[PATCH v4 2/3] Limit the size of the data block passed to SHA1_Update()

[atousa.p@gmail.com]

From: Atousa Pahlevan Duprat <apahlevan@ieee.org>

Use the previous commit's abstraction mechanism for SHA1 to
support a chunked implementation of SHA1_Update() which limits
the amount of data in the chunk passed to SHA1_Update().

This is enabled by using the SHA1_MAX_BLOCK_SIZE envvar to
specify chunk size.  When using Apple's CommonCrypto library
this is enable and set to 1GiB.

Signed-off-by: Atousa Pahlevan Duprat <apahlevan@ieee.org>
---
 Makefile                     | 13 +++++++++++++
 cache.h                      | 17 +++++++++++++++--
 compat/apple-common-crypto.h |  4 ++++
 compat/sha1-chunked.c        | 19 +++++++++++++++++++
 compat/sha1-chunked.h        |  2 ++
 5 files changed, 53 insertions(+), 2 deletions(-)
 create mode 100644 compat/sha1-chunked.c
 create mode 100644 compat/sha1-chunked.h

diff --git a/Makefile b/Makefile
index 04c2231..6a4ca59 100644
--- a/Makefile
+++ b/Makefile
@@ -141,6 +141,10 @@ all::
 # Define PPC_SHA1 environment variable when running make to make use of
 # a bundled SHA1 routine optimized for PowerPC.
 #
+# Define SHA1_MAX_BLOCK_SIZE to limit the amount of data that will be hashed
+# in one call to the platform's SHA1_Update(). e.g. APPLE_COMMON_CRYPTO
+# wants 'SHA1_MAX_BLOCK_SIZE=1024L*1024L*1024L' defined.
+#
 # Define NEEDS_CRYPTO_WITH_SSL if you need -lcrypto when using -lssl (Darwin).
 #
 # Define NEEDS_SSL_WITH_CRYPTO if you need -lssl when using -lcrypto (Darwin).
@@ -1335,6 +1339,11 @@ ifdef NO_POSIX_GOODIES
 	BASIC_CFLAGS += -DNO_POSIX_GOODIES
 endif
 
+ifdef APPLE_COMMON_CRYPTO
+	# Apple CommonCrypto requires chunking
+	SHA1_MAX_BLOCK_SIZE = 1024L*1024L*1024L
+endif
+
 ifdef BLK_SHA1
 	SHA1_HEADER = "block-sha1/sha1.h"
 	LIB_OBJS += block-sha1/sha1.o
@@ -1353,6 +1362,10 @@ endif
 endif
 endif
 
+ifdef SHA1_MAX_BLOCK_SIZE
+	LIB_OBJS += compat/sha1-chunked.o
+	BASIC_CFLAGS += -DSHA1_MAX_BLOCK_SIZE="$(SHA1_MAX_BLOCK_SIZE)"
+endif
 ifdef NO_PERL_MAKEMAKER
 	export NO_PERL_MAKEMAKER
 endif
diff --git a/cache.h b/cache.h
index a934a2e..182ac62 100644
--- a/cache.h
+++ b/cache.h
@@ -11,7 +11,7 @@
 #include "string-list.h"
 
 #include SHA1_HEADER
-#ifndef git_SHA_CTX
+#ifndef platform_SHA_CTX
 
 /* platform's underlying implementation of SHA1, could be OpenSSL,
    blk_SHA, Apple CommonCrypto, etc...  */
@@ -20,15 +20,28 @@
 #define platform_SHA1_Update	SHA1_Update
 #define platform_SHA1_Final    	SHA1_Final
 
+#endif
+
 /* git may call platform's underlying implementation of SHA1 directly,
    or may call it through a wrapper */
+
+#ifndef git_SHA_CTX
+
+#ifdef SHA1_MAX_BLOCK_SIZE
+#include "compat/sha1-chunked.h"
+#define git_SHA_CTX		platform_SHA_CTX
+#define git_SHA1_Init		platform_SHA1_Init
+#define git_SHA1_Update		git_SHA1_Update_Chunked
+#define git_SHA1_Final		platform_SHA1_Final
+#else
 #define git_SHA_CTX		platform_SHA_CTX
 #define git_SHA1_Init		platform_SHA1_Init
 #define git_SHA1_Update		platform_SHA1_Update
 #define git_SHA1_Final		platform_SHA1_Final
-
 #endif
 
+#endif 
+
 #include <zlib.h>
 typedef struct git_zstream {
 	z_stream z;
diff --git a/compat/apple-common-crypto.h b/compat/apple-common-crypto.h
index c8b9b0e..d3fb264 100644
--- a/compat/apple-common-crypto.h
+++ b/compat/apple-common-crypto.h
@@ -16,6 +16,10 @@
 #undef TYPE_BOOL
 #endif
 
+#ifndef SHA1_MAX_BLOCK_SIZE
+#error Using Apple Common Crypto library requires setting SHA1_MAX_BLOCK_SIZE
+#endif
+
 #ifdef APPLE_LION_OR_NEWER
 #define git_CC_error_check(pattern, err) \
 	do { \
diff --git a/compat/sha1-chunked.c b/compat/sha1-chunked.c
new file mode 100644
index 0000000..6adfcfd
--- /dev/null
+++ b/compat/sha1-chunked.c
@@ -0,0 +1,19 @@
+#include "cache.h"
+
+int git_SHA1_Update_Chunked(platform_SHA_CTX *c, const void *data, size_t len)
+{
+	size_t nr;
+	size_t total = 0;
+	const char *cdata = (const char*)data;
+
+	while (len) {
+		nr = len;
+		if (nr > SHA1_MAX_BLOCK_SIZE)
+			nr = SHA1_MAX_BLOCK_SIZE;
+		platform_SHA1_Update(c, cdata, nr);
+		total += nr;
+		cdata += nr;
+		len -= nr;
+	}
+	return total;
+}
diff --git a/compat/sha1-chunked.h b/compat/sha1-chunked.h
new file mode 100644
index 0000000..7b2df28
--- /dev/null
+++ b/compat/sha1-chunked.h
@@ -0,0 +1,2 @@
+
+int git_SHA1_Update_Chunked(platform_SHA_CTX *c, const void *data, size_t len);
-- 
2.4.9 (Apple Git-60)