data_dir_idx++] = CONFIG_QEMU_DATADIR;
     }
 
     /*
-- 
1.7.9.7