dir.c: optionally compute sha-1 of a .gitignore file

This is not used anywhere yet. But the goal is to compare quickly if a
.gitignore file has changed when we have the SHA-1 of both old (cached
somewhere) and new (from index or a tree) versions.

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/dir.c b/dir.c
index 3f7a0256b61552c6c3f80f710bd042b697d79da9..f23bd7bebcfcb3b108c507592d2f4a82339961fe 100644 (file)
--- a/dir.c
+++ b/dir.c
@@ -466,7 +466,8 @@ void add_exclude(const char *string, const char *base,
        x->el = el;
 }
 
-static void *read_skip_worktree_file_from_index(const char *path, size_t *size)
+static void *read_skip_worktree_file_from_index(const char *path, size_t *size,
+                                               struct sha1_stat *sha1_stat)
 {
        int pos, len;
        unsigned long sz;
@@ -485,6 +486,10 @@ static void *read_skip_worktree_file_from_index(const char *path, size_t *size)
                return NULL;
        }
        *size = xsize_t(sz);
+       if (sha1_stat) {
+               memset(&sha1_stat->stat, 0, sizeof(sha1_stat->stat));
+               hashcpy(sha1_stat->sha1, active_cache[pos]->sha1);
+       }
        return data;
 }
 
@@ -529,11 +534,18 @@ static void trim_trailing_spaces(char *buf)
                *last_space = '\0';
 }
 
-int add_excludes_from_file_to_list(const char *fname,
-                                  const char *base,
-                                  int baselen,
-                                  struct exclude_list *el,
-                                  int check_index)
+/*
+ * Given a file with name "fname", read it (either from disk, or from
+ * the index if "check_index" is non-zero), parse it and store the
+ * exclude rules in "el".
+ *
+ * If "ss" is not NULL, compute SHA-1 of the exclude file and fill
+ * stat data from disk (only valid if add_excludes returns zero). If
+ * ss_valid is non-zero, "ss" must contain good value as input.
+ */
+static int add_excludes(const char *fname, const char *base, int baselen,
+                       struct exclude_list *el, int check_index,
+                       struct sha1_stat *sha1_stat)
 {
        struct stat st;
        int fd, i, lineno = 1;
@@ -547,7 +559,7 @@ int add_excludes_from_file_to_list(const char *fname,
                if (0 <= fd)
                        close(fd);
                if (!check_index ||
-                   (buf = read_skip_worktree_file_from_index(fname, &size)) == NULL)
+                   (buf = read_skip_worktree_file_from_index(fname, &size, sha1_stat)) == NULL)
                        return -1;
                if (size == 0) {
                        free(buf);
@@ -560,6 +572,11 @@ int add_excludes_from_file_to_list(const char *fname,
        } else {
                size = xsize_t(st.st_size);
                if (size == 0) {
+                       if (sha1_stat) {
+                               fill_stat_data(&sha1_stat->stat, &st);
+                               hashcpy(sha1_stat->sha1, EMPTY_BLOB_SHA1_BIN);
+                               sha1_stat->valid = 1;
+                       }
                        close(fd);
                        return 0;
                }
@@ -571,6 +588,22 @@ int add_excludes_from_file_to_list(const char *fname,
                }
                buf[size++] = '\n';
                close(fd);
+               if (sha1_stat) {
+                       int pos;
+                       if (sha1_stat->valid &&
+                           !match_stat_data(&sha1_stat->stat, &st))
+                               ; /* no content change, ss->sha1 still good */
+                       else if (check_index &&
+                                (pos = cache_name_pos(fname, strlen(fname))) >= 0 &&
+                                !ce_stage(active_cache[pos]) &&
+                                ce_uptodate(active_cache[pos]) &&
+                                !would_convert_to_git(fname))
+                               hashcpy(sha1_stat->sha1, active_cache[pos]->sha1);
+                       else
+                               hash_sha1_file(buf, size, "blob", sha1_stat->sha1);
+                       fill_stat_data(&sha1_stat->stat, &st);
+                       sha1_stat->valid = 1;
+               }
        }
 
        el->filebuf = buf;
@@ -589,6 +622,13 @@ int add_excludes_from_file_to_list(const char *fname,
        return 0;
 }
 
+int add_excludes_from_file_to_list(const char *fname, const char *base,
+                                  int baselen, struct exclude_list *el,
+                                  int check_index)
+{
+       return add_excludes(fname, base, baselen, el, check_index, NULL);
+}
+
 struct exclude_list *add_exclude_list(struct dir_struct *dir,
                                      int group_type, const char *src)
 {

diff --git a/dir.h b/dir.h
index 6c45e9d4b9a9055539e443ba30166b0b5384bac5..cdca71b3b0b826ccb9c3633657bdde7febc91538 100644 (file)
--- a/dir.h
+++ b/dir.h
@@ -73,6 +73,12 @@ struct exclude_list_group {
        struct exclude_list *el;
 };
 
+struct sha1_stat {
+       struct stat_data stat;
+       unsigned char sha1[20];
+       int valid;
+};
+
 struct dir_struct {
        int nr, alloc;
        int ignored_nr, ignored_alloc;