Merge branch 'nm/grep-object-sha1-lock'

* nm/grep-object-sha1-lock:
  grep: Fix race condition in delta_base_cache

Conflicts:
	builtin/grep.c

diff --cc builtin/grep.c
index 1c359c2671536287d97f2049b27a390d33b51e88,0000000000000000000000000000000000000000..a286692e467710d92346ab6900e98f1126cb967d
mode 100644,000000..100644
--- 1/builtin/grep.c
--- /dev/null
+++ b/builtin/grep.c
@@@ -1,1072 -1,0 +1,1075 @@@
 +/*
 + * Builtin "git grep"
 + *
 + * Copyright (c) 2006 Junio C Hamano
 + */
 +#include "cache.h"
 +#include "blob.h"
 +#include "tree.h"
 +#include "commit.h"
 +#include "tag.h"
 +#include "tree-walk.h"
 +#include "builtin.h"
 +#include "parse-options.h"
 +#include "string-list.h"
 +#include "run-command.h"
 +#include "userdiff.h"
 +#include "grep.h"
 +#include "quote.h"
 +#include "dir.h"
 +#include "thread-utils.h"
 +
 +static char const * const grep_usage[] = {
 +      "git grep [options] [-e] <pattern> [<rev>...] [[--] <path>...]",
 +      NULL
 +};
 +
 +static int use_threads = 1;
 +
 +#ifndef NO_PTHREADS
 +#define THREADS 8
 +static pthread_t threads[THREADS];
 +
 +static void *load_sha1(const unsigned char *sha1, unsigned long *size,
 +                     const char *name);
 +static void *load_file(const char *filename, size_t *sz);
 +
 +enum work_type {WORK_SHA1, WORK_FILE};
 +
 +/* We use one producer thread and THREADS consumer
 + * threads. The producer adds struct work_items to 'todo' and the
 + * consumers pick work items from the same array.
 + */
 +struct work_item {
 +      enum work_type type;
 +      char *name;
 +
 +      /* if type == WORK_SHA1, then 'identifier' is a SHA1,
 +       * otherwise type == WORK_FILE, and 'identifier' is a NUL
 +       * terminated filename.
 +       */
 +      void *identifier;
 +      char done;
 +      struct strbuf out;
 +};
 +
 +/* In the range [todo_done, todo_start) in 'todo' we have work_items
 + * that have been or are processed by a consumer thread. We haven't
 + * written the result for these to stdout yet.
 + *
 + * The work_items in [todo_start, todo_end) are waiting to be picked
 + * up by a consumer thread.
 + *
 + * The ranges are modulo TODO_SIZE.
 + */
 +#define TODO_SIZE 128
 +static struct work_item todo[TODO_SIZE];
 +static int todo_start;
 +static int todo_end;
 +static int todo_done;
 +
 +/* Has all work items been added? */
 +static int all_work_added;
 +
 +/* This lock protects all the variables above. */
 +static pthread_mutex_t grep_mutex;
 +
 +/* Used to serialize calls to read_sha1_file. */
 +static pthread_mutex_t read_sha1_mutex;
 +
 +#define grep_lock() pthread_mutex_lock(&grep_mutex)
 +#define grep_unlock() pthread_mutex_unlock(&grep_mutex)
 +#define read_sha1_lock() pthread_mutex_lock(&read_sha1_mutex)
 +#define read_sha1_unlock() pthread_mutex_unlock(&read_sha1_mutex)
 +
 +/* Signalled when a new work_item is added to todo. */
 +static pthread_cond_t cond_add;
 +
 +/* Signalled when the result from one work_item is written to
 + * stdout.
