varint: use explicit width for integers

The varint subsystem currently uses implicit widths for integers. On the
one hand we use `uintmax_t` for the actual value. On the other hand, we
use `int` for the length of the encoded varint.

Both of these have known maximum values, as we only support at most 16
bytes when encoding varints. Thus, we know that we won't ever exceed
`uint64_t` for the actual value and `uint8_t` for the prefix length.

Refactor the code to use explicit widths. Besides making the logic
platform-independent, it also makes our life a bit easier in the next
commit, where we reimplement "varint.c" in Rust.

Suggested-by: Ezekiel Newren <ezekielnewren@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 8 deletions

diff --git a/dir.c b/dir.c
index 71108ac79b..0a67a99cb3 100644
--- a/dir.c
+++ b/dir.c
@@ -3579,7 +3579,8 @@ static void write_one_dir(struct untracked_cache_dir *untracked,
 	struct stat_data stat_data;
 	struct strbuf *out = &wd->out;
 	unsigned char intbuf[16];
-	unsigned int intlen, value;
+	unsigned int value;
+	uint8_t intlen;
 	int i = wd->index++;
 
 	/*
@@ -3632,7 +3633,7 @@ void write_untracked_extension(struct strbuf *out, struct untracked_cache *untra
 	struct ondisk_untracked_cache *ouc;
 	struct write_data wd;
 	unsigned char varbuf[16];
-	int varint_len;
+	uint8_t varint_len;
 	const unsigned hashsz = the_hash_algo->rawsz;
 
 	CALLOC_ARRAY(ouc, 1);
@@ -3738,7 +3739,7 @@ static int read_one_dir(struct untracked_cache_dir **untracked_,
 	struct untracked_cache_dir ud, *untracked;
 	const unsigned char *data = rd->data, *end = rd->end;
 	const unsigned char *eos;
-	unsigned int value;
+	uint64_t value;
 	int i;
 
 	memset(&ud, 0, sizeof(ud));
@@ -3830,7 +3831,8 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	struct read_data rd;
 	const unsigned char *next = data, *end = (const unsigned char *)data + sz;
 	const char *ident;
-	int ident_len;
+	uint64_t ident_len;
+	uint64_t varint_len;
 	ssize_t len;
 	const char *exclude_per_dir;
 	const unsigned hashsz = the_hash_algo->rawsz;
@@ -3867,8 +3869,8 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	if (next >= end)
 		goto done2;
 
-	len = decode_varint(&next);
-	if (next > end || len == 0)
+	varint_len = decode_varint(&next);
+	if (next > end || varint_len == 0)
 		goto done2;
 
 	rd.valid      = ewah_new();
@@ -3877,9 +3879,9 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	rd.data	      = next;
 	rd.end	      = end;
 	rd.index      = 0;
-	ALLOC_ARRAY(rd.ucd, len);
+	ALLOC_ARRAY(rd.ucd, varint_len);
 
-	if (read_one_dir(&uc->root, &rd) || rd.index != len)
+	if (read_one_dir(&uc->root, &rd) || rd.index != varint_len)
 		goto done;
 
 	next = rd.data;