root/builtin/cat-file.c

DEFINITIONS

1. cat_one_file
2. is_atom
3. expand_atom
4. expand_format
5. batch_write
6. print_object_or_die
7. batch_object_write
8. batch_one_object
9. batch_object_cb
10. batch_loose_object
11. batch_packed_object
12. batch_objects
13. git_cat_file_config
14. batch_option_callback
15. cmd_cat_file

/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"
#include "builtin.h"
#include "parse-options.h"
#include "userdiff.h"
#include "streaming.h"
#include "tree-walk.h"
#include "sha1-array.h"

struct batch_options {
        int enabled;
        int follow_symlinks;
        int print_contents;
        int buffer_output;
        int all_objects;
        const char *format;
};

static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
                        int unknown_type)
{
        unsigned char sha1[20];
        enum object_type type;
        char *buf;
        unsigned long size;
        struct object_context obj_context;
        struct object_info oi = {NULL};
        struct strbuf sb = STRBUF_INIT;
        unsigned flags = LOOKUP_REPLACE_OBJECT;

        if (unknown_type)
                flags |= LOOKUP_UNKNOWN_OBJECT;

        if (get_sha1_with_context(obj_name, 0, sha1, &obj_context))
                die("Not a valid object name %s", obj_name);

        buf = NULL;
        switch (opt) {
        case 't':
                oi.typename = &sb;
                if (sha1_object_info_extended(sha1, &oi, flags) < 0)
                        die("git cat-file: could not get object info");
                if (sb.len) {
                        printf("%s\n", sb.buf);
                        strbuf_release(&sb);
                        return 0;
                }
                break;

        case 's':
                oi.sizep = &size;
                if (sha1_object_info_extended(sha1, &oi, flags) < 0)
                        die("git cat-file: could not get object info");
                printf("%lu\n", size);
                return 0;

        case 'e':
                return !has_sha1_file(sha1);

        case 'c':
                if (!obj_context.path[0])
                        die("git cat-file --textconv %s: <object> must be <sha1:path>",
                            obj_name);

                if (textconv_object(obj_context.path, obj_context.mode, sha1, 1, &buf, &size))
                        break;

        case 'p':
                type = sha1_object_info(sha1, NULL);
                if (type < 0)
                        die("Not a valid object name %s", obj_name);

                /* custom pretty-print here */
                if (type == OBJ_TREE) {
                        const char *ls_args[3] = { NULL };
                        ls_args[0] =  "ls-tree";
                        ls_args[1] =  obj_name;
                        return cmd_ls_tree(2, ls_args, NULL);
                }

                if (type == OBJ_BLOB)
                        return stream_blob_to_fd(1, sha1, NULL, 0);
                buf = read_sha1_file(sha1, &type, &size);
                if (!buf)
                        die("Cannot read object %s", obj_name);

                /* otherwise just spit out the data */
                break;

        case 0:
                if (type_from_string(exp_type) == OBJ_BLOB) {
                        unsigned char blob_sha1[20];
                        if (sha1_object_info(sha1, NULL) == OBJ_TAG) {
                                char *buffer = read_sha1_file(sha1, &type, &size);
                                const char *target;
                                if (!skip_prefix(buffer, "object ", &target) ||
                                    get_sha1_hex(target, blob_sha1))
                                        die("%s not a valid tag", sha1_to_hex(sha1));
                                free(buffer);
                        } else
                                hashcpy(blob_sha1, sha1);

                        if (sha1_object_info(blob_sha1, NULL) == OBJ_BLOB)
                                return stream_blob_to_fd(1, blob_sha1, NULL, 0);
                        /*
                         * we attempted to dereference a tag to a blob
                         * and failed; there may be new dereference
                         * mechanisms this code is not aware of.
                         * fall-back to the usual case.
                         */
                }
                buf = read_object_with_reference(sha1, exp_type, &size, NULL);
                break;

        default:
                die("git cat-file: unknown option: %s", exp_type);
        }

        if (!buf)
                die("git cat-file %s: bad file", obj_name);

        write_or_die(1, buf, size);
        return 0;
}

struct expand_data {
        unsigned char sha1[20];
        enum object_type type;
        unsigned long size;
        unsigned long disk_size;
        const char *rest;
        unsigned char delta_base_sha1[20];

