Merge branch 'nf/maint-fix-index-ext-len-on-be64' into maint
[gitweb.git] / read-cache.c
index 053bcf19167ccc8b1d04365da244bc0b358831fe..9033dd3ab938e2ee7b4248ff97645414ee3688db 100644 (file)
@@ -8,6 +8,12 @@
 #include "cache-tree.h"
 #include "refs.h"
 #include "dir.h"
+#include "tree.h"
+#include "commit.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "revision.h"
+#include "blob.h"
 
 /* Index extensions.
  *
 
 struct index_state the_index;
 
+static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
+{
+       istate->cache[nr] = ce;
+       add_name_hash(istate, ce);
+}
+
+static void replace_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
+{
+       struct cache_entry *old = istate->cache[nr];
+
+       remove_name_hash(old);
+       set_index_entry(istate, nr, ce);
+       istate->cache_changed = 1;
+}
+
+void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
+{
+       struct cache_entry *old = istate->cache[nr], *new;
+       int namelen = strlen(new_name);
+
+       new = xmalloc(cache_entry_size(namelen));
+       copy_cache_entry(new, old);
+       new->ce_flags &= ~(CE_STATE_MASK | CE_NAMEMASK);
+       new->ce_flags |= (namelen >= CE_NAMEMASK ? CE_NAMEMASK : namelen);
+       memcpy(new->name, new_name, namelen + 1);
+
+       cache_tree_invalidate_path(istate->cache_tree, old->name);
+       remove_index_entry_at(istate, nr);
+       add_index_entry(istate, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+}
+
 /*
  * This only updates the "non-critical" parts of the directory
  * cache, ie the parts that aren't tracked by GIT, and only used
@@ -30,8 +67,10 @@ struct index_state the_index;
  */
 void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 {
-       ce->ce_ctime = st->st_ctime;
-       ce->ce_mtime = st->st_mtime;
+       ce->ce_ctime.sec = (unsigned int)st->st_ctime;
+       ce->ce_mtime.sec = (unsigned int)st->st_mtime;
+       ce->ce_ctime.nsec = ST_CTIME_NSEC(*st);
+       ce->ce_mtime.nsec = ST_MTIME_NSEC(*st);
        ce->ce_dev = st->st_dev;
        ce->ce_ino = st->st_ino;
        ce->ce_uid = st->st_uid;
@@ -40,6 +79,9 @@ void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 
        if (assume_unchanged)
                ce->ce_flags |= CE_VALID;
+
+       if (S_ISREG(st->st_mode))
+               ce_mark_uptodate(ce);
 }
 
 static int ce_compare_data(struct cache_entry *ce, struct stat *st)
@@ -59,27 +101,21 @@ static int ce_compare_data(struct cache_entry *ce, struct stat *st)
 static int ce_compare_link(struct cache_entry *ce, size_t expected_size)
 {
        int match = -1;
-       char *target;
        void *buffer;
        unsigned long size;
        enum object_type type;
-       int len;
+       struct strbuf sb = STRBUF_INIT;
 
-       target = xmalloc(expected_size);
-       len = readlink(ce->name, target, expected_size);
-       if (len != expected_size) {
-               free(target);
+       if (strbuf_readlink(&sb, ce->name, expected_size))
                return -1;
-       }
+
        buffer = read_sha1_file(ce->sha1, &type, &size);
-       if (!buffer) {
-               free(target);
-               return -1;
+       if (buffer) {
+               if (size == sb.len)
+                       match = memcmp(buffer, sb.buf, size);
+               free(buffer);
        }
-       if (size == expected_size)
-               match = memcmp(buffer, target, size);
-       free(buffer);
-       free(target);
+       strbuf_release(&sb);
        return match;
 }
 
@@ -113,13 +149,23 @@ static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
                break;
        case S_IFDIR:
                if (S_ISGITLINK(ce->ce_mode))
-                       return 0;
+                       return ce_compare_gitlink(ce) ? DATA_CHANGED : 0;
        default:
                return TYPE_CHANGED;
        }
        return 0;
 }
 
+int is_empty_blob_sha1(const unsigned char *sha1)
+{
+       static const unsigned char empty_blob_sha1[20] = {
+               0xe6,0x9d,0xe2,0x9b,0xb2,0xd1,0xd6,0x43,0x4b,0x8b,
+               0x29,0xae,0x77,0x5a,0xd8,0xc2,0xe4,0x8c,0x53,0x91
+       };
+
+       return !hashcmp(sha1, empty_blob_sha1);
+}
+
 static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
 {
        unsigned int changed = 0;
@@ -143,6 +189,7 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
                        changed |= TYPE_CHANGED;
                break;
        case S_IFGITLINK:
+               /* We ignore most of the st_xxx fields for gitlinks */
                if (!S_ISDIR(st->st_mode))
                        changed |= TYPE_CHANGED;
                else if (ce_compare_gitlink(ce))
@@ -151,11 +198,18 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
        default:
                die("internal error: ce_mode is %o", ce->ce_mode);
        }
-       if (ce->ce_mtime != (unsigned int) st->st_mtime)
+       if (ce->ce_mtime.sec != (unsigned int)st->st_mtime)
                changed |= MTIME_CHANGED;
-       if (ce->ce_ctime != (unsigned int) st->st_ctime)
+       if (trust_ctime && ce->ce_ctime.sec != (unsigned int)st->st_ctime)
                changed |= CTIME_CHANGED;
 
