Merge branch 'jc/maint-rerere-in-workdir'
[git/git.git] / sha1_file.c
index 0926643..df0edba 100644 (file)
@@ -13,6 +13,7 @@
 #include "commit.h"
 #include "tag.h"
 #include "tree.h"
+#include "tree-walk.h"
 #include "refs.h"
 #include "pack-revindex.h"
 #include "sha1-lookup.h"
 #endif
 #endif
 
-#ifdef NO_C99_FORMAT
-#define SZ_FMT "lu"
-static unsigned long sz_fmt(size_t s) { return (unsigned long)s; }
-#else
-#define SZ_FMT "zu"
-static size_t sz_fmt(size_t s) { return s; }
-#endif
+#define SZ_FMT PRIuMAX
+static inline uintmax_t sz_fmt(size_t s) { return s; }
 
 const unsigned char null_sha1[20];
 
-static inline int offset_1st_component(const char *path)
+static int git_open_noatime(const char *name, struct packed_git *p);
+
+/*
+ * This is meant to hold a *small* number of objects that you would
+ * want read_sha1_file() to be able to return, but yet you do not want
+ * to write them into the object store (e.g. a browse-only
+ * application).
+ */
+static struct cached_object {
+       unsigned char sha1[20];
+       enum object_type type;
+       void *buf;
+       unsigned long size;
+} *cached_objects;
+static int cached_object_nr, cached_object_alloc;
+
+static struct cached_object empty_tree = {
+       EMPTY_TREE_SHA1_BIN_LITERAL,
+       OBJ_TREE,
+       "",
+       0
+};
+
+static struct cached_object *find_cached_object(const unsigned char *sha1)
 {
-       if (has_dos_drive_prefix(path))
-               return 2 + (path[2] == '/');
-       return *path == '/';
+       int i;
+       struct cached_object *co = cached_objects;
+
+       for (i = 0; i < cached_object_nr; i++, co++) {
+               if (!hashcmp(co->sha1, sha1))
+                       return co;
+       }
+       if (!hashcmp(sha1, empty_tree.sha1))
+               return &empty_tree;
+       return NULL;
 }
 
 int mkdir_in_gitdir(const char *path)
@@ -138,20 +164,22 @@ static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
  */
 char *sha1_file_name(const unsigned char *sha1)
 {
-       static char *name, *base;
+       static char buf[PATH_MAX];
+       const char *objdir;
+       int len;
 
-       if (!base) {
-               const char *sha1_file_directory = get_object_directory();
-               int len = strlen(sha1_file_directory);
-               base = xmalloc(len + 60);
-               memcpy(base, sha1_file_directory, len);
-               memset(base+len, 0, 60);
-               base[len] = '/';
-               base[len+3] = '/';
-               name = base + len + 1;
-       }
-       fill_sha1_path(name, sha1);
-       return base;
+       objdir = get_object_directory();
+       len = strlen(objdir);
+
+       /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
+       if (len + 43 > PATH_MAX)
+               die("insanely long object directory %s", objdir);
+       memcpy(buf, objdir, len);
+       buf[len] = '/';
+       buf[len+3] = '/';
+       buf[len+42] = '\0';
+       fill_sha1_path(buf + len + 1, sha1);
+       return buf;
 }
 
 static char *sha1_get_pack_name(const unsigned char *sha1,
@@ -332,7 +360,7 @@ static void read_info_alternates(const char * relative_base, int depth)
        int fd;
 
        sprintf(path, "%s/%s", relative_base, alt_file_name);
-       fd = open(path, O_RDONLY);
+       fd = git_open_noatime(path, NULL);
        if (fd < 0)
                return;
        if (fstat(fd, &st) || (st.st_size == 0)) {
@@ -414,6 +442,8 @@ static unsigned int pack_used_ctr;
 static unsigned int pack_mmap_calls;
 static unsigned int peak_pack_open_windows;
 static unsigned int pack_open_windows;
+static unsigned int pack_open_fds;
+static unsigned int pack_max_fds;
 static size_t peak_pack_mapped;
 static size_t pack_mapped;
 struct packed_git *packed_git;
@@ -445,7 +475,7 @@ static int check_packed_git_idx(const char *path,  struct packed_git *p)
        struct pack_idx_header *hdr;
        size_t idx_size;
        uint32_t version, nr, i, *index;
-       int fd = open(path, O_RDONLY);
+       int fd = git_open_noatime(path, p);
        struct stat st;
 
