[Xen-devel] [PATCH] libxl: add libxl__forkexec function to libxl_exec

[Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>]

# HG changeset patch
# User Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>
# Date 1320677864 -3600
# Node ID df25a1143fcb3f8da24df033ac11d6e431992eb8
# Parent  26b36adc549cbb0856e15f59d3e69dd8255b3c3b
libxl: add libxl__forkexec function to libxl_exec

Add a new function to libxl_exec that performs a fork and executes the passed 
arguments using libxl__exec.

I was going to submit this as a part of the hotplug script calling from libxl 
series, but since it seems to be interesting for qcow/qcow2 support I decided 
to submit it separately.

Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>

diff -r 26b36adc549c -r df25a1143fcb tools/libxl/libxl_exec.c
--- a/tools/libxl/libxl_exec.c  Fri Sep 30 14:38:55 2011 +0200
+++ b/tools/libxl/libxl_exec.c  Mon Nov 07 15:57:44 2011 +0100
@@ -450,6 +450,40 @@ int libxl__spawn_check(libxl__gc *gc, li
     return ERROR_FAIL;
 }
 
+int libxl__forkexec(libxl__gc *gc, int stdinfd, int stdoutfd,
+                    int stderrfd, char **args)
+{
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+    int status;
+    int rc = 0;
+    pid_t pid = fork();
+
+    switch (pid) {
+    case -1:
+        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "fork failed\n");
+        rc = -1;
+        break;
+    case 0:
+        libxl__exec(stdinfd, stdoutfd, stderrfd, args[0], args);
+        /* libxl__exec never returns */
+    default:
+        while (waitpid(pid, &status, 0) < 0) {
+            if (errno != EINTR) {
+                LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "waitpid failed\n");
+                rc = -1;
+                break;
+            }
+        }
+        if (WIFEXITED(status)) {
+            rc = WEXITSTATUS(status);
+        } else {
+            rc = -1;
+        }
+        break;
+    }
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
diff -r 26b36adc549c -r df25a1143fcb tools/libxl/libxl_internal.h
--- a/tools/libxl/libxl_internal.h      Fri Sep 30 14:38:55 2011 +0200
+++ b/tools/libxl/libxl_internal.h      Mon Nov 07 15:57:44 2011 +0100
@@ -389,6 +389,20 @@ _hidden int libxl__spawn_check(libxl__gc
 _hidden void libxl__exec(int stdinfd, int stdoutfd, int stderrfd,
                const char *arg0, char **args); // logs errors, never returns
 
+/*
+ * libxl__forkexec - Executes a file synchronously
+ * gc: allocation pool
+ * stdinfd, stdoutfd, stderrfd: fds to pass to libxl__exec
+ * args: file to execute and arguments to pass in the following format
+ *      args[0]: file to execute
+ *      args[1]: first argument to pass to the called program
+ *      args[n]: nth argument to pass to the called program
+ *
+ * Returns 0 on success, and < 0 on error.
+ */
+_hidden int libxl__forkexec(libxl__gc *gc, int stdinfd, int stdoutfd,
+                            int stderrfd, char **args);
+
 /* from xl_create */
 _hidden int libxl__domain_make(libxl__gc *gc, libxl_domain_create_info *info, 
uint32_t *domid);
 _hidden int libxl__domain_build(libxl__gc *gc,

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