[PATCH 3/3] libfile: add support for not clobbering files in copy_file

[Ahmad Fatoum <a.fatoum@barebox.org>]

copy_file will always overwrite an existing file and so will copy_recursive.
This is not always the intended behavior, so add a flag to control this.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 commands/Kconfig  |  4 +++-
 commands/cp.c     |  8 ++++++--
 include/libfile.h |  1 +
 lib/libfile.c     | 17 ++++++++++++-----
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/commands/Kconfig b/commands/Kconfig
index 7b84ef70e875..3ed2598ab65e 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -933,11 +933,13 @@ config CMD_CP
 	help
 	  Copy files
 
-	  Usage: cp [-v] SRC DEST
+	  Usage: cp [-rnv] SRC DEST
 
 	  Copy file from SRC to DEST.
 
 	  Options:
+		  -r    recursive
+		  -n    do not overwrite an existing file
 		  -v	verbose
 
 config CMD_CMP
diff --git a/commands/cp.c b/commands/cp.c
index 5b8d976c3cfe..dc38cbab889d 100644
--- a/commands/cp.c
+++ b/commands/cp.c
@@ -28,11 +28,14 @@ static int do_cp(int argc, char *argv[])
 	int flags = 0, recursive = 0;
 	int argc_min;
 
-	while ((opt = getopt(argc, argv, "vr")) > 0) {
+	while ((opt = getopt(argc, argv, "vnr")) > 0) {
 		switch (opt) {
 		case 'v':
 			flags |= COPY_FILE_VERBOSE;
 			break;
+		case 'n':
+			flags |= COPY_FILE_NO_OVERWRITE;
+			break;
 		case 'r':
 			recursive = 1;
 			break;
@@ -87,13 +90,14 @@ BAREBOX_CMD_HELP_TEXT("Copy file from SRC to DEST.")
 BAREBOX_CMD_HELP_TEXT("")
 BAREBOX_CMD_HELP_TEXT("Options:")
 BAREBOX_CMD_HELP_OPT ("-r", "recursive")
+BAREBOX_CMD_HELP_OPT ("-n", "do not overwrite an existing file")
 BAREBOX_CMD_HELP_OPT ("-v", "verbose")
 BAREBOX_CMD_HELP_END
 
 BAREBOX_CMD_START(cp)
 	.cmd		= do_cp,
 	BAREBOX_CMD_DESC("copy files")
-	BAREBOX_CMD_OPTS("[-rv] SRC DEST")
+	BAREBOX_CMD_OPTS("[-rnv] SRC DEST")
 	BAREBOX_CMD_GROUP(CMD_GRP_FILE)
 	BAREBOX_CMD_HELP(cmd_cp_help)
 BAREBOX_CMD_END
diff --git a/include/libfile.h b/include/libfile.h
index 4cb6e11110f5..26571945f678 100644
--- a/include/libfile.h
+++ b/include/libfile.h
@@ -29,6 +29,7 @@ int write_file(const char *filename, const void *buf, size_t size);
 int write_file_flash(const char *filename, const void *buf, size_t size);
 
 #define COPY_FILE_VERBOSE	BIT(0)
+#define COPY_FILE_NO_OVERWRITE	BIT(1)
 
 int copy_file(const char *src, const char *dst, unsigned flags);
 
diff --git a/lib/libfile.c b/lib/libfile.c
index aaade34a4c34..995531248ea4 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -435,6 +435,7 @@ EXPORT_SYMBOL(write_file_flash);
  * @flags:	A bitmask of COPY_FILE_* flags. Possible values:
  *
  *                COPY_FILE_VERBOSE: show a progression bar
+ *                COPY_FILE_NO_OVERWRITE: don't clobber existing files
  *
  * Return: 0 for success or negative error code
  */
@@ -467,8 +468,13 @@ int copy_file(const char *src, const char *dst, unsigned flags)
 	}
 
 	/* Set O_TRUNC only if file exists and is a regular file */
-	if (!s && S_ISREG(dststat.st_mode))
+	if (!s && S_ISREG(dststat.st_mode)) {
+		if (flags & COPY_FILE_NO_OVERWRITE) {
+			ret = 0;
+			goto out;
+		}
 		mode |= O_TRUNC;
+	}
 
 	dstfd = open(dst, mode);
 	if (dstfd < 0) {
@@ -498,7 +504,7 @@ int copy_file(const char *src, const char *dst, unsigned flags)
 		if (r < 0) {
 			perror("read");
 			ret = r;
-			goto out;
+			goto out_newline;
 		}
 		if (!r)
 			break;
@@ -506,7 +512,7 @@ int copy_file(const char *src, const char *dst, unsigned flags)
 		ret = write_full(dstfd, rw_buf, r);
 		if (ret < 0) {
 			perror("write");
-			goto out;
+			goto out_newline;
 		}
 
 		total += r;
@@ -520,10 +526,10 @@ int copy_file(const char *src, const char *dst, unsigned flags)
 	}
 
 	ret = 0;
-out:
+out_newline:
 	if (flags & COPY_FILE_VERBOSE)
 		putchar('\n');
-
+out:
 	free(rw_buf);
 	if (srcfd > 0)
 		close(srcfd);
@@ -541,6 +547,7 @@ EXPORT_SYMBOL(copy_file);
  * @flags:	A bitmask of COPY_FILE_* flags. Possible values:
  *
  *                COPY_FILE_VERBOSE: show a progression bar
+ *                COPY_FILE_NO_OVERWRITE: don't clobber existing files
  *
  * Return: 0 for success or negative error code
  */
-- 
2.39.5