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: Thomas Rast <tr...@student.ethz.ch>
Signed-off-by: Thomas Gummerer <t.gumme...@gmail.com>
---
 cache.h      |   72 +++++++
 read-cache.c |  590 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 657 insertions(+), 5 deletions(-)

diff --git a/cache.h b/cache.h
index 076d6af..98adcd9 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 +137,58 @@ 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_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 +222,18 @@ 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 +271,8 @@ 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 +319,8 @@ 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.c b/read-cache.c
index 4243606..70334f9 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -234,6 +234,55 @@ static int ce_match_stat_basic_v2(struct cache_entry *ce,
        return changed;
 }
 
+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_MTIME_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_size);
+       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 ce_match_stat_basic_v5(struct cache_entry *ce,
+                               struct stat *st,
+                               int changed)
+{
+
+       if (ce->ce_mtime.sec != 0 && ce->ce_mtime.sec != (unsigned 
int)st->st_mtime)
+               changed |= MTIME_CHANGED;
+#ifdef USE_NSEC
+       if (ce->ce_mtime.nsec != 0 && ce->ce_mtime.nsec != ST_MTIME_NSEC(*st))
+               changed |= MTIME_CHANGED;
+#endif
+       if (!match_stat_crc(st, ce->ce_stat_crc)) {
+               changed |= OWNER_CHANGED;
+               changed |= INODE_CHANGED;
+       }
+       /* Racily smudged entry? */
+       if (!ce->ce_mtime.sec && !ce->ce_mtime.nsec) {
+               if (!changed && !is_empty_blob_sha1(ce->sha1) && 
ce_modified_check_fs(ce, st))
+                       changed |= DATA_CHANGED;
+       }
+       return changed;
+}
+
 static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
 {
        unsigned int changed = 0;
@@ -267,7 +316,10 @@ static int ce_match_stat_basic(struct cache_entry *ce, 
struct stat *st)
                die("internal error: ce_mode is %o", ce->ce_mode);
        }
 
-       changed = ce_match_stat_basic_v2(ce, st, changed);
+       if (the_index.version != 5)
+               changed = ce_match_stat_basic_v2(ce, st, changed);
+       else
+               changed = ce_match_stat_basic_v5(ce, st, changed);
        return changed;
 }
 
@@ -1245,6 +1297,14 @@ struct cache_header_v2 {
        unsigned int hdr_entries;
 };
 
+struct cache_header_v5 {
+       unsigned int hdr_ndir;
+       unsigned int hdr_nfile;
+       unsigned int hdr_fblockoffset;
+       unsigned int hdr_nextension;
+};
+
+
 /*
  * 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
@@ -1287,6 +1347,25 @@ struct ondisk_cache_entry_extended {
        char name[FLEX_ARRAY]; /* more */
 };
 
+struct ondisk_cache_entry_v5 {
+       unsigned short flags;
+       unsigned short mode;
+       struct cache_time mtime;
+       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;
+};
+
 /* These are only used for v3 or lower */
 #define align_flex_name(STRUCT,len) ((offsetof(struct STRUCT,name) + (len) + 
8) & ~7)
 #define ondisk_cache_entry_size(len) align_flex_name(ondisk_cache_entry,len)
@@ -1295,6 +1374,17 @@ struct ondisk_cache_entry_extended {
                            ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
                            ondisk_cache_entry_size(ce_namelen(ce)))
 
+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 verify_hdr_version(struct cache_version_header *hdr, unsigned long 
size)
 {
        int hdr_version;
@@ -1302,7 +1392,7 @@ static int verify_hdr_version(struct cache_version_header 
*hdr, unsigned long si
        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
                return error("bad signature");
        hdr_version = ntohl(hdr->hdr_version);
-       if (hdr_version < 2 || 4 < hdr_version)
+       if (hdr_version < 2 || 5 < hdr_version)
                return error("bad index version %d", hdr_version);
        return 0;
 }
@@ -1320,6 +1410,24 @@ static int verify_hdr_v2(struct cache_version_header 
*hdr, unsigned long size)
        return 0;
 }
 
