diff options
Diffstat (limited to 'tar-tree.c')
| -rw-r--r-- | tar-tree.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/tar-tree.c b/tar-tree.c new file mode 100644 index 0000000000..d078cb5a8d --- /dev/null +++ b/tar-tree.c @@ -0,0 +1,363 @@ +#include <time.h> +#include "cache.h" + +#define RECORDSIZE (512) +#define BLOCKSIZE (RECORDSIZE * 20) + +static const char *tar_tree_usage = "tar-tree <key> [basedir]"; + +static char block[BLOCKSIZE]; +static unsigned long offset; + +static const char *basedir; +static time_t archive_time; + +struct path_prefix { + struct path_prefix *prev; + const char *name; +}; + +/* tries hard to write, either succeeds or dies in the attempt */ +static void reliable_write(void *buf, unsigned long size) +{ + while (size > 0) { + long ret = write(1, buf, size); + if (ret < 0) { + if (errno == EAGAIN) + continue; + if (errno == EPIPE) + exit(0); + die("tar-tree: %s", strerror(errno)); + } else if (!ret) { + die("tar-tree: disk full?"); + } + size -= ret; + buf += ret; + } +} + +/* writes out the whole block, but only if it is full */ +static void write_if_needed(void) +{ + if (offset == BLOCKSIZE) { + reliable_write(block, BLOCKSIZE); + offset = 0; + } +} + +/* + * The end of tar archives is marked by 1024 nul bytes and after that + * follows the rest of the block (if any). + */ +static void write_trailer(void) +{ + memset(block + offset, 0, RECORDSIZE); + offset += RECORDSIZE; + write_if_needed(); + memset(block + offset, 0, RECORDSIZE); + offset += RECORDSIZE; + write_if_needed(); + if (offset) { + memset(block + offset, 0, BLOCKSIZE - offset); + reliable_write(block, BLOCKSIZE); + offset = 0; + } +} + +/* + * queues up writes, so that all our write(2) calls write exactly one + * full block; pads writes to RECORDSIZE + */ +static void write_blocked(void *buf, unsigned long size) +{ + unsigned long tail; + + if (offset) { + unsigned long chunk = BLOCKSIZE - offset; + if (size < chunk) + chunk = size; + memcpy(block + offset, buf, chunk); + size -= chunk; + offset += chunk; + buf += chunk; + write_if_needed(); + } + while (size >= BLOCKSIZE) { + reliable_write(buf, BLOCKSIZE); + size -= BLOCKSIZE; + buf += BLOCKSIZE; + } + if (size) { + memcpy(block + offset, buf, size); + buf += size; + offset += size; + } + tail = offset % RECORDSIZE; + if (tail) { + memset(block + offset, 0, RECORDSIZE - tail); + offset += RECORDSIZE - tail; + } + write_if_needed(); +} + +static void append_string(char **p, const char *s) +{ + unsigned int len = strlen(s); + memcpy(*p, s, len); + *p += len; +} + +static void append_char(char **p, char c) +{ + **p = c; + *p += 1; +} + +static void append_long(char **p, long n) +{ + int len = sprintf(*p, "%ld", n); + *p += len; +} + +static void append_path_prefix(char **buffer, struct path_prefix *prefix) +{ + if (!prefix) + return; + append_path_prefix(buffer, prefix->prev); + append_string(buffer, prefix->name); + append_char(buffer, '/'); +} + +static unsigned int path_prefix_len(struct path_prefix *prefix) +{ + if (!prefix) + return 0; + return path_prefix_len(prefix->prev) + strlen(prefix->name) + 1; +} + +static void append_path(char **p, int is_dir, const char *basepath, + struct path_prefix *prefix, const char *path) +{ + if (basepath) { + append_string(p, basepath); + append_char(p, '/'); + } + append_path_prefix(p, prefix); + append_string(p, path); + if (is_dir) + append_char(p, '/'); +} + +static unsigned int path_len(int is_dir, const char *basepath, + struct path_prefix *prefix, const char *path) +{ + unsigned int len = 0; + if (basepath) + len += strlen(basepath) + 1; + len += path_prefix_len(prefix) + strlen(path); + if (is_dir) + len++; + return len; +} + +static void write_header(const char *, const char *, struct path_prefix *, + const char *, unsigned int, unsigned long); + +/* stores a pax extended header directly in the block buffer */ +static void write_extended_header(const char *headerfilename, int is_dir, + const char *basepath, + struct path_prefix *prefix, + const char *path, unsigned int namelen) +{ + char *records, *p; + unsigned int size = 1 + 6 + namelen + 1; + if (size > 9) + size++; + if (size > 99) + size++; + if (size > RECORDSIZE) + die("tar-tree: extended header too big, wtf?"); + write_header(NULL, NULL, NULL, headerfilename, 0100600, size); + + records = block + offset; + memset(records, 0, RECORDSIZE); + offset += RECORDSIZE; + p = records; + append_long(&p, size); + append_string(&p, " path="); + append_path(&p, is_dir, basepath, prefix, path); + append_char(&p, '\n'); + write_if_needed(); +} + +/* stores