As of commit v5.9-rc1~160^2~3 the Linux kernel has close_range()
syscall, which closes not just one FD but whole range. Then, in
its commit glibc-2.34~115 glibc introduced closefrom() which is
just a wrapper over close_range(), but it allows us to use
FreeBSD-only implementation on Linux too, as both OS-es now have
the same function.
Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
meson.build | 1 +
src/util/vircommand.c | 124 ++++++++++++++++++++++--------------------
2 files changed, 66 insertions(+), 59 deletions(-)
diff --git a/meson.build b/meson.build
index aa391e7178..a4b52b6156 100644
--- a/meson.build
+++ b/meson.build
@@ -573,6 +573,7 @@ libvirt_export_dynamic = cc.first_supported_link_argument([
# check availability of various common functions (non-fatal if missing)
functions = [
+ 'closefrom',
'elf_aux_info',
'explicit_bzero',
'fallocate',
diff --git a/src/util/vircommand.c b/src/util/vircommand.c
index 49abb53c28..b8b8d48f92 100644
--- a/src/util/vircommand.c
+++ b/src/util/vircommand.c
@@ -479,7 +479,68 @@ virExecCommon(virCommand *cmd, gid_t *groups, int ngroups)
return 0;
}
-# ifdef __linux__
+# ifdef WITH_CLOSEFROM
+# define USE_CLOSEFROM
+# else
+# define USE_GENERIC
+# endif
+
+
+# ifdef USE_CLOSEFROM
+static int
+virCommandMassClose(virCommand *cmd,
+ int childin,
+ int childout,
+ int childerr)
+{
+ int lastfd = -1;
+ int fd = -1;
+ size_t i;
+
+ /*
+ * Two phases of closing.
+ *
+ * The first (inefficient) phase iterates over FDs,
+ * preserving certain FDs we need to pass down, and
+ * closing others. The number of iterations is bounded
+ * to the number of the biggest FD we need to preserve.
+ *
+ * The second (speedy) phase uses closefrom() to cull
+ * all remaining FDs in the process.
+ *
+ * Usually the first phase will be fairly quick only
+ * processing a handful of low FD numbers, and thus using
+ * closefrom() is a massive win for high ulimit() NFILES
+ * values.
+ */
+ lastfd = MAX(lastfd, childin);
+ lastfd = MAX(lastfd, childout);
+ lastfd = MAX(lastfd, childerr);
+
+ for (i = 0; i < cmd->npassfd; i++)
+ lastfd = MAX(lastfd, cmd->passfd[i].fd);
+
+ for (fd = 0; fd <= lastfd; fd++) {
+ if (fd == childin || fd == childout || fd == childerr)
+ continue;
+ if (!virCommandFDIsSet(cmd, fd)) {
+ int tmpfd = fd;
+ VIR_MASS_CLOSE(tmpfd);
+ } else if (virSetInherit(fd, true) < 0) {
+ virReportSystemError(errno, _("failed to preserve fd %1$d"), fd);
+ return -1;
+ }
+ }
+
+ closefrom(lastfd + 1);
+
+ return 0;
+}
+# endif /* ! WITH_CLOSEFROM */
+
+
+# ifdef USE_GENERIC
+# ifdef __linux__
/* On Linux, we can utilize procfs and read the table of opened
* FDs and selectively close only those FDs we don't want to pass
* onto child process (well, the one we will exec soon since this
@@ -515,7 +576,7 @@ virCommandMassCloseGetFDsLinux(virCommand *cmd G_GNUC_UNUSED,
return 0;
}
-# else /* !__linux__ */
+# else /* !__linux__ */
static int
virCommandMassCloseGetFDsGeneric(virCommand *cmd G_GNUC_UNUSED,
@@ -524,61 +585,7 @@ virCommandMassCloseGetFDsGeneric(virCommand *cmd G_GNUC_UNUSED,
virBitmapSetAll(fds);
return 0;
}
-# endif /* !__linux__ */
-
-# ifdef __FreeBSD__
-
-static int
-virCommandMassClose(virCommand *cmd,
- int childin,
- int childout,
- int childerr)
-{
- int lastfd = -1;
- int fd = -1;
- size_t i;
-
- /*
- * Two phases of closing.
- *
- * The first (inefficient) phase iterates over FDs,
- * preserving certain FDs we need to pass down, and
- * closing others. The number of iterations is bounded
- * to the number of the biggest FD we need to preserve.
- *
- * The second (speedy) phase uses closefrom() to cull
- * all remaining FDs in the process.
- *
- * Usually the first phase will be fairly quick only
- * processing a handful of low FD numbers, and thus using
- * closefrom() is a massive win for high ulimit() NFILES
- * values.
- */
- lastfd = MAX(lastfd, childin);
- lastfd = MAX(lastfd, childout);
- lastfd = MAX(lastfd, childerr);
-
- for (i = 0; i < cmd->npassfd; i++)
- lastfd = MAX(lastfd, cmd->passfd[i].fd);
-
- for (fd = 0; fd <= lastfd; fd++) {
- if (fd == childin || fd == childout || fd == childerr)
- continue;
- if (!virCommandFDIsSet(cmd, fd)) {
- int tmpfd = fd;
- VIR_MASS_CLOSE(tmpfd);
- } else if (virSetInherit(fd, true) < 0) {
- virReportSystemError(errno, _("failed to preserve fd %1$d"), fd);
- return -1;
- }
- }
-
- closefrom(lastfd + 1);
-
- return 0;
-}
-
-# else /* ! __FreeBSD__ */
+# endif /* !__linux__ */
static int
virCommandMassClose(virCommand *cmd,
@@ -628,8 +635,7 @@ virCommandMassClose(virCommand *cmd,
return 0;
}
-
-# endif /* ! __FreeBSD__ */
+# endif /* ! USE_GENERIC */
/*
--
2.39.3
