Make git read the index file version 5 without complaining.

This version of the reader doesn't read neither the cache-tree
nor the resolve undo data, but doesn't choke on an index that
includes such data.

Helped-by: Junio C Hamano <gits...@pobox.com>
Helped-by: Nguyen Thai Ngoc Duy <pclo...@gmail.com>
Helped-by: Thomas Rast <tr...@student.ethz.ch>
Signed-off-by: Thomas Gummerer <t.gumme...@gmail.com>
---
 Makefile        |   1 +
 cache.h         |  73 ++++++++
 read-cache-v5.c | 556 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 630 insertions(+)
 create mode 100644 read-cache-v5.c

diff --git a/Makefile b/Makefile
index 3ccd3a8..ef55509 100644
--- a/Makefile
+++ b/Makefile
@@ -770,6 +770,7 @@ LIB_OBJS += quote.o
 LIB_OBJS += reachable.o
 LIB_OBJS += read-cache.o
 LIB_OBJS += read-cache-v2.o
+LIB_OBJS += read-cache-v5.o
 LIB_OBJS += reflog-walk.o
 LIB_OBJS += refs.o
 LIB_OBJS += remote.o
diff --git a/cache.h b/cache.h
index bfe3099..bec9402 100644
--- a/cache.h
+++ b/cache.h
@@ -110,6 +110,15 @@ struct cache_time {
        unsigned int nsec;
 };
 
+/*
+ * The *next pointer is used in read_entries_v5 for holding
+ * all the elements of a directory, and points to the next
+ * cache_entry in a directory.
+ *
+ * It is reset by the add_name_hash call in set_index_entry
+ * to set it to point to the next cache_entry in the
+ * correct in-memory format ordering.
+ */
 struct cache_entry {
        struct cache_time ce_ctime;
        struct cache_time ce_mtime;
@@ -128,11 +137,59 @@ struct cache_entry {
        char name[FLEX_ARRAY]; /* more */
 };
 
+struct directory_entry {
+       struct directory_entry *next;
+       struct directory_entry *next_hash;
+       struct cache_entry *ce;
+       struct cache_entry *ce_last;
+       struct conflict_entry *conflict;
+       struct conflict_entry *conflict_last;
+       unsigned int conflict_size;
+       unsigned int de_foffset;
+       unsigned int de_cr;
+       unsigned int de_ncr;
+       unsigned int de_nsubtrees;
+       unsigned int de_nfiles;
+       unsigned int de_nentries;
+       unsigned char sha1[20];
+       unsigned short de_flags;
+       unsigned int de_pathlen;
+       char pathname[FLEX_ARRAY];
+};
+
+struct conflict_part {
+       struct conflict_part *next;
+       unsigned short flags;
+       unsigned short entry_mode;
+       unsigned char sha1[20];
+};
+
+struct conflict_entry {
+       struct conflict_entry *next;
+       unsigned int nfileconflicts;
+       struct conflict_part *entries;
+       unsigned int namelen;
+       unsigned int pathlen;
+       char name[FLEX_ARRAY];
+};
+
+struct ondisk_conflict_part {
+       unsigned short flags;
+       unsigned short entry_mode;
+       unsigned char sha1[20];
+};
+
+#define CE_NAMEMASK  (0x0fff)
 #define CE_STAGEMASK (0x3000)
 #define CE_EXTENDED  (0x4000)
 #define CE_VALID     (0x8000)
+#define CE_SMUDGED   (0x0400) /* index v5 only flag */
 #define CE_STAGESHIFT 12
 
+#define CONFLICT_CONFLICTED (0x8000)
+#define CONFLICT_STAGESHIFT 13
+#define CONFLICT_STAGEMASK (0x6000)
+
 /*
  * Range 0xFFFF0000 in ce_flags is divided into
  * two parts: in-memory flags and on-disk ones.
