[PATCH] add a diff-files command

[Nicolas Pitre <nico@cam.org>]

In the same spirit as diff-tree and diff-cache, here is a diff-files 
command that processes differences between the index cache and the 
working directory content.  It produces lists of files that are either 
changed (-c), deleted (-d) or outside (-o) from the current cache, or a 
combination of those, or all of them (-a).

The -p option can also be used to generate a patch describing the 
changes directly.

It also has the ability to accept exclude file patterns with -x and even 
a file containing a list of patterns to exclude with -X.  This is 
especially useful to use the famous dontdiff file when looking for 
uncommitted files in a compiled kernel tree.

Signed-off-by: Nicolas Pitre <nico@cam.org>

--- k/Makefile
+++ l/Makefile
@@ -18,7 +18,7 @@ PROG=   update-cache show-diff init-db w
 	cat-file fsck-cache checkout-cache diff-tree rev-tree show-files \
 	check-files ls-tree merge-base merge-cache unpack-file git-export \
 	diff-cache convert-cache http-pull rpush rpull rev-list git-mktag \
-	diff-tree-helper
+	diff-tree-helper diff-files
 
 all: $(PROG)
 
--- k/diff-files.c
+++ l/diff-files.c
@@ -0,0 +1,362 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ */
+
+#include <dirent.h>
+#include <fnmatch.h>
+#include "cache.h"
+#include "diff.h"
+
+static const char *diff_files_usage = "diff-files [-a] [-c] [-d] [-o] [-p | -z]"
+				      " [-x <pattern>] [-X <file>] [paths...]";
+
+/* What paths are we interested in? */
+static int nr_paths = 0;
+static char **paths = NULL;
+static int *pathlens = NULL;
+
+static int nr_excludes;
+static const char **excludes;
+static int excludes_alloc;
+
+static void add_exclude(const char *string)
+{
+	if (nr_excludes == excludes_alloc) {
+		excludes_alloc = alloc_nr(excludes_alloc);
+		excludes = realloc(excludes, excludes_alloc*sizeof(char *));
+	}
+	excludes[nr_excludes++] = string;
+}
+
+static void add_excludes_from_file(const char *fname)
+{
+	int fd, i;
+	long size;
+	char *buf, *entry;
+
+	fd = open(fname, O_RDONLY);
+	if (fd < 0)
+		goto err;
+	size = lseek(fd, 0, SEEK_END);
+	if (size < 0)
+		goto err;
+	lseek(fd, 0, SEEK_SET);
+	if (size == 0) {
+		close(fd);
+		return;
+	}
+	buf = malloc(size);
+	if (!buf) {
+		errno = ENOMEM;
+		goto err;
+	}
+	if (read(fd, buf, size) != size)
+		goto err;
+	close(fd);
+
+	entry = buf;
+	for (i = 0; i < size; i++) {
+		if (buf[i] == '\n') {
+			if (entry != buf + i) {
+				buf[i] = 0;
+				add_exclude(entry);
+			}
+			entry = buf + i + 1;
+		}
+	}
+	return;
+
+err:	perror(fname);
+	exit(1);
+}
+
+/*
+ * See if name matches our specified paths and is not excluded.
+ * return value:
+ *	-1 if no match
+ *	0 if partial match (name is a directory component)
+ *	1 = exact match
+ *	2 = name is under a specified directory path with no excludes
+ */
+static int path_match(const char *name, int namelen)
+{
+	int i, ret;
+
+	/* fast case: no path list and no exclude list */
+	if (!nr_paths && !nr_excludes)
+		return 2;
+
+	ret = (nr_paths) ? -1 : 1;
+	for (i = 0; i < nr_paths; i++) {
+		int pathlen = pathlens[i];
+		if (pathlen == namelen &&
+		    strncmp(paths[i], name, pathlen) == 0) {
+			ret = 1;
+			break;
+		} else if (pathlen > namelen && 
+			   strncmp(paths[i], name, namelen) == 0 &&
+			   paths[i][namelen] == '/') {
+			ret = 0;
+			break;
+		} else if (pathlen < namelen &&
+			   strncmp(paths[i], name, pathlen) == 0 &&
+			   name[pathlen] == '/') {
+			ret = (nr_excludes) ? 1 : 2;
+			break;
+		}
+	}
+
+	if (ret >= 0 && nr_excludes) {
+		const char *basename = strrchr(name, '/');
+		basename = (basename) ? basename+1 : name;
+		for (i = 0; i < nr_excludes; i++) {
+			if (fnmatch(excludes[i], basename, 0) == 0) {
+				ret = -1;
+				break;
+			}
+		}
+	}
+
+	return ret;
+}
+
+static const char **others;
+static int nr_others;
+static int others_alloc;
+
+static void add_name(const char *pathname, int len)
+{
+	char *name;
+
+	if (cache_name_pos(pathname, len) >= 0)
+		return;
+
+	if (nr_others == others_alloc) {
+		others_alloc = alloc_nr(others_alloc);
+		others = realloc(others, others_alloc*sizeof(char *));
+	}
+	name = malloc(len + 1);
+	memcpy(name, pathname, len + 1);
+	others[nr_others++] = name;
+}
+
+/*
+ * Read a directory tree. We currently ignore anything but
+ * directories and regular files. That's because git doesn't
+ * handle them at all yet. Maybe that will change some day.
+ *
+ * Also, we currently ignore all names starting with a dot.
+ * That likely will not change.
+ */
+static void read_directory(const char *path, const char *base, int baselen, int match)
+{
+	DIR *dir = opendir(path);
