[01/10] qga: add guest-set-user-password command

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index f6f3e3c..57409d0 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -1875,6 +1875,108 @@  int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
     return processed;
 }
 
+void qmp_guest_set_user_password(const char *username,
+                                 const char *password,
+                                 bool crypted,
+                                 Error **errp)
+{
+    Error *local_err = NULL;
+    char *passwd_path = NULL;
+    pid_t pid;
+    int status;
+    int datafd[2] = { -1, -1 };
+    char *rawpasswddata = NULL;
+    size_t rawpasswdlen;
+    char *chpasswddata = NULL;
+    size_t chpasswdlen;
+
+    rawpasswddata = (char *)g_base64_decode(password, &rawpasswdlen);
+    rawpasswddata = g_renew(char, rawpasswddata, rawpasswdlen + 1);
+    rawpasswddata[rawpasswdlen] = '\0';
+
+    if (strchr(rawpasswddata, '\n')) {
+        error_setg(errp, "forbidden characters in raw password");
+        goto out;
+    }
+
+    if (strchr(username, '\n') ||
+        strchr(username, ':')) {
+        error_setg(errp, "forbidden characters in username");
+        goto out;
+    }
+
+    chpasswddata = g_strdup_printf("%s:%s\n", username, rawpasswddata);
+    chpasswdlen = strlen(chpasswddata);
+
+    passwd_path = g_find_program_in_path("chpasswd");
+
+    if (!passwd_path) {
+        error_setg(errp, "cannot find 'passwd' program in PATH");
+        goto out;
+    }
+
+    if (pipe(datafd) < 0) {
+        error_setg(errp, "cannot create pipe FDs");
+        goto out;
+    }
+
+    pid = fork();
+    if (pid == 0) {
+        close(datafd[1]);
+        /* child */
+        setsid();
+        dup2(datafd[0], 0);
+        reopen_fd_to_null(1);
+        reopen_fd_to_null(2);
+
+        if (crypted) {
+            execle(passwd_path, "chpasswd", "-e", NULL, environ);
+        } else {
+            execle(passwd_path, "chpasswd", NULL, environ);
+        }
+        _exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        error_setg_errno(errp, errno, "failed to create child process");
+        goto out;
+    }
+    close(datafd[0]);
+    datafd[0] = -1;
+
+    if (qemu_write_full(datafd[1], chpasswddata, chpasswdlen) != chpasswdlen) {
+        error_setg_errno(errp, errno, "cannot write new account password");
+        goto out;
+    }
+    close(datafd[1]);
+    datafd[1] = -1;
+
+    ga_wait_child(pid, &status, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        goto out;
+    }
+
+    if (!WIFEXITED(status)) {
+        error_setg(errp, "child process has terminated abnormally");
+        goto out;
+    }
+
+    if (WEXITSTATUS(status)) {
+        error_setg(errp, "child process has failed to set user password");
+        goto out;
+    }
+
+out:
+    g_free(chpasswddata);
+    g_free(rawpasswddata);
+    g_free(passwd_path);
+    if (datafd[0] != -1) {
+        close(datafd[0]);
+    }
+    if (datafd[1] != -1) {
+        close(datafd[1]);
+    }
+}
+
 #else /* defined(__linux__) */
 
 void qmp_guest_suspend_disk(Error **errp)
@@ -1910,6 +2012,14 @@  int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
     return -1;
 }
 
+void qmp_guest_set_user_password(const char *username,
+                                 const char *password,
+                                 bool crypted,
+                                 Error **errp)
+{
+    error_set(errp, QERR_UNSUPPORTED);
+}
+
 #endif
 
 #if !defined(CONFIG_FSFREEZE)
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 3bcbeae..11876f6 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -446,6 +446,14 @@  int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
     return -1;
 }
 
+void qmp_guest_set_user_password(const char *username,
+                                 const char *password,
+                                 bool crypted,
+                                 Error **errp)
+{
+    error_set(errp, QERR_UNSUPPORTED);
+}
+
 /* add unsupported commands to the blacklist */
 GList *ga_command_blacklist_init(GList *blacklist)
 {
@@ -454,6 +462,7 @@  GList *ga_command_blacklist_init(GList *blacklist)
         "guest-file-write", "guest-file-seek", "guest-file-flush",
         "guest-suspend-hybrid", "guest-network-get-interfaces",
         "guest-get-vcpus", "guest-set-vcpus",
+        "guest-set-user-password",
         "guest-fsfreeze-freeze-list", "guest-get-fsinfo",
         "guest-fstrim", NULL};
     char **p = (char **)list_unsupported;
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 376e79f..5117b65 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -738,3 +738,30 @@ 
 ##
 { 'command': 'guest-get-fsinfo',
   'returns': ['GuestFilesystemInfo'] }
+
+##
+# @guest-set-user-password
+#
+# @username: the user account whose password to change
+# @password: the new password entry string, base64 encoded
+# @crypted: true if password is already crypt()d, false if raw
+#
+# If the @crypted flag is true, it is the caller's responsibility
+# to ensure the correct crypt() encryption scheme is used. This
+# command does not attempt to interpret or report on the encryption
+# scheme. Refer to the documentation of the guest operating system
+# in question to determine what is supported.
+#
+# Note all guest operating systems will support use of the
+# @crypted flag, as they may require the clear-text password
+#
+# The @password parameter must always be base64 encoded before
+# transmission, even if already crypt()d, to ensure it is 8-bit
+# safe when passed as JSON.
+#
+# Returns: Nothing on success.
+#
+# Since 2.3
+##
+{ 'command': 'guest-set-user-password',
+  'data': { 'username': 'str', 'password': 'str', 'crypted': 'bool' } }