 + */
 +static pthread_cond_t cond_write;
 +
 +/* Signalled when we are finished with everything. */
 +static pthread_cond_t cond_result;
 +
 +static int skip_first_line;
 +
 +static void add_work(enum work_type type, char *name, void *id)
 +{
 +      grep_lock();
 +
 +      while ((todo_end+1) % ARRAY_SIZE(todo) == todo_done) {
 +              pthread_cond_wait(&cond_write, &grep_mutex);
 +      }
 +
 +      todo[todo_end].type = type;
 +      todo[todo_end].name = name;
 +      todo[todo_end].identifier = id;
 +      todo[todo_end].done = 0;
 +      strbuf_reset(&todo[todo_end].out);
 +      todo_end = (todo_end + 1) % ARRAY_SIZE(todo);
 +
 +      pthread_cond_signal(&cond_add);
 +      grep_unlock();
 +}
 +
 +static struct work_item *get_work(void)
 +{
 +      struct work_item *ret;
 +
 +      grep_lock();
 +      while (todo_start == todo_end && !all_work_added) {
 +              pthread_cond_wait(&cond_add, &grep_mutex);
 +      }
 +
 +      if (todo_start == todo_end && all_work_added) {
 +              ret = NULL;
 +      } else {
 +              ret = &todo[todo_start];
 +              todo_start = (todo_start + 1) % ARRAY_SIZE(todo);
 +      }
 +      grep_unlock();
 +      return ret;
 +}
 +
 +static void grep_sha1_async(struct grep_opt *opt, char *name,
 +                          const unsigned char *sha1)
 +{
 +      unsigned char *s;
 +      s = xmalloc(20);
 +      memcpy(s, sha1, 20);
 +      add_work(WORK_SHA1, name, s);
 +}
 +
 +static void grep_file_async(struct grep_opt *opt, char *name,
 +                          const char *filename)
 +{
 +      add_work(WORK_FILE, name, xstrdup(filename));
 +}
 +
 +static void work_done(struct work_item *w)
 +{
 +      int old_done;
 +
 +      grep_lock();
 +      w->done = 1;
 +      old_done = todo_done;
 +      for(; todo[todo_done].done && todo_done != todo_start;
 +          todo_done = (todo_done+1) % ARRAY_SIZE(todo)) {
 +              w = &todo[todo_done];
 +              if (w->out.len) {
 +                      const char *p = w->out.buf;
 +                      size_t len = w->out.len;
 +
 +                      /* Skip the leading hunk mark of the first file. */
 +                      if (skip_first_line) {
 +                              while (len) {
 +                                      len--;
 +                                      if (*p++ == '\n')
 +                                              break;
 +                              }
 +                              skip_first_line = 0;
 +                      }
 +
 +                      write_or_die(1, p, len);
 +              }
 +              free(w->name);
 +              free(w->identifier);
 +      }
 +
 +      if (old_done != todo_done)
 +              pthread_cond_signal(&cond_write);
 +
 +      if (all_work_added && todo_done == todo_end)
 +              pthread_cond_signal(&cond_result);
 +
 +      grep_unlock();
 +}
 +
 +static void *run(void *arg)
 +{
 +      int hit = 0;
 +      struct grep_opt *opt = arg;
 +
 +      while (1) {
 +              struct work_item *w = get_work();
 +              if (!w)
 +                      break;
 +
 +              opt->output_priv = w;
 +              if (w->type == WORK_SHA1) {
 +                      unsigned long sz;
 +                      void* data = load_sha1(w->identifier, &sz, w->name);
 +
 +                      if (data) {
 +                              hit |= grep_buffer(opt, w->name, data, sz);
 +                              free(data);
 +                      }
 +              } else if (w->type == WORK_FILE) {
 +                      size_t sz;
 +                      void* data = load_file(w->identifier, &sz);
 +                      if (data) {
 +                              hit |= grep_buffer(opt, w->name, data, sz);
 +                              free(data);
 +                      }
 +              } else {
 +                      assert(0);
 +              }
 +
 +              work_done(w);
 +      }
 +      free_grep_patterns(arg);
 +      free(arg);
 +
 +      return (void*) (intptr_t) hit;
 +}
 +
 +static void strbuf_out(struct grep_opt *opt, const void *buf, size_t size)
 +{
 +      struct work_item *w = opt->output_priv;
 +      strbuf_add(&w->out, buf, size);
 +}
 +
 +static void start_threads(struct grep_opt *opt)
 +{
 +      int i;
 +
 +      pthread_mutex_init(&grep_mutex, NULL);
 +      pthread_mutex_init(&read_sha1_mutex, NULL);
 +      pthread_cond_init(&cond_add, NULL);
 +      pthread_cond_init(&cond_write, NULL);
 +      pthread_cond_init(&cond_result, NULL);
 +
 +      for (i = 0; i < ARRAY_SIZE(todo); i++) {
 +              strbuf_init(&todo[i].out, 0);
 +      }
 +
 +      for (i = 0; i < ARRAY_SIZE(threads); i++) {
 +              int err;
 +              struct grep_opt *o = grep_opt_dup(opt);
 +              o->output = strbuf_out;
 +              compile_grep_patterns(o);
 +              err = pthread_create(&threads[i], NULL, run, o);
 +
 +              if (err)
 +                      die(_("grep: failed to create thread: %s"),
 +                          strerror(err));
 +      }
 +}
 +
 +static int wait_all(void)
 +{
 +      int hit = 0;
 +      int i;
 +
 +      grep_lock();
 +      all_work_added = 1;
 +
 +      /* Wait until all work is done. */
 +      while (todo_done != todo_end)
 +              pthread_cond_wait(&cond_result, &grep_mutex);
 +
 +      /* Wake up all the consumer threads so they can see that there
 +       * is no more work to do.
