tag: factor out get_tagged_oid()
[gitweb.git] / server-info.c
index 92187c70db650ee0e4d5ea4bf3435e84a51c44b2..4d8199b1d916f70f136b767132916fdebb73318e 100644 (file)
 #include "tag.h"
 #include "packfile.h"
 #include "object-store.h"
+#include "strbuf.h"
+
+struct update_info_ctx {
+       FILE *cur_fp;
+       FILE *old_fp; /* becomes NULL if it differs from cur_fp */
+       struct strbuf cur_sb;
+       struct strbuf old_sb;
+};
+
+static void uic_mark_stale(struct update_info_ctx *uic)
+{
+       fclose(uic->old_fp);
+       uic->old_fp = NULL;
+}
+
+static int uic_is_stale(const struct update_info_ctx *uic)
+{
+       return uic->old_fp == NULL;
+}
+
+static int uic_printf(struct update_info_ctx *uic, const char *fmt, ...)
+{
+       va_list ap;
+       int ret = -1;
+
+       va_start(ap, fmt);
+
+       if (uic_is_stale(uic)) {
+               ret = vfprintf(uic->cur_fp, fmt, ap);
+       } else {
+               ssize_t r;
+               struct strbuf *cur = &uic->cur_sb;
+               struct strbuf *old = &uic->old_sb;
+
+               strbuf_reset(cur);
+               strbuf_vinsertf(cur, 0, fmt, ap);
+
+               strbuf_reset(old);
+               strbuf_grow(old, cur->len);
+               r = fread(old->buf, 1, cur->len, uic->old_fp);
+               if (r != cur->len || memcmp(old->buf, cur->buf, r))
+                       uic_mark_stale(uic);
+
+               if (fwrite(cur->buf, 1, cur->len, uic->cur_fp) == cur->len)
+                       ret = 0;
+       }
+
+       va_end(ap);
+
+       return ret;
+}
 
 /*
  * Create the file "path" by writing to a temporary file and renaming
  * it into place. The contents of the file come from "generate", which
  * should return non-zero if it encounters an error.
  */
-static int update_info_file(char *path, int (*generate)(FILE *))
+static int update_info_file(char *path,
+                       int (*generate)(struct update_info_ctx *),
+                       int force)
 {
        char *tmp = mkpathdup("%s_XXXXXX", path);
        int ret = -1;
        int fd = -1;
-       FILE *fp = NULL, *to_close;
+       FILE *to_close;
+       struct update_info_ctx uic = {
+               .cur_fp = NULL,
+               .old_fp = NULL,
+               .cur_sb = STRBUF_INIT,
+               .old_sb = STRBUF_INIT
+       };
 
        safe_create_leading_directories(path);
        fd = git_mkstemp_mode(tmp, 0666);
        if (fd < 0)
                goto out;
-       to_close = fp = fdopen(fd, "w");
-       if (!fp)
+       to_close = uic.cur_fp = fdopen(fd, "w");
+       if (!uic.cur_fp)
                goto out;
        fd = -1;
-       ret = generate(fp);
+
+       /* no problem on ENOENT and old_fp == NULL, it's stale, now */
+       if (!force)
+               uic.old_fp = fopen_or_warn(path, "r");
+
+       /*
+        * uic_printf will compare incremental comparison aginst old_fp
+        * and mark uic as stale if needed
+        */
+       ret = generate(&uic);
        if (ret)
                goto out;
-       fp = NULL;
+
+       /* new file may be shorter than the old one, check here */
+       if (!uic_is_stale(&uic)) {
+               struct stat st;
+               long new_len = ftell(uic.cur_fp);
+               int old_fd = fileno(uic.old_fp);
+
+               if (new_len < 0) {
+                       ret = -1;
+                       goto out;
+               }
+               if (fstat(old_fd, &st) || (st.st_size != (size_t)new_len))
+                       uic_mark_stale(&uic);
+       }
+
+       uic.cur_fp = NULL;
        if (fclose(to_close))
                goto out;
-       if (adjust_shared_perm(tmp) < 0)
-               goto out;
-       if (rename(tmp, path) < 0)
-               goto out;
+
+       if (uic_is_stale(&uic)) {
+               if (adjust_shared_perm(tmp) < 0)
+                       goto out;
+               if (rename(tmp, path) < 0)
+                       goto out;
+       } else {
+               unlink(tmp);
+       }
        ret = 0;
 
 out:
        if (ret) {
                error_errno("unable to update %s", path);
-               if (fp)
-                       fclose(fp);
+               if (uic.cur_fp)
+                       fclose(uic.cur_fp);
                else if (fd >= 0)
                        close(fd);
                unlink(tmp);
        }
        free(tmp);
+       if (uic.old_fp)
+               fclose(uic.old_fp);
+       strbuf_release(&uic.old_sb);
+       strbuf_release(&uic.cur_sb);
        return ret;
 }
 
 static int add_info_ref(const char *path, const struct object_id *oid,
                        int flag, void *cb_data)
 {
-       FILE *fp = cb_data;
+       struct update_info_ctx *uic = cb_data;
        struct object *o = parse_object(the_repository, oid);
        if (!o)
                return -1;
 
-       if (fprintf(fp, "%s     %s\n", oid_to_hex(oid), path) < 0)
+       if (uic_printf(uic, "%s %s\n", oid_to_hex(oid), path) < 0)
                return -1;
 
        if (o->type == OBJ_TAG) {
                o = deref_tag(the_repository, o, path, 0);
                if (o)
-                       if (fprintf(fp, "%s     %s^{}\n",
+                       if (uic_printf(uic, "%s %s^{}\n",
                                oid_to_hex(&o->oid), path) < 0)
                                return -1;
        }
        return 0;
 }
 
-static int generate_info_refs(FILE *fp)
+static int generate_info_refs(struct update_info_ctx *uic)
 {
-       return for_each_ref(add_info_ref, fp);
+       return for_each_ref(add_info_ref, uic);
 }
 
-static int update_info_refs(void)
+static int update_info_refs(int force)
 {
        char *path = git_pathdup("info/refs");
-       int ret = update_info_file(path, generate_info_refs);
+       int ret = update_info_file(path, generate_info_refs, force);
        free(path);
        return ret;
 }
@@ -232,14 +324,14 @@ static void free_pack_info(void)
        free(info);
 }
 
-static int write_pack_info_file(FILE *fp)
+static int write_pack_info_file(struct update_info_ctx *uic)
 {
        int i;
        for (i = 0; i < num_pack; i++) {
-               if (fprintf(fp, "P %s\n", pack_basename(info[i]->p)) < 0)
+               if (uic_printf(uic, "P %s\n", pack_basename(info[i]->p)) < 0)
                        return -1;
        }
-       if (fputc('\n', fp) == EOF)
+       if (uic_printf(uic, "\n") < 0)
                return -1;
        return 0;
 }
@@ -250,7 +342,7 @@ static int update_info_packs(int force)
        int ret;
 
        init_pack_info(infofile, force);
-       ret = update_info_file(infofile, write_pack_info_file);
+       ret = update_info_file(infofile, write_pack_info_file, force);
        free_pack_info();
        free(infofile);
        return ret;
@@ -265,7 +357,7 @@ int update_server_info(int force)
         */
        int errs = 0;
 
-       errs = errs | update_info_refs();
+       errs = errs | update_info_refs(force);
        errs = errs | update_info_packs(force);
 
        /* remove leftover rev-cache file if there is any */