[Qemu-devel] [PATCH v3 2/5] add qemu_fopen_err

[Alon Levy <alevy@redhat.com>]

This adds a helper to conveniently set the correct error based on the
errno after a failed fopen.

The added function is placed in it's own c file to allow libcacard to
not develop dependencies on everything that qerror will bring in, which
includes monitor and half of qemu. I tried to make it as less ugly as I
could, by naming an osdep-no-qerror-obj-y and having that included in
osdep-obj-y, and using only the former for libcacard.

Signed-off-by: Alon Levy <alevy@redhat.com>
---
 Makefile.objs      |    8 +++++---
 libcacard/Makefile |    2 +-
 osdep-qerror.c     |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 osdep-qerror.h     |    8 ++++++++
 osdep.c            |    1 -
 5 files changed, 66 insertions(+), 5 deletions(-)
 create mode 100644 osdep-qerror.c
 create mode 100644 osdep-qerror.h

diff --git a/Makefile.objs b/Makefile.objs
index 226b01d..fb5a73a 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -20,9 +20,11 @@ universal-obj-y += $(qom-obj-y)
 
 #######################################################################
 # oslib-obj-y is code depending on the OS (win32 vs posix)
-oslib-obj-y = osdep.o
-oslib-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o
-oslib-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
+oslib-no-qerror-obj-y = osdep.o
+oslib-no-qerror-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o
+oslib-no-qerror-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
+oslib-obj-y = $(oslib-no-qerror-obj-y)
+oslib-obj-y += osdep-qerror.o
 
 #######################################################################
 # coroutines
diff --git a/libcacard/Makefile b/libcacard/Makefile
index c6a896a..83f483f 100644
--- a/libcacard/Makefile
+++ b/libcacard/Makefile
@@ -8,7 +8,7 @@ libcacard_includedir=$(includedir)/cacard
 $(call set-vpath, $(SRC_PATH):$(libcacard_srcpath))
 
 # objects linked against normal qemu binaries, not compiled with libtool
-QEMU_OBJS=$(addprefix ../,$(oslib-obj-y) qemu-timer-common.o $(trace-obj-y))
+QEMU_OBJS=$(addprefix ../,$(oslib-no-qerror-obj-y) qemu-timer-common.o $(trace-obj-y))
 
 # objects linked into a shared library, built with libtool with -fPIC if required
 QEMU_OBJS_LIB=$(addsuffix .lo,$(basename $(QEMU_OBJS)))
diff --git a/osdep-qerror.c b/osdep-qerror.c
new file mode 100644
index 0000000..6dac984
--- /dev/null
+++ b/osdep-qerror.c
@@ -0,0 +1,52 @@
+#include "qerror.h"
+
+#include "osdep-qerror.h"
+
+/*
+ * Helper to set an Error after a failed fopen.
+ *
+ * Uses errno so it must not be changed by another intermediate call.
+ */
+void qemu_fopen_err(Error **errp, const char *file_name)
+{
+    const char *fmt = NULL;
+
+    switch (errno) {
+    case EACCES:
+        fmt = QERR_EACCES;
+        break;
+    case EINTR:
+        fmt = QERR_EINTR;
+        break;
+    case EEXIST:
+        fmt = QERR_EEXIST;
+        break;
+    case EMFILE:
+        fmt = QERR_OPEN_FILE_EMFILE;
+        break;
+    case ENOSPC:
+        fmt = QERR_ENOSPC;
+        break;
+    case EPERM:
+        fmt = QERR_EPERM;
+        break;
+    case EROFS:
+        fmt = QERR_READ_ONLY;
+        break;
+    case ENOTDIR:
+        fmt = QERR_ENOTDIR;
+        break;
+    case EFBIG:
+        fmt = QERR_EFBIG;
+        break;
+    default:
+        /*
+         * EINVAL and ENOTSUP will result in the default
+         *
+         * ENOENT too, it's used by (for instance) bdrv_create_file for
+         * a different purpose then open (2) so just give a generic error.
+         */
+        fmt = QERR_OPEN_FILE_FAILED;
+    }
+    error_set(errp, fmt, file_name);
+}
diff --git a/osdep-qerror.h b/osdep-qerror.h
new file mode 100644
index 0000000..7320f4a
--- /dev/null
+++ b/osdep-qerror.h
@@ -0,0 +1,8 @@
+#ifndef OSDEP_QERROR_H
+#define OSDEP_QERROR_H
+
+#include "error.h"
+
+void qemu_fopen_err(Error **errp, const char *file_name);
+
+#endif
diff --git a/osdep.c b/osdep.c
index 3e6bada..efdd21c 100644
--- a/osdep.c
+++ b/osdep.c
@@ -241,4 +241,3 @@ ssize_t qemu_recv_full(int fd, void *buf, size_t count, int flags)
 
     return total;
 }
-
-- 
1.7.9.3