Merge branch 'sp/stream-clean-filter'

When running a required clean filter, we do not have to mmap the
original before feeding the filter.  Instead, stream the file
contents directly to the filter and process its output.

* sp/stream-clean-filter:
  sha1_file: don't convert off_t to size_t too early to avoid potential die()
  convert: stream from fd to required clean filter to reduce used address space
  copy_fd(): do not close the input file descriptor
  mmap_limit: introduce GIT_MMAP_LIMIT to allow testing expected mmap size
  memory_limit: use git_env_ulong() to parse GIT_ALLOC_LIMIT
  config.c: add git_env_ulong() to parse environment variable
  convert: drop arguments other than 'path' from would_convert_to_git()

Author: gitster

cache.h

@@ -1324,6 +1324,7 @@ extern int git_config_rename_section_in_file(const char *, const char *, const c
 extern const char *git_etc_gitconfig(void);
 extern int check_repository_format_version(const char *var, const char *value, void *cb);
 extern int git_env_bool(const char *, int);
+extern unsigned long git_env_ulong(const char *, unsigned long);
 extern int git_config_system(void);
 extern int config_error_nonbool(const char *);
 #if defined(__GNUC__)

config.c

@@ -1139,12 +1139,28 @@ const char *git_etc_gitconfig(void)
 	return system_wide;
 }
 
+/*
+ * Parse environment variable 'k' as a boolean (in various
+ * possible spellings); if missing, use the default value 'def'.
+ */
 int git_env_bool(const char *k, int def)
 {
 	const char *v = getenv(k);
 	return v ? git_config_bool(k, v) : def;
 }
 
+/*
+ * Parse environment variable 'k' as ulong with possibly a unit
+ * suffix; if missing, use the default value 'val'.
+ */
+unsigned long git_env_ulong(const char *k, unsigned long val)
+{
+	const char *v = getenv(k);
+	if (v && !git_parse_ulong(v, &val))
+		die("failed to parse %s", k);
+	return val;
+}
+
 int git_config_system(void)
 {
 	return !git_env_bool("GIT_CONFIG_NOSYSTEM", 0);

convert.c

@@ -312,11 +312,12 @@ static int crlf_to_worktree(const char *path, const char *src, size_t len,
 struct filter_params {
 	const char *src;
 	unsigned long size;
+	int fd;
 	const char *cmd;
 	const char *path;
 };
 
-static int filter_buffer(int in, int out, void *data)
+static int filter_buffer_or_fd(int in, int out, void *data)
 {
 	/*
 	 * Spawn cmd and feed the buffer contents through its stdin.
@@ -354,7 +355,12 @@ static int filter_buffer(int in, int out, void *data)
 
 	sigchain_push(SIGPIPE, SIG_IGN);
 
-	write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
+	if (params->src) {
+		write_err = (write_in_full(child_process.in, params->src, params->size) < 0);
+	} else {
+		write_err = copy_fd(params->fd, child_process.in);
+	}
+
 	if (close(child_process.in))
 		write_err = 1;
 	if (write_err)
@@ -370,7 +376,7 @@ static int filter_buffer(int in, int out, void *data)
 	return (write_err || status);
 }
 
-static int apply_filter(const char *path, const char *src, size_t len,
+static int apply_filter(const char *path, const char *src, size_t len, int fd,
                         struct strbuf *dst, const char *cmd)
 {
 	/*
@@ -391,11 +397,12 @@ static int apply_filter(const char *path, const char *src, size_t len,
 		return 1;
 
 	memset(&async, 0, sizeof(async));
-	async.proc = filter_buffer;
+	async.proc = filter_buffer_or_fd;
 	async.data = &params;
 	async.out = -1;
 	params.src = src;
 	params.size = len;
+	params.fd = fd;
 	params.cmd = cmd;
 	params.path = path;
 
@@ -746,6 +753,25 @@ static void convert_attrs(struct conv_attrs *ca, const char *path)
 	}
 }
 
+int would_convert_to_git_filter_fd(const char *path)
+{
+	struct conv_attrs ca;
+
+	convert_attrs(&ca, path);
+	if (!ca.drv)
+		return 0;
+
+	/*
+	 * Apply a filter to an fd only if the filter is required to succeed.
+	 * We must die if the filter fails, because the original data before
+	 * filtering is not available.
+	 */
+	if (!ca.drv->required)
+		return 0;
+
+	return apply_filter(path, NULL, 0, -1, NULL, ca.drv->clean);
+}
+
 int convert_to_git(const char *path, const char *src, size_t len,
                    struct strbuf *dst, enum safe_crlf checksafe)
 {
@@ -760,7 +786,7 @@ int convert_to_git(const char *path, const char *src, size_t len,
 		required = ca.drv->required;
 	}
 
