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>

diff --git a/dir.c b/dir.c
index 71108ac79b78b84332b5306e8fe0327ce194d09b..0a67a99cb3dd3f29ab1984db5c090438106aac1b 100644 (file)
--- 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;

diff --git a/read-cache.c b/read-cache.c
index 06ad74db2286aee617b0f7bf5eb3c15cc252a3bf..41b44148b1e04fabb84a290ebf34a8838a507381 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -1807,7 +1807,7 @@ static struct cache_entry *create_from_disk(struct mem_pool *ce_mem_pool,
 
        if (expand_name_field) {
                const unsigned char *cp = (const unsigned char *)name;
-               size_t strip_len, previous_len;
+               uint64_t strip_len, previous_len;
 
                /* If we're at the beginning of a block, ignore the previous name */
                strip_len = decode_varint(&cp);
@@ -2655,8 +2655,10 @@ static int ce_write_entry(struct hashfile *f, struct cache_entry *ce,
                hashwrite(f, ce->name, len);
                hashwrite(f, padding, align_padding_size(size, len));
        } else {
-               int common, to_remove, prefix_size;
+               int common, to_remove;
+               uint8_t prefix_size;
                unsigned char to_remove_vi[16];
+
                for (common = 0;
                     (common < previous_name->len &&
                      ce->name[common] &&

diff --git a/varint.c b/varint.c
index 409c4977a1e3a3a72dcd1452b41abdcb5a42b665..03cd54416b6a46256fd31e27abb08af5a758edfc 100644 (file)
--- a/varint.c
+++ b/varint.c
@@ -1,11 +1,11 @@
 #include "git-compat-util.h"
 #include "varint.h"
 
-uintmax_t decode_varint(const unsigned char **bufp)
+uint64_t decode_varint(const unsigned char **bufp)
 {
        const unsigned char *buf = *bufp;
        unsigned char c = *buf++;
-       uintmax_t val = c & 127;
+       uint64_t val = c & 127;
        while (c & 128) {
                val += 1;
                if (!val || MSB(val, 7))
@@ -17,7 +17,7 @@ uintmax_t decode_varint(const unsigned char **bufp)
        return val;
 }
 
-int encode_varint(uintmax_t value, unsigned char *buf)
+uint8_t encode_varint(uint64_t value, unsigned char *buf)
 {
        unsigned char varint[16];
        unsigned pos = sizeof(varint) - 1;

diff --git a/varint.h b/varint.h
index f78bb0ca528dcd2b955fba8ca1d9e3db7f776abb..eb401935bd24c9040694497dc7d5d39b007c3aab 100644 (file)
--- a/varint.h
+++ b/varint.h
@@ -1,7 +1,7 @@
 #ifndef VARINT_H
 #define VARINT_H
 
-int encode_varint(uintmax_t, unsigned char *);
-uintmax_t decode_varint(const unsigned char **);
+uint8_t encode_varint(uint64_t, unsigned char *);
+uint64_t decode_varint(const unsigned char **);
 
 #endif /* VARINT_H */