[Qemu-devel] [PATCH 3/3] -readconfig: accept fd=<fd> option (v2)

[Eduardo Habkost <ehabkost@redhat.com>]

Chhanges v1 -> v2:
 - Moved code to qemu-config-arch.c

Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qemu-config-arch.c |   21 +++++++++++++++++++--
 qemu-config.c      |   16 ++++++++++++++++
 qemu-config.h      |    4 ++++
 qemu-options.hx    |    6 +++---
 4 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/qemu-config-arch.c b/qemu-config-arch.c
index 9180b73..ee5d515 100644
--- a/qemu-config-arch.c
+++ b/qemu-config-arch.c
@@ -23,6 +23,7 @@
  */
 #include "qemu-config-arch.h"
 #include "qemu-option.h"
+#include "qemu-error.h"
 
 /* Not on vm_config_groups because this is not a global option setable by -set
  * (QEMU_OPTION_set), just settings used to parse -readconfig argument.
@@ -36,21 +37,37 @@ static QemuOptsList qemu_readconfig_opts = {
             .name = "path",
             .type = QEMU_OPT_STRING,
         },
+        {
+            .name = "fd",
+            .type = QEMU_OPT_NUMBER,
+        },
         { /*End of list */ }
     },
 };
 
+
 /* Read Qemu config file based on parsed QemuOpts object
  *
  * Returns 0 on success, -errno on failure.
  */
 static int qemu_read_config_opts(QemuOpts *opts)
 {
+    int fd = -1;
+    uint64_t fd_arg = qemu_opt_get_number(opts, "fd", (uint64_t)-1);
     const char *path = qemu_opt_get(opts, "path");
-    if (!path) {
+
+    if (fd_arg != (uint64_t)-1) {
+        fd = fd_arg;
+    }
+
+    if (path) {
+        return qemu_read_config_filename(path);
+    } else if (fd >= 0) {
+        return qemu_read_config_fd(fd);
+    } else {
+        error_report("no fd or path set for config file");
         return -EINVAL;
     }
-    return qemu_read_config_filename(path);
 }
 
 /* Read config file based on option arguments on 'arg'
diff --git a/qemu-config.c b/qemu-config.c
index a2c8453..750626d 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -846,3 +846,19 @@ int qemu_read_config_filename(const char *filename)
     }
     return qemu_read_config_file(f, filename);
 }
+
+/* Read Qemu config file from file descriptor
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int qemu_read_config_fd(int fd)
+{
+    /* For the "<fd:%d>" pseudo-filename, used only for error messages */
+    char fname[16];
+    FILE *f = fdopen(fd, "r");
+    if (f == NULL) {
+        return -errno;
+    }
+    snprintf(fname, sizeof(fname), "<fd:%d>", fd);
+    return qemu_read_config_file(f, fname);
+}
diff --git a/qemu-config.h b/qemu-config.h
index c2ab4fc..28356a6 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -20,4 +20,8 @@ int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char *fname);
  */
 int qemu_read_config_filename(const char *filename);
 
+/* Read config from file descriptor
+ */
+int qemu_read_config_fd(int fd);
+
 #endif /* QEMU_CONFIG_H */
diff --git a/qemu-options.hx b/qemu-options.hx
index 5d14f92..ae64ca8 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2655,11 +2655,11 @@ Old param mode (ARM only).
 ETEXI
 
 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
-    "-readconfig [path=]<file>\n", QEMU_ARCH_ALL)
+    "-readconfig [path=]<file>|fd=<fd>\n", QEMU_ARCH_ALL)
 STEXI
-@item -readconfig [type=]@var{file}
+@item -readconfig [path=]@var{file}|fd=@var{fd}
 @findex -readconfig
-Read device configuration from @var{file}.
+Read device configuration from @var{file}, or from file descriptor @var{fd}.
 ETEXI
 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
     "-writeconfig <file>\n"
-- 
1.7.3.2