+
+	if (dir) {
+		struct dirent *de;
+		char fullname[MAXPATHLEN + 1];
+		memcpy(fullname, base, baselen);
+
+		while ((de = readdir(dir)) != NULL) {
+			int len;
+
+			if (de->d_name[0] == '.')
+				continue;
+			len = strlen(de->d_name);
+			memcpy(fullname + baselen, de->d_name, len+1);
+			if (match < 2)
+				match = path_match(fullname, baselen+len);
+			if (match < 0)
+				continue;
+
+			switch (de->d_type) {
+			struct stat st;
+			default:
+				continue;
+			case DT_UNKNOWN:
+				if (lstat(fullname, &st))
+					continue;
+				if (S_ISREG(st.st_mode))
+					break;
+				if (!S_ISDIR(st.st_mode))
+					continue;
+				/* fallthrough */
+			case DT_DIR:
+				memcpy(fullname + baselen + len, "/", 2);
+				read_directory(fullname, fullname,
+					       baselen + len + 1, match);
+				continue;
+			case DT_REG:
+				break;
+			}
+			if (match > 0)
+				add_name(fullname, baselen + len);
+		}
+		closedir(dir);
+	}
+}
+
+static int cmp_name(const void *p1, const void *p2)
+{
+	const char *n1 = *(const char **)p1;
+	const char *n2 = *(const char **)p2;
+	int l1 = strlen(n1), l2 = strlen(n2);
+
+	return cache_name_compare(n1, l1, n2, l2);
+}
+
+static int show_changed = 0;
+static int show_deleted = 0;
+static int show_others = 0;
+static int generate_patch = 0;
+static int line_terminator = '\n';
+
+static const char null_sha1[20];
+static const char null_sha1_hex[] = "0000000000000000000000000000000000000000";
+
+static void show_file(int prefix, unsigned int mode,
+		      const char *sha1, const char *name)
+{
+	if (generate_patch)
+		diff_addremove(prefix, mode, sha1, name, NULL);
+	else
+		printf("%c%o\t%s\t%s\t%s%c", prefix, mode, "blob",
+		       sha1_to_hex(sha1), name, line_terminator);
+}
+
+int main(int argc, char **argv)
+{
+	int i, entries;
+
+	for (i = 1; i < argc; i++) {
+		char *arg = argv[i];
+
+		if (*arg != '-')
+			break;
+
+		if (!strcmp(arg, "-z")) {
+			line_terminator = 0;
+			continue;
+		}
+		if (!strcmp(arg, "-a")) {
+			show_changed = show_deleted = show_others = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-c")) {
+			show_changed = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-d")) {
+			show_deleted = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-o")) {
+			show_others = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-p")) {
+			generate_patch = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-x") && i+1 < argc) {
+			arg = argv[++i];
+			add_exclude(arg);
+			continue;
+		}
+		if (!strcmp(arg, "-X") && i+1 < argc) {
+			arg = argv[++i];
+			add_excludes_from_file(arg);
+			continue;
+		}
+		if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+
+		usage(diff_files_usage);
+	}
+
+	/* default to -c if none of -c, -d nor -o have been specified */
+	if (!show_changed && !show_deleted && !show_others)
+		show_changed = 1;
+
+	if (i < argc) {
+		paths = &argv[i];
+		nr_paths = argc - i;
+		pathlens = malloc(nr_paths * sizeof(int));
+		for (i=0; i<nr_paths; i++) {
+			pathlens[i] = strlen(paths[i]);
+			if (paths[i][pathlens[i] - 1] == '/')
+				pathlens[i]--;
+		}
+	}
+
+	entries = read_cache();
+	if (entries < 0) {
+		perror("read_cache");
+		exit(1);
+	}
+
+	if (show_others) {
+		read_directory(".", "", 0, 0);
+		qsort(others, nr_others, sizeof(char *), cmp_name);
+		for (i = 0; i < nr_others; i++) {
+			struct stat st;
+			unsigned int mode;
+			if (stat(others[i], &st) < 0) {
+				perror(others[i]);
+			} else {
+				mode = S_IFREG | ce_permissions(st.st_mode);
+				show_file('+', mode, null_sha1, others[i]);
+			}
+		}
+	}
+
+	for (i = 0; i < entries; i++) {
+		struct stat st;
+		unsigned int ce_mode, mode;
+		struct cache_entry *ce = active_cache[i];
+
+		if (path_match(ce->name, ce_namelen(ce)) < 1)
+			continue;
+
+		if (show_changed && ce_stage(ce)) {
+			if (generate_patch)
+				diff_unmerge(ce->name);
+			else
+				printf("U %s%c", ce->name, line_terminator);
+			do {
+				i++;
+			} while (i < entries &&
+				 !strcmp(ce->name, active_cache[i]->name));
+			continue;
+		}
+
+		ce_mode = ntohl(ce->ce_mode);
+		if (stat(ce->name, &st) < 0) {
+			if (errno != ENOENT) {
+				perror(ce->name);
+			} else if (show_deleted) {
+				show_file('-', ce_mode, ce->sha1, ce->name);
+			}
+			continue;
+		}
+
+		if (!show_changed || !cache_match_stat(ce, &st))
+			continue;
+
+		mode = S_IFREG | ce_permissions(st.st_mode);
+		if (generate_patch)
+			diff_change(ce_mode, mode, ce->sha1,
+				    null_sha1, ce->name, NULL);
+		else
+			printf("*%o->%o\t%s\t%s->%s\t%s%c",
+			       ce_mode, mode, "blob",
+			       sha1_to_hex(ce->sha1), null_sha1_hex,
+			       ce->name, line_terminator);
+	}
+
+	return 0;
+}