path: root/hw
diff options
authorMarkus Armbruster <armbru@redhat.com>2012-02-07 15:09:08 +0100
committerAnthony Liguori <aliguori@us.ibm.com>2012-02-24 09:06:56 -0600
commit1f51470d044852592922f91000e741c381582cdc (patch)
tree4091bdadd329db689e7359c3fe6741ced57d029f /hw
parentf0cdc966fb8998bc6acc15fbd360e52061495557 (diff)
Revert "qemu-char: Print strerror message on failure" and deps
The commit's purpose is laudable: The only way for chardev drivers to communicate an error was to return a NULL pointer, which resulted in an error message that said _that_ something went wrong, but not _why_. It attempts to achieve it by changing the interface to return 0/-errno and update qemu_chr_open_opts() to use strerror() to display a more helpful error message. Unfortunately, it has serious flaws: 1. Backends "socket" and "udp" return bogus error codes, because qemu_chr_open_socket() and qemu_chr_open_udp() assume that unix_listen_opts(), unix_connect_opts(), inet_listen_opts(), inet_connect_opts() and inet_dgram_opts() fail with errno set appropriately. That assumption is wrong, and the commit turns unspecific error messages into misleading error messages. For instance: $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx inet_connect: host and/or port not specified chardev: opening backend "socket" failed: No such file or directory ENOENT is what happens to be in my errno when the backend returns -errno. Let's put ERANGE there just for giggles: $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx -drive if=none,iops=99999999999999999999 inet_connect: host and/or port not specified chardev: opening backend "socket" failed: Numerical result out of range Worse: when errno happens to be zero, return -errno erroneously signals success, and qemu_chr_new_from_opts() dies dereferencing uninitialized chr. I observe this with "-serial unix:". 2. All qemu_chr_open_opts() knows about the error is an errno error code. That's simply not enough for a decent message. For instance, when inet_dgram() can't resolve the parameter host, which errno code should it use? What if it can't resolve parameter localaddr? Clue: many backends already report errors in their open methods. Let's revert the flawed commit along with its dependencies, and fix up the silent error paths instead. This reverts commit 6e1db57b2ac9025c2443c665a0d9e78748637b26. Conflicts: console.c hw/baum.c qemu-char.c This reverts commit aad04cd024f0c59f0b96f032cde2e24eb3abba6d. The parts of commit db418a0a "Add stdio char device on windows" that depend on the reverted change fixed up. Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'hw')
4 files changed, 7 insertions, 9 deletions
diff --git a/hw/baum.c b/hw/baum.c
index 86d780a61..3e94f84e5 100644
--- a/hw/baum.c
+++ b/hw/baum.c
@@ -562,7 +562,7 @@ static void baum_close(struct CharDriverState *chr)
-int chr_baum_init(QemuOpts *opts, CharDriverState **_chr)
+CharDriverState *chr_baum_init(QemuOpts *opts)
BaumDriverState *baum;
CharDriverState *chr;
@@ -614,8 +614,7 @@ int chr_baum_init(QemuOpts *opts, CharDriverState **_chr)
- *_chr = chr;
- return 0;
+ return chr;
@@ -624,5 +623,5 @@ fail_handle:
- return -EIO;
+ return NULL;
diff --git a/hw/baum.h b/hw/baum.h
index 3f28cc339..8af710fa2 100644
--- a/hw/baum.h
+++ b/hw/baum.h
@@ -23,4 +23,4 @@
/* char device */
-int chr_baum_init(QemuOpts *opts, CharDriverState **_chr);
+CharDriverState *chr_baum_init(QemuOpts *opts);
diff --git a/hw/msmouse.c b/hw/msmouse.c
index c3b57ea31..9c492a463 100644
--- a/hw/msmouse.c
+++ b/hw/msmouse.c
@@ -64,7 +64,7 @@ static void msmouse_chr_close (struct CharDriverState *chr)
g_free (chr);
-int qemu_chr_open_msmouse(QemuOpts *opts, CharDriverState **_chr)
+CharDriverState *qemu_chr_open_msmouse(QemuOpts *opts)
CharDriverState *chr;
@@ -74,6 +74,5 @@ int qemu_chr_open_msmouse(QemuOpts *opts, CharDriverState **_chr)
qemu_add_mouse_event_handler(msmouse_event, chr, 0, "QEMU Microsoft Mouse");
- *_chr = chr;
- return 0;
+ return chr;
diff --git a/hw/msmouse.h b/hw/msmouse.h
index 8b853b35b..456cb2142 100644
--- a/hw/msmouse.h
+++ b/hw/msmouse.h
@@ -1,2 +1,2 @@
/* msmouse.c */
-int qemu_chr_open_msmouse(QemuOpts *opts, CharDriverState **_chr);
+CharDriverState *qemu_chr_open_msmouse(QemuOpts *opts);