        if (fd < 0)
@@ -591,8 +621,10 @@ static int unuse_one_window(struct packed_git *current, int keep_fd)
                        lru_l->next = lru_w->next;
                else {
                        lru_p->windows = lru_w->next;
-                       if (!lru_p->windows && lru_p->pack_fd != keep_fd) {
+                       if (!lru_p->windows && lru_p->pack_fd != -1
+                               && lru_p->pack_fd != keep_fd) {
                                close(lru_p->pack_fd);
+                               pack_open_fds--;
                                lru_p->pack_fd = -1;
                        }
                }
@@ -610,6 +642,21 @@ void release_pack_memory(size_t need, int fd)
                ; /* nothing */
 }
 
+void *xmmap(void *start, size_t length,
+       int prot, int flags, int fd, off_t offset)
+{
+       void *ret = mmap(start, length, prot, flags, fd, offset);
+       if (ret == MAP_FAILED) {
+               if (!length)
+                       return NULL;
+               release_pack_memory(length, fd);
+               ret = mmap(start, length, prot, flags, fd, offset);
+               if (ret == MAP_FAILED)
+                       die_errno("Out of memory? mmap failed");
+       }
+       return ret;
+}
+
 void close_pack_windows(struct packed_git *p)
 {
        while (p->windows) {
@@ -635,6 +682,14 @@ void unuse_pack(struct pack_window **w_cursor)
        }
 }
 
+void close_pack_index(struct packed_git *p)
+{
+       if (p->index_data) {
+               munmap((void *)p->index_data, p->index_size);
+               p->index_data = NULL;
+       }
+}
+
 /*
  * This is used by git-repack in case a newly created pack happens to
  * contain the same set of objects as an existing one.  In that case
@@ -654,10 +709,11 @@ void free_pack_by_name(const char *pack_name)
                if (strcmp(pack_name, p->pack_name) == 0) {
                        clear_delta_base_cache();
                        close_pack_windows(p);
-                       if (p->pack_fd != -1)
+                       if (p->pack_fd != -1) {
                                close(p->pack_fd);
-                       if (p->index_data)
-                               munmap((void *)p->index_data, p->index_size);
+                               pack_open_fds--;
+                       }
+                       close_pack_index(p);
                        free(p->bad_object_sha1);
                        *pp = p->next;
                        free(p);
@@ -682,11 +738,29 @@ static int open_packed_git_1(struct packed_git *p)
        if (!p->index_data && open_pack_index(p))
                return error("packfile %s index unavailable", p->pack_name);
 
-       p->pack_fd = open(p->pack_name, O_RDONLY);
-       while (p->pack_fd < 0 && errno == EMFILE && unuse_one_window(p, -1))
-               p->pack_fd = open(p->pack_name, O_RDONLY);
+       if (!pack_max_fds) {
+               struct rlimit lim;
+               unsigned int max_fds;
+
+               if (getrlimit(RLIMIT_NOFILE, &lim))
+                       die_errno("cannot get RLIMIT_NOFILE");
+
+               max_fds = lim.rlim_cur;
+
+               /* Save 3 for stdin/stdout/stderr, 22 for work */
+               if (25 < max_fds)
+                       pack_max_fds = max_fds - 25;
+               else
+                       pack_max_fds = 1;
+       }
+
+       while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
+               ; /* nothing */
+
+       p->pack_fd = git_open_noatime(p->pack_name, p);
        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
                return -1;
+       pack_open_fds++;
 