 +       */
 +      pthread_cond_broadcast(&cond_add);
 +      grep_unlock();
 +
 +      for (i = 0; i < ARRAY_SIZE(threads); i++) {
 +              void *h;
 +              pthread_join(threads[i], &h);
 +              hit |= (int) (intptr_t) h;
 +      }
 +
 +      pthread_mutex_destroy(&grep_mutex);
 +      pthread_mutex_destroy(&read_sha1_mutex);
 +      pthread_cond_destroy(&cond_add);
 +      pthread_cond_destroy(&cond_write);
 +      pthread_cond_destroy(&cond_result);
 +
 +      return hit;
 +}
 +#else /* !NO_PTHREADS */
 +#define read_sha1_lock()
 +#define read_sha1_unlock()
 +
 +static int wait_all(void)
 +{
 +      return 0;
 +}
 +#endif
 +
 +static int grep_config(const char *var, const char *value, void *cb)
 +{
 +      struct grep_opt *opt = cb;
 +      char *color = NULL;
 +
 +      switch (userdiff_config(var, value)) {
 +      case 0: break;
 +      case -1: return -1;
 +      default: return 0;
 +      }
 +
 +      if (!strcmp(var, "grep.extendedregexp")) {
 +              if (git_config_bool(var, value))
 +                      opt->regflags |= REG_EXTENDED;
 +              else
 +                      opt->regflags &= ~REG_EXTENDED;
 +              return 0;
 +      }
 +
 +      if (!strcmp(var, "grep.linenumber")) {
 +              opt->linenum = git_config_bool(var, value);
 +              return 0;
 +      }
 +
 +      if (!strcmp(var, "color.grep"))
 +              opt->color = git_config_colorbool(var, value);
 +      else if (!strcmp(var, "color.grep.context"))
 +              color = opt->color_context;
 +      else if (!strcmp(var, "color.grep.filename"))
 +              color = opt->color_filename;
 +      else if (!strcmp(var, "color.grep.function"))
 +              color = opt->color_function;
 +      else if (!strcmp(var, "color.grep.linenumber"))
 +              color = opt->color_lineno;
 +      else if (!strcmp(var, "color.grep.match"))
 +              color = opt->color_match;
 +      else if (!strcmp(var, "color.grep.selected"))
 +              color = opt->color_selected;
 +      else if (!strcmp(var, "color.grep.separator"))
 +              color = opt->color_sep;
 +      else
 +              return git_color_default_config(var, value, cb);
 +      if (color) {
 +              if (!value)
 +                      return config_error_nonbool(var);
 +              color_parse(value, var, color);
 +      }
 +      return 0;
 +}
 +
 +static void *lock_and_read_sha1_file(const unsigned char *sha1, enum object_type *type, unsigned long *size)
 +{
 +      void *data;
 +
 +      if (use_threads) {
 +              read_sha1_lock();
 +              data = read_sha1_file(sha1, type, size);
 +              read_sha1_unlock();
 +      } else {
 +              data = read_sha1_file(sha1, type, size);
 +      }
 +      return data;
 +}
 +
 +static void *load_sha1(const unsigned char *sha1, unsigned long *size,
 +                     const char *name)
 +{
 +      enum object_type type;
 +      void *data = lock_and_read_sha1_file(sha1, &type, size);
 +
 +      if (!data)
 +              error(_("'%s': unable to read %s"), name, sha1_to_hex(sha1));
 +
 +      return data;
 +}
 +
 +static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1,
 +                   const char *filename, int tree_name_len)
 +{
 +      struct strbuf pathbuf = STRBUF_INIT;
 +      char *name;
 +
 +      if (opt->relative && opt->prefix_length) {
 +              quote_path_relative(filename + tree_name_len, -1, &pathbuf,
 +                                  opt->prefix);
 +              strbuf_insert(&pathbuf, 0, filename, tree_name_len);
 +      } else {
 +              strbuf_addstr(&pathbuf, filename);
 +      }
 +
 +      name = strbuf_detach(&pathbuf, NULL);
 +
 +#ifndef NO_PTHREADS
 +      if (use_threads) {
 +              grep_sha1_async(opt, name, sha1);
 +              return 0;
 +      } else
 +#endif
 +      {
 +              int hit;
 +              unsigned long sz;
 +              void *data = load_sha1(sha1, &sz, name);
 +              if (!data)
 +                      hit = 0;
 +              else
 +                      hit = grep_buffer(opt, name, data, sz);
 +
 +              free(data);
 +              free(name);
 +              return hit;
 +      }
 +}
 +
 +static void *load_file(const char *filename, size_t *sz)
 +{
 +      struct stat st;
 +      char *data;
 +      int i;
 +
 +      if (lstat(filename, &st) < 0) {
 +      err_ret:
 +              if (errno != ENOENT)
 +                      error(_("'%s': %s"), filename, strerror(errno));
 +              return NULL;
 +      }
 +      if (!S_ISREG(st.st_mode))
 +              return NULL;
 +      *sz = xsize_t(st.st_size);
 +      i = open(filename, O_RDONLY);
 +      if (i < 0)