-	ret |= apply_filter(path, src, len, dst, filter);
+	ret |= apply_filter(path, src, len, -1, dst, filter);
 	if (!ret && required)
 		die("%s: clean filter '%s' failed", path, ca.drv->name);
 
@@ -777,6 +803,23 @@ int convert_to_git(const char *path, const char *src, size_t len,
 	return ret | ident_to_git(path, src, len, dst, ca.ident);
 }
 
+void convert_to_git_filter_fd(const char *path, int fd, struct strbuf *dst,
+			      enum safe_crlf checksafe)
+{
+	struct conv_attrs ca;
+	convert_attrs(&ca, path);
+
+	assert(ca.drv);
+	assert(ca.drv->clean);
+
+	if (!apply_filter(path, NULL, 0, fd, dst, ca.drv->clean))
+		die("%s: clean filter '%s' failed", path, ca.drv->name);
+
+	ca.crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
+	crlf_to_git(path, dst->buf, dst->len, dst, ca.crlf_action, checksafe);
+	ident_to_git(path, dst->buf, dst->len, dst, ca.ident);
+}
+
 static int convert_to_working_tree_internal(const char *path, const char *src,
 					    size_t len, struct strbuf *dst,
 					    int normalizing)
@@ -810,7 +853,7 @@ static int convert_to_working_tree_internal(const char *path, const char *src,
 		}
 	}
 
-	ret_filter = apply_filter(path, src, len, dst, filter);
+	ret_filter = apply_filter(path, src, len, -1, dst, filter);
 	if (!ret_filter && required)
 		die("%s: smudge filter %s failed", path, ca.drv->name);
 

convert.h

@@ -40,11 +40,15 @@ extern int convert_to_working_tree(const char *path, const char *src,
 				   size_t len, struct strbuf *dst);
 extern int renormalize_buffer(const char *path, const char *src, size_t len,
 			      struct strbuf *dst);
-static inline int would_convert_to_git(const char *path, const char *src,
-				       size_t len, enum safe_crlf checksafe)
+static inline int would_convert_to_git(const char *path)
 {
-	return convert_to_git(path, src, len, NULL, checksafe);
+	return convert_to_git(path, NULL, 0, NULL, 0);
 }
+/* Precondition: would_convert_to_git_filter_fd(path) == true */
+extern void convert_to_git_filter_fd(const char *path, int fd,
+				     struct strbuf *dst,
+				     enum safe_crlf checksafe);
+extern int would_convert_to_git_filter_fd(const char *path);
 
 /*****************************************************************
  *

copy.c

@@ -4,34 +4,17 @@ int copy_fd(int ifd, int ofd)
 {
 	while (1) {
 		char buffer[8192];
-		char *buf = buffer;
 		ssize_t len = xread(ifd, buffer, sizeof(buffer));
 		if (!len)
 			break;
 		if (len < 0) {
-			int read_error = errno;
-			close(ifd);
 			return error("copy-fd: read returned %s",
-				     strerror(read_error));
-		}
-		while (len) {
-			int written = xwrite(ofd, buf, len);
-			if (written > 0) {
-				buf += written;
-				len -= written;
-			}
-			else if (!written) {
-				close(ifd);
-				return error("copy-fd: write returned 0");
-			} else {
-				int write_error = errno;
-				close(ifd);
-				return error("copy-fd: write returned %s",
-					     strerror(write_error));
-			}
+				     strerror(errno));
 		}
+		if (write_in_full(ofd, buffer, len) < 0)
+			return error("copy-fd: write returned %s",
+				     strerror(errno));
 	}
-	close(ifd);
 	return 0;
 }
 
@@ -60,6 +43,7 @@ int copy_file(const char *dst, const char *src, int mode)
 		return fdo;
 	}
 	status = copy_fd(fdi, fdo);
+	close(fdi);
 	if (close(fdo) != 0)
 		return error("%s: close error: %s", dst, strerror(errno));
 

lockfile.c

@@ -224,8 +224,11 @@ int hold_lock_file_for_append(struct lock_file *lk, const char *path, int flags)
 	} else if (copy_fd(orig_fd, fd)) {
 		if (flags & LOCK_DIE_ON_ERROR)
 			exit(128);
+		close(orig_fd);
 		close(fd);
 		return -1;
+	} else {
+		close(orig_fd);
 	}
 	return fd;
 }

sha1_file.c

@@ -663,10 +663,26 @@ void release_pack_memory(size_t need)
 		; /* nothing */
 }
 
