1 files changed, 247 insertions, 0 deletions
diff --git a/sha1_file.c b/sha1_file.c
new file mode 100644
index 0000000..bb44a01
--- /dev/null
+++ b/sha1_file.c
@@ -0,0 +1,247 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ *
+ * This handles basic git sha1 object files - packing, unpacking,
+ * creation etc.
+ */
+#include <stdarg.h>
+#include "cache.h"
+
+const char *sha1_file_directory = NULL;
+
+static unsigned hexval(char c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'a' && c <= 'f')
+		return c - 'a' + 10;
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+	return ~0;
+}
+
+int get_sha1_hex(const char *hex, unsigned char *sha1)
+{
+	int i;
+	for (i = 0; i < 20; i++) {
+		unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
+		if (val & ~0xff)
+			return -1;
+		*sha1++ = val;
+		hex += 2;
+	}
+	return 0;
+}
+
+char * sha1_to_hex(const unsigned char *sha1)
+{
+	static char buffer[50];
+	static const char hex[] = "0123456789abcdef";
+	char *buf = buffer;
+	int i;
+
+	for (i = 0; i < 20; i++) {
+		unsigned int val = *sha1++;
+		*buf++ = hex[val >> 4];
+		*buf++ = hex[val & 0xf];
+	}
+	return buffer;
+}
+
+/*
+ * NOTE! This returns a statically allocated buffer, so you have to be
+ * careful about using it. Do a "strdup()" if you need to save the
+ * filename.
+ */
+char *sha1_file_name(const unsigned char *sha1)
+{
+	int i;
+	static char *name, *base;
+
+	if (!base) {
+		char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
+		int len = strlen(sha1_file_directory);
+		base = malloc(len + 60);
+		memcpy(base, sha1_file_directory, len);
+		memset(base+len, 0, 60);
+		base[len] = '/';
+		base[len+3] = '/';
+		name = base + len + 1;
+	}
+	for (i = 0; i < 20; i++) {
+		static char hex[] = "0123456789abcdef";
+		unsigned int val = sha1[i];
+		char *pos = name + i*2 + (i > 0);
+		*pos++ = hex[val >> 4];
+		*pos = hex[val & 0xf];
+	}
+	return base;
+}
+
+int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
+{
+	unsigned char real_sha1[20];
+	SHA_CTX c;
+
+	SHA1_Init(&c);
+	SHA1_Update(&c, map, size);
+	SHA1_Final(real_sha1, &c);
+	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
+}
+
+void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+{
+	char *filename = sha1_file_name(sha1);
+	int fd = open(filename, O_RDONLY);
+	struct stat st;
+	void *map;
+
+	if (fd < 0) {
+		perror(filename);
+		return NULL;
+	}
+	if (fstat(fd, &st) < 0) {
+		close(fd);
+		return NULL;
+	}
+	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if (-1 == (int)(long)map)
+		return NULL;
+	*size = st.st_size;
+	return map;
+}
+
+void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
+{
+	int ret, bytes;
+	z_stream stream;
+	char buffer[8192];
+	char *buf;
+
+	/* Get the data stream */
+	memset(&stream, 0, sizeof(stream));
+	stream.next_in = map;
+	stream.avail_in = mapsize;
+	stream.next_out = buffer;
+	stream.avail_out = sizeof(buffer);
+
+	inflateInit(&stream);
+	ret = inflate(&stream, 0);
+	if (sscanf(buffer, "%10s %lu", type, size) != 2)
+		return NULL;
+
+	bytes = strlen(buffer) + 1;
+	buf = malloc(*size);
+	if (!buf)
+		return NULL;
+
+	memcpy(buf, buffer + bytes, stream.total_out - bytes);
+	bytes = stream.total_out - bytes;
+	if (bytes < *size && ret == Z_OK) {
+		stream.next_out = buf + bytes;
+		stream.avail_out = *size - bytes;
+		while (inflate(&stream, Z_FINISH) == Z_OK)
+			/* nothing */;
+	}
+	inflateEnd(&stream);
+	return buf;
+}
+
+void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
+{
+	unsigned long mapsize;
+	void *map, *buf;
+
+	map = map_sha1_file(sha1, &mapsize);
+	if (map) {
+		buf = unpack_sha1_file(map, mapsize, type, size);
+		munmap(map, mapsize);
+		return buf;
+	}
+	return NULL;
+}
+
+int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
+{
+	int size;
+	char *compressed;
+	z_stream stream;
+	unsigned char sha1[20];
+	SHA_CTX c;
+
+	/* Set it up */
+	memset(&stream, 0, sizeof(stream));
+	deflateInit(&stream, Z_BEST_COMPRESSION);
+	size = deflateBound(&stream, len);
+	compressed = malloc(size);
+
+	/* Compress it */
+	stream.next_in = buf;
+	stream.avail_in = len;
+	stream.next_out = compressed;
+	stream.avail_out = size;
+	while (deflate(&stream, Z_FINISH) == Z_OK)
+		/* nothing */;
+	deflateEnd(&stream);
+	size = stream.total_out;
+
+	/* Sha1.. */
+	SHA1_Init(&c);
+	SHA1_Update(&c, compressed, size);
+	SHA1_Final(sha1, &c);
+
+	if (write_sha1_buffer(sha1, compressed, size) < 0)
+		return -1;
+	if (returnsha1)
+		memcpy(returnsha1, sha1, 20);
+	return 0;
+}
+
+static inline int collision_check(char *filename, void *buf, unsigned int size)
+{
+#ifdef COLLISION_CHECK
+	void *map;
+	int fd = open(filename, O_RDONLY);
+	struct stat st;
+	int cmp;
+
+	/* Unreadable object, or object went away? Strange. */
+	if (fd < 0)
+		return -1;
+
+	if (fstat(fd, &st) < 0 || size != st.st_size)
+		return -1;
+
+	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if (map == MAP_FAILED)
+		return -1;
+	cmp = memcmp(buf, map, size);
+	munmap(map, size);
+	if (cmp)
+		return -1;
+#endif
+	return 0;
+}
+
+int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
+{
+	char *filename = sha1_file_name(sha1);
+	int fd;
+
+	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
+	if (fd < 0) {
+		if (errno != EEXIST)
+			return -1;
+		if (collision_check(filename, buf, size))
+			return error("SHA1 collision detected!"
+					" This is bad, bad, BAD!\a\n");
+		return 0;
+	}
+	write(fd, buf, size);
+	close(fd);
+	return 0;
+}