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loop: refactor: extract subfunction set_loopdev_params()

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Extract subfunction set_loop_info() from set_loop()

function                                             old     new   delta
set_loop                                             760     784     +24

Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Xiaoming Ni 2022-12-13 13:13:23 +01:00 committed by Denys Vlasenko
parent 7dc76c9f21
commit a1856934ba
1 changed files with 51 additions and 39 deletions
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82
libbb/loop.c
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@ -110,6 +110,51 @@ static int get_next_free_loop(char *dev, int id)
return loopdevno; 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. /* 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 * *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. * 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 dev[LOOP_NAMESIZE];
char *try; char *try;
bb_loop_info loopinfo;
struct stat statbuf; struct stat statbuf;
int i, lfd, ffd, mode, rc; 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; goto try_next_loopN;
} }
rc = ioctl(lfd, BB_LOOP_GET_STATUS, &loopinfo); rc = set_loopdev_params(ffd, lfd, file, offset, sizelimit, flags);
/* 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) { if (rc == 0) {
/* SUCCESS! */ /* SUCCESS! */
if (!*device) /* was looping in search of free "/dev/loopN"? */ if (!*device)
*device = xstrdup(dev); *device = xstrdup(dev);
rc = lfd; /* return this */
break; break;
} }
/* failure, undo LOOP_SET_FD */
ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary
}
close_and_try_next_loopN:
close(lfd); close(lfd);
try_next_loopN: try_next_loopN:
rc = -1; rc = -1;