        /*
         * If mark_query is true, we do not expand anything, but rather
         * just mark the object_info with items we wish to query.
         */
        int mark_query;

        /*
         * Whether to split the input on whitespace before feeding it to
         * get_sha1; this is decided during the mark_query phase based on
         * whether we have a %(rest) token in our format.
         */
        int split_on_whitespace;

        /*
         * After a mark_query run, this object_info is set up to be
         * passed to sha1_object_info_extended. It will point to the data
         * elements above, so you can retrieve the response from there.
         */
        struct object_info info;
};

static int is_atom(const char *atom, const char *s, int slen)
{
        int alen = strlen(atom);
        return alen == slen && !memcmp(atom, s, alen);
}

static void expand_atom(struct strbuf *sb, const char *atom, int len,
                        void *vdata)
{
        struct expand_data *data = vdata;

        if (is_atom("objectname", atom, len)) {
                if (!data->mark_query)
                        strbuf_addstr(sb, sha1_to_hex(data->sha1));
        } else if (is_atom("objecttype", atom, len)) {
                if (data->mark_query)
                        data->info.typep = &data->type;
                else
                        strbuf_addstr(sb, typename(data->type));
        } else if (is_atom("objectsize", atom, len)) {
                if (data->mark_query)
                        data->info.sizep = &data->size;
                else
                        strbuf_addf(sb, "%lu", data->size);
        } else if (is_atom("objectsize:disk", atom, len)) {
                if (data->mark_query)
                        data->info.disk_sizep = &data->disk_size;
                else
                        strbuf_addf(sb, "%lu", data->disk_size);
        } else if (is_atom("rest", atom, len)) {
                if (data->mark_query)
                        data->split_on_whitespace = 1;
                else if (data->rest)
                        strbuf_addstr(sb, data->rest);
        } else if (is_atom("deltabase", atom, len)) {
                if (data->mark_query)
                        data->info.delta_base_sha1 = data->delta_base_sha1;
                else
                        strbuf_addstr(sb, sha1_to_hex(data->delta_base_sha1));
        } else
                die("unknown format element: %.*s", len, atom);
}

static size_t expand_format(struct strbuf *sb, const char *start, void *data)
{
        const char *end;

        if (*start != '(')
                return 0;
        end = strchr(start + 1, ')');
        if (!end)
                die("format element '%s' does not end in ')'", start);

        expand_atom(sb, start + 1, end - start - 1, data);

        return end - start + 1;
}

static void batch_write(struct batch_options *opt, const void *data, int len)
{
        if (opt->buffer_output) {
                if (fwrite(data, 1, len, stdout) != len)
                        die_errno("unable to write to stdout");
        } else
                write_or_die(1, data, len);
}

static void print_object_or_die(struct batch_options *opt, struct expand_data *data)
{
        const unsigned char *sha1 = data->sha1;

        assert(data->info.typep);

        if (data->type == OBJ_BLOB) {
                if (opt->buffer_output)
                        fflush(stdout);
                if (stream_blob_to_fd(1, sha1, NULL, 0) < 0)
                        die("unable to stream %s to stdout", sha1_to_hex(sha1));
        }
        else {
                enum object_type type;
                unsigned long size;
                void *contents;

                contents = read_sha1_file(sha1, &type, &size);
                if (!contents)
                        die("object %s disappeared", sha1_to_hex(sha1));
                if (type != data->type)
                        die("object %s changed type!?", sha1_to_hex(sha1));
                if (data->info.sizep && size != data->size)
                        die("object %s changed size!?", sha1_to_hex(sha1));

                batch_write(opt, contents, size);
                free(contents);
        }
}

static void batch_object_write(const char *obj_name, struct batch_options *opt,
                               struct expand_data *data)
{
        struct strbuf buf = STRBUF_INIT;

        if (sha1_object_info_extended(data->sha1, &data->info, LOOKUP_REPLACE_OBJECT) < 0) {
                printf("%s missing\n", obj_name ? obj_name : sha1_to_hex(data->sha1));
                fflush(stdout);
                return;
        }