 +              goto err_ret;
 +      data = xmalloc(*sz + 1);
 +      if (st.st_size != read_in_full(i, data, *sz)) {
 +              error(_("'%s': short read %s"), filename, strerror(errno));
 +              close(i);
 +              free(data);
 +              return NULL;
 +      }
 +      close(i);
 +      data[*sz] = 0;
 +      return data;
 +}
 +
 +static int grep_file(struct grep_opt *opt, const char *filename)
 +{
 +      struct strbuf buf = STRBUF_INIT;
 +      char *name;
 +
 +      if (opt->relative && opt->prefix_length)
 +              quote_path_relative(filename, -1, &buf, opt->prefix);
 +      else
 +              strbuf_addstr(&buf, filename);
 +      name = strbuf_detach(&buf, NULL);
 +
 +#ifndef NO_PTHREADS
 +      if (use_threads) {
 +              grep_file_async(opt, name, filename);
 +              return 0;
 +      } else
 +#endif
 +      {
 +              int hit;
 +              size_t sz;
 +              void *data = load_file(filename, &sz);
 +              if (!data)
 +                      hit = 0;
 +              else
 +                      hit = grep_buffer(opt, name, data, sz);
 +
 +              free(data);
 +              free(name);
 +              return hit;
 +      }
 +}
 +
 +static void append_path(struct grep_opt *opt, const void *data, size_t len)
 +{
 +      struct string_list *path_list = opt->output_priv;
 +
 +      if (len == 1 && *(const char *)data == '\0')
 +              return;
 +      string_list_append(path_list, xstrndup(data, len));
 +}
 +
 +static void run_pager(struct grep_opt *opt, const char *prefix)
 +{
 +      struct string_list *path_list = opt->output_priv;
 +      const char **argv = xmalloc(sizeof(const char *) * (path_list->nr + 1));
 +      int i, status;
 +
 +      for (i = 0; i < path_list->nr; i++)
 +              argv[i] = path_list->items[i].string;
 +      argv[path_list->nr] = NULL;
 +
 +      if (prefix && chdir(prefix))
 +              die(_("Failed to chdir: %s"), prefix);
 +      status = run_command_v_opt(argv, RUN_USING_SHELL);
 +      if (status)
 +              exit(status);
 +      free(argv);
 +}
 +
 +static int grep_cache(struct grep_opt *opt, const struct pathspec *pathspec, int cached)
 +{
 +      int hit = 0;
 +      int nr;
 +      read_cache();
 +
 +      for (nr = 0; nr < active_nr; nr++) {
 +              struct cache_entry *ce = active_cache[nr];
 +              if (!S_ISREG(ce->ce_mode))
 +                      continue;
 +              if (!match_pathspec_depth(pathspec, ce->name, ce_namelen(ce), 0, NULL))
 +                      continue;
 +              /*
 +               * If CE_VALID is on, we assume worktree file and its cache entry
 +               * are identical, even if worktree file has been modified, so use
 +               * cache version instead
 +               */
 +              if (cached || (ce->ce_flags & CE_VALID) || ce_skip_worktree(ce)) {
 +                      if (ce_stage(ce))
 +                              continue;
 +                      hit |= grep_sha1(opt, ce->sha1, ce->name, 0);
 +              }
 +              else
 +                      hit |= grep_file(opt, ce->name);
 +              if (ce_stage(ce)) {
 +                      do {
 +                              nr++;
 +                      } while (nr < active_nr &&
 +                               !strcmp(ce->name, active_cache[nr]->name));
 +                      nr--; /* compensate for loop control */
 +              }
 +              if (hit && opt->status_only)
 +                      break;
 +      }
 +      return hit;
 +}
 +
 +static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 +                   struct tree_desc *tree, struct strbuf *base, int tn_len)
 +{
 +      int hit = 0, match = 0;
 +      struct name_entry entry;
 +      int old_baselen = base->len;
 +
 +      while (tree_entry(tree, &entry)) {
 +              int te_len = tree_entry_len(entry.path, entry.sha1);
 +
 +              if (match != 2) {
 +                      match = tree_entry_interesting(&entry, base, tn_len, pathspec);
 +                      if (match < 0)
 +                              break;
 +                      if (match == 0)
 +                              continue;
 +              }
 +
 +              strbuf_add(base, entry.path, te_len);
 +
 +              if (S_ISREG(entry.mode)) {
 +                      hit |= grep_sha1(opt, entry.sha1, base->buf, tn_len);
 +              }
 +              else if (S_ISDIR(entry.mode)) {
 +                      enum object_type type;
 +                      struct tree_desc sub;
 +                      void *data;
 +                      unsigned long size;
 +
 +                      data = lock_and_read_sha1_file(entry.sha1, &type, &size);
