built-in "git grep"

This attempts to set up built-in "git grep" to further reduce
our dependence on the shell, while at the same time optionally
allowing to run grep against object database.  You could do
funky things like these:

	git grep --cached -e pattern	;# grep from index
	git grep -e pattern master	;# or in a rev
	git grep -e pattern master next ;# or in multiple revs
	git grep -e pattern pu^@	;# even like this with an
					;# extension from another topic ;-)
	git grep -e pattern master..next ;# or even from rev ranges
	git grep -e pattern master~20:Documentation
					;# or an arbitrary tree
	git grep -e pattern next:git-commit.sh
        				;# or an arbitrary blob

Right now, it does not understand and/or obey many options grep
should accept, and the pattern must be given with -e option due
to the way the parameter parser is structured, both of which
obviously need to be fixed for usability.

But this is going in the right direction.  The shell script
version is one of the worst Portability offender in the git
barebone Porcelainish; it uses xargs -0 to pass paths around and
shell arrays to sift flags and parameters.

Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 454 insertions, 0 deletions

diff --git a/builtin-grep.c b/builtin-grep.c
new file mode 100644
index 0000000000..36150bf4ef
--- /dev/null
+++ b/builtin-grep.c
@@ -0,0 +1,454 @@
+/*
+ * 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 "diff.h"
+#include "revision.h"
+#include "builtin.h"
+#include <regex.h>
+
+static int pathspec_matches(struct diff_options *opt, const char *name)
+{
+	int i, j;
+	int namelen;
+	if (!opt->nr_paths)
+		return 1;
+	namelen = strlen(name);
+	for (i = 0; i < opt->nr_paths; i++) {
+		const char *match = opt->paths[i];
+		int matchlen = opt->pathlens[i];
+		if (matchlen <= namelen) {
+			if (!strncmp(name, match, matchlen))
+				return 1;
+			continue;
+		}
+		/* If name is "Documentation" and pathspec is
+		 * "Documentation/", they should match.  Maybe
+		 * we would want to strip it in get_pathspec()???
+		 */
+		if (strncmp(name, match, namelen))
+			continue;
+		for (j = namelen; j < matchlen; j++)
+			if (match[j] != '/')
+				break;
+		if (matchlen <= j)
+			return 1;
+	}
+	return 0;
+}
+
+struct grep_opt {
+	const char *pattern;
+	regex_t regexp;
+	unsigned linenum:1;
+	unsigned invert:1;
+	int regflags;
+	unsigned pre_context;
+	unsigned post_context;
+};
+
+static char *end_of_line(char *cp, unsigned long *left)
+{
+	unsigned long l = *left;
+	while (l && *cp != '\n') {
+		l--;
+		cp++;
+	}
+	*left = l;
+	return cp;
+}
+
+static void show_line(struct grep_opt *opt, const char *bol, const char *eol,
+		      const char *name, unsigned lno, char sign)
+{
+	printf("%s%c", name, sign);
+	if (opt->linenum)
+		printf("%d%c", lno, sign);
+	printf("%.*s\n", eol-bol, bol);
+}
+
+static int grep_buffer(struct grep_opt *opt, const char *name,
+		       char *buf, unsigned long size)
+{
+	char *bol = buf;
+	unsigned long left = size;
+	unsigned lno = 1;
+	struct pre_context_line {
+		char *bol;
+		char *eol;
+	} *prev = NULL, *pcl;
+	unsigned last_hit = 0;
+	unsigned last_shown = 0;
+	const char *hunk_mark = "";
+
+	if (opt->pre_context)
+		prev = xcalloc(opt->pre_context, sizeof(*prev));
+	if (opt->pre_context || opt->post_context)
+		hunk_mark = "--\n";
+
+	while (left) {
+		regmatch_t pmatch[10];
+		char *eol, ch;
+		int hit;
+
+		eol = end_of_line(bol, &left);
+		ch = *eol;
+		*eol = 0;
+
+		hit = !regexec(&opt->regexp, bol, ARRAY_SIZE(pmatch),
+			       pmatch, 0);
+		if (opt->invert)
+			hit = !hit;
+		if (hit) {
+			/* Hit at this line.  If we haven't shown the
+			 * pre-context lines, we would need to show them.
+			 */
+			if (opt->pre_context) {
+				unsigned from;
+				if (opt->pre_context < lno)
+					from = lno - opt->pre_context;
+				else
+					from = 1;
+				if (from <= last_shown)
+					from = last_shown + 1;
+				if (last_shown && from != last_shown + 1)
+					printf(hunk_mark);
+				while (from < lno) {
+					pcl = &prev[lno-from-1];
