X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=sha1_file.c;h=942b673dc3c7fa9f057c5c452e3a1b73eaeb8707;hb=62d046a07b4cd4328d3d40aab097a1d97c4d7b20;hp=28ad1598e54200ca8ee1261ed7beb4e31e20b2f1;hpb=da6abf5d9c342a74dffbcc2015b9c27d7819a900;p=git.git

diff --git a/sha1_file.c b/sha1_file.c
index 28ad1598..942b673d 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -7,10 +7,9 @@
  * creation etc.
  */
 #include <stdarg.h>
+#include <limits.h>
 #include "cache.h"
 
-const char *sha1_file_directory = NULL;
-
 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
 #define O_NOATIME 01000000
@@ -45,6 +44,81 @@ int get_sha1_hex(const char *hex, unsigned char *sha1)
 	return 0;
 }
 
+int get_sha1_file(const char *path, unsigned char *result)
+{
+	char buffer[60];
+	int fd = open(path, O_RDONLY);
+	int len;
+
+	if (fd < 0)
+		return -1;
+	len = read(fd, buffer, sizeof(buffer));
+	close(fd);
+	if (len < 40)
+		return -1;
+	return get_sha1_hex(buffer, result);
+}
+
+static char *git_dir, *git_object_dir, *git_index_file;
+static void setup_git_env(void)
+{
+	git_dir = gitenv(GIT_DIR_ENVIRONMENT);
+	if (!git_dir)
+		git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
+	git_object_dir = gitenv(DB_ENVIRONMENT);
+	if (!git_object_dir) {
+		git_object_dir = xmalloc(strlen(git_dir) + 9);
+		sprintf(git_object_dir, "%s/objects", git_dir);
+	}
+	git_index_file = gitenv(INDEX_ENVIRONMENT);
+	if (!git_index_file) {
+		git_index_file = xmalloc(strlen(git_dir) + 7);
+		sprintf(git_index_file, "%s/index", git_dir);
+	}
+}
+
+char *get_object_directory(void)
+{
+	if (!git_object_dir)
+		setup_git_env();
+	return git_object_dir;
+}
+
+char *get_index_file(void)
+{
+	if (!git_index_file)
+		setup_git_env();
+	return git_index_file;
+}
+
+int get_sha1(const char *str, unsigned char *sha1)
+{
+	static char pathname[PATH_MAX];
+	static const char *prefix[] = {
+		"",
+		"refs",
+		"refs/tags",
+		"refs/heads",
+		"refs/snap",
+		NULL
+	};
+	const char **p;
+
+	if (!get_sha1_hex(str, sha1))
+		return 0;
+
+	if (!git_dir)
+		setup_git_env();
+	for (p = prefix; *p; p++) {
+		snprintf(pathname, sizeof(pathname), "%s/%s/%s",
+			 git_dir, *p, str);
+		if (!get_sha1_file(pathname, sha1))
+			return 0;
+	}
+
+	return -1;
+}
+
 char * sha1_to_hex(const unsigned char *sha1)
 {
 	static char buffer[50];
@@ -60,36 +134,130 @@ char * sha1_to_hex(const unsigned char *sha1)
 	return buffer;
 }
 
+static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
+{
+	int i;
+	for (i = 0; i < 20; i++) {
+		static char hex[] = "0123456789abcdef";
+		unsigned int val = sha1[i];
+		char *pos = pathbuf + i*2 + (i > 0);
+		*pos++ = hex[val >> 4];
+		*pos = hex[val & 0xf];
+	}
+}
+
 /*
  * 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.
+ *
+ * Also note that this returns the location for creating.  Reading
+ * SHA1 file can happen from any alternate directory listed in the
+ * DB_ENVIRONMENT environment variable if it is not found in
+ * the primary object database.
  */
 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;
+		const char *sha1_file_directory = get_object_directory();
 		int len = strlen(sha1_file_directory);
-		base = malloc(len + 60);
+		base = xmalloc(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];
-	}
+	fill_sha1_path(name, sha1);
 	return base;
 }
 
