docs: explain diff.*.binary option
[gitweb.git] / builtin-grep.c
index f477659100fdc63bff5938b4c96f28eaefc07460..371db0aa9e6572c5b25ea679a510bc8784a25759 100644 (file)
 #include "parse-options.h"
 #include "userdiff.h"
 #include "grep.h"
+#include "quote.h"
 
-#ifndef NO_EXTERNAL_GREP
-#ifdef __unix__
-#define NO_EXTERNAL_GREP 0
-#else
-#define NO_EXTERNAL_GREP 1
-#endif
+#ifndef NO_PTHREADS
+#include "thread-utils.h"
+#include <pthread.h>
 #endif
 
 static char const * const grep_usage[] = {
@@ -27,6 +25,266 @@ static char const * const grep_usage[] = {
        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 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];
+               write_or_die(1, w->out.buf, w->out.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;
@@ -41,8 +299,6 @@ static int grep_config(const char *var, const char *value, void *cb)
                opt->color = git_config_colorbool(var, value, -1);
                return 0;
        }
-       if (!strcmp(var, "color.grep.external"))
-               return git_config_string(&(opt->color_external), var, value);
        if (!strcmp(var, "color.grep.match")) {
                if (!value)
                        return config_error_nonbool(var);
@@ -52,26 +308,58 @@ static int grep_config(const char *var, const char *value, void *cb)
        return git_color_default_config(var, value, cb);
 }
 
+/*
+ * Return non-zero if max_depth is negative or path has no more then max_depth
+ * slashes.
+ */
+static int accept_subdir(const char *path, int max_depth)
+{
+       if (max_depth < 0)
+               return 1;
+
+       while ((path = strchr(path, '/')) != NULL) {
+               max_depth--;
+               if (max_depth < 0)
+                       return 0;
+               path++;
+       }
+       return 1;
+}
+
+/*
+ * Return non-zero if name is a subdirectory of match and is not too deep.
+ */
+static int is_subdir(const char *name, int namelen,
+               const char *match, int matchlen, int max_depth)
+{
+       if (matchlen > namelen || strncmp(name, match, matchlen))
+               return 0;
+
+       if (name[matchlen] == '\0') /* exact match */
+               return 1;
+
+       if (!matchlen || match[matchlen-1] == '/' || name[matchlen] == '/')
+               return accept_subdir(name + matchlen + 1, max_depth);
+
+       return 0;
+}
+
 /*
  * git grep pathspecs are somewhat different from diff-tree pathspecs;
  * pathname wildcards are allowed.
  */
-static int pathspec_matches(const char **paths, const char *name)
+static int pathspec_matches(const char **paths, const char *name, int max_depth)
 {
        int namelen, i;
        if (!paths || !*paths)
-               return 1;
+               return accept_subdir(name, max_depth);
        namelen = strlen(name);
        for (i = 0; paths[i]; i++) {
                const char *match = paths[i];
                int matchlen = strlen(match);
                const char *cp, *meta;
 
-               if (!matchlen ||
-                   ((matchlen <= namelen) &&
-                    !strncmp(name, match, matchlen) &&
-                    (match[matchlen-1] == '/' ||
-                     name[matchlen] == '\0' || name[matchlen] == '/')))
+               if (is_subdir(name, namelen, match, matchlen, max_depth))
                        return 1;
                if (!fnmatch(match, name, 0))
                        return 1;
@@ -120,49 +408,74 @@ static int pathspec_matches(const char **paths, const char *name)
        return 0;
 }
 
-static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1, const char *name, int tree_name_len)
+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)
 {
-       unsigned long size;
-       char *data;
        enum object_type type;
-       char *to_free = NULL;
-       int hit;
+       void *data = lock_and_read_sha1_file(sha1, &type, size);
 
-       data = read_sha1_file(sha1, &type, &size);
-       if (!data) {
+       if (!data)
                error("'%s': unable to read %s", name, sha1_to_hex(sha1));
-               return 0;
-       }
+
+       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) {
-               static char name_buf[PATH_MAX];
-               char *cp;
-               int name_len = strlen(name) - opt->prefix_length + 1;
-
-               if (!tree_name_len)
-                       name += opt->prefix_length;
-               else {
-                       if (ARRAY_SIZE(name_buf) <= name_len)
-                               cp = to_free = xmalloc(name_len);
-                       else
-                               cp = name_buf;
-                       memcpy(cp, name, tree_name_len);
-                       strcpy(cp + tree_name_len,
-                              name + tree_name_len + opt->prefix_length);
-                       name = cp;
-               }
+               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;
        }
-       hit = grep_buffer(opt, name, data, size);
-       free(data);
-       free(to_free);
-       return hit;
 }
 