+#ifdef USE_NSEC
+       if (ce->ce_mtime.nsec != ST_MTIME_NSEC(*st))
+               changed |= MTIME_CHANGED;
+       if (trust_ctime && ce->ce_ctime.nsec != ST_CTIME_NSEC(*st))
+               changed |= CTIME_CHANGED;
+#endif
+
        if (ce->ce_uid != (unsigned int) st->st_uid ||
            ce->ce_gid != (unsigned int) st->st_gid)
                changed |= OWNER_CHANGED;
@@ -175,10 +229,31 @@ static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
        if (ce->ce_size != (unsigned int) st->st_size)
                changed |= DATA_CHANGED;
 
+       /* Racily smudged entry? */
+       if (!ce->ce_size) {
+               if (!is_empty_blob_sha1(ce->sha1))
+                       changed |= DATA_CHANGED;
+       }
+
        return changed;
 }
 
-int ie_match_stat(struct index_state *istate,
+static int is_racy_timestamp(const struct index_state *istate, struct cache_entry *ce)
+{
+       return (!S_ISGITLINK(ce->ce_mode) &&
+               istate->timestamp.sec &&
+#ifdef USE_NSEC
+                /* nanosecond timestamped files can also be racy! */
+               (istate->timestamp.sec < ce->ce_mtime.sec ||
+                (istate->timestamp.sec == ce->ce_mtime.sec &&
+                 istate->timestamp.nsec <= ce->ce_mtime.nsec))
+#else
+               istate->timestamp.sec <= ce->ce_mtime.sec
+#endif
+                );
+}
+
+int ie_match_stat(const struct index_state *istate,
                  struct cache_entry *ce, struct stat *st,
                  unsigned int options)
 {
@@ -193,6 +268,14 @@ int ie_match_stat(struct index_state *istate,
        if (!ignore_valid && (ce->ce_flags & CE_VALID))
                return 0;
 
+       /*
+        * Intent-to-add entries have not been added, so the index entry
+        * by definition never matches what is in the work tree until it
+        * actually gets added.
+        */
+       if (ce->ce_flags & CE_INTENT_TO_ADD)
+               return DATA_CHANGED | TYPE_CHANGED | MODE_CHANGED;
+
        changed = ce_match_stat_basic(ce, st);
 
        /*
@@ -211,9 +294,7 @@ int ie_match_stat(struct index_state *istate,
         * whose mtime are the same as the index file timestamp more
         * carefully than others.
         */
-       if (!changed &&
-           istate->timestamp &&
-           istate->timestamp <= ce->ce_mtime) {
+       if (!changed && is_racy_timestamp(istate, ce)) {
                if (assume_racy_is_modified)
                        changed |= DATA_CHANGED;
                else
@@ -223,7 +304,7 @@ int ie_match_stat(struct index_state *istate,
        return changed;
 }
 
-int ie_modified(struct index_state *istate,
+int ie_modified(const struct index_state *istate,
                struct cache_entry *ce, struct stat *st, unsigned int options)
 {
        int changed, changed_fs;
@@ -238,11 +319,22 @@ int ie_modified(struct index_state *istate,
        if (changed & (MODE_CHANGED | TYPE_CHANGED))
                return changed;
 
-       /* Immediately after read-tree or update-index --cacheinfo,
-        * the length field is zero.  For other cases the ce_size
-        * should match the SHA1 recorded in the index entry.
+       /*
+        * Immediately after read-tree or update-index --cacheinfo,
+        * the length field is zero, as we have never even read the
+        * lstat(2) information once, and we cannot trust DATA_CHANGED
+        * returned by ie_match_stat() which in turn was returned by
+        * ce_match_stat_basic() to signal that the filesize of the
+        * blob changed.  We have to actually go to the filesystem to
+        * see if the contents match, and if so, should answer "unchanged".
+        *
+        * The logic does not apply to gitlinks, as ce_match_stat_basic()
+        * already has checked the actual HEAD from the filesystem in the
+        * subproject.  If ie_match_stat() already said it is different,
+        * then we know it is.
         */
-       if ((changed & DATA_CHANGED) && ce->ce_size != 0)
+       if ((changed & DATA_CHANGED) &&
+           (S_ISGITLINK(ce->ce_mode) || ce->ce_size != 0))
                return changed;
 
        changed_fs = ce_modified_check_fs(ce, st);
@@ -270,6 +362,41 @@ int base_name_compare(const char *name1, int len1, int mode1,
        return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
 }
 
+/*
+ * df_name_compare() is identical to base_name_compare(), except it
+ * compares conflicting directory/file entries as equal. Note that
+ * while a directory name compares as equal to a regular file, they
+ * then individually compare _differently_ to a filename that has
+ * a dot after the basename (because '\0' < '.' < '/').
+ *
+ * This is used by routines that want to traverse the git namespace
+ * but then handle conflicting entries together when possible.
+ */
+int df_name_compare(const char *name1, int len1, int mode1,
+                   const char *name2, int len2, int mode2)
+{
+       int len = len1 < len2 ? len1 : len2, cmp;
+       unsigned char c1, c2;
+
+       cmp = memcmp(name1, name2, len);
+       if (cmp)
+               return cmp;
+       /* Directories and files compare equal (same length, same name) */
+       if (len1 == len2)
+               return 0;
+       c1 = name1[len];
+       if (!c1 && S_ISDIR(mode1))
+               c1 = '/';
+       c2 = name2[len];
+       if (!c2 && S_ISDIR(mode2))
+               c2 = '/';
+       if (c1 == '/' && !c2)
+               return 0;
+       if (c2 == '/' && !c1)
+               return 0;
+       return c1 - c2;
+}
+
 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
 {
        int len1 = flags1 & CE_NAMEMASK;
@@ -296,7 +423,7 @@ int cache_name_compare(const char *name1, int flags1, const char *name2, int fla
        return 0;
 }
 