+					show_line(opt, pcl->bol, pcl->eol,
+						  name, from, '-');
+					from++;
+				}
+				last_shown = lno-1;
+			}
+			if (last_shown && lno != last_shown + 1)
+				printf(hunk_mark);
+			show_line(opt, bol, eol, name, lno, ':');
+			last_shown = last_hit = lno;
+		}
+		else if (last_hit &&
+			 lno <= last_hit + opt->post_context) {
+			/* If the last hit is within the post context,
+			 * we need to show this line.
+			 */
+			if (last_shown && lno != last_shown + 1)
+				printf(hunk_mark);
+			show_line(opt, bol, eol, name, lno, '-');
+			last_shown = lno;
+		}
+		if (opt->pre_context) {
+			memmove(prev+1, prev,
+				(opt->pre_context-1) * sizeof(*prev));
+			prev->bol = bol;
+			prev->eol = eol;
+		}
+		*eol = ch;
+		bol = eol + 1;
+		left--;
+		lno++;
+	}
+	return !!last_hit;
+}
+
+static int grep_sha1(struct grep_opt *opt, const unsigned char *sha1, const char *name)
+{
+	unsigned long size;
+	char *data;
+	char type[20];
+	int hit;
+	data = read_sha1_file(sha1, type, &size);
+	if (!data) {
+		error("'%s': unable to read %s", name, sha1_to_hex(sha1));
+		return 0;
+	}
+	hit = grep_buffer(opt, name, data, size);
+	free(data);
+	return hit;
+}
+
+static int grep_file(struct grep_opt *opt, const char *filename)
+{
+	struct stat st;
+	int i;
+	char *data;
+	if (lstat(filename, &st) < 0) {
+	err_ret:
+		if (errno != ENOENT)
+			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;
+	i = open(filename, O_RDONLY);
+	if (i < 0)
+		goto err_ret;
+	data = xmalloc(st.st_size + 1);
+	if (st.st_size != xread(i, data, st.st_size)) {
+		error("'%s': short read %s", filename, strerror(errno));
+		close(i);
+		free(data);
+		return 0;
+	}
+	close(i);
+	i = grep_buffer(opt, filename, data, st.st_size);
+	free(data);
+	return i;
+}
+
+static int grep_cache(struct grep_opt *opt, struct rev_info *revs, int cached)
+{
+	int hit = 0;
+	int nr;
+	read_cache();
+
+	for (nr = 0; nr < active_nr; nr++) {
+		struct cache_entry *ce = active_cache[nr];
+		if (ce_stage(ce) || !S_ISREG(ntohl(ce->ce_mode)))
+			continue;
+		if (!pathspec_matches(&revs->diffopt, ce->name))
+			continue;
+		if (cached)
+			hit |= grep_sha1(opt, ce->sha1, ce->name);
+		else
+			hit |= grep_file(opt, ce->name);
+	}
+	return hit;
+}
+
+static int grep_tree(struct grep_opt *opt, struct rev_info *revs,
+		     struct tree_desc *tree,
+		     const char *tree_name, const char *base)
+{
+	unsigned mode;
+	int len;
+	int hit = 0;
+	const char *path;
+	const unsigned char *sha1;
+	char *down_base;
+	char *path_buf = xmalloc(PATH_MAX + strlen(tree_name) + 100);
+
+	if (tree_name[0]) {
+		int offset = sprintf(path_buf, "%s:", tree_name);
+		down_base = path_buf + offset;
+		strcat(down_base, base);
+	}
+	else {
+		down_base = path_buf;
+		strcpy(down_base, base);
+	}
+	len = strlen(path_buf);
+
+	while (tree->size) {
+		int pathlen;
+		sha1 = tree_entry_extract(tree, &path, &mode);
+		pathlen = strlen(path);
+		strcpy(path_buf + len, path);
+
+		if (!pathspec_matches(&revs->diffopt, down_base))
+			;
+		else if (S_ISREG(mode))
+			hit |= grep_sha1(opt, sha1, path_buf);
+		else if (S_ISDIR(mode)) {
+			char type[20];
+			struct tree_desc sub;
+			void *data;
+			data = read_sha1_file(sha1, type, &sub.size);
+			if (!data)
+				die("unable to read tree (%s)",
+				    sha1_to_hex(sha1));
+			strcpy(path_buf + len + pathlen, "/");
+			sub.buf = data;
+			hit = grep_tree(opt, revs, &sub, tree_name, down_base);
+			free(data);
+		}
+		update_tree_entry(tree);
+	}
+	return hit;
+}
+
+static int grep_object(struct grep_opt *opt, struct rev_info *revs,
+		       struct object *obj, const char *name)
+{
+	if (!strcmp(obj->type, blob_type))
+		return grep_sha1(opt, obj->sha1, name);
+	if (!strcmp(obj->type, commit_type) ||
+	    !strcmp(obj->type, tree_type)) {
+		struct tree_desc tree;
+		void *data;
+		int hit;
+		data = read_object_with_reference(obj->sha1, tree_type,
+						  &tree.size, NULL);
+		if (!data)
+			die("unable to read tree (%s)", sha1_to_hex(obj->sha1));
+		tree.buf = data;
+		hit = grep_tree(opt, revs, &tree, name, "");
