v2: Add missing check on open
The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a fast path without fork for well-
behaved gzip files, benefiting all users of xmalloc_open_zipped_read_close.
"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster. And of course
a whole lot less processes -> much saved RAM.
function old new delta
inflate_get_next_window - 1877 +1877
xmalloc_unpack_gz - 356 +356
check_header_gzip - 298 +298
xmalloc_inflate_unzip_internal - 223 +223
xmalloc_open_zipped_read_close 73 176 +103
inflate_init - 97 +97
inflate_store_unused - 35 +35
unpack_gz_stream 567 299 -268
inflate_unzip_internal 2304 172 -2132
------------------------------------------------------------------------------
(add/remove: 6/0 grow/shrink: 1/2 up/down: 2989/-2400) Total: 589 bytes
--
http://www.fastmail.com - The way an email service should be
From e5a58da5d54b8a8e2eef657ac6be60231683a662 Mon Sep 17 00:00:00 2001
From: Lauri Kasanen <cur...@operamail.com>
Date: Thu, 27 Nov 2014 14:48:17 +0200
Subject: [PATCH] Add a gzip fastpath for the xmalloc readers
v2: Add missing check on open
The performance and number of processes for a "depmod -a" with gzipped
modules was abysmal. This patch adds a fast path without fork for well-
behaved gzip files, benefiting all users of xmalloc_open_zipped_read_close.
"modinfo radeon.ko.gz", a single-file reader, got 30% faster.
"depmod -a", which used to fork over 800 times, got 20% faster. And of course
a whole lot less processes -> much saved RAM.
function old new delta
inflate_get_next_window - 1877 +1877
xmalloc_unpack_gz - 356 +356
check_header_gzip - 298 +298
xmalloc_inflate_unzip_internal - 223 +223
xmalloc_open_zipped_read_close 73 176 +103
inflate_init - 97 +97
inflate_store_unused - 35 +35
unpack_gz_stream 567 299 -268
inflate_unzip_internal 2304 172 -2132
------------------------------------------------------------------------------
(add/remove: 6/0 grow/shrink: 1/2 up/down: 2989/-2400) Total: 589 bytes
Signed-off-by: Lauri Kasanen <cur...@operamail.com>
---
archival/libarchive/decompress_gunzip.c | 155 ++++++++++++++++++++++++++++----
archival/libarchive/open_transformer.c | 20 +++++
include/bb_archive.h | 1 +
3 files changed, 160 insertions(+), 16 deletions(-)
diff --git a/archival/libarchive/decompress_gunzip.c
b/archival/libarchive/decompress_gunzip.c
index 7c6f38e..1f68ebd 100644
--- a/archival/libarchive/decompress_gunzip.c
+++ b/archival/libarchive/decompress_gunzip.c
@@ -968,19 +968,12 @@ static int inflate_get_next_window(STATE_PARAM_ONLY)
/* Doesnt get here */
}
-
-/* Called from unpack_gz_stream() and inflate_unzip() */
-static IF_DESKTOP(long long) int
-inflate_unzip_internal(STATE_PARAM int in, int out)
+static void inflate_init(STATE_PARAM_ONLY)
{
- IF_DESKTOP(long long) int n = 0;
- ssize_t nwrote;
-
/* Allocate all global buffers (for DYN_ALLOC option) */
gunzip_window = xmalloc(GUNZIP_WSIZE);
gunzip_outbuf_count = 0;
gunzip_bytes_out = 0;
- gunzip_src_fd = in;
/* (re) initialize state */
method = -1;
@@ -994,6 +987,31 @@ inflate_unzip_internal(STATE_PARAM int in, int out)
gunzip_crc = ~0;
error_msg = "corrupted data";
+}
+
+static void inflate_store_unused(STATE_PARAM_ONLY)
+{
+ /* Store unused bytes in a global buffer so calling applets can access
it */
+ if (gunzip_bk >= 8) {
+ /* Undo too much lookahead. The next read will be byte aligned
+ * so we can discard unused bits in the last meaningful byte. */
+ bytebuffer_offset--;
+ bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
+ gunzip_bb >>= 8;
+ gunzip_bk -= 8;
+ }
+}
+
+/* Called from unpack_gz_stream() and inflate_unzip() */
+static IF_DESKTOP(long long) int
+inflate_unzip_internal(STATE_PARAM int in, int out)
+{
+ IF_DESKTOP(long long) int n = 0;
+ ssize_t nwrote;
+
+ gunzip_src_fd = in;
+ inflate_init(PASS_STATE_ONLY);
+
if (setjmp(error_jmp)) {
/* Error from deep inside zip machinery */
n = -1;
@@ -1012,15 +1030,48 @@ inflate_unzip_internal(STATE_PARAM int in, int out)
if (r == 0) break;
}
- /* Store unused bytes in a global buffer so calling applets can access
it */
- if (gunzip_bk >= 8) {
- /* Undo too much lookahead. The next read will be byte aligned
- * so we can discard unused bits in the last meaningful byte. */
- bytebuffer_offset--;
- bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
- gunzip_bb >>= 8;
- gunzip_bk -= 8;
+ inflate_store_unused(PASS_STATE_ONLY);
+ ret:
+ /* Cleanup */
+ free(gunzip_window);
+ free(gunzip_crc_table);
+ return n;
+}
+
+static long long int
+xmalloc_inflate_unzip_internal(STATE_PARAM int in, char **outptr, const size_t
uncompressed)
+{
+ long long int n = 0;
+ char *buf = xmalloc(uncompressed + 1);
+
+ gunzip_src_fd = in;
+ inflate_init(PASS_STATE_ONLY);
+
+ if (setjmp(error_jmp)) {
+ /* Error from deep inside zip machinery */
+ n = -1;
+ free(buf);
+ goto ret;
+ }
+
+ while (1) {
+ int r = inflate_get_next_window(PASS_STATE_ONLY);
+ if (n + gunzip_outbuf_count > uncompressed) {
+ /* The gzip trailer lied. Fall back on the fork method.