-int index_name_pos(struct index_state *istate, const char *name, int namelen)
+int index_name_pos(const struct index_state *istate, const char *name, int namelen)
 {
        int first, last;
 
@@ -320,6 +447,9 @@ int index_name_pos(struct index_state *istate, const char *name, int namelen)
 /* Remove entry, return true if there are more entries to go.. */
 int remove_index_entry_at(struct index_state *istate, int pos)
 {
+       struct cache_entry *ce = istate->cache[pos];
+
+       remove_name_hash(ce);
        istate->cache_changed = 1;
        istate->cache_nr--;
        if (pos >= istate->cache_nr)
@@ -330,6 +460,26 @@ int remove_index_entry_at(struct index_state *istate, int pos)
        return 1;
 }
 
+/*
+ * Remove all cache ententries marked for removal, that is where
+ * CE_REMOVE is set in ce_flags.  This is much more effective than
+ * calling remove_index_entry_at() for each entry to be removed.
+ */
+void remove_marked_cache_entries(struct index_state *istate)
+{
+       struct cache_entry **ce_array = istate->cache;
+       unsigned int i, j;
+
+       for (i = j = 0; i < istate->cache_nr; i++) {
+               if (ce_array[i]->ce_flags & CE_REMOVE)
+                       remove_name_hash(ce_array[i]);
+               else
+                       ce_array[j++] = ce_array[i];
+       }
+       istate->cache_changed = 1;
+       istate->cache_nr = j;
+}
+
 int remove_file_from_index(struct index_state *istate, const char *path)
 {
        int pos = index_name_pos(istate, path, strlen(path));
@@ -369,21 +519,63 @@ static int index_name_pos_also_unmerged(struct index_state *istate,
        return pos;
 }
 
-int add_file_to_index(struct index_state *istate, const char *path, int verbose)
+static int different_name(struct cache_entry *ce, struct cache_entry *alias)
 {
-       int size, namelen, pos;
-       struct stat st;
-       struct cache_entry *ce;
-       unsigned ce_option = CE_MATCH_IGNORE_VALID|CE_MATCH_RACY_IS_DIRTY;
+       int len = ce_namelen(ce);
+       return ce_namelen(alias) != len || memcmp(ce->name, alias->name, len);
+}
 
-       if (lstat(path, &st))
-               die("%s: unable to stat (%s)", path, strerror(errno));
+/*
+ * If we add a filename that aliases in the cache, we will use the
+ * name that we already have - but we don't want to update the same
+ * alias twice, because that implies that there were actually two
+ * different files with aliasing names!
+ *
+ * So we use the CE_ADDED flag to verify that the alias was an old
+ * one before we accept it as
+ */
+static struct cache_entry *create_alias_ce(struct cache_entry *ce, struct cache_entry *alias)
+{
+       int len;
+       struct cache_entry *new;
+
+       if (alias->ce_flags & CE_ADDED)
+               die("Will not add file alias '%s' ('%s' already exists in index)", ce->name, alias->name);
+
+       /* Ok, create the new entry using the name of the existing alias */
+       len = ce_namelen(alias);
+       new = xcalloc(1, cache_entry_size(len));
+       memcpy(new->name, alias->name, len);
+       copy_cache_entry(new, ce);
+       free(ce);
+       return new;
+}
 
-       if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode) && !S_ISDIR(st.st_mode))
-               die("%s: can only add regular files, symbolic links or git-directories", path);
+static void record_intent_to_add(struct cache_entry *ce)
+{
+       unsigned char sha1[20];
+       if (write_sha1_file("", 0, blob_type, sha1))
+               die("cannot create an empty blob in the object database");
+       hashcpy(ce->sha1, sha1);
+}
+
+int add_to_index(struct index_state *istate, const char *path, struct stat *st, int flags)
+{
+       int size, namelen, was_same;
+       mode_t st_mode = st->st_mode;
+       struct cache_entry *ce, *alias;
+       unsigned ce_option = CE_MATCH_IGNORE_VALID|CE_MATCH_RACY_IS_DIRTY;
+       int verbose = flags & (ADD_CACHE_VERBOSE | ADD_CACHE_PRETEND);
+       int pretend = flags & ADD_CACHE_PRETEND;
+       int intent_only = flags & ADD_CACHE_INTENT;
+       int add_option = (ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|
+                         (intent_only ? ADD_CACHE_NEW_ONLY : 0));
+
+       if (!S_ISREG(st_mode) && !S_ISLNK(st_mode) && !S_ISDIR(st_mode))
+               return error("%s: can only add regular files, symbolic links or git-directories", path);
 
        namelen = strlen(path);
-       if (S_ISDIR(st.st_mode)) {
+       if (S_ISDIR(st_mode)) {
                while (namelen && path[namelen-1] == '/')
                        namelen--;
        }
@@ -391,10 +583,13 @@ int add_file_to_index(struct index_state *istate, const char *path, int verbose)
        ce = xcalloc(1, size);
        memcpy(ce->name, path, namelen);
        ce->ce_flags = namelen;
-       fill_stat_cache_info(ce, &st);
+       if (!intent_only)
+               fill_stat_cache_info(ce, st);
+       else
+               ce->ce_flags |= CE_INTENT_TO_ADD;
 
        if (trust_executable_bit && has_symlinks)
-               ce->ce_mode = create_ce_mode(st.st_mode);
+               ce->ce_mode = create_ce_mode(st_mode);
        else {
                /* If there is an existing entry, pick the mode bits and type
                 * from it, otherwise assume unexecutable regular file.
@@ -403,27 +598,50 @@ int add_file_to_index(struct index_state *istate, const char *path, int verbose)
                int pos = index_name_pos_also_unmerged(istate, path, namelen);
 
                ent = (0 <= pos) ? istate->cache[pos] : NULL;
-               ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);
+               ce->ce_mode = ce_mode_from_stat(ent, st_mode);
        }
 