        strbuf_expand(&buf, opt->format, expand_format, data);
        strbuf_addch(&buf, '\n');
        batch_write(opt, buf.buf, buf.len);
        strbuf_release(&buf);

        if (opt->print_contents) {
                print_object_or_die(opt, data);
                batch_write(opt, "\n", 1);
        }
}

static void batch_one_object(const char *obj_name, struct batch_options *opt,
                             struct expand_data *data)
{
        struct object_context ctx;
        int flags = opt->follow_symlinks ? GET_SHA1_FOLLOW_SYMLINKS : 0;
        enum follow_symlinks_result result;

        result = get_sha1_with_context(obj_name, flags, data->sha1, &ctx);
        if (result != FOUND) {
                switch (result) {
                case MISSING_OBJECT:
                        printf("%s missing\n", obj_name);
                        break;
                case DANGLING_SYMLINK:
                        printf("dangling %"PRIuMAX"\n%s\n",
                               (uintmax_t)strlen(obj_name), obj_name);
                        break;
                case SYMLINK_LOOP:
                        printf("loop %"PRIuMAX"\n%s\n",
                               (uintmax_t)strlen(obj_name), obj_name);
                        break;
                case NOT_DIR:
                        printf("notdir %"PRIuMAX"\n%s\n",
                               (uintmax_t)strlen(obj_name), obj_name);
                        break;
                default:
                        die("BUG: unknown get_sha1_with_context result %d\n",
                               result);
                        break;
                }
                fflush(stdout);
                return;
        }

        if (ctx.mode == 0) {
                printf("symlink %"PRIuMAX"\n%s\n",
                       (uintmax_t)ctx.symlink_path.len,
                       ctx.symlink_path.buf);
                fflush(stdout);
                return;
        }

        batch_object_write(obj_name, opt, data);
}

struct object_cb_data {
        struct batch_options *opt;
        struct expand_data *expand;
};

static void batch_object_cb(const unsigned char sha1[20], void *vdata)
{
        struct object_cb_data *data = vdata;
        hashcpy(data->expand->sha1, sha1);
        batch_object_write(NULL, data->opt, data->expand);
}

static int batch_loose_object(const unsigned char *sha1,
                              const char *path,
                              void *data)
{
        sha1_array_append(data, sha1);
        return 0;
}

static int batch_packed_object(const unsigned char *sha1,
                               struct packed_git *pack,
                               uint32_t pos,
                               void *data)
{
        sha1_array_append(data, sha1);
        return 0;
}

static int batch_objects(struct batch_options *opt)
{
        struct strbuf buf = STRBUF_INIT;
        struct expand_data data;
        int save_warning;
        int retval = 0;

        if (!opt->format)
                opt->format = "%(objectname) %(objecttype) %(objectsize)";

        /*
         * Expand once with our special mark_query flag, which will prime the
         * object_info to be handed to sha1_object_info_extended for each
         * object.
         */
        memset(&data, 0, sizeof(data));
        data.mark_query = 1;
        strbuf_expand(&buf, opt->format, expand_format, &data);
        data.mark_query = 0;

        /*
         * If we are printing out the object, then always fill in the type,
         * since we will want to decide whether or not to stream.
         */
        if (opt->print_contents)
                data.info.typep = &data.type;

        if (opt->all_objects) {
                struct sha1_array sa = SHA1_ARRAY_INIT;
                struct object_cb_data cb;

                for_each_loose_object(batch_loose_object, &sa, 0);
                for_each_packed_object(batch_packed_object, &sa, 0);

                cb.opt = opt;
                cb.expand = &data;
                sha1_array_for_each_unique(&sa, batch_object_cb, &cb);

                sha1_array_clear(&sa);
                return 0;
        }

        /*
         * We are going to call get_sha1 on a potentially very large number of
         * objects. In most large cases, these will be actual object sha1s. The
         * cost to double-check that each one is not also a ref (just so we can
         * warn) ends up dwarfing the actual cost of the object lookups
         * themselves. We can work around it by just turning off the warning.
         */
        save_warning = warn_on_object_refname_ambiguity;
        warn_on_object_refname_ambiguity = 0;