        /* If we created the struct before we had the pack we lack size. */
        if (!p->pack_size) {
@@ -738,6 +812,7 @@ static int open_packed_git(struct packed_git *p)
                return 0;
        if (p->pack_fd != -1) {
                close(p->pack_fd);
+               pack_open_fds--;
                p->pack_fd = -1;
        }
        return -1;
@@ -763,14 +838,13 @@ unsigned char *use_pack(struct packed_git *p,
 {
        struct pack_window *win = *w_cursor;
 
-       if (p->pack_fd == -1 && open_packed_git(p))
-               die("packfile %s cannot be accessed", p->pack_name);
-
        /* Since packfiles end in a hash of their content and it's
         * pointless to ask for an offset into the middle of that
         * hash, and the in_window function above wouldn't match
         * don't allow an offset too close to the end of the file.
         */
+       if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
+               die("packfile %s cannot be accessed", p->pack_name);
        if (offset > (p->pack_size - 20))
                die("offset beyond end of packfile (truncated pack?)");
 
@@ -784,6 +858,10 @@ unsigned char *use_pack(struct packed_git *p,
                if (!win) {
                        size_t window_align = packed_git_window_size / 2;
                        off_t len;
+
+                       if (p->pack_fd == -1 && open_packed_git(p))
+                               die("packfile %s cannot be accessed", p->pack_name);
+
                        win = xcalloc(1, sizeof(*win));
                        win->offset = (offset / window_align) * window_align;
                        len = p->pack_size - win->offset;
@@ -801,6 +879,12 @@ unsigned char *use_pack(struct packed_git *p,
                                die("packfile %s cannot be mapped: %s",
                                        p->pack_name,
                                        strerror(errno));
+                       if (!win->offset && win->len == p->pack_size
+                               && !p->do_not_close) {
+                               close(p->pack_fd);
+                               pack_open_fds--;
+                               p->pack_fd = -1;
+                       }
                        pack_mmap_calls++;
                        pack_open_windows++;
                        if (pack_mapped > peak_pack_mapped)
@@ -830,11 +914,22 @@ static struct packed_git *alloc_packed_git(int extra)
        return p;
 }
 
+static void try_to_free_pack_memory(size_t size)
+{
+       release_pack_memory(size, -1);
+}
+
 struct packed_git *add_packed_git(const char *path, int path_len, int local)
 {
+       static int have_set_try_to_free_routine;
        struct stat st;
        struct packed_git *p = alloc_packed_git(path_len + 2);
 
+       if (!have_set_try_to_free_routine) {
+               have_set_try_to_free_routine = 1;
+               set_try_to_free_routine(try_to_free_pack_memory);
+       }
+
        /*
         * Make sure a corresponding .pack file exists and that
         * the index looks sane.
@@ -867,9 +962,8 @@ struct packed_git *add_packed_git(const char *path, int path_len, int local)
        return p;
 }
 
-struct packed_git *parse_pack_index(unsigned char *sha1)
+struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 {
-       const char *idx_path = sha1_pack_index_name(sha1);
        const char *path = sha1_pack_name(sha1);
        struct packed_git *p = alloc_packed_git(strlen(path) + 1);
 
@@ -885,6 +979,9 @@ struct packed_git *parse_pack_index(unsigned char *sha1)
 
 void install_packed_git(struct packed_git *pack)
 {
+       if (pack->pack_fd != -1)
+               pack_open_fds++;
+
        pack->next = packed_git;
        packed_git = pack;
 }
@@ -902,8 +999,6 @@ static void prepare_packed_git_one(char *objdir, int local)
        sprintf(path, "%s/pack", objdir);
        len = strlen(path);
        dir = opendir(path);
-       while (!dir && errno == EMFILE && unuse_one_window(packed_git, -1))
-               dir = opendir(path);
        if (!dir) {
                if (errno != ENOENT)
                        error("unable to open object pack directory: %s: %s",
@@ -1031,7 +1126,7 @@ static void mark_bad_packed_object(struct packed_git *p,
        p->num_bad_objects++;
 }
 
