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[PATCH v6 03/12] hex: introduce functions to print arbitrary hashes

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Nov 14, 2018, 04:09 UTC
Message-ID
<20181114040938.517289-4-sandals@crustytoothpaste.net>
In-Reply-To
<20181114040938.517289-1-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   | 32 ++++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 14 deletions(-)
diff --git a/cache.h b/cache.h
index ca36b44ee0..cb7268deea 100644
--- a/cache.h
+++ b/cache.h
@@ -1365,9 +1365,9 @@ 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
@@ -1375,10 +1375,13 @@ 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_algop_r(char *buffer, const unsigned char *hash, const struct git_hash_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_algop(const unsigned char *hash, const struct git_hash_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..7850a8879d 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)
+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 +90,35 @@ 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 *sha1_to_hex_r(char *buffer, const unsigned char *sha1)
 {
-	return sha1_to_hex_r(buffer, oid->hash);
+	return hash_to_hex_algop_r(buffer, sha1, &hash_algos[GIT_HASH_SHA1]);
 }
 
-char *sha1_to_hex(const unsigned char *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_algop(const unsigned char *hash, const struct git_hash_algo *algop)
 {
 	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_algop_r(hexbuffer[bufno], hash, algop);
+}
+
+char *sha1_to_hex(const unsigned char *sha1)
+{
+	return hash_to_hex_algop(sha1, &hash_algos[GIT_HASH_SHA1]);
+}
+
+char *hash_to_hex(const unsigned char *hash)
+{
+	return hash_to_hex_algop(hash, the_hash_algo);
 }
 
 char *oid_to_hex(const struct object_id *oid)
 {
-	return sha1_to_hex(oid->hash);
+	return hash_to_hex_algop(oid->hash, the_hash_algo);
 }
Previous: brian m. carlsonNext: brian m. carlson
Message 49 of 58 in “Base SHA-256 implementation”
  1. 00/12 Base SHA-256 implementationbrian m. carlson, Oct 25, 2018
  2. 01/12 sha1-file: rename algorithm to "sha1"brian m. carlson, Oct 25, 2018
  3. 02/12 sha1-file: provide functions to look up hash algorithmsbrian m. carlson, Oct 25, 2018
  4. 03/12 hex: introduce functions to print arbitrary hashesbrian m. carlson, Oct 25, 2018
  5. 04/12 cache: make hashcmp and hasheq work with larger hashesbrian m. carlson, Oct 25, 2018
  6. 05/12 t: add basic tests for our SHA-1 implementationbrian m. carlson, Oct 25, 2018
  7. 06/12 t: make the sha1 test-tool helper genericbrian m. carlson, Oct 25, 2018
  8. 07/12 sha1-file: add a constant for hash block sizebrian m. carlson, Oct 25, 2018
  9. 08/12 t/helper: add a test helper to compute hash speedbrian m. carlson, Oct 25, 2018
  10. 09/12 commit-graph: convert to using the_hash_algobrian m. carlson, Oct 25, 2018
  11. 10/12 Add a base implementation of SHA-256 supportbrian m. carlson, Oct 25, 2018
  12. Carlo ArenasOct 25, 2018
  13. brian m. carlsonOct 28, 2018
  14. Junio C HamanoOct 29, 2018
  15. brian m. carlsonOct 31, 2018
  16. Junio C HamanoNov 1, 2018
  17. Christian CouderOct 27, 2018
  18. 11/12 sha256: add an SHA-256 implementation using libgcryptbrian m. carlson, Oct 25, 2018
  19. 12/12 hash: add an SHA-256 implementation using OpenSSLbrian m. carlson, Oct 25, 2018
  20. 00/12 Base SHA-256 implementationbrian m. carlson, Nov 4, 2018
  21. 01/12 sha1-file: rename algorithm to "sha1"brian m. carlson, Nov 4, 2018
  22. Ævar Arnfjörð BjarmasonNov 5, 2018
  23. 02/12 sha1-file: provide functions to look up hash algorithmsbrian m. carlson, Nov 4, 2018
  24. Derrick StoleeNov 13, 2018
  25. Duy NguyenNov 13, 2018
  26. brian m. carlsonNov 14, 2018
  27. Ramsay JonesNov 14, 2018
  28. Ramsay JonesNov 14, 2018
  29. Jeff KingNov 14, 2018
  30. brian m. carlsonNov 14, 2018
  31. Ramsay JonesNov 14, 2018
  32. 03/12 hex: introduce functions to print arbitrary hashesbrian m. carlson, Nov 4, 2018
  33. 05/12 t: add basic tests for our SHA-1 implementationbrian m. carlson, Nov 4, 2018
  34. 04/12 cache: make hashcmp and hasheq work with larger hashesbrian m. carlson, Nov 4, 2018
  35. 07/12 sha1-file: add a constant for hash block sizebrian m. carlson, Nov 4, 2018
  36. 06/12 t: make the sha1 test-tool helper genericbrian m. carlson, Nov 4, 2018
  37. 08/12 t/helper: add a test helper to compute hash speedbrian m. carlson, Nov 4, 2018
  38. 09/12 commit-graph: convert to using the_hash_algobrian m. carlson, Nov 4, 2018
  39. 10/12 Add a base implementation of SHA-256 supportbrian m. carlson, Nov 4, 2018
  40. Ævar Arnfjörð BjarmasonNov 5, 2018
  41. brian m. carlsonNov 7, 2018
  42. Ævar Arnfjörð BjarmasonNov 10, 2018
  43. 11/12 sha256: add an SHA-256 implementation using libgcryptbrian m. carlson, Nov 4, 2018
  44. 12/12 hash: add an SHA-256 implementation using OpenSSLbrian m. carlson, Nov 4, 2018
  45. Junio C HamanoNov 5, 2018
  46. 00/12 Base SHA-256 implementationbrian m. carlson, Nov 14, 2018
  47. 01/12 sha1-file: rename algorithm to "sha1"brian m. carlson, Nov 14, 2018
  48. 02/12 sha1-file: provide functions to look up hash algorithmsbrian m. carlson, Nov 14, 2018
  49. 03/12 hex: introduce functions to print arbitrary hashesbrian m. carlson, Nov 14, 2018
  50. 04/12 cache: make hashcmp and hasheq work with larger hashesbrian m. carlson, Nov 14, 2018
  51. 06/12 t: make the sha1 test-tool helper genericbrian m. carlson, Nov 14, 2018
  52. 05/12 t: add basic tests for our SHA-1 implementationbrian m. carlson, Nov 14, 2018
  53. 07/12 sha1-file: add a constant for hash block sizebrian m. carlson, Nov 14, 2018
  54. 08/12 t/helper: add a test helper to compute hash speedbrian m. carlson, Nov 14, 2018
  55. 09/12 commit-graph: convert to using the_hash_algobrian m. carlson, Nov 14, 2018
  56. 10/12 Add a base implementation of SHA-256 supportbrian m. carlson, Nov 14, 2018
  57. 11/12 sha256: add an SHA-256 implementation using libgcryptbrian m. carlson, Nov 14, 2018
  58. 12/12 hash: add an SHA-256 implementation using OpenSSLbrian m. carlson, Nov 14, 2018

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