 +                      if (!data)
 +                              die(_("unable to read tree (%s)"),
 +                                  sha1_to_hex(entry.sha1));
 +
 +                      strbuf_addch(base, '/');
 +                      init_tree_desc(&sub, data, size);
 +                      hit |= grep_tree(opt, pathspec, &sub, base, tn_len);
 +                      free(data);
 +              }
 +              strbuf_setlen(base, old_baselen);
 +
 +              if (hit && opt->status_only)
 +                      break;
 +      }
 +      return hit;
 +}
 +
 +static int grep_object(struct grep_opt *opt, const struct pathspec *pathspec,
 +                     struct object *obj, const char *name)
 +{
 +      if (obj->type == OBJ_BLOB)
 +              return grep_sha1(opt, obj->sha1, name, 0);
 +      if (obj->type == OBJ_COMMIT || obj->type == OBJ_TREE) {
 +              struct tree_desc tree;
 +              void *data;
 +              unsigned long size;
 +              struct strbuf base;
 +              int hit, len;
 +
++              read_sha1_lock();
 +              data = read_object_with_reference(obj->sha1, tree_type,
 +                                                &size, NULL);
++              read_sha1_unlock();
++
 +              if (!data)
 +                      die(_("unable to read tree (%s)"), sha1_to_hex(obj->sha1));
 +
 +              len = name ? strlen(name) : 0;
 +              strbuf_init(&base, PATH_MAX + len + 1);
 +              if (len) {
 +                      strbuf_add(&base, name, len);
 +                      strbuf_addch(&base, ':');
 +              }
 +              init_tree_desc(&tree, data, size);
 +              hit = grep_tree(opt, pathspec, &tree, &base, base.len);
 +              strbuf_release(&base);
 +              free(data);
 +              return hit;
 +      }
 +      die(_("unable to grep from object of type %s"), typename(obj->type));
 +}
 +
 +static int grep_objects(struct grep_opt *opt, const struct pathspec *pathspec,
 +                      const struct object_array *list)
 +{
 +      unsigned int i;
 +      int hit = 0;
 +      const unsigned int nr = list->nr;
 +
 +      for (i = 0; i < nr; i++) {
 +              struct object *real_obj;
 +              real_obj = deref_tag(list->objects[i].item, NULL, 0);
 +              if (grep_object(opt, pathspec, real_obj, list->objects[i].name)) {
 +                      hit = 1;
 +                      if (opt->status_only)
 +                              break;
 +              }
 +      }
 +      return hit;
 +}
 +
 +static int grep_directory(struct grep_opt *opt, const struct pathspec *pathspec)
 +{
 +      struct dir_struct dir;
 +      int i, hit = 0;
 +
 +      memset(&dir, 0, sizeof(dir));
 +      setup_standard_excludes(&dir);
 +
 +      fill_directory(&dir, pathspec->raw);
 +      for (i = 0; i < dir.nr; i++) {
 +              const char *name = dir.entries[i]->name;
 +              int namelen = strlen(name);
 +              if (!match_pathspec_depth(pathspec, name, namelen, 0, NULL))
 +                      continue;
 +              hit |= grep_file(opt, dir.entries[i]->name);
 +              if (hit && opt->status_only)
 +                      break;
 +      }
 +      return hit;
 +}
 +
 +static int context_callback(const struct option *opt, const char *arg,
 +                          int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      int value;
 +      const char *endp;
 +
 +      if (unset) {
 +              grep_opt->pre_context = grep_opt->post_context = 0;
 +              return 0;
 +      }
 +      value = strtol(arg, (char **)&endp, 10);
 +      if (*endp) {
 +              return error(_("switch `%c' expects a numerical value"),
 +                           opt->short_name);
 +      }
 +      grep_opt->pre_context = grep_opt->post_context = value;
 +      return 0;
 +}
 +
 +static int file_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      int from_stdin = !strcmp(arg, "-");
 +      FILE *patterns;
 +      int lno = 0;
 +      struct strbuf sb = STRBUF_INIT;
 +
 +      patterns = from_stdin ? stdin : fopen(arg, "r");
 +      if (!patterns)
 +              die_errno(_("cannot open '%s'"), arg);
 +      while (strbuf_getline(&sb, patterns, '\n') == 0) {
 +              char *s;
 +              size_t len;
 +
 +              /* ignore empty line like grep does */
 +              if (sb.len == 0)
 +                      continue;
 +
 +              s = strbuf_detach(&sb, &len);
 +              append_grep_pat(grep_opt, s, len, arg, ++lno, GREP_PATTERN);
 +      }
 +      if (!from_stdin)
 +              fclose(patterns);
 +      strbuf_release(&sb);
 +      return 0;
 +}
 +