-static int has_packed_and_bad(const unsigned char *sha1)
+static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
 {
        struct packed_git *p;
        unsigned i;
@@ -1039,8 +1134,8 @@ static int has_packed_and_bad(const unsigned char *sha1)
        for (p = packed_git; p; p = p->next)
                for (i = 0; i < p->num_bad_objects; i++)
                        if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
-                               return 1;
-       return 0;
+                               return p;
+       return NULL;
 }
 
 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
@@ -1050,18 +1145,23 @@ int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long siz
        return hashcmp(sha1, real_sha1) ? -1 : 0;
 }
 
-static int git_open_noatime(const char *name)
+static int git_open_noatime(const char *name, struct packed_git *p)
 {
        static int sha1_file_open_flag = O_NOATIME;
-       int fd = open(name, O_RDONLY | sha1_file_open_flag);
 
-       /* Might the failure be due to O_NOATIME? */
-       if (fd < 0 && errno != ENOENT && sha1_file_open_flag) {
-               fd = open(name, O_RDONLY);
+       for (;;) {
+               int fd = open(name, O_RDONLY | sha1_file_open_flag);
                if (fd >= 0)
+                       return fd;
+
+               /* Might the failure be due to O_NOATIME? */
+               if (errno != ENOENT && sha1_file_open_flag) {
                        sha1_file_open_flag = 0;
+                       continue;
+               }
+
+               return -1;
        }
-       return fd;
 }
 
 static int open_sha1_file(const unsigned char *sha1)
@@ -1070,7 +1170,7 @@ static int open_sha1_file(const unsigned char *sha1)
        char *name = sha1_file_name(sha1);
        struct alternate_object_database *alt;
 
-       fd = git_open_noatime(name);
+       fd = git_open_noatime(name, NULL);
        if (fd >= 0)
                return fd;
 
@@ -1079,7 +1179,7 @@ static int open_sha1_file(const unsigned char *sha1)
        for (alt = alt_odb_list; alt; alt = alt->next) {
                name = alt->name;
                fill_sha1_path(name, sha1);
-               fd = git_open_noatime(alt->base);
+               fd = git_open_noatime(alt->base, NULL);
                if (fd >= 0)
                        return fd;
        }
@@ -1885,6 +1985,27 @@ off_t find_pack_entry_one(const unsigned char *sha1,
        return 0;
 }
 
+static int is_pack_valid(struct packed_git *p)
+{
+       /* An already open pack is known to be valid. */
+       if (p->pack_fd != -1)
+               return 1;
+
+       /* If the pack has one window completely covering the
+        * file size, the pack is known to be valid even if
+        * the descriptor is not currently open.
+        */
+       if (p->windows) {
+               struct pack_window *w = p->windows;
+
+               if (!w->offset && w->len == p->pack_size)
+                       return 1;
+       }
+
+       /* Force the pack to open to prove its valid. */
+       return !open_packed_git(p);
+}
+
 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 {
        static struct packed_git *last_found = (void *)1;
@@ -1914,7 +2035,7 @@ static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
                         * it may have been deleted since the index
                         * was loaded!
                         */
-                       if (p->pack_fd == -1 && open_packed_git(p)) {
+                       if (!is_pack_valid(p)) {
                                error("packfile %s cannot be accessed", p->pack_name);
                                goto next;
                        }
@@ -1974,9 +2095,17 @@ static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *size
 
 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 {
+       struct cached_object *co;
        struct pack_entry e;
        int status;
 
+       co = find_cached_object(sha1);
+       if (co) {
+               if (sizep)
+                       *sizep = co->size;
+               return co->type;
+       }
+
        if (!find_pack_entry(sha1, &e)) {
                /* Most likely it's a loose object. */
                status = sha1_loose_object_info(sha1, sizep);
@@ -2022,41 +2151,6 @@ static void *read_packed_sha1(const unsigned char *sha1,
        return data;
 }
 