+static int verify_hdr_v5(void *mmap)
+{
+       uint32_t *filecrc;
+       unsigned int header_size_v5;
+       struct cache_version_header *hdr;
+       struct cache_header_v5 *hdr_v5;
+
+       hdr = mmap;
+       hdr_v5 = mmap + sizeof(*hdr);
+       /* Size of the header + the size of the extensionoffsets */
+       header_size_v5 = sizeof(*hdr_v5) + hdr_v5->hdr_nextension * 4;
+       /* Initialize crc */
+       filecrc = mmap + sizeof(*hdr) + header_size_v5;
+       if (!check_crc32(0, hdr, sizeof(*hdr) + header_size_v5, 
ntohl(*filecrc)))
+               return error("bad index file header crc signature");
+       return 0;
+}
+
 static int read_index_extension(struct index_state *istate,
                                const char *ext, void *data, unsigned long sz)
 {
@@ -1390,6 +1498,98 @@ static struct cache_entry 
*cache_entry_from_ondisk(struct ondisk_cache_entry *on
        return ce;
 }
 
+static struct cache_entry *cache_entry_from_ondisk_v5(struct 
ondisk_cache_entry_v5 *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       = 0;
+       ce->ce_flags      = flags & CE_STAGEMASK;
+       ce->ce_flags     |= flags & CE_VALID;
+       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;
+}
+
 /*
  * Adjacent cache entries tend to share the leading paths, so it makes
  * sense to only store the differences in later entries.  In the v4
@@ -1457,6 +1657,345 @@ static struct cache_entry *create_from_disk(struct 
ondisk_cache_entry *ondisk,
        return ce;
 }
 
+static struct directory_entry *read_directories_v5(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 = (char *)mmap + *dir_offset;
+       beginning = mmap + *dir_table_offset;
+       end = mmap + *dir_table_offset + 4;
+       len = ntoh_l(*end) - ntoh_l(*beginning) - ondisk_directory_size - 5;
+       disk_de = (struct ondisk_directory_entry *)
+                       ((char *)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 = mmap + *dir_offset + data_len;
+       if (!check_crc32(0, 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_v5(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 struct cache_entry *read_entry_v5(struct directory_entry *de,
+                       unsigned long *entry_offset,
+                       void **mmap,
+                       unsigned long mmap_size,
+                       unsigned int *foffsetblock,
+                       int fd)
+{
+       int len, crc_wrong, i = 0, offset_to_offset;
+       char *name;
+       uint32_t foffsetblockcrc;
+       uint32_t *filecrc, *beginning, *end;
+       struct cache_entry *ce;
+       struct ondisk_cache_entry_v5 *disk_ce;
+
+       do {
+               name = (char *)*mmap + *entry_offset;
+               beginning = *mmap + *foffsetblock;
+               end = *mmap + *foffsetblock + 4;
+               len = ntoh_l(*end) - ntoh_l(*beginning) - sizeof(struct 
ondisk_cache_entry_v5) - 5;
+               disk_ce = (struct ondisk_cache_entry_v5 *)
+                               ((char *)*mmap + *entry_offset + len + 1);
+               ce = cache_entry_from_ondisk_v5(disk_ce, de, name, len, 
de->de_pathlen);
+               filecrc = *mmap + *entry_offset + len + 1 + sizeof(*disk_ce);
+               offset_to_offset = htonl(*foffsetblock);
+               foffsetblockcrc = crc32(0, (Bytef*)&offset_to_offset, 4);
+               crc_wrong = !check_crc32(foffsetblockcrc,
+                       *mmap + *entry_offset, len + 1 + sizeof(*disk_ce),
+                       ntoh_l(*filecrc));
+               if (crc_wrong) {
+                       /* wait for 10 milliseconds */
+                       usleep(10*1000);
+                       munmap(*mmap, mmap_size);
+                       *mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, 
MAP_PRIVATE, fd, 0);
+               }
+               i++;
+               /*
+                * Retry for 500 ms maximum, before giving up and saying the
+                * checksum is wrong.
+                */
+       } while (crc_wrong && i < 50);
+       if (crc_wrong)
+               goto unmap;
+       *entry_offset += len + 1 + sizeof(*disk_ce) + 4;
+       return ce;
+unmap:
+       munmap(*mmap, mmap_size);
+       die("file crc doesn't match for '%s'", ce->name);
+}
+
+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 struct conflict_entry *read_conflicts_v5(struct directory_entry *de,
+                                               void **mmap,
+                                               unsigned long mmap_size,
+                                               int fd)
+{
+       struct conflict_entry *head, *tail;
+       unsigned int croffset, i, j = 0;
+       char *full_name;
+
+       croffset = de->de_cr;
+       tail = NULL;
+       head = 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, crc_wrong;
+               uint32_t *filecrc;
+
+               do {
+                       offset = croffset;
+                       crc_start = *mmap + offset;
+                       name = (char *)*mmap + offset;
+                       len = strlen(name);
+                       offset += len + 1;
+                       nfileconflicts = *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 = *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 = *mmap + offset;
+                       crc_wrong = !check_crc32(0, crc_start,
+                               len + 1 + 4 + conflict_new->nfileconflicts
+                               * sizeof(struct ondisk_conflict_part),
+                               ntoh_l(*filecrc));
+                       if (crc_wrong) {
+                               /* wait for 10 milliseconds */
+                               usleep(10*1000);
+                               munmap(*mmap, mmap_size);
+                               *mmap = xmmap(NULL, mmap_size, PROT_READ | 
PROT_WRITE, MAP_PRIVATE, fd, 0);
+                       }
+                       free(full_name);
+                       j++;
+               } while (crc_wrong && j < 50);
+               if (crc_wrong)
+                       goto unmap;
+               croffset = offset + 4;
+               conflict_entry_push(&head, &tail, conflict_new);
+       }
+       return head;
+unmap:
+       munmap(*mmap, mmap_size);
+       die("wrong crc for conflict: %s", full_name);
+}
+
+static struct directory_entry *read_entries_v5(struct index_state *istate,
+                                       struct directory_entry *de,
+                                       unsigned long *entry_offset,
+                                       void **mmap,
+                                       unsigned long mmap_size,
+                                       int *nr,
+                                       unsigned int *foffsetblock,
+                                       int fd)
+{
+       struct cache_entry *head = NULL, *tail = NULL;
+       struct conflict_entry *conflict_queue;
+       struct cache_entry *ce;
+       int i;
+
+       conflict_queue = read_conflicts_v5(de, mmap, mmap_size, fd);
+       for (i = 0; i < de->de_nfiles; i++) {
+               ce = read_entry_v5(de,
+                               entry_offset,
+                               mmap,
+                               mmap_size,
+                               foffsetblock,
+                               fd);
+               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) {
+                       de = read_entries_v5(istate,
+                                       de,
+                                       entry_offset,
+                                       mmap,
+                                       mmap_size,
+                                       nr,
+                                       foffsetblock,
+                                       fd);
+               } else {
+                       ce = ce_queue_pop(&head);
+                       set_index_entry(istate, *nr, ce);
+                       (*nr)++;
+               }
+       }
+
+       return de;
+}
+
 static void read_index_v2(struct index_state *istate, void *mmap, int 
mmap_size)
 {
        int i;
@@ -1516,6 +2055,39 @@ unmap:
        die("index file corrupt");
 }
 