@@ -166,6 +223,18 @@ struct cache_entry {
 #define CE_EXTENDED_FLAGS (CE_INTENT_TO_ADD | CE_SKIP_WORKTREE)
 
 /*
+ * Representation of the extended on-disk flags in the v5 format.
+ * They must not collide with the ordinary on-disk flags, and need to
+ * fit in 16 bits.  Note however that v5 does not save the name
+ * length.
+ */
+#define CE_INTENT_TO_ADD_V5  (0x4000)
+#define CE_SKIP_WORKTREE_V5  (0x0800)
+#if (CE_VALID|CE_STAGEMASK) & (CE_INTENTTOADD_V5|CE_SKIPWORKTREE_V5)
+#error "v5 on-disk flags collide with ordinary on-disk flags"
+#endif
+
+/*
  * Safeguard to avoid saving wrong flags:
  *  - CE_EXTENDED2 won't get saved until its semantic is known
  *  - Bits in 0x0000FFFF have been saved in ce_flags already
@@ -203,6 +272,8 @@ static inline unsigned create_ce_flags(unsigned stage)
 #define ce_skip_worktree(ce) ((ce)->ce_flags & CE_SKIP_WORKTREE)
 #define ce_mark_uptodate(ce) ((ce)->ce_flags |= CE_UPTODATE)
 
+#define conflict_stage(c) ((CONFLICT_STAGEMASK & (c)->flags) >> 
CONFLICT_STAGESHIFT)
+
 #define ce_permissions(mode) (((mode) & 0100) ? 0755 : 0644)
 static inline unsigned int create_ce_mode(unsigned int mode)
 {
@@ -249,6 +320,8 @@ static inline unsigned int canon_mode(unsigned int mode)
 }
 
 #define cache_entry_size(len) (offsetof(struct cache_entry,name) + (len) + 1)
+#define directory_entry_size(len) (offsetof(struct directory_entry,pathname) + 
(len) + 1)
+#define conflict_entry_size(len) (offsetof(struct conflict_entry,name) + (len) 
+ 1)
 
 struct index_state {
        struct cache_entry **cache;
diff --git a/read-cache-v5.c b/read-cache-v5.c
new file mode 100644
index 0000000..2031969
--- /dev/null
+++ b/read-cache-v5.c
@@ -0,0 +1,556 @@
+#include "cache.h"
+#include "read-cache.h"
+#include "resolve-undo.h"
+#include "cache-tree.h"
+
+#define ptr_add(x,y) ((void *)(((char *)(x)) + (y)))
+
+struct cache_header {
+       unsigned int hdr_ndir;
+       unsigned int hdr_nfile;
+       unsigned int hdr_fblockoffset;
+       unsigned int hdr_nextension;
+};
+
+/*****************************************************************
+ * Index File I/O
+ *****************************************************************/
+
+struct ondisk_cache_entry {
+       unsigned short flags;
+       unsigned short mode;
+       struct cache_time mtime;
+       unsigned int size;
+       int stat_crc;
+       unsigned char sha1[20];
+};
+
+struct ondisk_directory_entry {
+       unsigned int foffset;
+       unsigned int cr;
+       unsigned int ncr;
+       unsigned int nsubtrees;
+       unsigned int nfiles;
+       unsigned int nentries;
+       unsigned char sha1[20];
+       unsigned short flags;
+};
+
+static int check_crc32(int initialcrc,
+                       void *data,
+                       size_t len,
+                       unsigned int expected_crc)
+{
+       int crc;
+
+       crc = crc32(initialcrc, (Bytef*)data, len);
+       return crc == expected_crc;
+}
+
+static int match_stat_crc(struct stat *st, uint32_t expected_crc)
+{
+       uint32_t data, stat_crc = 0;
+       unsigned int ctimens = 0;
+
+       data = htonl(st->st_ctime);
+       stat_crc = crc32(0, (Bytef*)&data, 4);
+#ifdef USE_NSEC
+       ctimens = ST_CTIME_NSEC(*st);
+#endif
+       data = htonl(ctimens);
+       stat_crc = crc32(stat_crc, (Bytef*)&data, 4);
+       data = htonl(st->st_ino);
+       stat_crc = crc32(stat_crc, (Bytef*)&data, 4);
+       data = htonl(st->st_dev);
+       stat_crc = crc32(stat_crc, (Bytef*)&data, 4);
+       data = htonl(st->st_uid);
+       stat_crc = crc32(stat_crc, (Bytef*)&data, 4);
+       data = htonl(st->st_gid);
