diff options
| -rw-r--r-- | Makefile | 40 | ||||
| -rw-r--r-- | README | 168 | ||||
| -rw-r--r-- | cache.h | 93 | ||||
| -rw-r--r-- | cat-file.c | 23 | ||||
| -rw-r--r-- | commit-tree.c | 172 | ||||
| -rw-r--r-- | init-db.c | 51 | ||||
| -rw-r--r-- | read-cache.c | 259 | ||||
| -rw-r--r-- | read-tree.c | 43 | ||||
| -rw-r--r-- | show-diff.c | 81 | ||||
| -rw-r--r-- | update-cache.c | 248 | ||||
| -rw-r--r-- | write-tree.c | 66 |
11 files changed, 1244 insertions, 0 deletions
diff --git a/Makefile b/Makefile new file mode 100644 index 0000000000..a6bba79ba1 --- /dev/null +++ b/Makefile @@ -0,0 +1,40 @@ +CFLAGS=-g +CC=gcc + +PROG=update-cache show-diff init-db write-tree read-tree commit-tree cat-file + +all: $(PROG) + +install: $(PROG) + install $(PROG) $(HOME)/bin/ + +LIBS= -lssl + +init-db: init-db.o + +update-cache: update-cache.o read-cache.o + $(CC) $(CFLAGS) -o update-cache update-cache.o read-cache.o $(LIBS) + +show-diff: show-diff.o read-cache.o + $(CC) $(CFLAGS) -o show-diff show-diff.o read-cache.o $(LIBS) + +write-tree: write-tree.o read-cache.o + $(CC) $(CFLAGS) -o write-tree write-tree.o read-cache.o $(LIBS) + +read-tree: read-tree.o read-cache.o + $(CC) $(CFLAGS) -o read-tree read-tree.o read-cache.o $(LIBS) + +commit-tree: commit-tree.o read-cache.o + $(CC) $(CFLAGS) -o commit-tree commit-tree.o read-cache.o $(LIBS) + +cat-file: cat-file.o read-cache.o + $(CC) $(CFLAGS) -o cat-file cat-file.o read-cache.o $(LIBS) + +read-cache.o: cache.h +show-diff.o: cache.h + +clean: + rm -f *.o $(PROG) temp_git_file_* + +backup: clean + cd .. ; tar czvf dircache.tar.gz dir-cache diff --git a/README b/README new file mode 100644 index 0000000000..27577f7684 --- /dev/null +++ b/README @@ -0,0 +1,168 @@ + + GIT - the stupid content tracker + +"git" can mean anything, depending on your mood. + + - random three-letter combination that is pronounceable, and not + actually used by any common UNIX command. The fact that it is a + mispronounciation of "get" may or may not be relevant. + - stupid. contemptible and despicable. simple. Take your pick from the + dictionary of slang. + - "global information tracker": you're in a good mood, and it actually + works for you. Angels sing, and a light suddenly fills the room. + - "goddamn idiotic truckload of sh*t": when it breaks + +This is a stupid (but extremely fast) directory content manager. It +doesn't do a whole lot, but what it _does_ do is track directory +contents efficiently. + +There are two object abstractions: the "object database", and the +"current directory cache". + + The Object Database (SHA1_FILE_DIRECTORY) + +The object database is literally just a content-addressable collection +of objects. All objects are named by their content, which is +approximated by the SHA1 hash of the object itself. Objects may refer +to other objects (by referencing their SHA1 hash), and so you can build +up a hierarchy of objects. + +There are several kinds of objects in the content-addressable collection +database. They are all in deflated with zlib, and start off with a tag +of their type, and size information about the data. The SHA1 hash is +always the hash of the _compressed_ object, not the original one. + +In particular, the consistency of an object can always be tested +independently of the contents or the type of the object: all objects can +be validated by verifying that (a) their hashes match the content of the +file and (b) the object successfully inflates to a stream of bytes that +forms a sequence of <ascii tag without space> + <space> + <ascii decimal +size> + <byte\0> + <binary object data>. + +BLOB: A "blob" object is nothing but a binary blob of data, and doesn't +refer to anything else. There is no signature or any other verification +of the data, so while the object is consistent (it _is_ indexed by its +sha1 hash, so the data itself is certainly correct), it has absolutely +no other attributes. No name associations, no permissions. It is +purely a blob of data (ie normally "file contents"). + +TREE: The next hierarchical object type is the "tree" object. A tree +object is a list of permission/name/blob data, sorted by name. In other +words