-static int grep_file(struct grep_opt *opt, const char *filename)
+static void *load_file(const char *filename, size_t *sz)
 {
        struct stat st;
-       int i;
        char *data;
-       size_t sz;
+       int i;
 
        if (lstat(filename, &st) < 0) {
        err_ret:
@@ -170,322 +483,74 @@ static int grep_file(struct grep_opt *opt, const char *filename)
                        error("'%s': %s", filename, strerror(errno));
                return 0;
        }
-       if (!st.st_size)
-               return 0; /* empty file -- no grep hit */
        if (!S_ISREG(st.st_mode))
                return 0;
-       sz = xsize_t(st.st_size);
+       *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)) {
+       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 0;
        }
        close(i);
-       if (opt->relative && opt->prefix_length)
-               filename += opt->prefix_length;
-       i = grep_buffer(opt, filename, data, sz);
-       free(data);
-       return i;
+       data[*sz] = 0;
+       return data;
 }
 
-#if !NO_EXTERNAL_GREP
-static int exec_grep(int argc, const char **argv)
+static int grep_file(struct grep_opt *opt, const char *filename)
 {
-       pid_t pid;
-       int status;
+       struct strbuf buf = STRBUF_INIT;
+       char *name;
 
-       argv[argc] = NULL;
-       pid = fork();
-       if (pid < 0)
-               return pid;
-       if (!pid) {
-               execvp("grep", (char **) argv);
-               exit(255);
-       }
-       while (waitpid(pid, &status, 0) < 0) {
-               if (errno == EINTR)
-                       continue;
-               return -1;
-       }
-       if (WIFEXITED(status)) {
-               if (!WEXITSTATUS(status))
-                       return 1;
+       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;
-       }
-       return -1;
-}
-
-#define MAXARGS 1000
-#define ARGBUF 4096
-#define push_arg(a) do { \
-       if (nr < MAXARGS) argv[nr++] = (a); \
-       else die("maximum number of args exceeded"); \
-       } while (0)
-
-/*
- * If you send a singleton filename to grep, it does not give
- * the name of the file.  GNU grep has "-H" but we would want
- * that behaviour in a portable way.
- *
- * So we keep two pathnames in argv buffer unsent to grep in
- * the main loop if we need to do more than one grep.
- */
-static int flush_grep(struct grep_opt *opt,
-                     int argc, int arg0, const char **argv, int *kept)
-{
-       int status;
-       int count = argc - arg0;
-       const char *kept_0 = NULL;
-
-       if (count <= 2) {
-               /*
-                * Because we keep at least 2 paths in the call from
-                * the main loop (i.e. kept != NULL), and MAXARGS is
-                * far greater than 2, this usually is a call to
-                * conclude the grep.  However, the user could attempt
-                * to overflow the argv buffer by giving too many
-                * options to leave very small number of real
-                * arguments even for the call in the main loop.
-                */
-               if (kept)
-                       die("insanely many options to grep");
-
-               /*
-                * If we have two or more paths, we do not have to do
-                * anything special, but we need to push /dev/null to
-                * get "-H" behaviour of GNU grep portably but when we
-                * are not doing "-l" nor "-L" nor "-c".
-                */
-               if (count == 1 &&
-                   !opt->name_only &&
-                   !opt->unmatch_name_only &&
-                   !opt->count) {
-                       argv[argc++] = "/dev/null";
-                       argv[argc] = NULL;
-               }
-       }
-
-       else if (kept) {
-               /*
-                * Called because we found many paths and haven't finished
-                * iterating over the cache yet.  We keep two paths
-                * for the concluding call.  argv[argc-2] and argv[argc-1]
-                * has the last two paths, so save the first one away,
-                * replace it with NULL while sending the list to grep,
-                * and recover them after we are done.
-                */
-               *kept = 2;
-               kept_0 = argv[argc-2];
-               argv[argc-2] = NULL;
-               argc -= 2;
-       }
-
-       if (opt->pre_context || opt->post_context) {
-               /*
-                * grep handles hunk marks between files, but we need to
-                * do that ourselves between multiple calls.
-                */
-               if (opt->show_hunk_mark)
-                       write_or_die(1, "--\n", 3);
+       } else
+#endif
+       {
+               int hit;
+               size_t sz;
+               void *data = load_file(filename, &sz);
+               if (!data)
+                       hit = 0;
                else
-                       opt->show_hunk_mark = 1;
-       }
-
-       status = exec_grep(argc, argv);
+                       hit = grep_buffer(opt, name, data, sz);
 
