>From 5442f45aea522a728fa5b06396d4f08d8506d7de Mon Sep 17 00:00:00 2001 From: Richard Jones Date: Tue, 16 Mar 2010 21:44:26 +0000 Subject: [PATCH 1/2] Allow qemu_supports to run earlier. Reimplement qemu_supports() internal function. Allow it to run before launch so we can test qemu features. Document that you should run guestfs_set_qemu as early as possible to make sure these tests are reliable. --- src/generator.ml | 10 +++++++++- src/guestfs.c | 27 ++++++++++++++++++--------- 2 files changed, 27 insertions(+), 10 deletions(-) diff --git a/src/generator.ml b/src/generator.ml index 486b9d8..4f569ba 100755 --- a/src/generator.ml +++ b/src/generator.ml @@ -581,7 +581,15 @@ configure script. You can also override this by setting the C environment variable. -Setting C to C restores the default qemu binary."); +Setting C to C restores the default qemu binary. + +Note that you should call this function as early as possible +after creating the handle. This is because some pre-launch +operations depend on testing qemu features (by running C). +If the qemu binary changes, we don't retest features, and +so you might see inconsistent results. Using the environment +variable C is safest of all since that picks +the qemu binary at the same time as the handle is created."); ("get_qemu", (RConstString "qemu", []), -1, [], [InitNone, Always, TestRun ( diff --git a/src/guestfs.c b/src/guestfs.c index 2ba062c..af60699 100644 --- a/src/guestfs.c +++ b/src/guestfs.c @@ -91,6 +91,7 @@ static int recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn); static int accept_from_daemon (guestfs_h *g); static int check_peer_euid (guestfs_h *g, int sock, uid_t *rtn); static void close_handles (void); +static int qemu_supports (guestfs_h *g, const char *option); #define UNIX_PATH_MAX 108 @@ -870,8 +871,6 @@ dir_contains_files (const char *dir, ...) static void print_timestamped_message (guestfs_h *g, const char *fs, ...); static int build_supermin_appliance (guestfs_h *g, const char *path, char **kernel, char **initrd); -static int test_qemu (guestfs_h *g); -static int qemu_supports (guestfs_h *g, const char *option); static int is_openable (guestfs_h *g, const char *path, int flags); static void print_cmdline (guestfs_h *g); @@ -1023,7 +1022,7 @@ guestfs__launch (guestfs_h *g) print_timestamped_message (g, "begin testing qemu features"); /* Get qemu help text and version. */ - if (test_qemu (g) == -1) + if (qemu_supports (g, NULL) == -1) goto cleanup0; /* Choose which vmchannel implementation to use. */ @@ -1607,11 +1606,6 @@ test_qemu (guestfs_h *g) char cmd[1024]; FILE *fp; - free (g->qemu_help); - free (g->qemu_version); - g->qemu_help = NULL; - g->qemu_version = NULL; - snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -help", g->qemu); fp = popen (cmd, "r"); @@ -1672,11 +1666,26 @@ read_all (guestfs_h *g, FILE *fp, char **ret) /* Test if option is supported by qemu command line (just by grepping * the help text). + * + * The first time this is used, it has to run the external qemu + * binary. If that fails, it returns -1. + * + * To just do the first-time run of the qemu binary, call this with + * option == NULL, in which case it will return -1 if there was an + * error doing that. */ static int qemu_supports (guestfs_h *g, const char *option) { - return g->qemu_help && strstr (g->qemu_help, option) != NULL; + if (!g->qemu_help) { + if (test_qemu (g) == -1) + return -1; + } + + if (option == NULL) + return 1; + + return strstr (g->qemu_help, option) != NULL; } /* Check if a file can be opened. */ -- 1.7.0.1