-       pos = index_name_pos(istate, ce->name, namelen);
-       if (0 <= pos &&
-           !ce_stage(istate->cache[pos]) &&
-           !ie_match_stat(istate, istate->cache[pos], &st, ce_option)) {
+       alias = index_name_exists(istate, ce->name, ce_namelen(ce), ignore_case);
+       if (alias && !ce_stage(alias) && !ie_match_stat(istate, alias, st, ce_option)) {
                /* Nothing changed, really */
                free(ce);
+               ce_mark_uptodate(alias);
+               alias->ce_flags |= CE_ADDED;
                return 0;
        }
-
-       if (index_path(ce->sha1, path, &st, 1))
-               die("unable to index file %s", path);
-       if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
-               die("unable to add %s to index",path);
-       if (verbose)
+       if (!intent_only) {
+               if (index_path(ce->sha1, path, st, 1))
+                       return error("unable to index file %s", path);
+       } else
+               record_intent_to_add(ce);
+
+       if (ignore_case && alias && different_name(ce, alias))
+               ce = create_alias_ce(ce, alias);
+       ce->ce_flags |= CE_ADDED;
+
+       /* It was suspected to be racily clean, but it turns out to be Ok */
+       was_same = (alias &&
+                   !ce_stage(alias) &&
+                   !hashcmp(alias->sha1, ce->sha1) &&
+                   ce->ce_mode == alias->ce_mode);
+
+       if (pretend)
+               ;
+       else if (add_index_entry(istate, ce, add_option))
+               return error("unable to add %s to index",path);
+       if (verbose && !was_same)
                printf("add '%s'\n", path);
        return 0;
 }
 
+int add_file_to_index(struct index_state *istate, const char *path, int flags)
+{
+       struct stat st;
+       if (lstat(path, &st))
+               die_errno("unable to stat '%s'", path);
+       return add_to_index(istate, path, &st, flags);
+}
+
 struct cache_entry *make_cache_entry(unsigned int mode,
                const unsigned char *sha1, const char *path, int stage,
                int refresh)
@@ -431,8 +649,10 @@ struct cache_entry *make_cache_entry(unsigned int mode,
        int size, len;
        struct cache_entry *ce;
 
-       if (!verify_path(path))
+       if (!verify_path(path)) {
+               error("Invalid path '%s'", path);
                return NULL;
+       }
 
        len = strlen(path);
        size = cache_entry_size(len);
@@ -611,7 +831,7 @@ static int has_dir_name(struct index_state *istate,
                         * it is Ok to have a directory at the same
                         * path.
                         */
-                       if (stage || istate->cache[pos]->ce_mode) {
+                       if (!(istate->cache[pos]->ce_flags & CE_REMOVE)) {
                                retval = -1;
                                if (!ok_to_replace)
                                        break;
@@ -633,8 +853,9 @@ static int has_dir_name(struct index_state *istate,
                            (p->name[len] != '/') ||
                            memcmp(p->name, name, len))
                                break; /* not our subdirectory */
-                       if (ce_stage(p) == stage && (stage || p->ce_mode))
-                               /* p is at the same stage as our entry, and
+                       if (ce_stage(p) == stage && !(p->ce_flags & CE_REMOVE))
+                               /*
+                                * p is at the same stage as our entry, and
                                 * is a subdirectory of what we are looking
                                 * at, so we cannot have conflicts at our
                                 * level or anything shorter.
@@ -687,14 +908,15 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
        int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
        int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
        int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
+       int new_only = option & ADD_CACHE_NEW_ONLY;
 
        cache_tree_invalidate_path(istate->cache_tree, ce->name);
        pos = index_name_pos(istate, ce->name, ce->ce_flags);
 
        /* existing match? Just replace it. */
        if (pos >= 0) {
-               istate->cache_changed = 1;
-               istate->cache[pos] = ce;
+               if (!new_only)
+                       replace_index_entry(istate, pos, ce);
                return 0;
        }
        pos = -pos-1;
@@ -714,7 +936,7 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
        if (!ok_to_add)
                return -1;
        if (!verify_path(ce->name))
-               return -1;
+               return error("Invalid path '%s'", ce->name);
 
        if (!skip_df_check &&
            check_file_directory_conflict(istate, ce, pos, ok_to_replace)) {
@@ -754,7 +976,7 @@ int add_index_entry(struct index_state *istate, struct cache_entry *ce, int opti
                memmove(istate->cache + pos + 1,
                        istate->cache + pos,
                        (istate->cache_nr - pos - 1) * sizeof(ce));
-       istate->cache[pos] = ce;
+       set_index_entry(istate, pos, ce);
        istate->cache_changed = 1;
        return 0;
 }
@@ -779,6 +1001,18 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
        int changed, size;
        int ignore_valid = options & CE_MATCH_IGNORE_VALID;
 
