[openwrt/openwrt] scripts: mkhash fail on hashing a folder

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/fcd3e13779ca644bfbb0940f39fdf13203bf8211

commit fcd3e13779ca644bfbb0940f39fdf13203bf8211
Author: Paul Spooren <mail at aparcar.org>
AuthorDate: Thu Jul 16 22:19:32 2020 -1000

    scripts: mkhash fail on hashing a folder
    
    mkhash currently returns the hash of an empty input when trying to hash
    a folder. This can be missleading in caseswhere e.g. an env variable is
    undefined which should contain a filename. `mkhash ./path/to/$FILE`
    would exit with code 0 and return a legit looking checksum.
    
    A better behaviour would be to fail with exit code 1, which imitates the
    behaviour of `md5sum` and `sha256sum`.
    
    To avoid hashing of folders the `stat()` is checked.
    
    Hashing empty inputs result in the following checksums:
    md5: d41d8cd98f00b204e9800998ecf8427e
    sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
    
    Signed-off-by: Paul Spooren <mail at aparcar.org>
---
 scripts/mkhash.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/scripts/mkhash.c b/scripts/mkhash.c
index ce156e979d..ced4f3c34a 100644
--- a/scripts/mkhash.c
+++ b/scripts/mkhash.c
@@ -85,6 +85,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #define ARRAY_SIZE(_n) (sizeof(_n) / sizeof((_n)[0]))
 
@@ -770,6 +771,13 @@ static int hash_file(struct hash_type *t, const char *filename, bool add_filenam
 	if (!filename || !strcmp(filename, "-")) {
 		str = t->func(stdin);
 	} else {
+		struct stat path_stat;
+		stat(filename, &path_stat);
+		if (S_ISDIR(path_stat.st_mode)) {
+			fprintf(stderr, "Failed to open '%s': Is a directory\n", filename);
+			return 1;
+		}
+
 		FILE *f = fopen(filename, "r");
 
 		if (!f) {