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[PATCH v2 03/13] hex: introduce functions to print arbitrary hashes

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Oct 15, 2018, 02:18 UTC
Message-ID
<20181015021900.1030041-4-sandals@crustytoothpaste.net>
In-Reply-To
<20181015021900.1030041-1-sandals@crustytoothpaste.net>

Currently, we have functions that turn an arbitrary SHA-1 value or an object ID into hex format, either using a static buffer or with a user-provided buffer. Add variants of these functions that can handle an arbitrary hash algorithm, specified by constant. Update the documentation as well.

While we're at it, remove the "extern" declaration from this family of functions, since it's not needed and our style now recommends against it.

We use the variant taking the algorithm structure pointer as the internal variant, since taking an algorithm pointer is the easiest way to handle all of the variants in use.

Note that we maintain these functions because there are hashes which must change based on the hash algorithm in use but are not object IDs (such as pack checksums).

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 cache.h | 15 +++++++++------
 hex.c   | 37 +++++++++++++++++++++++++++++--------
 2 files changed, 38 insertions(+), 14 deletions(-)
diff --git a/cache.h b/cache.h
index d508f3d4f8..a13d14ce0a 100644
--- a/cache.h
+++ b/cache.h
@@ -1361,9 +1361,9 @@ extern int get_oid_hex(const char *hex, struct object_id *sha1);
 extern int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
 
 /*
- * Convert a binary sha1 to its hex equivalent. The `_r` variant is reentrant,
+ * Convert a binary hash to its hex equivalent. The `_r` variant is reentrant,
  * and writes the NUL-terminated output to the buffer `out`, which must be at
- * least `GIT_SHA1_HEXSZ + 1` bytes, and returns a pointer to out for
+ * least `GIT_MAX_HEXSZ + 1` bytes, and returns a pointer to out for
  * convenience.
  *
  * The non-`_r` variant returns a static buffer, but uses a ring of 4
@@ -1371,10 +1371,13 @@ extern int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
  *
  *   printf("%s -> %s", sha1_to_hex(one), sha1_to_hex(two));
  */
-extern char *sha1_to_hex_r(char *out, const unsigned char *sha1);
-extern char *oid_to_hex_r(char *out, const struct object_id *oid);
-extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */
-extern char *oid_to_hex(const struct object_id *oid);	/* same static buffer as sha1_to_hex */
+char *hash_to_hex_algo_r(char *buffer, const unsigned char *hash, int algo);
+char *sha1_to_hex_r(char *out, const unsigned char *sha1);
+char *oid_to_hex_r(char *out, const struct object_id *oid);
+char *hash_to_hex_algo(const unsigned char *hash, int algo);	/* static buffer result! */
+char *sha1_to_hex(const unsigned char *sha1);			/* same static buffer */
+char *hash_to_hex(const unsigned char *hash);			/* same static buffer */
+char *oid_to_hex(const struct object_id *oid);			/* same static buffer */
 
 /*
  * Parse a 40-character hexadecimal object ID starting from hex, updating the
diff --git a/hex.c b/hex.c
index 10af1a29e8..080597ad3f 100644
--- a/hex.c
+++ b/hex.c
@@ -73,14 +73,15 @@ int parse_oid_hex(const char *hex, struct object_id *oid, const char **end)
 	return ret;
 }
 
-char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
+static inline char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,
+					const struct git_hash_algo *algop)
 {
 	static const char hex[] = "0123456789abcdef";
 	char *buf = buffer;
 	int i;
 
-	for (i = 0; i < the_hash_algo->rawsz; i++) {
-		unsigned int val = *sha1++;
+	for (i = 0; i < algop->rawsz; i++) {
+		unsigned int val = *hash++;
 		*buf++ = hex[val >> 4];
 		*buf++ = hex[val & 0xf];
 	}
@@ -89,20 +90,40 @@ char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
 	return buffer;
 }
 
-char *oid_to_hex_r(char *buffer, const struct object_id *oid)
+char *hash_to_hex_algo_r(char *buffer, const unsigned char *hash, int algo)
 {
-	return sha1_to_hex_r(buffer, oid->hash);
+	return hash_to_hex_algop_r(buffer, hash, &hash_algos[algo]);
 }
 