+       if (ce_uptodate(ce))
+               return ce;
+
+       /*
+        * CE_VALID means the user promised us that the change to
+        * the work tree does not matter and told us not to worry.
+        */
+       if (!ignore_valid && (ce->ce_flags & CE_VALID)) {
+               ce_mark_uptodate(ce);
+               return ce;
+       }
+
        if (lstat(ce->name, &st) < 0) {
                if (err)
                        *err = errno;
@@ -797,8 +1031,15 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
                if (ignore_valid && assume_unchanged &&
                    !(ce->ce_flags & CE_VALID))
                        ; /* mark this one VALID again */
-               else
+               else {
+                       /*
+                        * We do not mark the index itself "modified"
+                        * because CE_UPTODATE flag is in-core only;
+                        * we are not going to write this change out.
+                        */
+                       ce_mark_uptodate(ce);
                        return ce;
+               }
        }
 
        if (ie_modified(istate, ce, &st, options)) {
@@ -824,7 +1065,18 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
        return updated;
 }
 
-int refresh_index(struct index_state *istate, unsigned int flags, const char **pathspec, char *seen)
+static void show_file(const char * fmt, const char * name, int in_porcelain,
+                     int * first, char *header_msg)
+{
+       if (in_porcelain && *first && header_msg) {
+               printf("%s\n", header_msg);
+               *first=0;
+       }
+       printf(fmt, name);
+}
+
+int refresh_index(struct index_state *istate, unsigned int flags, const char **pathspec,
+                 char *seen, char *header_msg)
 {
        int i;
        int has_errors = 0;
@@ -832,13 +1084,23 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
        int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
        int quiet = (flags & REFRESH_QUIET) != 0;
        int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
+       int ignore_submodules = (flags & REFRESH_IGNORE_SUBMODULES) != 0;
+       int first = 1;
+       int in_porcelain = (flags & REFRESH_IN_PORCELAIN);
        unsigned int options = really ? CE_MATCH_IGNORE_VALID : 0;
+       const char *needs_update_fmt;
+       const char *needs_merge_fmt;
 
+       needs_update_fmt = (in_porcelain ? "M\t%s\n" : "%s: needs update\n");
+       needs_merge_fmt = (in_porcelain ? "U\t%s\n" : "%s: needs merge\n");
        for (i = 0; i < istate->cache_nr; i++) {
                struct cache_entry *ce, *new;
                int cache_errno = 0;
 
                ce = istate->cache[i];
+               if (ignore_submodules && S_ISGITLINK(ce->ce_mode))
+                       continue;
+
                if (ce_stage(ce)) {
                        while ((i < istate->cache_nr) &&
                               ! strcmp(istate->cache[i]->name, ce->name))
@@ -846,7 +1108,7 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
                        i--;
                        if (allow_unmerged)
                                continue;
-                       printf("%s: needs merge\n", ce->name);
+                       show_file(needs_merge_fmt, ce->name, in_porcelain, &first, header_msg);
                        has_errors = 1;
                        continue;
                }
@@ -869,15 +1131,12 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
                        }
                        if (quiet)
                                continue;
-                       printf("%s: needs update\n", ce->name);
+                       show_file(needs_update_fmt, ce->name, in_porcelain, &first, header_msg);
                        has_errors = 1;
                        continue;
                }
-               istate->cache_changed = 1;
-               /* You can NOT just free istate->cache[i] here, since it
-                * might not be necessarily malloc()ed but can also come
-                * from mmap(). */
-               istate->cache[i] = new;
+
+               replace_index_entry(istate, i, new);
        }
        return has_errors;
 }
@@ -889,16 +1148,16 @@ struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
 
 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 {
-       SHA_CTX c;
+       git_SHA_CTX c;
        unsigned char sha1[20];
 
        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
                return error("bad signature");
-       if (hdr->hdr_version != htonl(2))
+       if (hdr->hdr_version != htonl(2) && hdr->hdr_version != htonl(3))
                return error("bad index version");
-       SHA1_Init(&c);
-       SHA1_Update(&c, hdr, size - 20);
-       SHA1_Final(sha1, &c);
+       git_SHA1_Init(&c);
+       git_SHA1_Update(&c, hdr, size - 20);
+       git_SHA1_Final(sha1, &c);
        if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
                return error("bad index file sha1 signature");
        return 0;
@@ -928,8 +1187,13 @@ int read_index(struct index_state *istate)
 
 static void convert_from_disk(struct ondisk_cache_entry *ondisk, struct cache_entry *ce)
 {
-       ce->ce_ctime = ntohl(ondisk->ctime.sec);
-       ce->ce_mtime = ntohl(ondisk->mtime.sec);
+       size_t len;
+       const char *name;
+
+       ce->ce_ctime.sec = ntohl(ondisk->ctime.sec);
+       ce->ce_mtime.sec = ntohl(ondisk->mtime.sec);
+       ce->ce_ctime.nsec = ntohl(ondisk->ctime.nsec);
+       ce->ce_mtime.nsec = ntohl(ondisk->mtime.nsec);
        ce->ce_dev   = ntohl(ondisk->dev);
        ce->ce_ino   = ntohl(ondisk->ino);
        ce->ce_mode  = ntohl(ondisk->mode);
@@ -938,8 +1202,46 @@ static void convert_from_disk(struct ondisk_cache_entry *ondisk, struct cache_en
        ce->ce_size  = ntohl(ondisk->size);
        /* On-disk flags are just 16 bits */
        ce->ce_flags = ntohs(ondisk->flags);
+
        hashcpy(ce->sha1, ondisk->sha1);
-       memcpy(ce->name, ondisk->name, ce_namelen(ce)+1);
+
+       len = ce->ce_flags & CE_NAMEMASK;
+
+       if (ce->ce_flags & CE_EXTENDED) {
+               struct ondisk_cache_entry_extended *ondisk2;
+               int extended_flags;
+               ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
+               extended_flags = ntohs(ondisk2->flags2) << 16;
+               /* We do not yet understand any bit out of CE_EXTENDED_FLAGS */
+               if (extended_flags & ~CE_EXTENDED_FLAGS)
+                       die("Unknown index entry format %08x", extended_flags);
+               ce->ce_flags |= extended_flags;
+               name = ondisk2->name;
+       }
+       else
+               name = ondisk->name;
+
+       if (len == CE_NAMEMASK)
+               len = strlen(name);
+       /*
+        * NEEDSWORK: If the original index is crafted, this copy could
+        * go unchecked.
+        */
+       memcpy(ce->name, name, len + 1);
+}
+
+static inline size_t estimate_cache_size(size_t ondisk_size, unsigned int entries)
+{
+       long per_entry;
+
+       per_entry = sizeof(struct cache_entry) - sizeof(struct ondisk_cache_entry);
+
+       /*
+        * Alignment can cause differences. This should be "alignof", but
+        * since that's a gcc'ism, just use the size of a pointer.
+        */
+       per_entry += sizeof(void *);
+       return ondisk_size + entries*per_entry;
 }
 