-/*
- * This is meant to hold a *small* number of objects that you would
- * want read_sha1_file() to be able to return, but yet you do not want
- * to write them into the object store (e.g. a browse-only
- * application).
- */
-static struct cached_object {
-       unsigned char sha1[20];
-       enum object_type type;
-       void *buf;
-       unsigned long size;
-} *cached_objects;
-static int cached_object_nr, cached_object_alloc;
-
-static struct cached_object empty_tree = {
-       EMPTY_TREE_SHA1_BIN,
-       OBJ_TREE,
-       "",
-       0
-};
-
-static struct cached_object *find_cached_object(const unsigned char *sha1)
-{
-       int i;
-       struct cached_object *co = cached_objects;
-
-       for (i = 0; i < cached_object_nr; i++, co++) {
-               if (!hashcmp(co->sha1, sha1))
-                       return co;
-       }
-       if (!hashcmp(sha1, empty_tree.sha1))
-               return &empty_tree;
-       return NULL;
-}
-
 int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
                      unsigned char *sha1)
 {
@@ -2107,27 +2201,48 @@ static void *read_object(const unsigned char *sha1, enum object_type *type,
        return read_packed_sha1(sha1, type, size);
 }
 
+/*
+ * This function dies on corrupt objects; the callers who want to
+ * deal with them should arrange to call read_object() and give error
+ * messages themselves.
+ */
 void *read_sha1_file_repl(const unsigned char *sha1,
                          enum object_type *type,
                          unsigned long *size,
                          const unsigned char **replacement)
 {
        const unsigned char *repl = lookup_replace_object(sha1);
-       void *data = read_object(repl, type, size);
+       void *data;
+       char *path;
+       const struct packed_git *p;
+
+       errno = 0;
+       data = read_object(repl, type, size);
+       if (data) {
+               if (replacement)
+                       *replacement = repl;
+               return data;
+       }
+
+       if (errno && errno != ENOENT)
+               die_errno("failed to read object %s", sha1_to_hex(sha1));
 
        /* die if we replaced an object with one that does not exist */
-       if (!data && repl != sha1)
+       if (repl != sha1)
                die("replacement %s not found for %s",
                    sha1_to_hex(repl), sha1_to_hex(sha1));
 
-       /* legacy behavior is to die on corrupted objects */
-       if (!data && (has_loose_object(repl) || has_packed_and_bad(repl)))
-               die("object %s is corrupted", sha1_to_hex(repl));
+       if (has_loose_object(repl)) {
+               path = sha1_file_name(sha1);
+               die("loose object %s (stored in %s) is corrupt",
+                   sha1_to_hex(repl), path);
+       }
 
-       if (replacement)
-               *replacement = repl;
+       if ((p = has_packed_and_bad(repl)) != NULL)
+               die("packed object %s (stored in %s) is corrupt",
+                   sha1_to_hex(repl), p->pack_name);
 
-       return data;
+       return NULL;
 }
 
 void *read_object_with_reference(const unsigned char *sha1,
@@ -2307,7 +2422,7 @@ static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
 }
 
 static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
-                             void *buf, unsigned long len, time_t mtime)
+                             const void *buf, unsigned long len, time_t mtime)
 {
        int fd, ret;
        unsigned char compressed[4096];
@@ -2319,8 +2434,6 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
 
        filename = sha1_file_name(sha1);
        fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
-       while (fd < 0 && errno == EMFILE && unuse_one_window(packed_git, -1))
-               fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
        if (fd < 0) {
                if (errno == EACCES)
                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
@@ -2343,7 +2456,7 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
        git_SHA1_Update(&c, hdr, hdrlen);
 
        /* Then the data itself.. */
-       stream.next_in = buf;
+       stream.next_in = (void *)buf;
        stream.avail_in = len;
        do {
                unsigned char *in0 = stream.next_in;
@@ -2378,7 +2491,7 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
        return move_temp_to_file(tmpfile, filename);
 }
 
