qemu-config: add error propagation to qemu_config_parse

This enables some simplification of vl.c via error_fatal, and improves
error messages.  Before:

  $ ./qemu-system-x86_64 -readconfig .
  qemu-system-x86_64: error reading file
  qemu-system-x86_64: -readconfig .: read config .: Invalid argument
  $ /usr/libexec/qemu-kvm -readconfig foo
  qemu-kvm: -readconfig foo: read config foo: No such file or directory

After:

  $ ./qemu-system-x86_64 -readconfig .
  qemu-system-x86_64: -readconfig .: Cannot read config file: Is a directory
  $ ./qemu-system-x86_64 -readconfig foo
  qemu-system-x86_64: -readconfig foo: Could not open 'foo': No such file or directory

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210226170816.231173-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 12 insertions, 11 deletions

diff --git a/util/qemu-config.c b/util/qemu-config.c
index e2a700b284..670bd6ebca 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -350,7 +350,7 @@ void qemu_config_write(FILE *fp)
 }
 
 /* Returns number of config groups on success, -errno on error */
-int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
+int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname, Error **errp)
 {
     char line[1024], group[64], id[64], arg[64], value[1024];
     Location loc;
@@ -375,7 +375,7 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
             /* group with id */
             list = find_list(lists, group, &local_err);
             if (local_err) {
-                error_report_err(local_err);
+                error_propagate(errp, local_err);
                 goto out;
             }
             opts = qemu_opts_create(list, id, 1, NULL);
@@ -386,7 +386,7 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
             /* group without id */
             list = find_list(lists, group, &local_err);
             if (local_err) {
-                error_report_err(local_err);
+                error_propagate(errp, local_err);
                 goto out;
             }
             opts = qemu_opts_create(list, NULL, 0, &error_abort);
@@ -398,21 +398,21 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname)
             sscanf(line, " %63s = \"\"", arg) == 1) {
             /* arg = value */
             if (opts == NULL) {
-                error_report("no group defined");
+                error_setg(errp, "no group defined");
                 goto out;
             }
-            if (!qemu_opt_set(opts, arg, value, &local_err)) {
-                error_report_err(local_err);
+            if (!qemu_opt_set(opts, arg, value, errp)) {
                 goto out;
             }
             continue;
         }
-        error_report("parse error");
+        error_setg(errp, "parse error");
         goto out;
     }
     if (ferror(fp)) {
-        error_report("error reading file");
-        goto out;
+        loc_pop(&loc);
+        error_setg_errno(errp, errno, "Cannot read config file");
+        return res;
     }
     res = count;
 out:
@@ -420,16 +420,17 @@ out:
     return res;
 }
 
-int qemu_read_config_file(const char *filename)
+int qemu_read_config_file(const char *filename, Error **errp)
 {
     FILE *f = fopen(filename, "r");
     int ret;
 
     if (f == NULL) {
+        error_setg_file_open(errp, errno, filename);
         return -errno;
     }
 
-    ret = qemu_config_parse(f, vm_config_groups, filename);
+    ret = qemu_config_parse(f, vm_config_groups, filename, errp);
     fclose(f);
     return ret;
 }