 /* remember to discard_cache() before reading a different cache! */
@@ -953,20 +1255,21 @@ int read_index_from(struct index_state *istate, const char *path)
        size_t mmap_size;
 
        errno = EBUSY;
-       if (istate->alloc)
+       if (istate->initialized)
                return istate->cache_nr;
 
        errno = ENOENT;
-       istate->timestamp = 0;
+       istate->timestamp.sec = 0;
+       istate->timestamp.nsec = 0;
        fd = open(path, O_RDONLY);
        if (fd < 0) {
                if (errno == ENOENT)
                        return 0;
-               die("index file open failed (%s)", strerror(errno));
+               die_errno("index file open failed");
        }
 
        if (fstat(fd, &st))
-               die("cannot stat the open index (%s)", strerror(errno));
+               die_errno("cannot stat the open index");
 
        errno = EINVAL;
        mmap_size = xsize_t(st.st_size);
@@ -976,7 +1279,7 @@ int read_index_from(struct index_state *istate, const char *path)
        mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
        close(fd);
        if (mmap == MAP_FAILED)
-               die("unable to map index file");
+               die_errno("unable to map index file");
 
        hdr = mmap;
        if (verify_hdr(hdr, mmap_size) < 0)
@@ -992,7 +1295,8 @@ int read_index_from(struct index_state *istate, const char *path)
         * has room for a few  more flags, we can allocate using the same
         * index size
         */
-       istate->alloc = xmalloc(mmap_size);
+       istate->alloc = xmalloc(estimate_cache_size(mmap_size, istate->cache_nr));
+       istate->initialized = 1;
 
        src_offset = sizeof(*hdr);
        dst_offset = 0;
@@ -1003,12 +1307,14 @@ int read_index_from(struct index_state *istate, const char *path)
                disk_ce = (struct ondisk_cache_entry *)((char *)mmap + src_offset);
                ce = (struct cache_entry *)((char *)istate->alloc + dst_offset);
                convert_from_disk(disk_ce, ce);
-               istate->cache[i] = ce;
+               set_index_entry(istate, i, ce);
 
                src_offset += ondisk_ce_size(ce);
                dst_offset += ce_size(ce);
        }
-       istate->timestamp = st.st_mtime;
+       istate->timestamp.sec = st.st_mtime;
+       istate->timestamp.nsec = ST_MTIME_NSEC(st);
+
        while (src_offset <= mmap_size - 20 - 8) {
                /* After an array of active_nr index entries,
                 * there can be arbitrary number of extended
@@ -1036,28 +1342,47 @@ int read_index_from(struct index_state *istate, const char *path)
        die("index file corrupt");
 }
 
+int is_index_unborn(struct index_state *istate)
+{
+       return (!istate->cache_nr && !istate->alloc && !istate->timestamp.sec);
+}
+
 int discard_index(struct index_state *istate)
 {
        istate->cache_nr = 0;
        istate->cache_changed = 0;
-       istate->timestamp = 0;
+       istate->timestamp.sec = 0;
+       istate->timestamp.nsec = 0;
+       istate->name_hash_initialized = 0;
+       free_hash(&istate->name_hash);
        cache_tree_free(&(istate->cache_tree));
        free(istate->alloc);
        istate->alloc = NULL;
+       istate->initialized = 0;
 
        /* no need to throw away allocated active_cache */
        return 0;
 }
 
+int unmerged_index(const struct index_state *istate)
+{
+       int i;
+       for (i = 0; i < istate->cache_nr; i++) {
+               if (ce_stage(istate->cache[i]))
+                       return 1;
+       }
+       return 0;
+}
+
 #define WRITE_BUFFER_SIZE 8192
 static unsigned char write_buffer[WRITE_BUFFER_SIZE];
 static unsigned long write_buffer_len;
 
-static int ce_write_flush(SHA_CTX *context, int fd)
+static int ce_write_flush(git_SHA_CTX *context, int fd)
 {
        unsigned int buffered = write_buffer_len;
        if (buffered) {
-               SHA1_Update(context, write_buffer, buffered);
+               git_SHA1_Update(context, write_buffer, buffered);
                if (write_in_full(fd, write_buffer, buffered) != buffered)
                        return -1;
                write_buffer_len = 0;
@@ -1065,7 +1390,7 @@ static int ce_write_flush(SHA_CTX *context, int fd)
        return 0;
 }
 
-static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
+static int ce_write(git_SHA_CTX *context, int fd, void *data, unsigned int len)
 {
        while (len) {
                unsigned int buffered = write_buffer_len;
@@ -1087,7 +1412,7 @@ static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
        return 0;
 }
 
