[Libguestfs] [PATCH nbdkit 2/5] vddk: Move reexec code to a new file.
Richard W.M. Jones
rjones at redhat.com
Tue Jun 2 12:27:03 UTC 2020
Pure refactoring. Just decouples the complicated reexec code from the
rest.
---
plugins/vddk/Makefile.am | 2 +
plugins/vddk/vddk.h | 42 +++++++++
plugins/vddk/reexec.c | 196 +++++++++++++++++++++++++++++++++++++++
plugins/vddk/vddk.c | 151 ++----------------------------
4 files changed, 246 insertions(+), 145 deletions(-)
diff --git a/plugins/vddk/Makefile.am b/plugins/vddk/Makefile.am
index 740c42d6..d4b123e9 100644
--- a/plugins/vddk/Makefile.am
+++ b/plugins/vddk/Makefile.am
@@ -42,6 +42,8 @@ plugin_LTLIBRARIES = nbdkit-vddk-plugin.la
nbdkit_vddk_plugin_la_SOURCES = \
vddk.c \
+ vddk.h \
+ reexec.c \
vddk-structs.h \
vddk-stubs.h \
$(top_srcdir)/include/nbdkit-plugin.h \
diff --git a/plugins/vddk/vddk.h b/plugins/vddk/vddk.h
new file mode 100644
index 00000000..e229e55e
--- /dev/null
+++ b/plugins/vddk/vddk.h
@@ -0,0 +1,42 @@
+/* nbdkit
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef NBDKIT_VDDK_H
+#define NBDKIT_VDDK_H
+
+extern char *libdir;
+extern char *reexeced;
+
+extern void reexec_if_needed (const char *prepend);
+extern int restore_ld_library_path (void);
+
+#endif /* NBDKIT_VDDK_H */
diff --git a/plugins/vddk/reexec.c b/plugins/vddk/reexec.c
new file mode 100644
index 00000000..5a5e9844
--- /dev/null
+++ b/plugins/vddk/reexec.c
@@ -0,0 +1,196 @@
+/* nbdkit
+ * Copyright (C) 2013-2020 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#define NBDKIT_API_VERSION 2
+#include <nbdkit-plugin.h>
+
+#include "cleanup.h"
+#include "vector.h"
+
+#include "vddk.h"
+
+char *reexeced; /* orig LD_LIBRARY_PATH on reexec */
+
+DEFINE_VECTOR_TYPE(string_vector, char *);
+
+#define CLEANUP_FREE_STRING_VECTOR \
+ __attribute__((cleanup (cleanup_free_string_vector)))
+
+static void
+cleanup_free_string_vector (string_vector *v)
+{
+ string_vector_iter (v, (void *) free);
+ free (v->ptr);
+}
+
+/* Perform a re-exec that temporarily modifies LD_LIBRARY_PATH. Does
+ * not return on success; on failure, problems have been logged, but
+ * the caller prefers to proceed as if this had not been attempted.
+ * Thus, no return value is needed.
+ */
+static void
+perform_reexec (const char *env, const char *prepend)
+{
+ CLEANUP_FREE char *library = NULL;
+ CLEANUP_FREE_STRING_VECTOR string_vector argv = empty_vector;
+ int fd;
+ size_t len = 0, buflen = 512;
+ CLEANUP_FREE char *buf = NULL;
+
+ /* In order to re-exec, we need our original command line. The
+ * Linux kernel does not make it easy to know in advance how large
+ * it was, so we just slurp in the whole file, doubling our reads
+ * until we get a short read. This assumes nbdkit did not alter its
+ * original argv[].
