[Qemu-devel] [PATCH 1/2] create ga_run_program() helper for guest-set-user-password

[Denis V. Lunev]

From: Yuriy Pudgorodskiy <address@hidden>

This helper properly starts chpasswd and collects stdout/stderr of this
program to report it as error to the caller.

The code will be reused later to run useradd in addition to chpasswd.

This code is made specifically for Linux and is inside ifdef Linux braces.

Signed-off-by: Yuri Pudgorodskiy <address@hidden>
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Eric Blake <address@hidden>
CC: Michael Roth <address@hidden>
---
 qga/commands-posix.c | 201 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 141 insertions(+), 60 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 8fe708f..53e8d3b 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -75,6 +75,28 @@ static void ga_wait_child(pid_t pid, int *status, Error 
**errp)
     g_assert(rpid == pid);
 }
 
+static void ga_pipe_read_str(int fd[2], char **str, size_t *len)
+{
+    ssize_t n;
+    char buf[1024];
+    close(fd[1]);
+    fd[1] = -1;
+    while ((n = read(fd[0], buf, sizeof(buf))) != 0) {
+        if (n < 0) {
+            if (errno == EINTR) {
+                continue;
+            } else {
+                break;
+            }
+        }
+        *str = g_realloc(*str, *len + n);
+        memcpy(*str + *len, buf, n);
+        *len += n;
+    }
+    close(fd[0]);
+    fd[0] = -1;
+}
+
 void qmp_guest_shutdown(bool has_mode, const char *mode, Error **errp)
 {
     const char *shutdown_flag;
@@ -1952,20 +1974,128 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList 
*vcpus, Error **errp)
     return processed;
 }
 
+/* Helper to run command with input/output redirection,
+ * sending string to stdin and taking error message from
+ * stdout/err
+ */
+static void ga_run_program(const char *argv[],
+                           const char *in_str,
+                           const char *action, Error **errp)
+{
+    pid_t pid;
+    int status;
+    int infd[2] = { -1, -1 };
+    int outfd[2] = { -1, -1 };
+    char *str = NULL;
+    size_t len = 0;
+
+    if (in_str) {
+        if (pipe(infd) < 0) {
+            error_setg(errp, "cannot create pipe FDs");
+            goto out;
+        }
+    }
+
+    if (pipe(outfd) < 0) {
+        error_setg(errp, "cannot create pipe FDs");
+        goto out;
+    }
+
+    pid = fork();
+    if (pid == 0) {
+        /* child */
+        setsid();
+        if (in_str) {
+            /* redirect stdin to infd */
+            close(infd[1]);
+            dup2(infd[0], 0);
+            close(infd[0]);
+        } else {
+            reopen_fd_to_null(0);
+        }
+
+        /* redirect stdout/stderr to outfd */
+        close(outfd[0]);
+        dup2(outfd[1], 1);
+        dup2(outfd[1], 2);
+        close(outfd[1]);
+
+        execve(argv[0], (char *const *)argv, environ);
+        _exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        error_setg_errno(errp, errno, "failed to create child process");
+        goto out;
+    }
+
+    if (in_str) {
+        close(infd[0]);
+        infd[0] = -1;
+        if (qemu_write_full(infd[1],
+                    in_str, strlen(in_str)) != strlen(in_str)) {
+            error_setg_errno(errp, errno,
+                    "%s: cannot write to stdin pipe", action);
+            goto out;
+        }
+        close(infd[1]);
+        infd[1] = -1;
+    }
+
+
+    ga_pipe_read_str(outfd, &str, &len);
+
+    ga_wait_child(pid, &status, errp);
+    if (*errp) {
+        goto out;
+    }
+
+    if (!WIFEXITED(status)) {
+        if (len) {
+            error_setg(errp, "child process has terminated abnormally: "
+                    "%s", str);
+        } else {
+            error_setg(errp, "child process has terminated abnormally");
+        }
+        goto out;
+    }
+
+    if (WEXITSTATUS(status)) {
+        if (len) {
+            error_setg(errp, "child process has failed to %s: %s",
+                    action, str);
+        } else {
+            error_setg(errp, "child process has failed to %s: exit status %d",
+                    action, WEXITSTATUS(status));
+        }
+        goto out;
+    }
+
+out:
+    g_free(str);
+
+    if (infd[0] != -1) {
+        close(infd[0]);
+    }
+    if (infd[1] != -1) {
+        close(infd[1]);
+    }
+    if (outfd[0] != -1) {
+        close(outfd[0]);
+    }
+    if (outfd[1] != -1) {
+        close(outfd[1]);
+    }
+}
+
 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;
+    const char *chpasswd_argv[] = { NULL /*path*/, "chpasswd", "-e", NULL };
 
     rawpasswddata = (char *)qbase64_decode(password, -1, &rawpasswdlen, errp);
     if (!rawpasswddata) {
@@ -1986,75 +2116,26 @@ void qmp_guest_set_user_password(const char *username,
     }
 
     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;
-    }
+    chpasswd_argv[0] = passwd_path;
 
-    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;
+    /* set password for existed user */
+    if (!crypted) {
+        /* wipe -e option */
+        chpasswd_argv[2] = NULL;
     }
+    ga_run_program(chpasswd_argv, chpasswddata, "set user password", errp);
 
 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]);
-    }
 }
 
 static void ga_read_sysfs_file(int dirfd, const char *pathname, char *buf,
-- 
2.1.4