xxd: allow "-" as file name meaning stdin

[oweals/busybox.git] / libbb / loop.c

diff --git a/libbb/loop.c b/libbb/loop.c
index d30b378d7541d5ab4bff00a0b12082f317b57486..f0d4296ae9454020b26eea3aec7f39e7b18c07a7 100644 (file)
--- a/libbb/loop.c
+++ b/libbb/loop.c
@@ -78,22 +78,24 @@ int FAST_FUNC del_loop(const char *device)
        return rc;
 }
 
-/* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
-   *device is loop device to use, or if *device==NULL finds a loop device to
-   mount it on and sets *device to a strdup of that loop device name.  This
-   search will re-use an existing loop device already bound to that
-   file/offset if it finds one.
+/* Returns opened fd to the loop device, <0 on error.
+ * *device is loop device to use, or if *device==NULL finds a loop device to
+ * mount it on and sets *device to a strdup of that loop device name.  This
+ * search will re-use an existing loop device already bound to that
+ * file/offset if it finds one.
  */
-int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, int ro)
+int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, unsigned flags)
 {
        char dev[LOOP_NAMESIZE];
        char *try;
        bb_loop_info loopinfo;
        struct stat statbuf;
-       int i, dfd, ffd, mode, rc = -1;
+       int i, dfd, ffd, mode, rc;
+
+       rc = dfd = -1;
 
        /* Open the file.  Barf if this doesn't work.  */
-       mode = ro ? O_RDONLY : O_RDWR;
+       mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
  open_ffd:
        ffd = open(file, mode);
        if (ffd < 0) {
@@ -144,20 +146,35 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse
 
                /* If device is free, claim it.  */
                if (rc && errno == ENXIO) {
-                       memset(&loopinfo, 0, sizeof(loopinfo));
-                       safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
-                       loopinfo.lo_offset = offset;
                        /* Associate free loop device with file.  */
                        if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
-                               if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
-                                       rc = 0;
-                               else
+                               memset(&loopinfo, 0, sizeof(loopinfo));
+                               safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
+                               loopinfo.lo_offset = offset;
+                               /*
+                                * Used by mount to set LO_FLAGS_AUTOCLEAR.
+                                * LO_FLAGS_READ_ONLY is not set because RO is controlled by open type of the file.
+                                * Note that closing LO_FLAGS_AUTOCLEARed dfd before mount
+                                * is wrong (would free the loop device!)
+                                */
+                               loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
+                               rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
+                               if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
+                                       /* Old kernel, does not support LO_FLAGS_AUTOCLEAR? */
+                                       /* (this code path is not tested) */
+                                       loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
+                                       rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
+                               }
+                               if (rc != 0) {
                                        ioctl(dfd, LOOP_CLR_FD, 0);
+                               }
                        }
                } else {
                        rc = -1;
                }
-               close(dfd);
+               if (rc != 0) {
+                       close(dfd);
+               }
  try_again:
                if (*device) break;
        }
@@ -165,7 +182,7 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse
        if (rc == 0) {
                if (!*device)
                        *device = xstrdup(dev);
-               return (mode == O_RDONLY); /* 1:ro, 0:rw */
+               return dfd;
        }
        return rc;
 }