the tree object is uniquely determined by the set contents, and so +two separate but identical trees will always share the exact same +object. + +Again, a "tree" object is just a pure data abstraction: it has no +history, no signatures, no verification of validity, except that the +contents are again protected by the hash itself. So you can trust the +contents of a tree, the same way you can trust the contents of a blob, +but you don't know where those contents _came_ from. + +Side note on trees: since a "tree" object is a sorted list of +"filename+content", you can create a diff between two trees without +actually having to unpack two trees. Just ignore all common parts, and +your diff will look right. In other words, you can effectively (and +efficiently) tell the difference between any two random trees by O(n) +where "n" is the size of the difference, rather than the size of the +tree. + +Side note 2 on trees: since the name of a "blob" depends entirely and +exclusively on its contents (ie there are no names or permissions +involved), you can see trivial renames or permission changes by noticing +that the blob stayed the same. However, renames with data changes need +a smarter "diff" implementation. + +CHANGESET: The "changeset" object is an object that introduces the +notion of history into the picture. In contrast to the other objects, +it doesn't just describe the physical state of a tree, it describes how +we got there, and why. + +A "changeset" is defined by the tree-object that it results in, the +parent changesets (zero, one or more) that led up to that point, and a +comment on what happened. Again, a changeset is not trusted per se: +the contents are well-defined and "safe" due to the cryptographically +strong signatures at all levels, but there is no reason to believe that +the tree is "good" or that the merge information makes sense. The +parents do not have to actually have any relationship with the result, +for example. + +Note on changesets: unlike real SCM's, changesets do not contain rename +information or file mode chane information. All of that is implicit in +the trees involved (the result tree, and the result trees of the +parents), and describing that makes no sense in this idiotic file +manager. + +TRUST: The notion of "trust" is really outside the scope of "git", but +it's worth noting a few things. First off, since everything is hashed +with SHA1, you _can_ trust that an object is intact and has not been +messed with by external sources. So the name of an object uniquely +identifies a known state - just not a state that you may want to trust. + +Furthermore, since the SHA1 signature of a changeset refers to the +SHA1 signatures of the tree it is associated with and the signatures +of the parent, a single named changeset specifies uniquely a whole +set of history, with full contents. You can't later fake any step of +the way once you have the name of a changeset. + +So to introduce some real trust in the system, the only thing you need +to do is to digitally sign just _one_ special note, which includes the +name of a top-level changeset. Your digital signature shows others that +you trust that changeset, and the immutability of the history of +changesets tells others that they can trust the whole history. + +In other words, you can easily validate a whole archive by just sending +out a single email that tells the people the name (SHA1 hash) of the top +changeset, and digitally sign that email using something like GPG/PGP. + +In particular, you can also have a separate archive of "trust points" or +tags, which document your (and other peoples) trust. You may, of +course, archive these "certificates of trust" using "git" itself, but +it's not something "git" does for you. + +Another way of saying the same thing: "git" itself only handles content +integrity, the trust has to come from outside. + + Current Directory Cache (".dircache/index") + +The "current directory cache" is a simple binary file, which contains an +efficient representation of a virtual directory content at some random +time. It does so by a simple array that associates a set of names, +dates, permissions