+		free(data);
+		return hit;
+	}
+	die("unable to grep from object of type %s", obj->type);
+}
+
+static const char builtin_grep_usage[] =
+"git-grep <option>* <rev>* [-e] <pattern> [<path>...]";
+
+int cmd_grep(int argc, const char **argv, char **envp)
+{
+	struct rev_info rev;
+	const char **dst, **src;
+	int err;
+	int hit = 0;
+	int no_more_arg = 0;
+	int seen_range = 0;
+	int seen_noncommit = 0;
+	int cached = 0;
+	struct grep_opt opt;
+	struct object_list *list;
+
+	memset(&opt, 0, sizeof(opt));
+	opt.regflags = REG_NEWLINE;
+
+	/*
+	 * Interpret and remove the grep options upfront.  Sigh...
+	 */
+	for (dst = src = &argv[1]; src < argc + argv; ) {
+		const char *arg = *src++;
+		if (!no_more_arg) {
+			if (!strcmp("--", arg)) {
+				no_more_arg = 1;
+				*dst++ = arg;
+				continue;
+			}
+			if (!strcmp("--cached", arg)) {
+				cached = 1;
+				continue;
+			}
+			if (!strcmp("-i", arg) ||
+			    !strcmp("--ignore-case", arg)) {
+				opt.regflags |= REG_ICASE;
+				continue;
+			}
+			if (!strcmp("-v", arg) ||
+			    !strcmp("--invert-match", arg)) {
+				opt.invert = 1;
+				continue;
+			}
+			if (!strcmp("-E", arg) ||
+			    !strcmp("--extended-regexp", arg)) {
+				opt.regflags |= REG_EXTENDED;
+				continue;
+			}
+			if (!strcmp("-G", arg) ||
+			    !strcmp("--basic-regexp", arg)) {
+				opt.regflags &= ~REG_EXTENDED;
+				continue;
+			}
+			if (!strcmp("-e", arg)) {
+				if (src < argc + argv) {
+					opt.pattern = *src++;
+					continue;
+				}
+				usage(builtin_grep_usage);
+			}
+			if (!strcmp("-n", arg)) {
+				opt.linenum = 1;
+				continue;
+			}
+			if (!strcmp("-H", arg)) {
+				/* We always show the pathname, so this
+				 * is a noop.
+				 */
+				continue;
+			}
+			if (!strcmp("-A", arg) ||
+			    !strcmp("-B", arg) ||
+			    !strcmp("-C", arg)) {
+				unsigned num;
+				if ((argc + argv <= src) ||
+				    sscanf(*src++, "%u", &num) != 1)
+					usage(builtin_grep_usage);
+				switch (arg[1]) {
+				case 'A':
+					opt.post_context = num;
+					break;
+				case 'C':
+					opt.post_context = num;
+				case 'B':
+					opt.pre_context = num;
+					break;
+				}
+				continue;
+			}
+		}
+		*dst++ = arg;
+	}
+	if (!opt.pattern)
+		die("no pattern given.");
+
+	err = regcomp(&opt.regexp, opt.pattern, opt.regflags);
+	if (err) {
+		char errbuf[1024];
+		regerror(err, &opt.regexp, errbuf, 1024);
+		regfree(&opt.regexp);
+		die("'%s': %s", opt.pattern, errbuf);
+	}
+
+	init_revisions(&rev);
+	*dst = NULL;
+	argc = setup_revisions(dst - argv, argv, &rev, NULL);
+
+	/*
+	 * Do not walk "grep -e foo master next pu -- Documentation/"
+	 * but do walk "grep -e foo master..next -- Documentation/".
+	 * Ranged request mixed with a blob or tree object, like
+	 * "grep -e foo v1.0.0:Documentation/ master..next"
+	 * so detect that and complain.
+	 */
+	for (list = rev.pending_objects; list; list = list->next) {
+		struct object *real_obj;
+		if (list->item->flags & UNINTERESTING)
+			seen_range = 1;
+		real_obj = deref_tag(list->item, NULL, 0);
+		if (strcmp(real_obj->type, commit_type))
+			seen_noncommit = 1;
+	}
+	if (!rev.pending_objects)
+		return !grep_cache(&opt, &rev, cached);
+	if (cached)
+		die("both --cached and revisions given.");
+
+	if (seen_range && seen_noncommit)
+		die("both A..B and non commit are given.");
+	if (seen_range) {
+		struct commit *commit;
+		prepare_revision_walk(&rev);
+		while ((commit = get_revision(&rev)) != NULL) {
+			unsigned char *sha1 = commit->object.sha1;
+			const char *n = find_unique_abbrev(sha1, rev.abbrev);
+			char rev_name[41];
+			strcpy(rev_name, n);
+			if (grep_object(&opt, &rev, &commit->object, rev_name))
+				hit = 1;
+			commit->buffer = NULL;
+		}
+		return !hit;
+	}
+
+	/* all of them are non-commit; do not walk, and
+	 * do not lose their names.
+	 */
+	for (list = rev.pending_objects; list; list = list->next) {
+		struct object *real_obj;
+		real_obj = deref_tag(list->item, NULL, 0);
+		if (grep_object(&opt, &rev, real_obj, list->name))
+			hit = 1;
+	}
+	return !hit;
+}