-int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
+int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 {
        unsigned char sha1[20];
        char hdr[32];
@@ -2439,8 +2552,37 @@ int has_sha1_file(const unsigned char *sha1)
        return has_loose_object(sha1);
 }
 
+static void check_tree(const void *buf, size_t size)
+{
+       struct tree_desc desc;
+       struct name_entry entry;
+
+       init_tree_desc(&desc, buf, size);
+       while (tree_entry(&desc, &entry))
+               /* do nothing
+                * tree_entry() will die() on malformed entries */
+               ;
+}
+
+static void check_commit(const void *buf, size_t size)
+{
+       struct commit c;
+       memset(&c, 0, sizeof(c));
+       if (parse_commit_buffer(&c, buf, size))
+               die("corrupt commit");
+}
+
+static void check_tag(const void *buf, size_t size)
+{
+       struct tag t;
+       memset(&t, 0, sizeof(t));
+       if (parse_tag_buffer(&t, buf, size))
+               die("corrupt tag");
+}
+
 static int index_mem(unsigned char *sha1, void *buf, size_t size,
-                    int write_object, enum object_type type, const char *path)
+                    int write_object, enum object_type type,
+                    const char *path, int format_check)
 {
        int ret, re_allocated = 0;
 
@@ -2458,6 +2600,14 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
                        re_allocated = 1;
                }
        }
+       if (format_check) {
+               if (type == OBJ_TREE)
+                       check_tree(buf, size);
+               if (type == OBJ_COMMIT)
+                       check_commit(buf, size);
+               if (type == OBJ_TAG)
+                       check_tag(buf, size);
+       }
 
        if (write_object)
                ret = write_sha1_file(buf, size, typename(type), sha1);
@@ -2471,7 +2621,7 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
 #define SMALL_FILE_SIZE (32*1024)
 
 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
-            enum object_type type, const char *path)
+            enum object_type type, const char *path, int format_check)
 {
        int ret;
        size_t size = xsize_t(st->st_size);
@@ -2480,24 +2630,27 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
                struct strbuf sbuf = STRBUF_INIT;
                if (strbuf_read(&sbuf, fd, 4096) >= 0)
                        ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
-                                       type, path);
+                                       type, path, format_check);
                else
                        ret = -1;
                strbuf_release(&sbuf);
+       } else if (!size) {
+               ret = index_mem(sha1, NULL, size, write_object, type, path,
+                               format_check);
        } else if (size <= SMALL_FILE_SIZE) {
                char *buf = xmalloc(size);
                if (size == read_in_full(fd, buf, size))
                        ret = index_mem(sha1, buf, size, write_object, type,
-                                       path);
+                                       path, format_check);
                else
                        ret = error("short read %s", strerror(errno));
                free(buf);
-       } else if (size) {
+       } else {
                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
-               ret = index_mem(sha1, buf, size, write_object, type, path);
+               ret = index_mem(sha1, buf, size, write_object, type, path,
+                               format_check);
                munmap(buf, size);
-       } else
-               ret = index_mem(sha1, NULL, size, write_object, type, path);
+       }
        close(fd);
        return ret;
 }
@@ -2513,7 +2666,7 @@ int index_path(unsigned char *sha1, const char *path, struct stat *st, int write
                if (fd < 0)
                        return error("open(\"%s\"): %s", path,
                                     strerror(errno));
-               if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
+               if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path, 0) < 0)
                        return error("%s: failed to insert into database",
                                     path);
                break;
@@ -2552,3 +2705,13 @@ int read_pack_header(int fd, struct pack_header *header)
                return PH_ERROR_PROTOCOL;
        return 0;
 }
+
+void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
+{
+       enum object_type type = sha1_object_info(sha1, NULL);
+       if (type < 0)
+               die("%s is not a valid object", sha1_to_hex(sha1));
+       if (type != expect)
+               die("%s is not a valid '%s' object", sha1_to_hex(sha1),
+                   typename(expect));
+}