+       stat_crc = crc32(stat_crc, (Bytef*)&data, 4);
+
+       return stat_crc == expected_crc;
+}
+
+static int match_stat_basic(struct cache_entry *ce,
+                               struct stat *st,
+                               int changed)
+{
+
+       if (ce->ce_mtime.sec != (unsigned int)st->st_mtime)
+               changed |= MTIME_CHANGED;
+#ifdef USE_NSEC
+       if (ce->ce_mtime.nsec != ST_MTIME_NSEC(*st))
+               changed |= MTIME_CHANGED;
+#endif
+       if (ce->ce_size != (unsigned int)st->st_size)
+               changed |= DATA_CHANGED;
+
+       if (trust_ctime && ce->ce_stat_crc != 0 && !match_stat_crc(st, 
ce->ce_stat_crc)) {
+               changed |= OWNER_CHANGED;
+               changed |= INODE_CHANGED;
+       }
+       /* Racily smudged entry? */
+       if (ce->ce_flags & CE_SMUDGED) {
+               if (!changed && !is_empty_blob_sha1(ce->sha1) && 
ce_modified_check_fs(ce, st))
+                       changed |= DATA_CHANGED;
+       }
+       return changed;
+}
+
+static int verify_hdr(void *mmap, unsigned long size)
+{
+       uint32_t *filecrc;
+       unsigned int header_size;
+       struct cache_version_header *hdr;
+       struct cache_header *hdr_v5;
+
+       if (size < sizeof(struct cache_version_header)
+                       + sizeof (struct cache_header) + 4)
+               die("index file smaller than expected");
+
+       hdr = mmap;
+       hdr_v5 = ptr_add(mmap, sizeof(*hdr));
+       /* Size of the header + the size of the extensionoffsets */
+       header_size = sizeof(*hdr) + sizeof(*hdr_v5) + hdr_v5->hdr_nextension * 
4;
+       /* Initialize crc */
+       filecrc = ptr_add(mmap, header_size);
+       if (!check_crc32(0, hdr, header_size, ntohl(*filecrc)))
+               return error("bad index file header crc signature");
+       return 0;
+}
+
+static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry 
*ondisk,
+                                                  struct directory_entry *de,
+                                                  char *name,
+                                                  size_t len,
+                                                  size_t prefix_len)
+{
+       struct cache_entry *ce = xmalloc(cache_entry_size(len + 
de->de_pathlen));
+       int flags;
+
+       flags = ntoh_s(ondisk->flags);
+       ce->ce_ctime.sec  = 0;
+       ce->ce_mtime.sec  = ntoh_l(ondisk->mtime.sec);
+       ce->ce_ctime.nsec = 0;
+       ce->ce_mtime.nsec = ntoh_l(ondisk->mtime.nsec);
+       ce->ce_dev        = 0;
+       ce->ce_ino        = 0;
+       ce->ce_mode       = ntoh_s(ondisk->mode);
+       ce->ce_uid        = 0;
+       ce->ce_gid        = 0;
+       ce->ce_size       = ntoh_l(ondisk->size);
+       ce->ce_flags      = flags & CE_STAGEMASK;
+       ce->ce_flags     |= flags & CE_VALID;
+       ce->ce_flags     |= flags & CE_SMUDGED;
+       if (flags & CE_INTENT_TO_ADD_V5)
+               ce->ce_flags |= CE_INTENT_TO_ADD;
+       if (flags & CE_SKIP_WORKTREE_V5)
+               ce->ce_flags |= CE_SKIP_WORKTREE;
+       ce->ce_stat_crc   = ntoh_l(ondisk->stat_crc);
+       ce->ce_namelen    = len + de->de_pathlen;
+       hashcpy(ce->sha1, ondisk->sha1);
+       memcpy(ce->name, de->pathname, de->de_pathlen);
+       memcpy(ce->name + de->de_pathlen, name, len);
+       ce->name[len + de->de_pathlen] = '\0';
+       return ce;
+}
+
+static struct directory_entry *directory_entry_from_ondisk(struct 
ondisk_directory_entry *ondisk,
+                                                  const char *name,
+                                                  size_t len)
+{