and content (aka "blob") objects together. The cache +is always kept ordered by name, and names are unique at any point in +time, but the cache has no long-term meaning, and can be partially +updated at any time. + +In particular, the "current directory cache" certainly does not need to +be consistent with the current directory contents, but it has two very +important attributes: + + (a) it can re-generate the full state it caches (not just the directory + structure: through the "blob" object it can regenerate the data too) + + As a special case, there is a clear and unambiguous one-way mapping + from a current directory cache to a "tree object", which can be + efficiently created from just the current directory cache without + actually looking at any other data. So a directory cache at any + one time uniquely specifies one and only one "tree" object (but + has additional data to make it easy to match up that tree object + with what has happened in the directory) + + +and + + (b) it has efficient methods for finding inconsistencies between that + cached state ("tree object waiting to be instantiated") and the + current state. + +Those are the two ONLY things that the directory cache does. It's a +cache, and the normal operation is to re-generate it completely from a +known tree object, or update/compare it with a live tree that is being +developed. If you blow the directory cache away entirely, you haven't +lost any information as long as you have the name of the tree that it +described. + +(But directory caches can also have real information in them: in +particular, they can have the representation of an intermediate tree +that has not yet been instantiated. So they do have meaning and usage +outside of caching - in one sense you can think of the current directory +cache as being the "work in progress" towards a tree commit). diff --git a/cache.h b/cache.h new file mode 100644 index 0000000000..98a32a9ad3 --- /dev/null +++ b/cache.h @@ -0,0 +1,93 @@ +#ifndef CACHE_H +#define CACHE_H + +#include <stdio.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <stddef.h> +#include <stdlib.h> +#include <stdarg.h> +#include <errno.h> +#include <sys/mman.h> + +#include <openssl/sha.h> +#include <zlib.h> + +/* + * Basic data structures for the directory cache + * + * NOTE NOTE NOTE! This is all in the native CPU byte format. It's + * not even trying to be portable. It's trying to be efficient. It's + * just a cache, after all. + */ + +#define CACHE_SIGNATURE 0x44495243 /* "DIRC" */ +struct cache_header { + unsigned int signature; + unsigned int version; + unsigned int entries; + unsigned char sha1[20]; +}; + +/* + * The "cache_time" is just the low 32 bits of the + * time. It doesn't matter if it overflows - we only + * check it for equality in the 32 bits we save. + */ +struct cache_time { + unsigned int sec; + unsigned int nsec; +}; + +/* + * dev/ino/uid/gid/size are also just tracked to the low 32 bits + * Again - this is just a (very strong in practice) heuristic that + * the inode hasn't changed. + */ +struct cache_entry { + struct cache_time ctime; + struct cache_time mtime; + unsigned int st_dev; + unsigned int st_ino; + unsigned int st_mode; + unsigned int st_uid; + unsigned int st_gid; + unsigned int st_size; + unsigned char sha1[20]; + unsigned short namelen; + unsigned char name[0]; +}; + +const char *sha1_file_directory; +struct cache_entry **active_cache; +unsigned int active_nr, active_alloc; + +#define DB_ENVIRONMENT "SHA1_FILE_DIRECTORY" +#define DEFAULT_DB_ENVIRONMENT ".dircache/objects" + +#define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7) +#define ce_size(ce) cache_entry_size((ce)->namelen) + +#define alloc_nr(x) (((x)+16)*3/2) + +/* Initialize the cache information */ +extern int read_cache(void); + +/* Return a statically allocated filename matching the sha1 signature */ +extern char *sha1_file_name(unsigned char *sha1); + +/* Write a memory buffer out to the sha file */ +extern int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size); + +/* Read and unpack a sha1 file into memory, write memory to a sha1 file */ +extern