-       if (kept_0) {
-               /*
-                * Then recover them.  Now the last arg is beyond the
-                * terminating NULL which is at argc, and the second
-                * from the last is what we saved away in kept_0
-                */
-               argv[arg0++] = kept_0;
-               argv[arg0] = argv[argc+1];
-       }
-       return status;
-}
-
-static void grep_add_color(struct strbuf *sb, const char *escape_seq)
-{
-       size_t orig_len = sb->len;
-
-       while (*escape_seq) {
-               if (*escape_seq == 'm')
-                       strbuf_addch(sb, ';');
-               else if (*escape_seq != '\033' && *escape_seq  != '[')
-                       strbuf_addch(sb, *escape_seq);
-               escape_seq++;
+               free(data);
+               free(name);
+               return hit;
        }
-       if (sb->len > orig_len && sb->buf[sb->len - 1] == ';')
-               strbuf_setlen(sb, sb->len - 1);
 }
 
-static int external_grep(struct grep_opt *opt, const char **paths, int cached)
-{
-       int i, nr, argc, hit, len, status;
-       const char *argv[MAXARGS+1];
-       char randarg[ARGBUF];
-       char *argptr = randarg;
-       struct grep_pat *p;
-
-       if (opt->extended || (opt->relative && opt->prefix_length))
-               return -1;
-       len = nr = 0;
-       push_arg("grep");
-       if (opt->fixed)
-               push_arg("-F");
-       if (opt->linenum)
-               push_arg("-n");
-       if (!opt->pathname)
-               push_arg("-h");
-       if (opt->regflags & REG_EXTENDED)
-               push_arg("-E");
-       if (opt->regflags & REG_ICASE)
-               push_arg("-i");
-       if (opt->binary == GREP_BINARY_NOMATCH)
-               push_arg("-I");
-       if (opt->word_regexp)
-               push_arg("-w");
-       if (opt->name_only)
-               push_arg("-l");
-       if (opt->unmatch_name_only)
-               push_arg("-L");
-       if (opt->null_following_name)
-               /* in GNU grep git's "-z" translates to "-Z" */
-               push_arg("-Z");
-       if (opt->count)
-               push_arg("-c");
-       if (opt->post_context || opt->pre_context) {
-               if (opt->post_context != opt->pre_context) {
-                       if (opt->pre_context) {
-                               push_arg("-B");
-                               len += snprintf(argptr, sizeof(randarg)-len,
-                                               "%u", opt->pre_context) + 1;
-                               if (sizeof(randarg) <= len)
-                                       die("maximum length of args exceeded");
-                               push_arg(argptr);
-                               argptr += len;
-                       }
-                       if (opt->post_context) {
-                               push_arg("-A");
-                               len += snprintf(argptr, sizeof(randarg)-len,
-                                               "%u", opt->post_context) + 1;
-                               if (sizeof(randarg) <= len)
-                                       die("maximum length of args exceeded");
-                               push_arg(argptr);
-                               argptr += len;
-                       }
-               }
-               else {
-                       push_arg("-C");
-                       len += snprintf(argptr, sizeof(randarg)-len,
-                                       "%u", opt->post_context) + 1;
-                       if (sizeof(randarg) <= len)
-                               die("maximum length of args exceeded");
-                       push_arg(argptr);
-                       argptr += len;
-               }
-       }
-       for (p = opt->pattern_list; p; p = p->next) {
-               push_arg("-e");
-               push_arg(p->pattern);
-       }
-       if (opt->color) {
-               struct strbuf sb = STRBUF_INIT;
-
-               grep_add_color(&sb, opt->color_match);
-               setenv("GREP_COLOR", sb.buf, 1);
-
-               strbuf_reset(&sb);
-               strbuf_addstr(&sb, "mt=");
-               grep_add_color(&sb, opt->color_match);
-               strbuf_addstr(&sb, ":sl=:cx=:fn=:ln=:bn=:se=");
-               setenv("GREP_COLORS", sb.buf, 1);
-
-               strbuf_release(&sb);
-
-               if (opt->color_external && strlen(opt->color_external) > 0)
-                       push_arg(opt->color_external);
-       }
-
-       hit = 0;
-       argc = nr;
-       for (i = 0; i < active_nr; i++) {
-               struct cache_entry *ce = active_cache[i];
-               char *name;
-               int kept;
-               if (!S_ISREG(ce->ce_mode))
-                       continue;
-               if (!pathspec_matches(paths, ce->name))
-                       continue;
-               name = ce->name;
-               if (name[0] == '-') {
-                       int len = ce_namelen(ce);
-                       name = xmalloc(len + 3);
-                       memcpy(name, "./", 2);
-                       memcpy(name + 2, ce->name, len + 1);
-               }
-               argv[argc++] = name;
-               if (MAXARGS <= argc) {
-                       status = flush_grep(opt, argc, nr, argv, &kept);
-                       if (0 < status)
-                               hit = 1;
-                       argc = nr + kept;
-               }
-               if (ce_stage(ce)) {
-                       do {
-                               i++;
-                       } while (i < active_nr &&
-                                !strcmp(ce->name, active_cache[i]->name));
-                       i--; /* compensate for loop control */
-               }
-       }
-       if (argc > nr) {
-               status = flush_grep(opt, argc, nr, argv, NULL);
-               if (0 < status)
-                       hit = 1;
-       }
-       return hit;
-}
-#endif
-
-static int grep_cache(struct grep_opt *opt, const char **paths, int cached,
-                     int external_grep_allowed)
+static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 {
        int hit = 0;
        int nr;
        read_cache();
 