+       struct directory_entry *de = xmalloc(directory_entry_size(len));
+
+
+       memcpy(de->pathname, name, len);
+       de->pathname[len] = '\0';
+       de->de_flags      = ntoh_s(ondisk->flags);
+       de->de_foffset    = ntoh_l(ondisk->foffset);
+       de->de_cr         = ntoh_l(ondisk->cr);
+       de->de_ncr        = ntoh_l(ondisk->ncr);
+       de->de_nsubtrees  = ntoh_l(ondisk->nsubtrees);
+       de->de_nfiles     = ntoh_l(ondisk->nfiles);
+       de->de_nentries   = ntoh_l(ondisk->nentries);
+       de->de_pathlen    = len;
+       hashcpy(de->sha1, ondisk->sha1);
+       return de;
+}
+
+static struct conflict_part *conflict_part_from_ondisk(struct 
ondisk_conflict_part *ondisk)
+{
+       struct conflict_part *cp = xmalloc(sizeof(struct conflict_part));
+
+       cp->flags      = ntoh_s(ondisk->flags);
+       cp->entry_mode = ntoh_s(ondisk->entry_mode);
+       hashcpy(cp->sha1, ondisk->sha1);
+       return cp;
+}
+
+static struct cache_entry *convert_conflict_part(struct conflict_part *cp,
+                                               char * name,
+                                               unsigned int len)
+{
+
+       struct cache_entry *ce = xmalloc(cache_entry_size(len));
+
+       ce->ce_ctime.sec  = 0;
+       ce->ce_mtime.sec  = 0;
+       ce->ce_ctime.nsec = 0;
+       ce->ce_mtime.nsec = 0;
+       ce->ce_dev        = 0;
+       ce->ce_ino        = 0;
+       ce->ce_mode       = cp->entry_mode;
+       ce->ce_uid        = 0;
+       ce->ce_gid        = 0;
+       ce->ce_size       = 0;
+       ce->ce_flags      = conflict_stage(cp) << CE_STAGESHIFT;
+       ce->ce_stat_crc   = 0;
+       ce->ce_namelen    = len;
+       hashcpy(ce->sha1, cp->sha1);
+       memcpy(ce->name, name, len);
+       ce->name[len] = '\0';
+       return ce;
+}
+
+static struct directory_entry *read_directories(unsigned int *dir_offset,
+                               unsigned int *dir_table_offset,
+                               void *mmap,
+                               int mmap_size)
+{
+       int i, ondisk_directory_size;
+       uint32_t *filecrc, *beginning, *end;
+       struct directory_entry *current = NULL;
+       struct ondisk_directory_entry *disk_de;
+       struct directory_entry *de;
+       unsigned int data_len, len;
+       char *name;
+
+       ondisk_directory_size = sizeof(disk_de->flags)
+               + sizeof(disk_de->foffset)
+               + sizeof(disk_de->cr)
+               + sizeof(disk_de->ncr)
+               + sizeof(disk_de->nsubtrees)
+               + sizeof(disk_de->nfiles)
+               + sizeof(disk_de->nentries)
+               + sizeof(disk_de->sha1);
+       name = ptr_add(mmap, *dir_offset);
+       beginning = ptr_add(mmap, *dir_table_offset);
+       end = ptr_add(mmap, *dir_table_offset + 4);
+       len = ntoh_l(*end) - ntoh_l(*beginning) - ondisk_directory_size - 5;
+       disk_de = ptr_add(mmap, *dir_offset + len + 1);
+       de = directory_entry_from_ondisk(disk_de, name, len);
+       de->next = NULL;
+
+       /* Length of pathname + nul byte for termination + size of
+        * members of ondisk_directory_entry. (Just using the size
+        * of the stuct doesn't work, because there may be padding
+        * bytes for the struct)
+        */
+       data_len = len + 1 + ondisk_directory_size;
+
+       filecrc = ptr_add(mmap, *dir_offset + data_len);
+       if (!check_crc32(0, ptr_add(mmap, *dir_offset), data_len, 
ntoh_l(*filecrc)))
+               goto unmap;
+
+       *dir_table_offset += 4;
+       *dir_offset += data_len + 4; /* crc code */
+
+       current = de;