+static void read_index_v5(struct index_state *istate, void *mmap, int 
mmap_size, int fd)
+{
+       unsigned long entry_offset;
+       unsigned int dir_offset, dir_table_offset;
+       struct cache_version_header *hdr;
+       struct cache_header_v5 *hdr_v5;
+       struct directory_entry *root_directory, *de;
+       int nr;
+       unsigned int foffsetblock;
+
+       hdr = mmap;
+       hdr_v5 = 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_v5(&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)
+               de = read_entries_v5(istate, de, &entry_offset,
+                               &mmap, mmap_size, &nr, &foffsetblock, fd);
+}
+
 /* remember to discard_cache() before reading a different cache! */
 int read_index_from(struct index_state *istate, const char *path)
 {
@@ -1555,10 +2127,18 @@ int read_index_from(struct index_state *istate, const 
char *path)
        if (verify_hdr_version(hdr, mmap_size) < 0)
                goto unmap;
 
-       if (verify_hdr_v2(hdr, mmap_size) < 0)
-               goto unmap;
+       if (htonl(hdr->hdr_version) != 5) {
+               if (verify_hdr_v2(hdr, mmap_size) < 0)
+                       goto unmap;
 
-       read_index_v2(istate, mmap, mmap_size);
+               read_index_v2(istate, mmap, mmap_size);
+       } else {
+               if (verify_hdr_v5(hdr) < 0)
+                       goto unmap;
+
+               read_index_v5(istate, mmap, mmap_size, fd);
+       }
+       close(fd);
        istate->timestamp.sec = st.st_mtime;
        istate->timestamp.nsec = ST_MTIME_NSEC(st);
 
-- 
1.7.10.GIT

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