+static struct alternate_object_database {
+	char *base;
+	char *name;
+} *alt_odb;
+
+/*
+ * Prepare alternate object database registry.
+ * alt_odb points at an array of struct alternate_object_database.
+ * This array is terminated with an element that has both its base
+ * and name set to NULL.  alt_odb[n] comes from n'th non-empty
+ * element from colon separated ALTERNATE_DB_ENVIRONMENT environment
+ * variable, and its base points at a statically allocated buffer
+ * that contains "/the/directory/corresponding/to/.git/objects/...",
+ * while its name points just after the slash at the end of
+ * ".git/objects/" in the example above, and has enough space to hold
+ * 40-byte hex SHA1, an extra slash for the first level indirection,
+ * and the terminating NUL.
+ * This function allocates the alt_odb array and all the strings
+ * pointed by base fields of the array elements with one xmalloc();
+ * the string pool immediately follows the array.
+ */
+static void prepare_alt_odb(void)
+{
+	int pass, totlen, i;
+	const char *cp, *last;
+	char *op = 0;
+	const char *alt = gitenv(ALTERNATE_DB_ENVIRONMENT) ? : "";
+
+	/* The first pass counts how large an area to allocate to
+	 * hold the entire alt_odb structure, including array of
+	 * structs and path buffers for them.  The second pass fills
+	 * the structure and prepares the path buffers for use by
+	 * fill_sha1_path().
+	 */
+	for (totlen = pass = 0; pass < 2; pass++) {
+		last = alt;
+		i = 0;
+		do {
+			cp = strchr(last, ':') ? : last + strlen(last);
+			if (last != cp) {
+				/* 43 = 40-byte + 2 '/' + terminating NUL */
+				int pfxlen = cp - last;
+				int entlen = pfxlen + 43;
+				if (pass == 0)
+					totlen += entlen;
+				else {
+					alt_odb[i].base = op;
+					alt_odb[i].name = op + pfxlen + 1;
+					memcpy(op, last, pfxlen);
+					op[pfxlen] = op[pfxlen + 3] = '/';
+					op[entlen-1] = 0;
+					op += entlen;
+				}
+				i++;
+			}
+			while (*cp && *cp == ':')
+				cp++;
+			last = cp;
+		} while (*cp);
+		if (pass)
+			break;
+		alt_odb = xmalloc(sizeof(*alt_odb) * (i + 1) + totlen);
+		alt_odb[i].base = alt_odb[i].name = 0;
+		op = (char*)(&alt_odb[i+1]);
+	}
+}
+
+static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
+{
+	int i;
+	char *name = sha1_file_name(sha1);
+
+	if (!stat(name, st))
+		return name;
+	if (!alt_odb)
+		prepare_alt_odb();
+	for (i = 0; (name = alt_odb[i].name) != NULL; i++) {
+		fill_sha1_path(name, sha1);
+		if (!stat(alt_odb[i].base, st))
+			return alt_odb[i].base;
+	}
+	return NULL;
+}
+
 int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, const char *type)
 {
 	char header[100];
@@ -105,10 +273,15 @@ int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size, con
 
 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 {
-	char *filename = sha1_file_name(sha1);
 	struct stat st;
 	void *map;
 	int fd;
+	char *filename = find_sha1_file(sha1, &st);
+
+	if (!filename) {
+		error("cannot map sha1 file %s", sha1_to_hex(sha1));
+		return NULL;
+	}
 
 	fd = open(filename, O_RDONLY | sha1_file_open_flag);
 	if (fd < 0) {
@@ -127,10 +300,6 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 		/* If it failed once, it will probably fail again. Stop using O_NOATIME */
 		sha1_file_open_flag = 0;
 	}
-	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)
@@ -155,15 +324,13 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
 
 	inflateInit(&stream);
 	ret = inflate(&stream, 0);
-       if (ret < Z_OK)
-               return NULL;
+	if (ret < Z_OK)
+		return NULL;
 	if (sscanf(buffer, "%10s %lu", type, size) != 2)
 		return NULL;
 
 	bytes = strlen(buffer) + 1;
-	buf = malloc(*size);
-	if (!buf)
-		return NULL;
+	buf = xmalloc(*size);
 
 	memcpy(buf, buffer + bytes, stream.total_out - bytes);
 	bytes = stream.total_out - bytes;
@@ -191,47 +358,52 @@ void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size
 	return NULL;
 }
 
