Refuse a config directory before reading it

Git's build swaps in an fopen that refuses a directory, but only where
it defines FREAD_READS_DIRECTORIES, and not every system's build does.
There a directory opened, and only a failed read(2) reported it. POSIX
leaves that failure to the system, and one that read the raw entries
would have parsed them as settings.

1 file changed, 7 insertions, 1 deletion

diff --git a/source/config.c b/source/config.cindex bfd31b6..84c7293 100644--- a/source/config.c+++ b/source/config.c@@ -103,6 +103,7 @@ int config_file_parse(const char *filename, config_file_value_fn fn) 	int outer_lines_read = lines_read; 	struct strbuf name = STRBUF_INIT; 	struct strbuf value = STRBUF_INIT;+	struct stat st; 	FILE *f; 	int err = 0; @@ -112,12 +113,17 @@ int config_file_parse(const char *filename, config_file_value_fn fn) 		return 0; 	if (!(f = fopen(filename, "r"))) 		return errno;+	// Git's fopen refuses a directory only where its build defines+	// FREAD_READS_DIRECTORIES, and elsewhere read(2) need not fail on one.+	if (!fstat(fileno(f), &st) && S_ISDIR(st.st_mode)) {+		fclose(f);+		return EISDIR;+	} 	config_origin.file = filename; 	lines_read = 0; 	nesting++; 	while (read_entry(f, &name, &value, &config_origin.line)) 		fn(name.buf, value.buf);-	// A directory opens like a file and fails only once it is read. 	if (ferror(f)) 		err = errno; 	nesting--;
diff --git a/source/config.c b/source/config.c
index bfd31b6..84c7293 100644
--- a/source/config.c
+++ b/source/config.c
@@ -103,6 +103,7 @@ int config_file_parse(const char *filename, config_file_value_fn fn)
 	int outer_lines_read = lines_read;
 	struct strbuf name = STRBUF_INIT;
 	struct strbuf value = STRBUF_INIT;
+	struct stat st;
 	FILE *f;
 	int err = 0;
 
@@ -112,12 +113,17 @@ int config_file_parse(const char *filename, config_file_value_fn fn)
 		return 0;
 	if (!(f = fopen(filename, "r")))
 		return errno;
+	// Git's fopen refuses a directory only where its build defines
+	// FREAD_READS_DIRECTORIES, and elsewhere read(2) need not fail on one.
+	if (!fstat(fileno(f), &st) && S_ISDIR(st.st_mode)) {
+		fclose(f);
+		return EISDIR;
+	}
 	config_origin.file = filename;
 	lines_read = 0;
 	nesting++;
 	while (read_entry(f, &name, &value, &config_origin.line))
 		fn(name.buf, value.buf);
-	// A directory opens like a file and fails only once it is read.
 	if (ferror(f))
 		err = errno;
 	nesting--;