diff options
Diffstat (limited to 'libbb/loop.c')
| -rw-r--r-- | libbb/loop.c | 49 |
1 files changed, 33 insertions, 16 deletions
diff --git a/libbb/loop.c b/libbb/loop.c index d30b378d7..f0d4296ae 100644 --- 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; } |