        while (strbuf_getline(&buf, stdin, '\n') != EOF) {
                if (data.split_on_whitespace) {
                        /*
                         * Split at first whitespace, tying off the beginning
                         * of the string and saving the remainder (or NULL) in
                         * data.rest.
                         */
                        char *p = strpbrk(buf.buf, " \t");
                        if (p) {
                                while (*p && strchr(" \t", *p))
                                        *p++ = '\0';
                        }
                        data.rest = p;
                }

                batch_one_object(buf.buf, opt, &data);
        }

        strbuf_release(&buf);
        warn_on_object_refname_ambiguity = save_warning;
        return retval;
}

static const char * const cat_file_usage[] = {
        N_("git cat-file (-t [--allow-unknown-type]|-s [--allow-unknown-type]|-e|-p|<type>|--textconv) <object>"),
        N_("git cat-file (--batch | --batch-check) [--follow-symlinks]"),
        NULL
};

static int git_cat_file_config(const char *var, const char *value, void *cb)
{
        if (userdiff_config(var, value) < 0)
                return -1;

        return git_default_config(var, value, cb);
}

static int batch_option_callback(const struct option *opt,
                                 const char *arg,
                                 int unset)
{
        struct batch_options *bo = opt->value;

        if (bo->enabled) {
                return 1;
        }

        bo->enabled = 1;
        bo->print_contents = !strcmp(opt->long_name, "batch");
        bo->format = arg;

        return 0;
}

int cmd_cat_file(int argc, const char **argv, const char *prefix)
{
        int opt = 0;
        const char *exp_type = NULL, *obj_name = NULL;
        struct batch_options batch = {0};
        int unknown_type = 0;

        const struct option options[] = {
                OPT_GROUP(N_("<type> can be one of: blob, tree, commit, tag")),
                OPT_CMDMODE('t', NULL, &opt, N_("show object type"), 't'),
                OPT_CMDMODE('s', NULL, &opt, N_("show object size"), 's'),
                OPT_CMDMODE('e', NULL, &opt,
                            N_("exit with zero when there's no error"), 'e'),
                OPT_CMDMODE('p', NULL, &opt, N_("pretty-print object's content"), 'p'),
                OPT_CMDMODE(0, "textconv", &opt,
                            N_("for blob objects, run textconv on object's content"), 'c'),
                OPT_BOOL(0, "allow-unknown-type", &unknown_type,
                          N_("allow -s and -t to work with broken/corrupt objects")),
                OPT_BOOL(0, "buffer", &batch.buffer_output, N_("buffer --batch output")),
                { OPTION_CALLBACK, 0, "batch", &batch, "format",
                        N_("show info and content of objects fed from the standard input"),
                        PARSE_OPT_OPTARG, batch_option_callback },
                { OPTION_CALLBACK, 0, "batch-check", &batch, "format",
                        N_("show info about objects fed from the standard input"),
                        PARSE_OPT_OPTARG, batch_option_callback },
                OPT_BOOL(0, "follow-symlinks", &batch.follow_symlinks,
                         N_("follow in-tree symlinks (used with --batch or --batch-check)")),
                OPT_BOOL(0, "batch-all-objects", &batch.all_objects,
                         N_("show all objects with --batch or --batch-check")),
                OPT_END()
        };

        git_config(git_cat_file_config, NULL);

        argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0);

        if (opt) {
                if (argc == 1)
                        obj_name = argv[0];
                else
                        usage_with_options(cat_file_usage, options);
        }
        if (!opt && !batch.enabled) {
                if (argc == 2) {
                        exp_type = argv[0];
                        obj_name = argv[1];
                } else
                        usage_with_options(cat_file_usage, options);
        }
        if (batch.enabled && (opt || argc)) {
                usage_with_options(cat_file_usage, options);
        }

        if ((batch.follow_symlinks || batch.all_objects) && !batch.enabled) {
                usage_with_options(cat_file_usage, options);
        }

        if (batch.enabled)
                return batch_objects(&batch);

        if (unknown_type && opt != 't' && opt != 's')
                die("git cat-file --allow-unknown-type: use with -s or -t");
        return cat_one_file(opt, exp_type, obj_name, unknown_type);
}