-char *sha1_to_hex(const unsigned char *sha1)
+char *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
+{
+	return hash_to_hex_algo_r(buffer, sha1, GIT_HASH_SHA1);
+}
+
+char *oid_to_hex_r(char *buffer, const struct object_id *oid)
+{
+	return hash_to_hex_algop_r(buffer, oid->hash, the_hash_algo);
+}
+
+char *hash_to_hex_algo(const unsigned char *hash, int algo)
 {
 	static int bufno;
 	static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 	bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
-	return sha1_to_hex_r(hexbuffer[bufno], sha1);
+	return hash_to_hex_algo_r(hexbuffer[bufno], hash, algo);
+}
+
+char *sha1_to_hex(const unsigned char *sha1)
+{
+	return hash_to_hex_algo(sha1, GIT_HASH_SHA1);
+}
+
+char *hash_to_hex(const unsigned char *hash)
+{
+	return hash_to_hex_algo(hash, hash_algo_by_ptr(the_hash_algo));
 }
 
 char *oid_to_hex(const struct object_id *oid)
 {
-	return sha1_to_hex(oid->hash);
+	return hash_to_hex_algo(oid->hash, hash_algo_by_ptr(the_hash_algo));
 }
Previous: brian m. carlsonNext: Junio C Hamano
Message 11 of 44 in “Base SHA-256 implementation”
  1. 00/13 Base SHA-256 implementationbrian m. carlson, Oct 15, 2018
  2. 01/13 sha1-file: rename algorithm to "sha1"brian m. carlson, Oct 15, 2018
  3. Duy NguyenOct 16, 2018
  4. brian m. carlsonOct 17, 2018
  5. 02/13 sha1-file: provide functions to look up hash algorithmsbrian m. carlson, Oct 15, 2018
  6. SZEDER GáborOct 17, 2018
  7. 04/13 cache: make hashcmp and hasheq work with larger hashesbrian m. carlson, Oct 15, 2018
  8. Duy NguyenOct 16, 2018
  9. 06/13 t: make the sha1 test-tool helper genericbrian m. carlson, Oct 15, 2018
  10. 07/13 sha1-file: add a constant for hash block sizebrian m. carlson, Oct 15, 2018
  11. 03/13 hex: introduce functions to print arbitrary hashesbrian m. carlson, Oct 15, 2018
  12. Junio C HamanoOct 16, 2018
  13. brian m. carlsonOct 17, 2018
  14. 05/13 t: add basic tests for our SHA-1 implementationbrian m. carlson, Oct 15, 2018
  15. 08/13 t/helper: add a test helper to compute hash speedbrian m. carlson, Oct 15, 2018
  16. 09/13 commit-graph: convert to using the_hash_algobrian m. carlson, Oct 15, 2018
  17. Derrick StoleeOct 15, 2018
  18. 11/13 sha256: add an SHA-256 implementation using libgcryptbrian m. carlson, Oct 15, 2018
  19. 12/13 hash: add an SHA-256 implementation using OpenSSLbrian m. carlson, Oct 15, 2018
  20. Duy NguyenOct 16, 2018
  21. 13/13 commit-graph: specify OID version for SHA-256brian m. carlson, Oct 15, 2018
  22. Derrick StoleeOct 15, 2018
  23. Junio C HamanoOct 16, 2018
  24. brian m. carlsonOct 16, 2018
  25. Duy NguyenOct 16, 2018
  26. Derrick StoleeOct 16, 2018
  27. Duy NguyenOct 16, 2018
  28. brian m. carlsonOct 16, 2018
  29. Duy NguyenOct 17, 2018
  30. brian m. carlsonOct 18, 2018
  31. Derrick StoleeOct 18, 2018
  32. brian m. carlsonOct 19, 2018
  33. Derrick StoleeOct 17, 2018
  34. brian m. carlsonOct 17, 2018
  35. 10/13 Add a base implementation of SHA-256 supportbrian m. carlson, Oct 15, 2018
  36. Duy NguyenOct 15, 2018
  37. brian m. carlsonOct 15, 2018
  38. Duy NguyenOct 16, 2018
  39. SZEDER GáborOct 17, 2018
  40. brian m. carlsonOct 17, 2018
  41. Junio C HamanoOct 16, 2018
  42. Junio C HamanoOct 16, 2018
  43. brian m. carlsonOct 16, 2018
  44. Duy NguyenOct 16, 2018

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