 +static int not_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      append_grep_pattern(grep_opt, "--not", "command line", 0, GREP_NOT);
 +      return 0;
 +}
 +
 +static int and_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      append_grep_pattern(grep_opt, "--and", "command line", 0, GREP_AND);
 +      return 0;
 +}
 +
 +static int open_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      append_grep_pattern(grep_opt, "(", "command line", 0, GREP_OPEN_PAREN);
 +      return 0;
 +}
 +
 +static int close_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      append_grep_pattern(grep_opt, ")", "command line", 0, GREP_CLOSE_PAREN);
 +      return 0;
 +}
 +
 +static int pattern_callback(const struct option *opt, const char *arg,
 +                          int unset)
 +{
 +      struct grep_opt *grep_opt = opt->value;
 +      append_grep_pattern(grep_opt, arg, "-e option", 0, GREP_PATTERN);
 +      return 0;
 +}
 +
 +static int help_callback(const struct option *opt, const char *arg, int unset)
 +{
 +      return -1;
 +}
 +
 +int cmd_grep(int argc, const char **argv, const char *prefix)
 +{
 +      int hit = 0;
 +      int cached = 0;
 +      int seen_dashdash = 0;
 +      int external_grep_allowed__ignored;
 +      const char *show_in_pager = NULL, *default_pager = "dummy";
 +      struct grep_opt opt;
 +      struct object_array list = OBJECT_ARRAY_INIT;
 +      const char **paths = NULL;
 +      struct pathspec pathspec;
 +      struct string_list path_list = STRING_LIST_INIT_NODUP;
 +      int i;
 +      int dummy;
 +      int use_index = 1;
 +      enum {
 +              pattern_type_unspecified = 0,
 +              pattern_type_bre,
 +              pattern_type_ere,
 +              pattern_type_fixed,
 +              pattern_type_pcre,
 +      };
 +      int pattern_type = pattern_type_unspecified;
 +
 +      struct option options[] = {
 +              OPT_BOOLEAN(0, "cached", &cached,
 +                      "search in index instead of in the work tree"),
 +              OPT_BOOLEAN(0, "index", &use_index,
 +                      "--no-index finds in contents not managed by git"),
 +              OPT_GROUP(""),
 +              OPT_BOOLEAN('v', "invert-match", &opt.invert,
 +                      "show non-matching lines"),
 +              OPT_BOOLEAN('i', "ignore-case", &opt.ignore_case,
 +                      "case insensitive matching"),
 +              OPT_BOOLEAN('w', "word-regexp", &opt.word_regexp,
 +                      "match patterns only at word boundaries"),
 +              OPT_SET_INT('a', "text", &opt.binary,
 +                      "process binary files as text", GREP_BINARY_TEXT),
 +              OPT_SET_INT('I', NULL, &opt.binary,
 +                      "don't match patterns in binary files",
 +                      GREP_BINARY_NOMATCH),
 +              { OPTION_INTEGER, 0, "max-depth", &opt.max_depth, "depth",
 +                      "descend at most <depth> levels", PARSE_OPT_NONEG,
 +                      NULL, 1 },
 +              OPT_GROUP(""),
 +              OPT_SET_INT('E', "extended-regexp", &pattern_type,
 +                          "use extended POSIX regular expressions",
 +                          pattern_type_ere),
 +              OPT_SET_INT('G', "basic-regexp", &pattern_type,
 +                          "use basic POSIX regular expressions (default)",
 +                          pattern_type_bre),
 +              OPT_SET_INT('F', "fixed-strings", &pattern_type,
 +                          "interpret patterns as fixed strings",
 +                          pattern_type_fixed),
 +              OPT_SET_INT('P', "perl-regexp", &pattern_type,
 +                          "use Perl-compatible regular expressions",
 +                          pattern_type_pcre),
 +              OPT_GROUP(""),
 +              OPT_BOOLEAN('n', "line-number", &opt.linenum, "show line numbers"),
 +              OPT_NEGBIT('h', NULL, &opt.pathname, "don't show filenames", 1),
 +              OPT_BIT('H', NULL, &opt.pathname, "show filenames", 1),
 +              OPT_NEGBIT(0, "full-name", &opt.relative,
 +                      "show filenames relative to top directory", 1),
 +              OPT_BOOLEAN('l', "files-with-matches", &opt.name_only,
 +                      "show only filenames instead of matching lines"),
 +              OPT_BOOLEAN(0, "name-only", &opt.name_only,
 +                      "synonym for --files-with-matches"),
 +              OPT_BOOLEAN('L', "files-without-match",
 +                      &opt.unmatch_name_only,
 +                      "show only the names of files without match"),
 +              OPT_BOOLEAN('z', "null", &opt.null_following_name,
 +                      "print NUL after filenames"),