-static int write_index_ext_header(SHA_CTX *context, int fd,
+static int write_index_ext_header(git_SHA_CTX *context, int fd,
                                  unsigned int ext, unsigned int sz)
 {
        ext = htonl(ext);
@@ -1096,13 +1421,13 @@ static int write_index_ext_header(SHA_CTX *context, int fd,
                (ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
 }
 
-static int ce_flush(SHA_CTX *context, int fd)
+static int ce_flush(git_SHA_CTX *context, int fd)
 {
        unsigned int left = write_buffer_len;
 
        if (left) {
                write_buffer_len = 0;
-               SHA1_Update(context, write_buffer, left);
+               git_SHA1_Update(context, write_buffer, left);
        }
 
        /* Flush first if not enough space for SHA1 signature */
@@ -1113,7 +1438,7 @@ static int ce_flush(SHA_CTX *context, int fd)
        }
 
        /* Append the SHA1 signature at the end */
-       SHA1_Final(write_buffer + left, context);
+       git_SHA1_Final(write_buffer + left, context);
        left += 20;
        return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
 }
@@ -1125,6 +1450,11 @@ static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
         * falsely clean entry due to touch-update-touch race, so we leave
         * everything else as they are.  We are called for entries whose
         * ce_mtime match the index file mtime.
+        *
+        * Note that this actually does not do much for gitlinks, for
+        * which ce_match_stat_basic() always goes to the actual
+        * contents.  The caller checks with is_racy_timestamp() which
+        * always says "no" for gitlinks, so we are not called for them ;-)
         */
        struct stat st;
 
@@ -1162,15 +1492,16 @@ static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
        }
 }
 
-static int ce_write_entry(SHA_CTX *c, int fd, struct cache_entry *ce)
+static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce)
 {
        int size = ondisk_ce_size(ce);
        struct ondisk_cache_entry *ondisk = xcalloc(1, size);
+       char *name;
 
-       ondisk->ctime.sec = htonl(ce->ce_ctime);
-       ondisk->ctime.nsec = 0;
-       ondisk->mtime.sec = htonl(ce->ce_mtime);
-       ondisk->mtime.nsec = 0;
+       ondisk->ctime.sec = htonl(ce->ce_ctime.sec);
+       ondisk->mtime.sec = htonl(ce->ce_mtime.sec);
+       ondisk->ctime.nsec = htonl(ce->ce_ctime.nsec);
+       ondisk->mtime.nsec = htonl(ce->ce_mtime.nsec);
        ondisk->dev  = htonl(ce->ce_dev);
        ondisk->ino  = htonl(ce->ce_ino);
        ondisk->mode = htonl(ce->ce_mode);
@@ -1179,28 +1510,46 @@ static int ce_write_entry(SHA_CTX *c, int fd, struct cache_entry *ce)
        ondisk->size = htonl(ce->ce_size);
        hashcpy(ondisk->sha1, ce->sha1);
        ondisk->flags = htons(ce->ce_flags);
-       memcpy(ondisk->name, ce->name, ce_namelen(ce));
+       if (ce->ce_flags & CE_EXTENDED) {
+               struct ondisk_cache_entry_extended *ondisk2;
+               ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
+               ondisk2->flags2 = htons((ce->ce_flags & CE_EXTENDED_FLAGS) >> 16);
+               name = ondisk2->name;
+       }
+       else
+               name = ondisk->name;
+       memcpy(name, ce->name, ce_namelen(ce));
 
        return ce_write(c, fd, ondisk, size);
 }
 
 int write_index(struct index_state *istate, int newfd)
 {
-       SHA_CTX c;
+       git_SHA_CTX c;
        struct cache_header hdr;
-       int i, err, removed;
+       int i, err, removed, extended;
        struct cache_entry **cache = istate->cache;
        int entries = istate->cache_nr;
+       struct stat st;
 
-       for (i = removed = 0; i < entries; i++)
+       for (i = removed = extended = 0; i < entries; i++) {
                if (cache[i]->ce_flags & CE_REMOVE)
                        removed++;
 
+               /* reduce extended entries if possible */
+               cache[i]->ce_flags &= ~CE_EXTENDED;
+               if (cache[i]->ce_flags & CE_EXTENDED_FLAGS) {
+                       extended++;
+                       cache[i]->ce_flags |= CE_EXTENDED;
+               }
+       }
+
        hdr.hdr_signature = htonl(CACHE_SIGNATURE);
-       hdr.hdr_version = htonl(2);
+       /* for extended format, increase version so older git won't try to read it */
+       hdr.hdr_version = htonl(extended ? 3 : 2);
        hdr.hdr_entries = htonl(entries - removed);
 
-       SHA1_Init(&c);
+       git_SHA1_Init(&c);
        if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
                return -1;
 
@@ -1208,8 +1557,7 @@ int write_index(struct index_state *istate, int newfd)
                struct cache_entry *ce = cache[i];
                if (ce->ce_flags & CE_REMOVE)
                        continue;
-               if (istate->timestamp &&
-                   istate->timestamp <= ce->ce_mtime)
+               if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
                        ce_smudge_racily_clean_entry(ce);
                if (ce_write_entry(&c, newfd, ce) < 0)
                        return -1;
@@ -1217,9 +1565,8 @@ int write_index(struct index_state *istate, int newfd)
 
        /* Write extension data here */
        if (istate->cache_tree) {
-               struct strbuf sb;
+               struct strbuf sb = STRBUF_INIT;
 