+       for (i = 0; i < de->de_nsubtrees; i++) {
+               current->next = read_directories(dir_offset, dir_table_offset,
+                                               mmap, mmap_size);
+               while (current->next)
+                       current = current->next;
+       }
+
+       return de;
+unmap:
+       munmap(mmap, mmap_size);
+       die("directory crc doesn't match for '%s'", de->pathname);
+}
+
+static int read_entry(struct cache_entry **ce, struct directory_entry *de,
+                     unsigned long *entry_offset,
+                     void **mmap, unsigned long mmap_size,
+                     unsigned int *foffsetblock)
+{
+       int len, offset_to_offset;
+       char *name;
+       uint32_t foffsetblockcrc;
+       uint32_t *filecrc, *beginning, *end;
+       struct ondisk_cache_entry *disk_ce;
+
+       name = ptr_add(*mmap, *entry_offset);
+       beginning = ptr_add(*mmap, *foffsetblock);
+       end = ptr_add(*mmap, *foffsetblock + 4);
+       len = ntoh_l(*end) - ntoh_l(*beginning) - sizeof(struct 
ondisk_cache_entry) - 5;
+       disk_ce = ptr_add(*mmap, *entry_offset + len + 1);
+       *ce = cache_entry_from_ondisk(disk_ce, de, name, len, de->de_pathlen);
+       filecrc = ptr_add(*mmap, *entry_offset + len + 1 + sizeof(*disk_ce));
+       offset_to_offset = htonl(*foffsetblock);
+       foffsetblockcrc = crc32(0, (Bytef*)&offset_to_offset, 4);
+       if (!check_crc32(foffsetblockcrc,
+               ptr_add(*mmap, *entry_offset), len + 1 + sizeof(*disk_ce),
+               ntoh_l(*filecrc)))
+               return -1;
+
+       /* TODO: return error if crc code is wrong */
+       *entry_offset += len + 1 + sizeof(*disk_ce) + 4;
+       return 0;
+}
+
+static void ce_queue_push(struct cache_entry **head,
+                            struct cache_entry **tail,
+                            struct cache_entry *ce)
+{
+       if (!*head) {
+               *head = *tail = ce;
+               (*tail)->next = NULL;
+               return;
+       }
+
+       (*tail)->next = ce;
+       ce->next = NULL;
+       *tail = (*tail)->next;
+}
+
+static void conflict_entry_push(struct conflict_entry **head,
+                               struct conflict_entry **tail,
+                               struct conflict_entry *conflict_entry)
+{
+       if (!*head) {
+               *head = *tail = conflict_entry;
+               (*tail)->next = NULL;
+               return;
+       }
+
+       (*tail)->next = conflict_entry;
+       conflict_entry->next = NULL;
+       *tail = (*tail)->next;
+}
+
+static struct cache_entry *ce_queue_pop(struct cache_entry **head)
+{
+       struct cache_entry *ce;
+
+       ce = *head;
+       *head = (*head)->next;
+       return ce;
+}
+
+static void conflict_part_head_remove(struct conflict_part **head)
+{
+       struct conflict_part *to_free;
+
+       to_free = *head;
+       *head = (*head)->next;
+       free(to_free);
+}
+
+static void conflict_entry_head_remove(struct conflict_entry **head)
+{
+       struct conflict_entry *to_free;
+
+       to_free = *head;
+       *head = (*head)->next;
+       free(to_free);
+}
+
+struct conflict_entry *create_new_conflict(char *name, int len, int pathlen)
+{
+       struct conflict_entry *conflict_entry;
+
+       if (pathlen)
+               pathlen++;
+       conflict_entry = xmalloc(conflict_entry_size(len));
+       conflict_entry->entries = NULL;
+       conflict_entry->nfileconflicts = 0;
+       conflict_entry->namelen = len;
+       memcpy(conflict_entry->name, name, len);
+       conflict_entry->name[len] = '\0';
+       conflict_entry->pathlen = pathlen;