 +              OPT_BOOLEAN('c', "count", &opt.count,
 +                      "show the number of matches instead of matching lines"),
 +              OPT__COLOR(&opt.color, "highlight matches"),
 +              OPT_BOOLEAN(0, "break", &opt.file_break,
 +                      "print empty line between matches from different files"),
 +              OPT_BOOLEAN(0, "heading", &opt.heading,
 +                      "show filename only once above matches from same file"),
 +              OPT_GROUP(""),
 +              OPT_CALLBACK('C', "context", &opt, "n",
 +                      "show <n> context lines before and after matches",
 +                      context_callback),
 +              OPT_INTEGER('B', "before-context", &opt.pre_context,
 +                      "show <n> context lines before matches"),
 +              OPT_INTEGER('A', "after-context", &opt.post_context,
 +                      "show <n> context lines after matches"),
 +              OPT_NUMBER_CALLBACK(&opt, "shortcut for -C NUM",
 +                      context_callback),
 +              OPT_BOOLEAN('p', "show-function", &opt.funcname,
 +                      "show a line with the function name before matches"),
 +              OPT_BOOLEAN('W', "function-context", &opt.funcbody,
 +                      "show the surrounding function"),
 +              OPT_GROUP(""),
 +              OPT_CALLBACK('f', NULL, &opt, "file",
 +                      "read patterns from file", file_callback),
 +              { OPTION_CALLBACK, 'e', NULL, &opt, "pattern",
 +                      "match <pattern>", PARSE_OPT_NONEG, pattern_callback },
 +              { OPTION_CALLBACK, 0, "and", &opt, NULL,
 +                "combine patterns specified with -e",
 +                PARSE_OPT_NOARG | PARSE_OPT_NONEG, and_callback },
 +              OPT_BOOLEAN(0, "or", &dummy, ""),
 +              { OPTION_CALLBACK, 0, "not", &opt, NULL, "",
 +                PARSE_OPT_NOARG | PARSE_OPT_NONEG, not_callback },
 +              { OPTION_CALLBACK, '(', NULL, &opt, NULL, "",
 +                PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_NODASH,
 +                open_callback },
 +              { OPTION_CALLBACK, ')', NULL, &opt, NULL, "",
 +                PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_NODASH,
 +                close_callback },
 +              OPT__QUIET(&opt.status_only,
 +                         "indicate hit with exit status without output"),
 +              OPT_BOOLEAN(0, "all-match", &opt.all_match,
 +                      "show only matches from files that match all patterns"),
 +              OPT_GROUP(""),
 +              { OPTION_STRING, 'O', "open-files-in-pager", &show_in_pager,
 +                      "pager", "show matching files in the pager",
 +                      PARSE_OPT_OPTARG, NULL, (intptr_t)default_pager },
 +              OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed__ignored,
 +                          "allow calling of grep(1) (ignored by this build)"),
 +              { OPTION_CALLBACK, 0, "help-all", &options, NULL, "show usage",
 +                PARSE_OPT_HIDDEN | PARSE_OPT_NOARG, help_callback },
 +              OPT_END()
 +      };
 +
 +      /*
 +       * 'git grep -h', unlike 'git grep -h <pattern>', is a request
 +       * to show usage information and exit.
 +       */
 +      if (argc == 2 && !strcmp(argv[1], "-h"))
 +              usage_with_options(grep_usage, options);
 +
 +      memset(&opt, 0, sizeof(opt));
 +      opt.prefix = prefix;
 +      opt.prefix_length = (prefix && *prefix) ? strlen(prefix) : 0;
 +      opt.relative = 1;
 +      opt.pathname = 1;
 +      opt.pattern_tail = &opt.pattern_list;
 +      opt.header_tail = &opt.header_list;
 +      opt.regflags = REG_NEWLINE;
 +      opt.max_depth = -1;
 +
 +      strcpy(opt.color_context, "");
 +      strcpy(opt.color_filename, "");
 +      strcpy(opt.color_function, "");
 +      strcpy(opt.color_lineno, "");
 +      strcpy(opt.color_match, GIT_COLOR_BOLD_RED);
 +      strcpy(opt.color_selected, "");
 +      strcpy(opt.color_sep, GIT_COLOR_CYAN);
 +      opt.color = -1;
 +      git_config(grep_config, &opt);
 +
 +      /*
 +       * If there is no -- then the paths must exist in the working
 +       * tree.  If there is no explicit pattern specified with -e or
 +       * -f, we take the first unrecognized non option to be the
 +       * pattern, but then what follows it must be zero or more
 +       * valid refs up to the -- (if exists), and then existing
 +       * paths.  If there is an explicit pattern, then the first
 +       * unrecognized non option is the beginning of the refs list
 +       * that continues up to the -- (if exists), and then paths.