void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size); +extern int write_sha1_file(char *buf, unsigned len); + +/* Convert to/from hex/sha1 representation */ +extern int get_sha1_hex(char *hex, unsigned char *sha1); +extern char *sha1_to_hex(unsigned char *sha1); /* static buffer! */ + +/* General helper functions */ +extern void usage(const char *err); + +#endif /* CACHE_H */ diff --git a/cat-file.c b/cat-file.c new file mode 100644 index 0000000000..74a0a234dd --- /dev/null +++ b/cat-file.c @@ -0,0 +1,23 @@ +#include "cache.h" + +int main(int argc, char **argv) +{ + unsigned char sha1[20]; + char type[20]; + void *buf; + unsigned long size; + char template[] = "temp_git_file_XXXXXX"; + int fd; + + if (argc != 2 || get_sha1_hex(argv[1], sha1)) + usage("cat-file: cat-file <sha1>"); + buf = read_sha1_file(sha1, type, &size); + if (!buf) + exit(1); + fd = mkstemp(template); + if (fd < 0) + usage("unable to create tempfile"); + if (write(fd, buf, size) != size) + strcpy(type, "bad"); + printf("%s: %s\n", template, type); +} diff --git a/commit-tree.c b/commit-tree.c new file mode 100644 index 0000000000..840307af0c --- /dev/null +++ b/commit-tree.c @@ -0,0 +1,172 @@ +#include "cache.h" + +#include <pwd.h> +#include <time.h> + +#define BLOCKING (1ul << 14) +#define ORIG_OFFSET (40) + +/* + * Leave space at the beginning to insert the tag + * once we know how big things are. + * + * FIXME! Share the code with "write-tree.c" + */ +static void init_buffer(char **bufp, unsigned int *sizep) +{ + char *buf = malloc(BLOCKING); + memset(buf, 0, ORIG_OFFSET); + *sizep = ORIG_OFFSET; + *bufp = buf; +} + +static void add_buffer(char **bufp, unsigned int *sizep, const char *fmt, ...) +{ + char one_line[2048]; + va_list args; + int len; + unsigned long alloc, size, newsize; + char *buf; + + va_start(args, fmt); + len = vsnprintf(one_line, sizeof(one_line), fmt, args); + va_end(args); + size = *sizep; + newsize = size + len; + alloc = (size + 32767) & ~32767; + buf = *bufp; + if (newsize > alloc) { + alloc = (newsize + 32767) & ~32767; + buf = realloc(buf, alloc); + *bufp = buf; + } + *sizep = newsize; + memcpy(buf + size, one_line, len); +} + +static int prepend_integer(char *buffer, unsigned val, int i) +{ + buffer[--i] = '\0'; + do { + buffer[--i] = '0' + (val % 10); + val /= 10; + } while (val); + return i; +} + +static void finish_buffer(char *tag, char **bufp, unsigned int *sizep) +{ + int taglen; + int offset; + char *buf = *bufp; + unsigned int size = *sizep; + + offset = prepend_integer(buf, size - ORIG_OFFSET, ORIG_OFFSET); + taglen = strlen(tag); + offset -= taglen; + buf += offset; + size -= offset; + memcpy(buf, tag, taglen); + + *bufp = buf; + *sizep = size; +} + +static void remove_special(char *p) +{ + char c; + char *dst = p; + + for (;;) { + c = *p; + p++; + switch(c) { + case '\n': case '<': case '>': + continue; + } + *dst++ = c; + if (!c) + break; + } +} + +/* + * Having more than two parents may be strange, but hey, there's + * no conceptual reason why the file format couldn't accept multi-way + * merges. It might be the "union" of several packages, for example. + * + * I don't really expect that to happen, but this is here to make + * it clear that _conceptually_ it's ok.. + */ +#define MAXPARENT (16) + +int main(int argc, char **argv) +{ + int i, len; + int parents = 0; + unsigned char tree_sha1[20]; + unsigned char parent_sha1[MAXPARENT][20]; + char *gecos, *realgecos; + char *email, realemail[1000]; + char *date, *realdate; + char comment[1000]; + struct passwd *pw; + time_t now; + char *buffer; + unsigned int size; + + if (argc < 2 || get_sha1_hex(argv[1], tree_sha1) < 0) + usage("commit-tree <sha1> [-p <sha1>]* < changelog"); + + for (i = 2; i < argc; i += 2) { + char *a, *b; + a = argv[i]; b = argv[i+1]; + if (!b || strcmp(a, "-p") || get_sha1_hex(b, parent_sha1[parents])) + usage("commit-tree <sha1> [-p <sha1>]* < changelog"); + parents++; + } + if (!parents) + fprintf(stderr, "Committing initial tree %s\n", argv[1]); + pw = getpwuid(getuid()); + if (!pw) + usage("You don't exist. Go away!"); + realgecos = pw->pw_gecos; + len = strlen(pw->pw_name); + memcpy(realemail, pw->pw_name, len); + realemail[len] = '@'; + gethostname(realemail+len+1, sizeof(realemail)-len-1); + time(&now); + realdate = ctime(&now); + + gecos = getenv("COMMITTER_NAME") ? : realgecos; + email = getenv("COMMITTER_EMAIL") ? : realemail; + date = getenv("COMMITTER_DATE") ? : realdate; + + remove_special(gecos); remove_special(realgecos); + remove_special(email); remove_special(realemail); + remove_special(date); remove_special(realdate); + + init_buffer(&buffer, &size); + add_buffer(&buffer, &size, "tree %s\n", sha1_to_hex(tree_sha1)); + + /* + * NOTE! This ordering means that the same exact tree merged with a + * different order of parents will be a _different_ changeset even + * if everything else stays the same. + */ + for (i = 0; i < parents; i++) + add_buffer(&buffer, &size, "parent %s\n", sha1_to_hex(parent_sha1[i])); + + /* Person/date information */ + add_buffer(&buffer, &size, "author %s <%s> %s\n", gecos, email, date); + add_buffer(&buffer, &size, "committer %s <%s> %s\n\n", realgecos, realemail, realdate); + + /* And add the comment */ + while (fgets(comment, sizeof(comment), stdin) != NULL) + add_buffer(&buffer, &size, "%s", comment); + + finish_buffer("commit ", &buffer, &size); + + write_sha1_file(buffer, size); + return 0; +} diff --git a/init-db.c b/init-db.c new file mode 100644 index 0000000000..25dc13fe10 --- /dev/null +++ b/init-db.c @@ -0,0 +1,51 @@ +#include "cache.h" + +int main(int argc, char **argv) +{ + char *sha1_dir = getenv(DB_ENVIRONMENT), *path; + int len, i, fd; + + if (mkdir(".dircache", 0700) < 0) { + perror("unable to create .dircache"); + exit(1); + } + + /* + * If you want to, you can share the DB area with any number of branches. + * That has advantages: you can save space by sharing all the SHA1 objects. + * On the other hand, it might just make lookup slower and messier. You + * be the judge. + */ + sha1_dir = getenv(DB_ENVIRONMENT); + if (sha1_dir) { + struct stat st; + if (!stat(sha1_dir, &st) < 0 && S_ISDIR(st.st_mode)) + return; + fprintf(stderr, "DB_ENVIRONMENT set to bad directory %s: ", sha1_dir); + } + + /* + * The default case is to have a DB per managed directory. + */ + sha1_dir = DEFAULT_DB_ENVIRONMENT; + fprintf(stderr, "defaulting to private storage area\n"); + len = strlen(sha1_dir); + if (mkdir(sha1_dir, 0700) < 0) { + if (errno != EEXIST) { + perror(sha1_dir); + exit(1); + } + } + path = malloc(len + 40); + memcpy(path, sha1_dir, len); + for (i = 0; i < 256; i++) { + sprintf(path+len, "/%02x", i); + if (mkdir(path, 0700) < 0) { + if (errno != EEXIST) { + perror(path); + exit(1); + } + } + } + return 0; +} diff --git a/read-cache.c b/read-cache.c new file mode 100644 index 0000000000..c924a6e0fc --- /dev/null +++ b/read-cache.c @@ -0,0 +1,259 @@ +#include "cache.h" + +const char *sha1_file_directory = NULL; +struct cache_entry **active_cache = NULL; +unsigned int active_nr = 0, active_alloc = 0; + +void usage(const char *err) +{ + fprintf(stderr, "read-tree: %s\n", err); + exit(1); +} + +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(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(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(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; +} + +void * read_sha1_file(unsigned char *sha1, char *type, unsigned long *size) +{ + z_stream stream; + char buffer[8192]; + struct stat st; + int i, fd, ret, bytes; + void *map, *buf; + char *filename = sha1_file_name(sha1); + + fd = open(filename, O_RDONLY); + 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; + + /* Get the data stream */ + memset(&stream, 0, sizeof(stream)); + stream.next_in = map; + stream.avail_in = st.st_size; + 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; +} + +int write_sha1_file(char *buf, unsigned len) +{ + 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; + printf("%s\n", sha1_to_hex(sha1)); + return 0; +} + +int write_sha1_buffer(unsigned char *sha1, void *buf, unsigned int size) +{ + char *filename = sha1_file_name(sha1); + int i, fd; + + fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666); + if (fd < 0) + return (errno == EEXIST) ? 