[PATCH v4 5/9] loop:refactor: extract subfunction set_loop_configure()

[Xiaoming Ni]

Step 5 of micro-refactoring the set_loop():
	Extract subfunction set_loop_configure()

function                                             old     new   delta
set_loop                                             700     708      +8
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 8/0)                 Total: 8 bytes

Signed-off-by: Xiaoming Ni <nixiaoming at huawei.com>
---
 libbb/loop.c | 63 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 36 insertions(+), 27 deletions(-)

diff --git a/libbb/loop.c b/libbb/loop.c
index 5dd4d4e59..0d4d0398c 100644
--- a/libbb/loop.c
+++ b/libbb/loop.c
@@ -129,6 +129,41 @@ static int open_file(const char *file, unsigned flags, int *mode)
 	return ffd;
 }
 
+static int set_loop_configure(int ffd, int lfd, const char *file,
+		unsigned long long offset, unsigned long long sizelimit, unsigned flags)
+{
+	int rc;
+	bb_loop_info loopinfo;
+	/* Associate free loop device with file */
+	if (ioctl(lfd, LOOP_SET_FD, ffd)) {
+		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 lfd;
+	}
+	/* failure, undo LOOP_SET_FD */
+	ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary
+	return -1;
+}
+
 static int set_loop_info(int ffd, int lfd, const char *file,
 		unsigned long long offset, unsigned long long sizelimit, unsigned flags)
 {
@@ -139,33 +174,7 @@ static int set_loop_info(int ffd, int lfd, const char *file,
 
 	/* If device is free, try to claim it */
 	if (rc && errno == ENXIO) {
-		/* Associate free loop device with file */
-		if (ioctl(lfd, LOOP_SET_FD, ffd)) {
-			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 lfd;
-		}
-		/* failure, undo LOOP_SET_FD */
-		ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary
+		return set_loop_configure(ffd, lfd, file, offset, sizelimit, flags);
 	}
 	return -1;
 }
-- 
2.27.0