+       conflict_entry->next = NULL;
+
+       return conflict_entry;
+}
+
+void add_part_to_conflict_entry(struct directory_entry *de,
+                                       struct conflict_entry *entry,
+                                       struct conflict_part *conflict_part)
+{
+
+       struct conflict_part *conflict_search;
+
+       entry->nfileconflicts++;
+       de->conflict_size += sizeof(struct ondisk_conflict_part);
+       if (!entry->entries)
+               entry->entries = conflict_part;
+       else {
+               conflict_search = entry->entries;
+               while (conflict_search->next)
+                       conflict_search = conflict_search->next;
+               conflict_search->next = conflict_part;
+       }
+}
+
+static int read_conflicts(struct conflict_entry **head,
+                         struct directory_entry *de,
+                         void **mmap, unsigned long mmap_size)
+{
+       struct conflict_entry *tail;
+       unsigned int croffset, i;
+       char *full_name;
+
+       croffset = de->de_cr;
+       tail = NULL;
+       for (i = 0; i < de->de_ncr; i++) {
+               struct conflict_entry *conflict_new;
+               unsigned int len, *nfileconflicts;
+               char *name;
+               void *crc_start;
+               int k, offset;
+               uint32_t *filecrc;
+
+               offset = croffset;
+               crc_start = ptr_add(*mmap, offset);
+               name = ptr_add(*mmap, offset);
+               len = strlen(name);
+               offset += len + 1;
+               nfileconflicts = ptr_add(*mmap, offset);
+               offset += 4;
+
+               full_name = xmalloc(sizeof(char) * (len + de->de_pathlen));
+               memcpy(full_name, de->pathname, de->de_pathlen);
+               memcpy(full_name + de->de_pathlen, name, len);
+               conflict_new = create_new_conflict(full_name,
+                               len + de->de_pathlen, de->de_pathlen);
+               for (k = 0; k < ntoh_l(*nfileconflicts); k++) {
+                       struct ondisk_conflict_part *ondisk;
+                       struct conflict_part *cp;
+
+                       ondisk = ptr_add(*mmap, offset);
+                       cp = conflict_part_from_ondisk(ondisk);
+                       cp->next = NULL;
+                       add_part_to_conflict_entry(de, conflict_new, cp);
+                       offset += sizeof(struct ondisk_conflict_part);
+               }
+               filecrc = ptr_add(*mmap, offset);
+               free(full_name);
+               if (!check_crc32(0, crc_start,
+                       len + 1 + 4 + conflict_new->nfileconflicts
+                       * sizeof(struct ondisk_conflict_part),
+                       ntoh_l(*filecrc)))
+                       return -1;
+               croffset = offset + 4;
+               conflict_entry_push(head, &tail, conflict_new);
+       }
+       return 0;
+}
+
+static int read_entries(struct index_state *istate, struct directory_entry 
**de,
+                       unsigned long *entry_offset, void **mmap,
+                       unsigned long mmap_size, int *nr,
+                       unsigned int *foffsetblock)
+{
+       struct cache_entry *head = NULL, *tail = NULL;
+       struct conflict_entry *conflict_queue;
+       struct cache_entry *ce;
+       int i;
+
+       conflict_queue = NULL;
+       if (read_conflicts(&conflict_queue, *de, mmap, mmap_size) < 0)
+               return -1;
+       for (i = 0; i < (*de)->de_nfiles; i++) {
+               if (read_entry(&ce,
+                               *de,