+ */
+ fd = open ("/proc/self/cmdline", O_RDONLY);
+ if (fd == -1) {
+ nbdkit_debug ("failure to parse original argv: %m");
+ return;
+ }
+
+ do {
+ char *p = realloc (buf, buflen * 2);
+ ssize_t r;
+
+ if (!p) {
+ nbdkit_debug ("failure to parse original argv: %m");
+ return;
+ }
+ buf = p;
+ buflen *= 2;
+ r = read (fd, buf + len, buflen - len);
+ if (r == -1) {
+ nbdkit_debug ("failure to parse original argv: %m");
+ return;
+ }
+ len += r;
+ } while (len == buflen);
+ nbdkit_debug ("original command line occupies %zu bytes", len);
+
+ /* Split cmdline into argv, then append one more arg. */
+ buflen = len;
+ len = 0;
+ while (len < buflen) {
+ if (string_vector_append (&argv, buf + len) == -1) {
+ argv_realloc_fail:
+ nbdkit_debug ("argv: realloc: %m");
+ return;
+ }
+ len += strlen (buf + len) + 1;
+ }
+ if (!env)
+ env = "";
+ nbdkit_debug ("adding reexeced_=%s", env);
+ if (asprintf (&reexeced, "reexeced_=%s", env) == -1)
+ goto argv_realloc_fail;
+ if (string_vector_append (&argv, reexeced) == -1)
+ goto argv_realloc_fail;
+ if (string_vector_append (&argv, NULL) == -1)
+ goto argv_realloc_fail;
+
+ if (env[0]) {
+ if (asprintf (&library, "%s:%s", prepend, env) == -1)
+ assert (library == NULL);
+ }
+ else
+ library = strdup (prepend);
+ if (!library || setenv ("LD_LIBRARY_PATH", library, 1) == -1) {
+ nbdkit_debug ("failure to set LD_LIBRARY_PATH: %m");
+ return;
+ }
+
+ nbdkit_debug ("re-executing with updated LD_LIBRARY_PATH=%s", library);
+ fflush (NULL);
+ execvp ("/proc/self/exe", argv.ptr);
+ nbdkit_debug ("failure to execvp: %m");
+}
+
+/* See if prepend is already in LD_LIBRARY_PATH; if not, re-exec. */
+void
+reexec_if_needed (const char *prepend)
+{
+ const char *env = getenv ("LD_LIBRARY_PATH");
+ CLEANUP_FREE char *haystack = NULL;
+ CLEANUP_FREE char *needle = NULL;
+
+ if (reexeced)
+ return;
+ if (env && asprintf (&haystack, ":%s:", env) >= 0 &&
+ asprintf (&needle, ":%s:", prepend) >= 0 &&
+ strstr (haystack, needle) != NULL)
+ return;
+
+ perform_reexec (env, prepend);
+}
+
+/* If load_library caused a re-execution with an expanded
+ * LD_LIBRARY_PATH, restore it back to its original contents, passed
+ * as the value of "reexeced_". dlopen uses the value of
+ * LD_LIBRARY_PATH cached at program startup; our change is for the
+ * sake of child processes (such as --run) to see the same
+ * environment as the original nbdkit saw before re-exec.
+ */
+int
+restore_ld_library_path (void)
+{
+ if (reexeced) {
+ char *env = getenv ("LD_LIBRARY_PATH");
+
+ nbdkit_debug ("cleaning up after re-exec");
+ if (!env || strstr (env, reexeced) == NULL ||
+ (libdir && strncmp (env, libdir, strlen (libdir)) != 0)) {
+ nbdkit_error ("'reexeced_' set with garbled environment");
+ return -1;
+ }
+ if (reexeced[0]) {
+ if (setenv ("LD_LIBRARY_PATH", reexeced, 1) == -1) {
+ nbdkit_error ("setenv: %m");
+ return -1;
+ }
+ }
+ else if (unsetenv ("LD_LIBRARY_PATH") == -1) {
+ nbdkit_error ("unsetenv: %m");
+ return -1;
+ }
+ }
+
+ return 0;
+}
diff --git a/plugins/vddk/vddk.c b/plugins/vddk/vddk.c
index 4815a43e..eb865cc2 100644
--- a/plugins/vddk/vddk.c
+++ b/plugins/vddk/vddk.c
@@ -40,7 +40,6 @@
#include <string.h>
#include <unistd.h>
#include <dlfcn.h>
-#include <fcntl.h>
#include <libgen.h>
#include <pthread.h>
@@ -52,8 +51,8 @@
#include "isaligned.h"
#include "minmax.h"
#include "rounding.h"
-#include "vector.h"
+#include "vddk.h"
#include "vddk-structs.h"
/* Debug flags. */
@@ -76,13 +75,12 @@ int vddk_debug_datapath = 1;
static void *dl; /* dlopen handle */
static bool init_called; /* was InitEx called */
-static char *reexeced; /* orig LD_LIBRARY_PATH on reexec */
static pthread_key_t error_suppression; /* threadlocal error suppression */
static char *config; /* config */
static const char *cookie; /* cookie */
static const char *filename; /* file */
-static char *libdir; /* libdir */
+char *libdir; /* libdir */
static uint16_t nfc_host_port; /* nfchostport */
static char *password; /* password */
static uint16_t port; /* port */
@@ -293,119 +291,6 @@ vddk_config (const char *key, const char *value)
return 0;
}
-/* Perform a re-exec that temporarily modifies LD_LIBRARY_PATH. Does
- * not return on success; on failure, problems have been logged, but
- * the caller prefers to proceed as if this had not been attempted.
- * Thus, no return value is needed.
- */
-DEFINE_VECTOR_TYPE(string_vector, char *);
-
-#define CLEANUP_FREE_STRING_VECTOR \
- __attribute__((cleanup (cleanup_free_string_vector)))
-
-static void
-cleanup_free_string_vector (string_vector *v)
-{
- string_vector_iter (v, (void *) free);
- free (v->ptr);
-}
-
-static void
-perform_reexec (const char *env, const char *prepend)
-{
- CLEANUP_FREE char *library = NULL;
- CLEANUP_FREE_STRING_VECTOR string_vector argv = empty_vector;
- int fd;
- size_t len = 0, buflen = 512;
- CLEANUP_FREE char *buf = NULL;
-
- /* In order to re-exec, we need our original command line. The
- * Linux kernel does not make it easy to know in advance how large
- * it was, so we just slurp in the whole file, doubling our reads
- * until we get a short read. This assumes nbdkit did not alter its
- * original argv[].