-               strbuf_init(&sb, 0);
                cache_tree_write(&sb, istate->cache_tree);
                err = write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sb.len) < 0
                        || ce_write(&c, newfd, sb.buf, sb.len) < 0;
@@ -1227,5 +1574,149 @@ int write_index(struct index_state *istate, int newfd)
                if (err)
                        return -1;
        }
-       return ce_flush(&c, newfd);
+
+       if (ce_flush(&c, newfd) || fstat(newfd, &st))
+               return -1;
+       istate->timestamp.sec = (unsigned int)st.st_mtime;
+       istate->timestamp.nsec = ST_MTIME_NSEC(st);
+       return 0;
+}
+
+/*
+ * Read the index file that is potentially unmerged into given
+ * index_state, dropping any unmerged entries.  Returns true if
+ * the index is unmerged.  Callers who want to refuse to work
+ * from an unmerged state can call this and check its return value,
+ * instead of calling read_cache().
+ */
+int read_index_unmerged(struct index_state *istate)
+{
+       int i;
+       int unmerged = 0;
+
+       read_index(istate);
+       for (i = 0; i < istate->cache_nr; i++) {
+               struct cache_entry *ce = istate->cache[i];
+               struct cache_entry *new_ce;
+               int size, len;
+
+               if (!ce_stage(ce))
+                       continue;
+               unmerged = 1;
+               len = strlen(ce->name);
+               size = cache_entry_size(len);
+               new_ce = xcalloc(1, size);
+               hashcpy(new_ce->sha1, ce->sha1);
+               memcpy(new_ce->name, ce->name, len);
+               new_ce->ce_flags = create_ce_flags(len, 0);
+               new_ce->ce_mode = ce->ce_mode;
+               if (add_index_entry(istate, new_ce, 0))
+                       return error("%s: cannot drop to stage #0",
+                                    ce->name);
+               i = index_name_pos(istate, new_ce->name, len);
+       }
+       return unmerged;
+}
+
+struct update_callback_data
+{
+       int flags;
+       int add_errors;
+};
+
+static void update_callback(struct diff_queue_struct *q,
+                           struct diff_options *opt, void *cbdata)
+{
+       int i;
+       struct update_callback_data *data = cbdata;
+
+       for (i = 0; i < q->nr; i++) {
+               struct diff_filepair *p = q->queue[i];
+               const char *path = p->one->path;
+               switch (p->status) {
+               default:
+                       die("unexpected diff status %c", p->status);
+               case DIFF_STATUS_UNMERGED:
+                       /*
+                        * ADD_CACHE_IGNORE_REMOVAL is unset if "git
+                        * add -u" is calling us, In such a case, a
+                        * missing work tree file needs to be removed
+                        * if there is an unmerged entry at stage #2,
+                        * but such a diff record is followed by
+                        * another with DIFF_STATUS_DELETED (and if
+                        * there is no stage #2, we won't see DELETED
+                        * nor MODIFIED).  We can simply continue
+                        * either way.
+                        */
+                       if (!(data->flags & ADD_CACHE_IGNORE_REMOVAL))
+                               continue;
+                       /*
+                        * Otherwise, it is "git add path" is asking
+                        * to explicitly add it; we fall through.  A
+                        * missing work tree file is an error and is
+                        * caught by add_file_to_index() in such a
+                        * case.
+                        */
+               case DIFF_STATUS_MODIFIED:
+               case DIFF_STATUS_TYPE_CHANGED:
+                       if (add_file_to_index(&the_index, path, data->flags)) {
+                               if (!(data->flags & ADD_CACHE_IGNORE_ERRORS))
+                                       die("updating files failed");
+                               data->add_errors++;
+                       }
+                       break;
+               case DIFF_STATUS_DELETED:
+                       if (data->flags & ADD_CACHE_IGNORE_REMOVAL)
+                               break;
+                       if (!(data->flags & ADD_CACHE_PRETEND))
+                               remove_file_from_index(&the_index, path);
+                       if (data->flags & (ADD_CACHE_PRETEND|ADD_CACHE_VERBOSE))
+                               printf("remove '%s'\n", path);
+                       break;
+               }
+       }
+}
+
+int add_files_to_cache(const char *prefix, const char **pathspec, int flags)
+{
+       struct update_callback_data data;
+       struct rev_info rev;
+       init_revisions(&rev, prefix);
+       setup_revisions(0, NULL, &rev, NULL);
+       rev.prune_data = pathspec;
+       rev.diffopt.output_format = DIFF_FORMAT_CALLBACK;
+       rev.diffopt.format_callback = update_callback;
+       data.flags = flags;
+       data.add_errors = 0;
+       rev.diffopt.format_callback_data = &data;
+       run_diff_files(&rev, DIFF_RACY_IS_MODIFIED);
+       return !!data.add_errors;
+}
+
+/*
+ * Returns 1 if the path is an "other" path with respect to
+ * the index; that is, the path is not mentioned in the index at all,
+ * either as a file, a directory with some files in the index,
+ * or as an unmerged entry.
+ *
+ * We helpfully remove a trailing "/" from directories so that
+ * the output of read_directory can be used as-is.
+ */
+int index_name_is_other(const struct index_state *istate, const char *name,
+               int namelen)
+{
+       int pos;
+       if (namelen && name[namelen - 1] == '/')
+               namelen--;
+       pos = index_name_pos(istate, name, namelen);
+       if (0 <= pos)
+               return 0;       /* exact match */
+       pos = -pos - 1;
+       if (pos < istate->cache_nr) {
+               struct cache_entry *ce = istate->cache[pos];
+               if (ce_namelen(ce) == namelen &&
+                   !memcmp(ce->name, name, namelen))
+                       return 0; /* Yup, this one exists unmerged */
+       }
+       return 1;
 }