a1856934b
Xiaoming Ni
2022-12-13
Subject
loop: refactor: extract subfunction set_loopdev_params()
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libbb/loop.c+51 -39
| @@ -110,6 +110,51 @@ static int get_next_free_loop(char *dev, int id) | |
| return loopdevno; | |
| } | |
| + | static int set_loopdev_params(int ffd, |
| + | int lfd, const char *file, |
| + | unsigned long long offset, |
| + | unsigned long long sizelimit, |
| + | unsigned flags) |
| + | { |
| + | int rc; |
| + | bb_loop_info loopinfo; |
| + | |
| + | rc = ioctl(lfd, BB_LOOP_GET_STATUS, &loopinfo); |
| + | |
| + | /* If device is free, try to claim it */ |
| + | if (rc && errno == ENXIO) { |
| + | /* Associate free loop device with file */ |
| + | rc = ioctl(lfd, LOOP_SET_FD, ffd); |
| + | if (rc != 0) { |
| + | /* Ouch... race: the device already has a fd */ |
| + | return -1; |
| + | } |
| + | memset(&loopinfo, 0, sizeof(loopinfo)); |
| + | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE); |
| + | loopinfo.lo_offset = offset; |
| + | loopinfo.lo_sizelimit = sizelimit; |
| + | /* |
| + | * 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 lfd before mount |
| + | * is wrong (would free the loop device!) |
| + | */ |
| + | loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY); |
| + | rc = ioctl(lfd, 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(lfd, BB_LOOP_SET_STATUS, &loopinfo); |
| + | } |
| + | if (rc == 0) |
| + | return rc; /* SUCCESS! */ |
| + | /* failure, undo LOOP_SET_FD */ |
| + | ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary |
| + | } |
| + | return -1; |
| + | } |
| + | |
| /* 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. | |
| @@ -119,7 +164,6 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse | |
| { | |
| char dev[LOOP_NAMESIZE]; | |
| char *try; | |
| - | bb_loop_info loopinfo; |
| struct stat statbuf; | |
| int i, lfd, ffd, mode, rc; | |
| @@ -183,45 +227,13 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse | |
| goto try_next_loopN; | |
| } | |
| - | rc = ioctl(lfd, BB_LOOP_GET_STATUS, &loopinfo); |
| - | |
| - | /* If device is free, try to claim it */ |
| - | if (rc && errno == ENXIO) { |
| - | /* Associate free loop device with file */ |
| - | rc = ioctl(lfd, LOOP_SET_FD, ffd); |
| - | if (rc != 0) { |
| - | /* Ouch... race: the device already has a fd */ |
| - | goto close_and_try_next_loopN; |
| - | } |
| - | memset(&loopinfo, 0, sizeof(loopinfo)); |
| - | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE); |
| - | loopinfo.lo_offset = offset; |
| - | loopinfo.lo_sizelimit = sizelimit; |
| - | /* |
| - | * 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 lfd before mount |
| - | * is wrong (would free the loop device!) |
| - | */ |
| - | loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY); |
| - | rc = ioctl(lfd, 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(lfd, BB_LOOP_SET_STATUS, &loopinfo); |
| - | } |
| - | if (rc == 0) { |
| - | /* SUCCESS! */ |
| - | if (!*device) /* was looping in search of free "/dev/loopN"? */ |
| - | *device = xstrdup(dev); |
| - | rc = lfd; /* return this */ |
| - | break; |
| - | } |
| - | /* failure, undo LOOP_SET_FD */ |
| - | ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary |
| + | rc = set_loopdev_params(ffd, lfd, file, offset, sizelimit, flags); |
| + | if (rc == 0) { |
| + | /* SUCCESS! */ |
| + | if (!*device) |
| + | *device = xstrdup(dev); |
| + | break; |
| } | |
| - | close_and_try_next_loopN: |
| close(lfd); | |
| try_next_loopN: | |
| rc = -1; | |