Re: [Libguestfs] [p2v PATCH 03/10] nbd.c: simplify start_nbdkit()

The previous patch guarantees that start_nbdkit() is only called with a non-NULL "fds" parameter (and, consequently, that start_nbdkit() does not use "ipaddr" and "port" for anything beyond logging). Remove the branch in start_nbdkit() that starts nbdkit without socket activation, and trim the start_nbdkit() prototype too. This patch is best viewed with "git show -b" due to the unindentation in it. Ref: https://listman.redhat.com/archives/libguestfs/2022-March/028475.html Suggested-by: Richard W.M. Jones <rjones(a)redhat.com&gt; Signed-off-by: Laszlo Ersek <lersek(a)redhat.com&gt;

nbd.c | 54 ++++++-------------- 1 file changed, 16 insertions(+), 38 deletions(-) diff --git a/nbd.c b/nbd.c index edc3ab51d889..cda962d03bdd 100644 --- a/nbd.c +++ b/nbd.c @@ -80,7 +80,7 @@ static const enum nbd_server standard_servers[] = */ static enum nbd_server use_server; -static pid_t start_nbdkit (const char *device, const char *ipaddr, int port, int *fds, size_t nr_fds); +static pid_t start_nbdkit (const char *device, int *fds, size_t nr_fds); static int open_listening_socket (const char *ipaddr, int **fds, size_t *nr_fds); static int bind_tcpip_socket (const char *ipaddr, const char *port, int **fds, size_t *nr_fds); static int connect_with_source_port (const char *hostname, int dest_port, int source_port); @@ -238,29 +238,29 @@ pid_t start_nbd_server (const char **ipaddr, int *port, const char *device) { int *fds = NULL; size_t i, nr_fds; pid_t pid; switch (use_server) { case NBDKIT: /* nbdkit with socket activation */ *ipaddr = "localhost"; *port = open_listening_socket (*ipaddr, &fds, &nr_fds); if (*port == -1) return -1; - pid = start_nbdkit (device, *ipaddr, *port, fds, nr_fds); + pid = start_nbdkit (device, fds, nr_fds); for (i = 0; i < nr_fds; ++i) close (fds[i]); free (fds); return pid; } abort (); } #define FIRST_SOCKET_ACTIVATION_FD 3 /** * Set up file descriptors and environment variables for * socket activation. * * Note this function runs in the child between fork and exec. */ @@ -268,106 +268,84 @@ static inline void socket_activation (int *fds, size_t nr_fds) { size_t i; char nr_fds_str[16]; char pid_str[16]; if (fds == NULL) return; for (i = 0; i < nr_fds; ++i) { int fd = FIRST_SOCKET_ACTIVATION_FD + i; if (fds[i] != fd) { dup2 (fds[i], fd); close (fds[i]); } } snprintf (nr_fds_str, sizeof nr_fds_str, "%zu", nr_fds); setenv ("LISTEN_FDS", nr_fds_str, 1); snprintf (pid_str, sizeof pid_str, "%d", (int) getpid ()); setenv ("LISTEN_PID", pid_str, 1); } /** * Start a local L<nbdkit(1)> process using the * L<nbdkit-file-plugin(1)>. * - * If we are using socket activation, C<fds> and C<nr_fds> will - * contain the locally pre-opened file descriptors for this. - * Otherwise if C<fds == NULL> we pass the port number. + * C<fds> and C<nr_fds> will contain the locally pre-opened file descriptors + * for this. * * Returns the process ID (E<gt> 0) or C<0> if there is an error. */ static pid_t -start_nbdkit (const char *device, - const char *ipaddr, int port, int *fds, size_t nr_fds) +start_nbdkit (const char *device, int *fds, size_t nr_fds) { pid_t pid; - char port_str[64]; CLEANUP_FREE char *file_str = NULL; #if DEBUG_STDERR - fprintf (stderr, "starting nbdkit for %s on %s:%d%s\n", - device, ipaddr, port, - fds == NULL ? "" : " using socket activation"); + fprintf (stderr, "starting nbdkit for %s using socket activation\n", device); #endif - snprintf (port_str, sizeof port_str, "%d", port); - if (asprintf (&file_str, "file=%s", device) == -1) error (EXIT_FAILURE, errno, "asprintf"); pid = fork (); if (pid == -1) { set_nbd_error ("fork: %m"); return 0; } if (pid == 0) { /* Child. */ close (0); if (open ("/dev/null", O_RDONLY) == -1) { perror ("open: /dev/null"); _exit (EXIT_FAILURE); } - if (fds == NULL) { /* without socket activation */ - execlp ("nbdkit", - "nbdkit", - "-r", /* readonly (vital!) */ - "-p", port_str, /* listening port */ - "-i", ipaddr, /* listen only on loopback interface */ - "-f", /* don't fork */ - "file", /* file plugin */ - file_str, /* a device like file=/dev/sda */ - NULL); - perror ("nbdkit"); - _exit (EXIT_FAILURE); - } - else { /* socket activation */ - socket_activation (fds, nr_fds); + socket_activation (fds, nr_fds); - execlp ("nbdkit", - "nbdkit", - "-r", /* readonly (vital!) */ - "-f", /* don't fork */ - "file", /* file plugin */ - file_str, /* a device like file=/dev/sda */ - NULL); - perror ("nbdkit"); - _exit (EXIT_FAILURE); - } + execlp ("nbdkit", + "nbdkit", + "-r", /* readonly (vital!) */ + "-f", /* don't fork */ + "file", /* file plugin */ + file_str, /* a device like file=/dev/sda */ + NULL); + perror ("nbdkit"); + _exit (EXIT_FAILURE); } /* Parent. */ return pid; } /** * This is used when we are starting an NBD server which supports * socket activation. We can open a listening socket on an unused * local port and return it. * * Returns the port number on success or C<-1> on error. * * The file descriptor(s) bound are returned in the array *fds, *nr_fds. * The caller must free the array. */ -- 2.19.1.3.g30247aa5d201 _______________________________________________ Libguestfs mailing list Libguestfs(a)redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs