include/qemu/osdep.h: Add Emscripten-specific OS dependencies

On emscripten, some implementations in os-posix.c can't be used such as
daemonizing and changing user. This commit introduces os-wasm.c and
os-wasm.h which are forked from os-posix.c and os-posix.h and patched for
targetting Emscripten.

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
Link: https://lore.kernel.org/r/9fc7b106ecf86675b4532bd6778b7b5945442f89.1745820062.git.ktokunaga.mail@gmail.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -628,6 +628,12 @@ F: .gitlab-ci.d/cirrus/macos-*
 F: */*.m
 F: scripts/entitlement.sh
 
+WebAssembly
+M: Kohei Tokunaga <ktokunaga.mail@gmail.com>
+S: Maintained
+F: include/system/os-wasm.h
+F: os-wasm.c
+
 Alpha Machines
 --------------
 M: Richard Henderson <richard.henderson@linaro.org>

include/qemu/osdep.h

@@ -8,7 +8,7 @@
  * To avoid getting into possible circular include dependencies, this
  * file should not include any other QEMU headers, with the exceptions
  * of config-host.h, config-target.h, qemu/compiler.h,
- * system/os-posix.h, system/os-win32.h, glib-compat.h and
+ * system/os-posix.h, system/os-win32.h, system/os-wasm.h, glib-compat.h and
  * qemu/typedefs.h, all of which are doing a similar job to this file
  * and are under similar constraints.
  *
@@ -164,10 +164,14 @@ QEMU_EXTERN_C int daemon(int, int);
 #include "system/os-win32.h"
 #endif
 
-#ifdef CONFIG_POSIX
+#if defined(CONFIG_POSIX) && !defined(EMSCRIPTEN)
 #include "system/os-posix.h"
 #endif
 
+#if defined(EMSCRIPTEN)
+#include "system/os-wasm.h"
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif

include/system/os-wasm.h

@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * posix specific declarations forked from os-posix.h, removing functions not
+ * working on Emscripten
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2010 Jes Sorensen <Jes.Sorensen@redhat.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef QEMU_OS_WASM_H
+#define QEMU_OS_WASM_H
+
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <sys/un.h>
+
+#ifdef CONFIG_SYSMACROS
+#include <sys/sysmacros.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void os_set_line_buffering(void);
+void os_setup_early_signal_handling(void);
+void os_set_proc_name(const char *s);
+void os_setup_signal_handling(void);
+void os_setup_limits(void);
+void os_setup_post(void);
+int os_mlock(bool on_fault);
+static inline int os_set_daemonize(bool d)
+{
+    return -1;
+};
+bool is_daemonized(void);
+static inline void os_daemonize(void) {}
+
+/**
+ * qemu_alloc_stack:
+ * @sz: pointer to a size_t holding the requested usable stack size
+ *
+ * Allocate memory that can be used as a stack, for instance for
+ * coroutines. If the memory cannot be allocated, this function
+ * will abort (like g_malloc()). This function also inserts an
+ * additional guard page to catch a potential stack overflow.
+ * Note that the memory required for the guard page and alignment
+ * and minimal stack size restrictions will increase the value of sz.
+ *
+ * The allocated stack must be freed with qemu_free_stack().
+ *
+ * Returns: pointer to (the lowest address of) the stack memory.
+ */
+void *qemu_alloc_stack(size_t *sz);
+
+/**
+ * qemu_free_stack:
+ * @stack: stack to free
+ * @sz: size of stack in bytes
+ *
+ * Free a stack allocated via qemu_alloc_stack(). Note that sz must
+ * be exactly the adjusted stack size returned by qemu_alloc_stack.
+ */
+void qemu_free_stack(void *stack, size_t sz);
+
+/* POSIX and Mingw32 differ in the name of the stdio lock functions.  */
+
+static inline void qemu_flockfile(FILE *f)
+{
+    flockfile(f);
+}
+
+static inline void qemu_funlockfile(FILE *f)
+{
+    funlockfile(f);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

os-wasm.c

@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * os-wasm.c
+ * Forked from os-posix.c, removing functions not working on Emscripten
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2010 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include <sys/resource.h>
+#include <sys/wait.h>
+#include <pwd.h>
+#include <grp.h>
+#include <libgen.h>
+
+#include "qemu/error-report.h"
+#include "qemu/log.h"
+#include "system/runstate.h"
+#include "qemu/cutils.h"
+
+void os_setup_post(void){}
+void os_set_line_buffering(void)
+{
+    setvbuf(stdout, NULL, _IOLBF, 0);
+}
+void os_setup_early_signal_handling(void)
+{
+    struct sigaction act;
+    sigfillset(&act.sa_mask);
+    act.sa_flags = 0;
+    act.sa_handler = SIG_IGN;
+    sigaction(SIGPIPE, &act, NULL);
+}
+void os_set_proc_name(const char *s)
+{
+    error_report("Change of process name not supported by your OS");
+    exit(1);
+}
+static void termsig_handler(int signal, siginfo_t *info, void *c)
+{
+    qemu_system_killed(info->si_signo, info->si_pid);
+}
+
+void os_setup_signal_handling(void)
+{
+    struct sigaction act;
+
+    memset(&act, 0, sizeof(act));
+    act.sa_sigaction = termsig_handler;
+    act.sa_flags = SA_SIGINFO;
+    sigaction(SIGINT,  &act, NULL);
+    sigaction(SIGHUP,  &act, NULL);
+    sigaction(SIGTERM, &act, NULL);
+}
+void os_setup_limits(void)
+{
+    struct rlimit nofile;
+
+    if (getrlimit(RLIMIT_NOFILE, &nofile) < 0) {
+        warn_report("unable to query NOFILE limit: %s", strerror(errno));
+        return;
+    }
+
+    if (nofile.rlim_cur == nofile.rlim_max) {
+        return;
+    }
+
+    nofile.rlim_cur = nofile.rlim_max;
+
+    if (setrlimit(RLIMIT_NOFILE, &nofile) < 0) {
+        warn_report("unable to set NOFILE limit: %s", strerror(errno));
+        return;
+    }
+}
+int os_mlock(bool on_fault)
+{
+#ifdef HAVE_MLOCKALL
+    int ret = 0;
+    int flags = MCL_CURRENT | MCL_FUTURE;
+
+    if (on_fault) {
+#ifdef HAVE_MLOCK_ONFAULT
+        flags |= MCL_ONFAULT;
+#else
+        error_report("mlockall: on_fault not supported");
+        return -EINVAL;
+#endif
+    }
+
+    ret = mlockall(flags);
+    if (ret < 0) {
+        error_report("mlockall: %s", strerror(errno));
+    }
+
+    return ret;
+#else
+    (void)on_fault;
+    return -ENOSYS;
+#endif
+}