0 : -1; + write(fd, buf, size); + close(fd); + return 0; +} + +static int error(const char * string) +{ + fprintf(stderr, "error: %s\n", string); + return -1; +} + +static int verify_hdr(struct cache_header *hdr, unsigned long size) +{ + SHA_CTX c; + unsigned char sha1[20]; + + if (hdr->signature != CACHE_SIGNATURE) + return error("bad signature"); + if (hdr->version != 1) + return error("bad version"); + SHA1_Init(&c); + SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1)); + SHA1_Update(&c, hdr+1, size - sizeof(*hdr)); + SHA1_Final(sha1, &c); + if (memcmp(sha1, hdr->sha1, 20)) + return error("bad header sha1"); + return 0; +} + +int read_cache(void) +{ + int fd, i; + struct stat st; + unsigned long size, offset; + void *map; + struct cache_header *hdr; + + errno = EBUSY; + if (active_cache) + return error("more than one cachefile"); + errno = ENOENT; + sha1_file_directory = getenv(DB_ENVIRONMENT); + if (!sha1_file_directory) + sha1_file_directory = DEFAULT_DB_ENVIRONMENT; + if (access(sha1_file_directory, X_OK) < 0) + return error("no access to SHA1 file directory"); + fd = open(".dircache/index", O_RDONLY); + if (fd < 0) + return (errno == ENOENT) ? 0 : error("open failed"); + + map = (void *)-1; + if (!fstat(fd, &st)) { + map = NULL; + size = st.st_size; + errno = EINVAL; + if (size > sizeof(struct cache_header)) + map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0); + } + close(fd); + if (-1 == (int)(long)map) + return error("mmap failed"); + + hdr = map; + if (verify_hdr(hdr, size) < 0) + goto unmap; + + active_nr = hdr->entries; + active_alloc = alloc_nr(active_nr); + active_cache = calloc(active_alloc, sizeof(struct cache_entry *)); + + offset = sizeof(*hdr); + for (i = 0; i < hdr->entries; i++) { + struct cache_entry *ce = map + offset; + offset = offset + ce_size(ce); + active_cache[i] = ce; + } + return active_nr; + +unmap: + munmap(map, size); + errno = EINVAL; + return error("verify header failed"); +} + diff --git a/read-tree.c b/read-tree.c new file mode 100644 index 0000000000..1b47742d8c --- /dev/null +++ b/read-tree.c @@ -0,0 +1,43 @@ +#include "cache.h" + +static int unpack(unsigned char *sha1) +{ + void *buffer; + unsigned long size; + char type[20]; + + buffer = read_sha1_file(sha1, type, &size); + if (!buffer) + usage("unable to read sha1 file"); + if (strcmp(type, "tree")) + usage("expected a 'tree' node"); + while (size) { + int len = strlen(buffer)+1; + unsigned char *sha1 = buffer + len; + char *path = strchr(buffer, ' ')+1; + unsigned int mode; + if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1) + usage("corrupt 'tree' file"); + buffer = sha1 + 20; + size -= len + 20; + printf("%o %s (%s)\n", mode, path, sha1_to_hex(sha1)); + } + return 0; +} + +int main(int argc, char **argv) +{ + int fd; + unsigned char sha1[20]; + + if (argc != 2) + usage("read-tree <key>"); + if (get_sha1_hex(argv[1], sha1) < 0) + usage("read-tree <key>"); + sha1_file_directory = getenv(DB_ENVIRONMENT); + if (!sha1_file_directory) + sha1_file_directory = DEFAULT_DB_ENVIRONMENT; + if (unpack(sha1) < 0) + usage("unpack failed"); + return 0; +} diff --git a/show-diff.c b/show-diff.c new file mode 100644 index 0000000000..b8522886a1 --- /dev/null +++ b/show-diff.c @@ -0,0 +1,81 @@ +#include "cache.h" + +#define MTIME_CHANGED 0x0001 +#define CTIME_CHANGED 0x0002 +#define OWNER_CHANGED 0x0004 +#define MODE_CHANGED 0x0008 +#define INODE_CHANGED 0x0010 +#define DATA_CHANGED 0x0020 + +static int match_stat(struct cache_entry *ce, struct stat *st) +{ + unsigned int changed = 0; + + if (ce->mtime.sec != (unsigned int)st->st_mtim.tv_sec || + ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec) + changed |= MTIME_CHANGED; + if (ce->ctime.sec != (unsigned int)st->st_ctim.tv_sec || + ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec) + changed |= CTIME_CHANGED; + if (ce->st_uid != (unsigned int)st->st_uid || + ce->st_gid != (unsigned int)st->st_gid) + changed |= OWNER_CHANGED; + if (ce->st_mode != (unsigned int)st->st_mode) + changed |= MODE_CHANGED; + if (ce->st_dev != (unsigned int)st->st_dev || + ce->st_ino != (unsigned int)st->st_ino) + changed |= INODE_CHANGED; + if (ce->st_size != (unsigned int)st->st_size) + changed |= DATA_CHANGED; + return