-void *read_tree_with_tree_or_commit_sha1(const unsigned char *sha1,
-					 unsigned long *size,
-					 unsigned char *tree_sha1_return)
+void *read_object_with_reference(const unsigned char *sha1,
+				 const unsigned char *required_type,
+				 unsigned long *size,
+				 unsigned char *actual_sha1_return)
 {
 	char type[20];
 	void *buffer;
 	unsigned long isize;
-	int was_commit = 0;
-	unsigned char tree_sha1[20];
+	unsigned char actual_sha1[20];
 
-	buffer = read_sha1_file(sha1, type, &isize);
+	memcpy(actual_sha1, sha1, 20);
+	while (1) {
+		int ref_length = -1;
+		const char *ref_type = NULL;
 
-	/* 
-	 * We might have read a commit instead of a tree, in which case
-	 * we parse out the tree_sha1 and attempt to read from there.
-	 * (buffer + 5) is because the tree sha1 is always at offset 5
-	 * in a commit record ("tree ").
-	 */
-	if (buffer &&
-	    !strcmp(type, "commit") &&
-	    !get_sha1_hex(buffer + 5, tree_sha1)) {
-		free(buffer);
-		buffer = read_sha1_file(tree_sha1, type, &isize);
-		was_commit = 1;
-	}
+		buffer = read_sha1_file(actual_sha1, type, &isize);
+		if (!buffer)
+			return NULL;
+		if (!strcmp(type, required_type)) {
+			*size = isize;
+			if (actual_sha1_return)
+				memcpy(actual_sha1_return, actual_sha1, 20);
+			return buffer;
+		}
+		/* Handle references */
+		else if (!strcmp(type, "commit"))
+			ref_type = "tree ";
+		else if (!strcmp(type, "tag"))
+			ref_type = "object ";
+		else {
+			free(buffer);
+			return NULL;
+		}
+		ref_length = strlen(ref_type);
 
-	/*
-	 * Now do we have something and if so is it a tree?
-	 */
-	if (!buffer || strcmp(type, "tree")) {
-		free(buffer);
-		return NULL;
+		if (memcmp(buffer, ref_type, ref_length) ||
+		    get_sha1_hex(buffer + ref_length, actual_sha1)) {
+			free(buffer);
+			return NULL;
+		}
+		/* Now we have the ID of the referred-to object in
+		 * actual_sha1.  Check again. */
 	}
-
-	*size = isize;
-	if (tree_sha1_return)
-		memcpy(tree_sha1_return, was_commit ? tree_sha1 : sha1, 20);
-	return buffer;
 }
 
-int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
+int write_sha1_file(char *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 {
 	int size;
 	char *compressed;
@@ -239,10 +411,16 @@ int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 	unsigned char sha1[20];
 	SHA_CTX c;
 	char *filename;
-	int fd;
+	static char tmpfile[PATH_MAX];
+	char hdr[50];
+	int fd, hdrlen, ret;
+
+	/* Generate the header */
+	hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
 
 	/* Sha1.. */
 	SHA1_Init(&c);
+	SHA1_Update(&c, hdr, hdrlen);
 	SHA1_Update(&c, buf, len);
 	SHA1_Final(sha1, &c);
 