-#if !NO_EXTERNAL_GREP
-       /*
-        * Use the external "grep" command for the case where
-        * we grep through the checked-out files. It tends to
-        * be a lot more optimized
-        */
-       if (!cached && external_grep_allowed) {
-               hit = external_grep(opt, paths, cached);
-               if (hit >= 0)
-                       return hit;
-       }
-#endif
-
        for (nr = 0; nr < active_nr; nr++) {
                struct cache_entry *ce = active_cache[nr];
                if (!S_ISREG(ce->ce_mode))
                        continue;
-               if (!pathspec_matches(paths, ce->name))
+               if (!pathspec_matches(paths, ce->name, opt->max_depth))
                        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)) {
+               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);
@@ -499,6 +564,8 @@ static int grep_cache(struct grep_opt *opt, const char **paths, int cached,
                                 !strcmp(ce->name, active_cache[nr]->name));
                        nr--; /* compensate for loop control */
                }
+               if (hit && opt->status_only)
+                       break;
        }
        free_grep_patterns(opt);
        return hit;
@@ -538,7 +605,7 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
                        strbuf_addch(&pathbuf, '/');
 
                down = pathbuf.buf + tn_len;
-               if (!pathspec_matches(paths, down))
+               if (!pathspec_matches(paths, down, opt->max_depth))
                        ;
                else if (S_ISREG(entry.mode))
                        hit |= grep_sha1(opt, entry.sha1, pathbuf.buf, tn_len);
@@ -548,7 +615,7 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
                        void *data;
                        unsigned long size;
 
-                       data = read_sha1_file(entry.sha1, &type, &size);
+                       data = lock_and_read_sha1_file(entry.sha1, &type, &size);
                        if (!data)
                                die("unable to read tree (%s)",
                                    sha1_to_hex(entry.sha1));
@@ -556,6 +623,8 @@ static int grep_tree(struct grep_opt *opt, const char **paths,
                        hit |= grep_tree(opt, paths, &sub, tree_name, down);
                        free(data);
                }
+               if (hit && opt->status_only)
+                       break;
        }
        strbuf_release(&pathbuf);
        return hit;
@@ -608,7 +677,7 @@ static int file_callback(const struct option *opt, const char *arg, int unset)
        struct grep_opt *grep_opt = opt->value;
        FILE *patterns;
        int lno = 0;
-       struct strbuf sb;
+       struct strbuf sb = STRBUF_INIT;
 