+                               entry_offset,
+                               mmap,
+                               mmap_size,
+                               foffsetblock) < 0)
+                       return -1;
+               ce_queue_push(&head, &tail, ce);
+               *foffsetblock += 4;
+
+               /* Add the conflicted entries at the end of the index file
+                * to the in memory format
+                */
+               if (conflict_queue &&
+                   (conflict_queue->entries->flags & CONFLICT_CONFLICTED) != 0 
&&
+                   !cache_name_compare(conflict_queue->name, 
conflict_queue->namelen,
+                                       ce->name, ce_namelen(ce))) {
+                       struct conflict_part *cp;
+                       cp = conflict_queue->entries;
+                       cp = cp->next;
+                       while (cp) {
+                               ce = convert_conflict_part(cp,
+                                               conflict_queue->name,
+                                               conflict_queue->namelen);
+                               ce_queue_push(&head, &tail, ce);
+                               conflict_part_head_remove(&cp);
+                       }
+                       conflict_entry_head_remove(&conflict_queue);
+               }
+       }
+
+       *de = (*de)->next;
+
+       while (head) {
+               if (*de != NULL
+                   && strcmp(head->name, (*de)->pathname) > 0) {
+                       read_entries(istate,
+                                       de,
+                                       entry_offset,
+                                       mmap,
+                                       mmap_size,
+                                       nr,
+                                       foffsetblock);
+               } else {
+                       ce = ce_queue_pop(&head);
+                       set_index_entry(istate, *nr, ce);
+                       (*nr)++;
+               }
+       }
+       return 0;
+}
+
+static int read_index_v5(struct index_state *istate, void *mmap, int mmap_size)
+{
+       unsigned long entry_offset;
+       unsigned int dir_offset, dir_table_offset;
+       struct cache_version_header *hdr;
+       struct cache_header *hdr_v5;
+       struct directory_entry *root_directory, *de;
+       int nr;
+       unsigned int foffsetblock;
+
+       hdr = mmap;
+       hdr_v5 = ptr_add(mmap, sizeof(*hdr));
+       istate->version = ntohl(hdr->hdr_version);
+       istate->cache_nr = ntohl(hdr_v5->hdr_nfile);
+       istate->cache_alloc = alloc_nr(istate->cache_nr);
+       istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry 
*));
+       istate->initialized = 1;
+
+       /* Skip size of the header + crc sum + size of offsets */
+       dir_offset = sizeof(*hdr) + sizeof(*hdr_v5) + 4 + 
(ntohl(hdr_v5->hdr_ndir) + 1) * 4;
+       dir_table_offset = sizeof(*hdr) + sizeof(*hdr_v5) + 4;
+       root_directory = read_directories(&dir_offset, &dir_table_offset, mmap, 
mmap_size);
+
+       entry_offset = ntohl(hdr_v5->hdr_fblockoffset);
+
+       nr = 0;
+       foffsetblock = dir_offset;
+       de = root_directory;
+       while (de)
+               if (read_entries(istate, &de, &entry_offset,
+                               &mmap, mmap_size, &nr, &foffsetblock) < 0)
+                       return -1;
+       return 0;
+}
+
+struct index_ops v5_ops = {
+       match_stat_basic,
+       verify_hdr,
+       read_index_v5,
+       NULL
+};
-- 
1.7.11.2

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