+static void mmap_limit_check(size_t length)
+{
+	static size_t limit = 0;
+	if (!limit) {
+		limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
+		if (!limit)
+			limit = SIZE_MAX;
+	}
+	if (length > limit)
+		die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
+		    (uintmax_t)length, (uintmax_t)limit);
+}
+
 void *xmmap(void *start, size_t length,
 	int prot, int flags, int fd, off_t offset)
 {
-	void *ret = mmap(start, length, prot, flags, fd, offset);
+	void *ret;
+
+	mmap_limit_check(length);
+	ret = mmap(start, length, prot, flags, fd, offset);
 	if (ret == MAP_FAILED) {
 		if (!length)
 			return NULL;
@@ -3076,6 +3092,29 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
 	return ret;
 }
 
+static int index_stream_convert_blob(unsigned char *sha1, int fd,
+				     const char *path, unsigned flags)
+{
+	int ret;
+	const int write_object = flags & HASH_WRITE_OBJECT;
+	struct strbuf sbuf = STRBUF_INIT;
+
+	assert(path);
+	assert(would_convert_to_git_filter_fd(path));
+
+	convert_to_git_filter_fd(path, fd, &sbuf,
+				 write_object ? safe_crlf : SAFE_CRLF_FALSE);
+
+	if (write_object)
+		ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
+				      sha1);
+	else
+		ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
+				     sha1);
+	strbuf_release(&sbuf);
+	return ret;
+}
+
 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
 		      const char *path, unsigned flags)
 {
@@ -3141,15 +3180,22 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st,
 	     enum object_type type, const char *path, unsigned flags)
 {
 	int ret;
-	size_t size = xsize_t(st->st_size);
 
-	if (!S_ISREG(st->st_mode))
+	/*
+	 * Call xsize_t() only when needed to avoid potentially unnecessary
+	 * die() for large files.
+	 */
+	if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
+		ret = index_stream_convert_blob(sha1, fd, path, flags);
+	else if (!S_ISREG(st->st_mode))
 		ret = index_pipe(sha1, fd, type, path, flags);
-	else if (size <= big_file_threshold || type != OBJ_BLOB ||
-		 (path && would_convert_to_git(path, NULL, 0, 0)))
-		ret = index_core(sha1, fd, size, type, path, flags);
+	else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
+		 (path && would_convert_to_git(path)))
+		ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
+				 flags);
 	else
-		ret = index_stream(sha1, fd, size, type, path, flags);
+		ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
+				   flags);
 	close(fd);
 	return ret;
 }

t/t0021-conversion.sh

@@ -153,17 +153,23 @@ test_expect_success 'filter shell-escaped filenames' '
 	:
 '
 
-test_expect_success 'required filter success' '
-	git config filter.required.smudge cat &&
-	git config filter.required.clean cat &&
+test_expect_success 'required filter should filter data' '
+	git config filter.required.smudge ./rot13.sh &&
+	git config filter.required.clean ./rot13.sh &&
 	git config filter.required.required true &&
 
 	echo "*.r filter=required" >.gitattributes &&
 
-	echo test >test.r &&
+	cat test.o >test.r &&
 	git add test.r &&
+
 	rm -f test.r &&
-	git checkout -- test.r
+	git checkout -- test.r &&
+	cmp test.o test.r &&
+
+	./rot13.sh <test.o >expected &&
+	git cat-file blob :test.r >actual &&
+	cmp expected actual
 '
 
 test_expect_success 'required filter smudge failure' '
@@ -190,6 +196,14 @@ test_expect_success 'required filter clean failure' '
 	test_must_fail git add test.fc
 '
 
+test_expect_success 'filtering large input to small output should use little memory' '
+	git config filter.devnull.clean "cat >/dev/null" &&
+	git config filter.devnull.required true &&
+	for i in $(test_seq 1 30); do printf "%1048576d" 1; done >30MB &&
+	echo "30MB filter=devnull" >.gitattributes &&
+	GIT_MMAP_LIMIT=1m GIT_ALLOC_LIMIT=1m git add 30MB
+'
+
 test_expect_success EXPENSIVE 'filter large file' '
 	git config filter.largefile.smudge cat &&
 	git config filter.largefile.clean cat &&

t/t1050-large.sh

@@ -13,7 +13,7 @@ test_expect_success setup '
 	echo X | dd of=large2 bs=1k seek=2000 &&
 	echo X | dd of=large3 bs=1k seek=2000 &&
 	echo Y | dd of=huge bs=1k seek=2500 &&
-	GIT_ALLOC_LIMIT=1500 &&
+	GIT_ALLOC_LIMIT=1500k &&
 	export GIT_ALLOC_LIMIT
 '