        patterns = fopen(arg, "r");
        if (!patterns)
@@ -670,8 +739,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 {
        int hit = 0;
        int cached = 0;
-       int external_grep_allowed = 1;
        int seen_dashdash = 0;
+       int external_grep_allowed__ignored;
        struct grep_opt opt;
        struct object_array list = { 0, 0, NULL };
        const char **paths = NULL;
@@ -683,8 +752,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                OPT_GROUP(""),
                OPT_BOOLEAN('v', "invert-match", &opt.invert,
                        "show non-matching lines"),
-               OPT_BIT('i', "ignore-case", &opt.regflags,
-                       "case insensitive matching", REG_ICASE),
+               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,
@@ -692,6 +761,9 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                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_BIT('E', "extended-regexp", &opt.regflags,
                        "use extended POSIX regular expressions", REG_EXTENDED),
@@ -747,27 +819,34 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                { OPTION_CALLBACK, ')', NULL, &opt, NULL, "",
                  PARSE_OPT_NOARG | PARSE_OPT_NONEG | PARSE_OPT_NODASH,
                  close_callback },
+               OPT_BOOLEAN('q', "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(""),
-#if NO_EXTERNAL_GREP
-               OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed,
-                       "allow calling of grep(1) (ignored by this build)"),
-#else
-               OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed,
-                       "allow calling of grep(1) (default)"),
-#endif
+               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_match, GIT_COLOR_RED GIT_COLOR_BOLD);
        opt.color = -1;
@@ -790,6 +869,16 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                             PARSE_OPT_STOP_AT_NON_OPTION |
                             PARSE_OPT_NO_INTERNAL_HELP);
 
+       /*
+        * 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,
@@ -798,12 +887,23 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                argc--;
        }
 
-       if ((opt.color && !opt.color_external) || opt.funcname)
-               external_grep_allowed = 0;
        if (!opt.pattern_list)
                die("no pattern given.");
+       if (!opt.fixed && opt.ignore_case)
+               opt.regflags |= REG_ICASE;
        if ((opt.regflags != REG_NEWLINE) && opt.fixed)
                die("cannot mix --fixed-strings and regexp");
+
+#ifndef NO_PTHREADS
+       if (online_cpus() == 1 || !grep_threads_ok(&opt))
+               use_threads = 0;
+
+       if (use_threads)
+               start_threads(&opt);
+#else
+       use_threads = 0;
+#endif
+
        compile_grep_patterns(&opt);
 
        /* Check revs and then paths */
@@ -832,15 +932,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
                        verify_filename(prefix, argv[j]);
        }
 
-       if (i < argc) {
+       if (i < argc)
                paths = get_pathspec(prefix, argv + i);
-               if (opt.prefix_length && opt.relative) {
-                       /* Make sure we do not get outside of paths */
-                       for (i = 0; paths[i]; i++)
-                               if (strncmp(prefix, paths[i], opt.prefix_length))
-                                       die("git grep: cannot generate relative filenames containing '..'");
-               }
-       }
        else if (prefix) {
                paths = xcalloc(2, sizeof(const char *));
                paths[0] = prefix;
@@ -848,9 +941,14 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
        }
 
        if (!list.nr) {
+               int hit;
                if (!cached)
                        setup_work_tree();
-               return !grep_cache(&opt, paths, cached, external_grep_allowed);
+
+               hit = grep_cache(&opt, paths, cached);
+               if (use_threads)
+                       hit |= wait_all();
+               return !hit;
        }
 
        if (cached)
@@ -859,9 +957,15 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
        for (i = 0; i < list.nr; i++) {
                struct object *real_obj;
                real_obj = deref_tag(list.objects[i].item, NULL, 0);
-               if (grep_object(&opt, paths, real_obj, list.objects[i].name))
+               if (grep_object(&opt, paths, real_obj, list.objects[i].name)) {
                        hit = 1;
+                       if (opt.status_only)
+                               break;
+               }
        }
+
+       if (use_threads)
+               hit |= wait_all();
        free_grep_patterns(&opt);
        return !hit;
 }