- */
- fd = open ("/proc/self/cmdline", O_RDONLY);
- if (fd == -1) {
- nbdkit_debug ("failure to parse original argv: %m");
- return;
- }
-
- do {
- char *p = realloc (buf, buflen * 2);
- ssize_t r;
-
- if (!p) {
- nbdkit_debug ("failure to parse original argv: %m");
- return;
- }
- buf = p;
- buflen *= 2;
- r = read (fd, buf + len, buflen - len);
- if (r == -1) {
- nbdkit_debug ("failure to parse original argv: %m");
- return;
- }
- len += r;
- } while (len == buflen);
- nbdkit_debug ("original command line occupies %zu bytes", len);
-
- /* Split cmdline into argv, then append one more arg. */
- buflen = len;
- len = 0;
- while (len < buflen) {
- if (string_vector_append (&argv, buf + len) == -1) {
- argv_realloc_fail:
- nbdkit_debug ("argv: realloc: %m");
- return;
- }
- len += strlen (buf + len) + 1;
- }
- if (!env)
- env = "";
- nbdkit_debug ("adding reexeced_=%s", env);
- if (asprintf (&reexeced, "reexeced_=%s", env) == -1)
- goto argv_realloc_fail;
- if (string_vector_append (&argv, reexeced) == -1)
- goto argv_realloc_fail;
- if (string_vector_append (&argv, NULL) == -1)
- goto argv_realloc_fail;
-
- if (env[0]) {
- if (asprintf (&library, "%s:%s", prepend, env) == -1)
- assert (library == NULL);
- }
- else
- library = strdup (prepend);
- if (!library || setenv ("LD_LIBRARY_PATH", library, 1) == -1) {
- nbdkit_debug ("failure to set LD_LIBRARY_PATH: %m");
- return;
- }
-
- nbdkit_debug ("re-executing with updated LD_LIBRARY_PATH=%s", library);
- fflush (NULL);
- execvp ("/proc/self/exe", argv.ptr);
- nbdkit_debug ("failure to execvp: %m");
-}
-
-/* See if prepend is already in LD_LIBRARY_PATH; if not, re-exec. */
-static void
-check_reexec (const char *prepend)
-{
- const char *env = getenv ("LD_LIBRARY_PATH");
- CLEANUP_FREE char *haystack = NULL;
- CLEANUP_FREE char *needle = NULL;
-
- if (reexeced)
- return;
- if (env && asprintf (&haystack, ":%s:", env) >= 0 &&
- asprintf (&needle, ":%s:", prepend) >= 0 &&
- strstr (haystack, needle) != NULL)
- return;
-
- perform_reexec (env, prepend);
-}
-
/* Load the VDDK library. */
static void
load_library (bool load_error_is_fatal)
@@ -453,7 +338,7 @@ load_library (bool load_error_is_fatal)
* includes its directory for all future loads. This may modify
* path in-place and/or re-exec nbdkit, but that's okay.
*/
- check_reexec (dirname (path));
+ reexec_if_needed (dirname (path));
break;
}
if (i == 0) {
@@ -498,33 +383,9 @@ vddk_config_complete (void)
return -1;
}
- /* If load_library caused a re-execution with an expanded
- * LD_LIBRARY_PATH, restore it back to its original contents, passed
- * as the value of "reexeced_". dlopen uses the value of
- * LD_LIBRARY_PATH cached at program startup; our change is for the
- * sake of child processes (such as --run) to see the same
- * environment as the original nbdkit saw before re-exec.
- */
- if (reexeced) {
- char *env = getenv ("LD_LIBRARY_PATH");
-
- nbdkit_debug ("cleaning up after re-exec");
- if (!env || strstr (env, reexeced) == NULL ||
- (libdir && strncmp (env, libdir, strlen (libdir)) != 0)) {
- nbdkit_error ("'reexeced_' set with garbled environment");
- return -1;
- }
- if (reexeced[0]) {
- if (setenv ("LD_LIBRARY_PATH", reexeced, 1) == -1) {
- nbdkit_error ("setenv: %m");
- return -1;
- }
- }
- else if (unsetenv ("LD_LIBRARY_PATH") == -1) {
- nbdkit_error ("unsetenv: %m");
- return -1;
- }
- }
+ /* Restore original LD_LIBRARY_PATH after reexec. */
+ if (restore_ld_library_path () == -1)
+ return -1;
/* For remote connections, check all the parameters have been
* passed. Note that VDDK will segfault if parameters that it
--
2.25.0
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