changed; +} + +static void show_differences(struct cache_entry *ce, struct stat *cur, + void *old_contents, unsigned long long old_size) +{ + static char cmd[1000]; + FILE *f; + + snprintf(cmd, sizeof(cmd), "diff -u - %s", ce->name); + f = popen(cmd, "w"); + fwrite(old_contents, old_size, 1, f); + pclose(f); +} + +int main(int argc, char **argv) +{ + int entries = read_cache(); + int i; + + if (entries < 0) { + perror("read_cache"); + exit(1); + } + for (i = 0; i < entries; i++) { + struct stat st; + struct cache_entry *ce = active_cache[i]; + int n, changed; + unsigned int mode; + unsigned long size; + char type[20]; + void *new; + + if (stat(ce->name, &st) < 0) { + printf("%s: %s\n", ce->name, strerror(errno)); + continue; + } + changed = match_stat(ce, &st); + if (!changed) { + printf("%s: ok\n", ce->name); + continue; + } + printf("%.*s: ", ce->namelen, ce->name); + for (n = 0; n < 20; n++) + printf("%02x", ce->sha1[n]); + printf("\n"); + new = read_sha1_file(ce->sha1, type, &size); + show_differences(ce, &st, new, size); + free(new); + } + return 0; +} diff --git a/update-cache.c b/update-cache.c new file mode 100644 index 0000000000..5085a5cb53 --- /dev/null +++ b/update-cache.c @@ -0,0 +1,248 @@ +#include "cache.h" + +static int cache_name_compare(const char *name1, int len1, const char *name2, int len2) +{ + int len = len1 < len2 ? len1 : len2; + int cmp; + + cmp = memcmp(name1, name2, len); + if (cmp) + return cmp; + if (len1 < len2) + return -1; + if (len1 > len2) + return 1; + return 0; +} + +static int cache_name_pos(const char *name, int namelen) +{ + int first, last; + + first = 0; + last = active_nr; + while (last > first) { + int next = (last + first) >> 1; + struct cache_entry *ce = active_cache[next]; + int cmp = cache_name_compare(name, namelen, ce->name, ce->namelen); + if (!cmp) + return -next-1; + if (cmp < 0) { + last = next; + continue; + } + first = next+1; + } + return first; +} + +static int remove_file_from_cache(char *path) +{ + int pos = cache_name_pos(path, strlen(path)); + if (pos < 0) { + pos = -pos-1; + active_nr--; + if (pos < active_nr) + memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *)); + } +} + +static int add_cache_entry(struct cache_entry *ce) +{ + int pos; + + pos = cache_name_pos(ce->name, ce->namelen); + + /* existing match? Just replace it */ + if (pos < 0) { + active_cache[-pos-1] = ce; + return 0; + } + + /* Make sure the array is big enough .. */ + if (active_nr == active_alloc) { + active_alloc = alloc_nr(active_alloc); + active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *)); + } + + /* Add it in.. */ + active_nr++; + if (active_nr > pos) + memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce)); + active_cache[pos] = ce; + return 0; +} + +static int index_fd(const char *path, int namelen, struct cache_entry *ce, int fd, struct stat *st) +{ + z_stream stream; + int max_out_bytes = namelen + st->st_size + 200; + void *out = malloc(max_out_bytes); + void *metadata = malloc(namelen + 200); + void *in = mmap(NULL, st->st_size, PROT_READ, MAP_PRIVATE, fd, 0); + SHA_CTX c; + + close(fd); + if (!out || (int)(long)in == -1) + return -1; + + memset(&stream, 0, sizeof(stream)); + deflateInit(&stream, Z_BEST_COMPRESSION); + + /* + * ASCII size + nul byte + */ + stream.next_in = metadata; + stream.avail_in = 1+sprintf(metadata, "blob %lu", (unsigned long) st->st_size); + stream.next_out = out; + stream.avail_out = max_out_bytes; + while (deflate(&stream, 0) == Z_OK) + /* nothing */; + + /* + * File content + */ + stream.next_in = in; + stream.avail_in = st->st_size; + while (deflate(&stream, Z_FINISH) == Z_OK) + /*nothing */; + + deflateEnd(&stream); + + SHA1_Init(&c); + SHA1_Update(&c, out, stream.total_out); + SHA1_Final(ce->sha1, &c); + + return write_sha1_buffer(ce->sha1, out, stream.total_out); +} + +static int add_file_to_cache(char *path) +{ + int size, namelen; + struct cache_entry *ce; + struct stat st; + int fd; + + fd = open(path, O_RDONLY); + if (fd < 0) { + if (errno == ENOENT) + return remove_file_from_cache(path); + return -1; + } + if (fstat(fd, &st) < 0) { + close(fd); + return -1; + } + namelen = strlen(path); + size = cache_entry_size(namelen); + ce = malloc(size); + memset(ce, 0, size); + memcpy(ce->name, path, namelen); + ce->ctime.sec = st.st_ctime; + ce->ctime.nsec = st.st_ctim.tv_nsec; + ce->mtime.sec = st.st_mtime; + ce->mtime.nsec = st.st_mtim.tv_nsec; + ce->st_dev = st.st_dev; + ce->st_ino = st.st_ino; + ce->st_mode = st.st_mode; + ce->st_uid = st.st_uid; + ce->st_gid = st.st_gid; + ce->st_size = st.st_size; + ce->namelen = namelen; + + if (index_fd(path, namelen, ce, fd, &st) < 0) + return -1; + + return add_cache_entry(ce); +} + +static int write_cache(int newfd, struct cache_entry **cache, int entries) +{ + SHA_CTX c; + struct cache_header hdr; + int i; + + hdr.signature = CACHE_SIGNATURE; + hdr.version = 1; + hdr.entries = entries; + + SHA1_Init(&c); + SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1)); + for (i = 0; i < entries; i++) { + struct cache_entry *ce = cache[i]; + int size = ce_size(ce); + SHA1_Update(&c, ce, size); + } + SHA1_Final(hdr.sha1, &c); + + if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr)) + return -1; + + for (i = 0; i < entries; i++) { + struct cache_entry *ce = cache[i]; + int size = ce_size(ce); + if (write(newfd, ce, size) != size) + return -1; + } + return 0; +} + +/* + * We fundamentally don't like some paths: we don't want + * dot or dot-dot anywhere, and in fact, we don't even want + * any other dot-files (.dircache or anything else). They + * are hidden, for chist sake. + * + * Also, we don't want double slashes or slashes at the + * end that can make pathnames ambiguous. + */ +static int verify_path(char *path) +{ + char c; + + goto inside; + for (;;) { + if (!c) + return 1; + if (c == '/') { +inside: + c = *path++; + if (c != '/' && c != '.' && c != '\0') + continue; + return 0; + } + c = *path++; + } +} + +int main(int argc, char **argv) +{ + int i, newfd, entries; + + entries = read_cache(); + if (entries < 0) { + perror("cache corrupted"); + return -1; + } + + newfd = open(".dircache/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600); + if (newfd < 0) { + perror("unable to create new cachefile"); + return -1; + } + for (i = 1 ; i < argc; i++) { + char *path = argv[i]; + if (!verify_path(path)) { + fprintf(stderr, "Ignoring path %s\n", argv[i]); + continue; + } + if (add_file_to_cache(path)) { + fprintf(stderr, "Unable to add %s to database\n", path); + goto out; + } + } + if (!write_cache(newfd, active_cache, active_nr) && !rename(".dircache/index.lock", ".dircache/index")) + return 0; +out: + unlink(".dircache/index.lock"); +} diff --git a/write-tree.c b/write-tree.c new file mode 100644 index 0000000000..921f981353 --- /dev/null +++ b/write-tree.c @@ -0,0 +1,66 @@ +#include "cache.h" + +static int check_valid_sha1(unsigned char *sha1) +{ + char *filename = sha1_file_name(sha1); + int ret; + + /* If we were anal, we'd check that the sha1 of the contents actually matches */ + ret = access(filename, R_OK); + if (ret) + perror(filename); + return ret; +} + +static int prepend_integer(char *buffer, unsigned val, int i) +{ + buffer[--i] = '\0'; + do { + buffer[--i] = '0' + (val % 10); + val /= 10; + } while (val); + return i; +} + +#define ORIG_OFFSET (40) /* Enough space to add the header of "tree <size>\0" */ + +int main(int argc, char **argv) +{ + unsigned long size, offset, val; + int i, entries = read_cache(); + char *buffer; + + if (entries <= 0) { + fprintf(stderr, "No file-cache to create a tree of\n"); + exit(1); + } + + /* Guess at an initial size */ + size = entries * 40 + 400; + buffer = malloc(size); + offset = ORIG_OFFSET; + + for (i = 0; i < entries; i++) { + struct cache_entry *ce = active_cache[i]; + if (check_valid_sha1(ce->sha1) < 0) + exit(1); + if (offset + ce->namelen + 60 > size) { + size = alloc_nr(offset + ce->namelen + 60); + buffer = realloc(buffer, size); + } + offset += sprintf(buffer + offset, "%o %s", ce->st_mode, ce->name); + buffer[offset++] = 0; + memcpy(buffer + offset, ce->sha1, 20); + offset += 20; + } + + i = prepend_integer(buffer, offset - ORIG_OFFSET, ORIG_OFFSET); + i -= 5; + memcpy(buffer+i, "tree ", 5); + + buffer += i; + offset -= i; + + write_sha1_file(buffer, offset); + return 0; +} |