 +       */
 +      argc = parse_options(argc, argv, prefix, options, grep_usage,
 +                           PARSE_OPT_KEEP_DASHDASH |
 +                           PARSE_OPT_STOP_AT_NON_OPTION |
 +                           PARSE_OPT_NO_INTERNAL_HELP);
 +      switch (pattern_type) {
 +      case pattern_type_fixed:
 +              opt.fixed = 1;
 +              opt.pcre = 0;
 +              break;
 +      case pattern_type_bre:
 +              opt.fixed = 0;
 +              opt.pcre = 0;
 +              opt.regflags &= ~REG_EXTENDED;
 +              break;
 +      case pattern_type_ere:
 +              opt.fixed = 0;
 +              opt.pcre = 0;
 +              opt.regflags |= REG_EXTENDED;
 +              break;
 +      case pattern_type_pcre:
 +              opt.fixed = 0;
 +              opt.pcre = 1;
 +              break;
 +      default:
 +              break; /* nothing */
 +      }
 +
 +      if (use_index && !startup_info->have_repository)
 +              /* die the same way as if we did it at the beginning */
 +              setup_git_directory();
 +
 +      /*
 +       * skip a -- separator; we know it cannot be
 +       * separating revisions from pathnames if
 +       * we haven't even had any patterns yet
 +       */
 +      if (argc > 0 && !opt.pattern_list && !strcmp(argv[0], "--")) {
 +              argv++;
 +              argc--;
 +      }
 +
 +      /* First unrecognized non-option token */
 +      if (argc > 0 && !opt.pattern_list) {
 +              append_grep_pattern(&opt, argv[0], "command line", 0,
 +                                  GREP_PATTERN);
 +              argv++;
 +              argc--;
 +      }
 +
 +      if (show_in_pager == default_pager)
 +              show_in_pager = git_pager(1);
 +      if (show_in_pager) {
 +              opt.color = 0;
 +              opt.name_only = 1;
 +              opt.null_following_name = 1;
 +              opt.output_priv = &path_list;
 +              opt.output = append_path;
 +              string_list_append(&path_list, show_in_pager);
 +              use_threads = 0;
 +      }
 +
 +      if (!opt.pattern_list)
 +              die(_("no pattern given."));
 +      if (!opt.fixed && opt.ignore_case)
 +              opt.regflags |= REG_ICASE;
 +
 +#ifndef NO_PTHREADS
 +      if (online_cpus() == 1 || !grep_threads_ok(&opt))
 +              use_threads = 0;
 +
 +      if (use_threads) {
 +              if (opt.pre_context || opt.post_context || opt.file_break ||
 +                  opt.funcbody)
 +                      skip_first_line = 1;
 +              start_threads(&opt);
 +      }
 +#else
 +      use_threads = 0;
 +#endif
 +
 +      compile_grep_patterns(&opt);
 +
 +      /* Check revs and then paths */
 +      for (i = 0; i < argc; i++) {
 +              const char *arg = argv[i];
 +              unsigned char sha1[20];
 +              /* Is it a rev? */
 +              if (!get_sha1(arg, sha1)) {
 +                      struct object *object = parse_object(sha1);
 +                      if (!object)
 +                              die(_("bad object %s"), arg);
 +                      add_object_array(object, arg, &list);
 +                      continue;
 +              }
 +              if (!strcmp(arg, "--")) {
 +                      i++;
 +                      seen_dashdash = 1;
 +              }
 +              break;
 +      }
 +
 +      /* The rest are paths */
 +      if (!seen_dashdash) {
 +              int j;
 +              for (j = i; j < argc; j++)
 +                      verify_filename(prefix, argv[j]);
 +      }
 +
 +      paths = get_pathspec(prefix, argv + i);
 +      init_pathspec(&pathspec, paths);
 +      pathspec.max_depth = opt.max_depth;
 +      pathspec.recursive = 1;
 +
 +      if (show_in_pager && (cached || list.nr))
 +              die(_("--open-files-in-pager only works on the worktree"));
 +
 +      if (show_in_pager && opt.pattern_list && !opt.pattern_list->next) {
 +              const char *pager = path_list.items[0].string;
 +              int len = strlen(pager);
 +
 +              if (len > 4 && is_dir_sep(pager[len - 5]))
 +                      pager += len - 4;
 +
 +              if (!strcmp("less", pager) || !strcmp("vi", pager)) {
 +                      struct strbuf buf = STRBUF_INIT;
 +                      strbuf_addf(&buf, "+/%s%s",
 +                                      strcmp("less", pager) ? "" : "*",
 +                                      opt.pattern_list->pattern);
 +                      string_list_append(&path_list, buf.buf);
 +                      strbuf_detach(&buf, NULL);
 +              }
 +      }
 +
 +      if (!show_in_pager)
 +              setup_pager();
 +
 +
 +      if (!use_index) {
 +              if (cached)
 +                      die(_("--cached cannot be used with --no-index."));
 +              if (list.nr)
 +                      die(_("--no-index cannot be used with revs."));
 +              hit = grep_directory(&opt, &pathspec);
 +      } else if (!list.nr) {
 +              if (!cached)
 +                      setup_work_tree();
 +
 +              hit = grep_cache(&opt, &pathspec, cached);
 +      } else {
 +              if (cached)
 +                      die(_("both --cached and trees are given."));
 +              hit = grep_objects(&opt, &pathspec, &list);
 +      }
 +
 +      if (use_threads)
 +              hit |= wait_all();
 +      if (hit && show_in_pager)
 +              run_pager(&opt, prefix);
 +      free_grep_patterns(&opt);
 +      return !hit;
 +}