@@ -250,29 +428,48 @@ int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 		memcpy(returnsha1, sha1, 20);
 
 	filename = sha1_file_name(sha1);
-	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
-	if (fd < 0) {
-		if (errno != EEXIST)
-			return -1;
-
+	fd = open(filename, O_RDONLY);
+	if (fd >= 0) {
 		/*
-		 * We might do collision checking here, but we'd need to
-		 * uncompress the old file and check it. Later.
+		 * FIXME!!! We might do collision checking here, but we'd
+		 * need to uncompress the old file and check it. Later.
 		 */
+		close(fd);
 		return 0;
 	}
 
+	if (errno != ENOENT) {
+		fprintf(stderr, "sha1 file %s: %s", filename, strerror(errno));
+		return -1;
+	}
+
+	snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
+
+	fd = mkstemp(tmpfile);
+	if (fd < 0) {
+		fprintf(stderr, "unable to create temporary sha1 filename %s: %s", tmpfile, strerror(errno));
+		return -1;
+	}
+
 	/* Set it up */
 	memset(&stream, 0, sizeof(stream));
 	deflateInit(&stream, Z_BEST_COMPRESSION);
-	size = deflateBound(&stream, len);
-	compressed = malloc(size);
+	size = deflateBound(&stream, len+hdrlen);
+	compressed = xmalloc(size);
 
 	/* Compress it */
-	stream.next_in = buf;
-	stream.avail_in = len;
 	stream.next_out = compressed;
 	stream.avail_out = size;
+
+	/* First header.. */
+	stream.next_in = hdr;
+	stream.avail_in = hdrlen;
+	while (deflate(&stream, 0) == Z_OK)
+		/* nothing */;
+
+	/* Then the data itself.. */
+	stream.next_in = buf;
+	stream.avail_in = len;
 	while (deflate(&stream, Z_FINISH) == Z_OK)
 		/* nothing */;
 	deflateEnd(&stream);
@@ -280,54 +477,35 @@ int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
 
 	if (write(fd, compressed, size) != size)
 		die("unable to write file");
+	fchmod(fd, 0444);
 	close(fd);
-		
-	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;
-}
+	free(compressed);
 
-int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
-{
-	char *filename = sha1_file_name(sha1);
-	int fd;
+	ret = link(tmpfile, filename);
+	if (ret < 0) {
+		ret = errno;
 
-	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
-	if (fd < 0) {
-		if (errno != EEXIST)
+		/*
+		 * Coda hack - coda doesn't like cross-directory links,
+		 * so we fall back to a rename, which will mean that it
+		 * won't be able to check collisions, but that's not a
+		 * big deal.
+		 *
+		 * When this succeeds, we just return 0. We have nothing
+		 * left to unlink.
+		 */
+		if (ret == EXDEV && !rename(tmpfile, filename))
+			return 0;
+	}
+	unlink(tmpfile);
+	if (ret) {
+		if (ret != EEXIST) {
+			fprintf(stderr, "unable to write sha1 filename %s: %s", filename, strerror(ret));
 			return -1;
-		if (collision_check(filename, buf, size))
-			return error("SHA1 collision detected!"
-					" This is bad, bad, BAD!\a\n");
-		return 0;
+		}
+		/* FIXME!!! Collision check here ? */
 	}
-	write(fd, buf, size);
-	close(fd);
+
 	return 0;
 }
 
@@ -395,10 +573,25 @@ int write_sha1_from_fd(const unsigned char *sha1, int fd)
 
 int has_sha1_file(const unsigned char *sha1)
 {
-	char *filename = sha1_file_name(sha1);
 	struct stat st;
+	return !!find_sha1_file(sha1, &st);
+}
 
-	if (!stat(filename, &st))
-		return 1;
-	return 0;
+int index_fd(unsigned char *sha1, int fd, struct stat *st)
+{
+	unsigned long size = st->st_size;
+	void *buf;
+	int ret;
+
+	buf = "";
+	if (size)
+		buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if ((int)(long)buf == -1)
+		return -1;
+
+	ret = write_sha1_file(buf, size, "blob", sha1);
+	if (size)
+		munmap(buf, size);
+	return ret;
 }