linux: Apply v2 version of patch for CLOEXEC changes

Somehow I managed to push v1 of the patch, which didn't handle older
versions of the kernel or C library that don't support the O_CLOEXEC
flag (suggested by Tim Roberts). This commit amends the original
changes in aa73b2e and provides this backwards compatibility.

Closes libusb#286

Signed-off-by: Chris Dickens <[email protected]>

libusb/os/linux_usbfs.c

@@ -81,6 +81,10 @@ static const char *usbfs_path = NULL;
 /* use usbdev*.* device names in /dev instead of the usbfs bus directories */
 static int usbdev_names = 0;
 
+/* Linux 2.6.23 adds support for O_CLOEXEC when opening files, which marks the
+ * close-on-exec flag in the underlying file descriptor. */
+static int supports_flag_cloexec = -1;
+
 /* Linux 2.6.32 adds support for a bulk continuation URB flag. this basically
  * allows us to mark URBs as being part of a specific logical transfer when
  * we submit them to the kernel. then, on any error except a cancellation, all
@@ -180,6 +184,16 @@ struct linux_transfer_priv {
  int iso_packet_offset;
 };
 
+static int _open(const char *path, int flags)
+{
+#if defined(O_CLOEXEC)
+ if (supports_flag_cloexec)
+ return open(path, flags | O_CLOEXEC);
+ else
+#endif
+ return open(path, flags);
+}
+
 static int _get_usbfs_fd(struct libusb_device *dev, mode_t mode, int silent)
 {
  struct libusb_context *ctx = DEVICE_CTX(dev);
@@ -194,7 +208,7 @@ static int _get_usbfs_fd(struct libusb_device *dev, mode_t mode, int silent)
  snprintf(path, PATH_MAX, "%s/%03d/%03d",
  usbfs_path, dev->bus_number, dev->device_address);
 
- fd = open(path, mode | O_CLOEXEC);
+ fd = _open(path, mode);
  if (fd != -1)
  return fd; /* Success */
 
@@ -205,7 +219,7 @@ static int _get_usbfs_fd(struct libusb_device *dev, mode_t mode, int silent)
  /* Wait 10ms for USB device path creation.*/
  nanosleep(&(struct timespec){delay / 1000000, (delay * 1000) % 1000000000UL}, NULL);
 
- fd = open(path, mode | O_CLOEXEC);
+ fd = _open(path, mode);
  if (fd != -1)
  return fd; /* Success */
  }
@@ -387,6 +401,15 @@ static int op_init(struct libusb_context *ctx)
  if (monotonic_clkid == -1)
  monotonic_clkid = find_monotonic_clock();
 
+ if (supports_flag_cloexec == -1) {
+ /* O_CLOEXEC flag available from Linux 2.6.23 */
+ supports_flag_cloexec = kernel_version_ge(2,6,23);
+ if (supports_flag_cloexec == -1) {
+ usbi_err(ctx, "error checking for O_CLOEXEC support");
+ return LIBUSB_ERROR_OTHER;
+ }
+ }
+
  if (supports_flag_bulk_continuation == -1) {
  /* bulk continuation URB flag available from Linux 2.6.32 */
  supports_flag_bulk_continuation = kernel_version_ge(2,6,32);
@@ -526,7 +549,7 @@ static int _open_sysfs_attr(struct libusb_device *dev, const char *attr)
 
  snprintf(filename, PATH_MAX, "%s/%s/%s",
  SYSFS_DEVICE_PATH, priv->sysfs_dir, attr);
- fd = open(filename, O_RDONLY | O_CLOEXEC);
+ fd = _open(filename, O_RDONLY);
  if (fd < 0) {
  usbi_err(DEVICE_CTX(dev),
  "open %s failed ret=%d errno=%d", filename, fd, errno);
@@ -542,12 +565,12 @@ static int __read_sysfs_attr(struct libusb_context *ctx,
 {
  char filename[PATH_MAX];
  FILE *f;
- int r, value;
+ int fd, r, value;
 
  snprintf(filename, PATH_MAX, "%s/%s/%s", SYSFS_DEVICE_PATH,
  devname, attr);
- f = fopen(filename, "re");
- if (f == NULL) {
+ fd = _open(filename, O_RDONLY);
+ if (fd == -1) {
  if (errno == ENOENT) {
  /* File doesn't exist. Assume the device has been
  disconnected (see trac ticket #70). */
@@ -557,6 +580,13 @@ static int __read_sysfs_attr(struct libusb_context *ctx,
  return LIBUSB_ERROR_IO;
  }
 
+ f = fdopen(fd, "r");
+ if (f == NULL) {
+ usbi_err(ctx, "fdopen %s failed errno=%d", filename, errno);
+ close(fd);
+ return LIBUSB_ERROR_OTHER;
+ }
+
  r = fscanf(f, "%d", &value);
  fclose(f);
  if (r != 1) {

libusb/version_nano.h

@@ -1 +1 @@
-#define LIBUSB_NANO 11194
+#define LIBUSB_NANO 11195