a ustar header directly in the block buffer */ +static void write_header(const char *sha1, const char *basepath, + struct path_prefix *prefix, const char *path, + unsigned int mode, unsigned long size) +{ + unsigned int namelen; + char *p, *header = NULL; + unsigned int checksum = 0; + int i; + + namelen = path_len(S_ISDIR(mode), basepath, prefix, path); + if (namelen > 500) { + die("tar-tree: name too log of object %s\n", sha1_to_hex(sha1)); + } else if (namelen > 100) { + char *sha1_hex = sha1_to_hex(sha1); + char headerfilename[51]; + sprintf(headerfilename, "%s.paxheader", sha1_hex); + /* the extended header must be written before the normal one */ + write_extended_header(headerfilename, S_ISDIR(mode), basepath, + prefix, path, namelen); + + header = block + offset; + memset(header, 0, RECORDSIZE); + offset += RECORDSIZE; + sprintf(header, "%s.data", sha1_hex); + } else { + header = block + offset; + memset(header, 0, RECORDSIZE); + offset += RECORDSIZE; + p = header; + append_path(&p, S_ISDIR(mode), basepath, prefix, path); + } + + if (S_ISDIR(mode)) + mode |= 0755; /* GIT doesn't store permissions of dirs */ + sprintf(&header[100], "%07o", mode & 07777); + + /* XXX: should we provide more meaningful info here? */ + sprintf(&header[108], "%07o", 0); /* uid */ + sprintf(&header[116], "%07o", 0); /* gid */ + strncpy(&header[265], "git", 31); /* uname */ + strncpy(&header[297], "git", 31); /* gname */ + + sprintf(&header[124], "%011lo", S_ISDIR(mode) ? 0 : size); + sprintf(&header[136], "%011lo", archive_time); + + /* typeflag */ + if (!sha1) + header[156] = 'x'; /* extended header */ + else + header[156] = S_ISDIR(mode) ? '5' : '0'; + + memcpy(&header[257], "ustar", 6); + memcpy(&header[263], "00", 2); + + printf(&header[329], "%07o", 0); /* devmajor */ + printf(&header[337], "%07o", 0); /* devminor */ + + memset(&header[148], ' ', 8); + for (i = 0; i < RECORDSIZE; i++) + checksum += header[i]; + sprintf(&header[148], "%07o", checksum & 0x1fffff); + + write_if_needed(); +} + +static void traverse_tree(void *buffer, unsigned long size, + struct path_prefix *prefix) +{ + struct path_prefix this_prefix; + this_prefix.prev = prefix; + + while (size) { + int namelen = strlen(buffer)+1; + void *eltbuf; + char elttype[20]; + unsigned long eltsize; + unsigned char *sha1 = buffer + namelen; + char *path = strchr(buffer, ' ') + 1; + unsigned int mode; + + if (size < namelen + 20 || sscanf(buffer, "%o", &mode) != 1) + die("corrupt 'tree' file"); + buffer = sha1 + 20; + size -= namelen + 20; + + eltbuf = read_sha1_file(sha1, elttype, &eltsize); + if (!eltbuf) + die("cannot read %s", sha1_to_hex(sha1)); + write_header(sha1, basedir, prefix, path, mode, eltsize); + if (!strcmp(elttype, "tree")) { + this_prefix.name = path; + traverse_tree(eltbuf, eltsize, &this_prefix); + } else if (!strcmp(elttype, "blob")) { + write_blocked(eltbuf, eltsize); + } + free(eltbuf); + } +} + +/* get commit time from committer line of commit object */ +time_t commit_time(const unsigned char *sha1) +{ + char type[20]; + void *buffer; + unsigned long size; + time_t result = 0; + + buffer = read_sha1_file(sha1, type, &size); + if (buffer) { + char *p = buffer; + while (size > 0) { + char *endp = memchr(p, '\n', size); + if (!endp || endp == p) + break; + *endp = '\0'; + if (endp - p > 10 && !memcmp(p, "committer ", 10)) { + char *nump = strrchr(p, '>'); + if (!nump) + break; + nump++; + result = strtoul(nump, &endp, 10); + if (*endp != ' ') + result = 0; + break; + } + size -= endp - p - 1; + p = endp + 1; + } + free(buffer); + } + return result; +} + +int main(int argc, char **argv) +{ + unsigned char sha1[20]; + void *buffer; + unsigned long size; + unsigned char tree_sha1[20]; + + switch (argc) { + case 3: + basedir = argv[2]; + /* FALLTHROUGH */ + case 2: + if (get_sha1_hex(argv[1], sha1) < 0) + usage(tar_tree_usage); + break; + default: + usage(tar_tree_usage); + } + + sha1_file_directory = getenv(DB_ENVIRONMENT); + if (!sha1_file_directory) + sha1_file_directory = DEFAULT_DB_ENVIRONMENT; + + buffer = read_tree_with_tree_or_commit_sha1(sha1, &size, tree_sha1); + if (!buffer) + die("unable to read sha1 file"); + if (memcmp(sha1, tree_sha1, 20)) /* is sha1 a commit object? */ + archive_time = commit_time(sha1); + if (!archive_time) + archive_time = time(NULL); + if (basedir) + write_header("0", NULL, NULL, basedir, 040755, 0); + traverse_tree(buffer, size, NULL); + free(buffer); + write_trailer(); + return 0; +} |