*/
+ n = -1;
+ free(buf);
+ goto ret;
+ }
+ memcpy(buf + n, gunzip_window, gunzip_outbuf_count);
+ n += gunzip_outbuf_count;
+ if (r == 0) break;
}
+
+ inflate_store_unused(PASS_STATE_ONLY);
+
+ buf[uncompressed] = '\0';
+ *outptr = buf;
+
ret:
/* Cleanup */
free(gunzip_window);
@@ -1269,3 +1320,75 @@ unpack_gz_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd)
DEALLOC_STATE;
return total;
}
+
+void FAST_FUNC
+xmalloc_unpack_gz(transformer_aux_data_t *aux, int src_fd, char **outptr,
size_t *maxsz_p)
+{
+ uint32_t v32, uncompressed;
+ long long int n;
+ off_t compressed;
+ char *tmp = NULL;
+ DECLARE_STATE;
+
+ ALLOC_STATE;
+ to_read = -1;
+ bytebuffer = xmalloc(bytebuffer_max);
+ gunzip_src_fd = src_fd;
+
+ compressed = xlseek(src_fd, -4, SEEK_END);
+ xread(src_fd, &uncompressed, 4);
+ IF_BIG_ENDIAN(uncompressed = SWAP_LE32(uncompressed);)
+ xlseek(src_fd, 2, SEEK_SET);
+
+ if (!uncompressed || uncompressed > *maxsz_p || compressed > 4198404) {
+ /* The last check makes sure the uncompressed size is less than
4GB.
+ The maximum compression ratio for zlib is 1:1023, and the
uncompressed
+ size field is u32 - it wraps when uncompressed size is > 4GB.
+
+ 4096 * 1024 * 1024 / 1023 = 4198404 bytes.
+ */
+ goto err;
+ }
+
+ if (!check_header_gzip(PASS_STATE aux)) {
+ bb_error_msg("corrupted data");
+ goto err;
+ }
+
+ n = xmalloc_inflate_unzip_internal(PASS_STATE src_fd, &tmp,
uncompressed);
+ if (n < 0 || !tmp) {
+ goto err;
+ }
+
+ if (!top_up(PASS_STATE 8)) {
+ bb_error_msg("corrupted data");
+ goto err;
+ }
+
+ /* Validate decompression - crc */
+ v32 = buffer_read_le_u32(PASS_STATE_ONLY);
+ if ((~gunzip_crc) != v32) {
+ bb_error_msg("crc error");
+ goto err;
+ }
+
+ /* Validate decompression - size */
+ v32 = buffer_read_le_u32(PASS_STATE_ONLY);
+ if ((uint32_t)gunzip_bytes_out != v32) {
+ bb_error_msg("incorrect length");
+ goto err;
+ }
+
+ if (top_up(PASS_STATE 2)) {
+ goto err; /* Concatenated stream, bail out */
+ }
+
+ *outptr = tmp;
+ *maxsz_p = uncompressed;
+ goto ret;
+ err:
+ free(tmp);
+ ret:
+ free(bytebuffer);
+ DEALLOC_STATE;
+}
diff --git a/archival/libarchive/open_transformer.c
b/archival/libarchive/open_transformer.c
index 1986630..009a810 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -213,6 +213,26 @@ void* FAST_FUNC xmalloc_open_zipped_read_close(const char
*fname, size_t *maxsz_
int fd;
char *image;
+ /* Fast path for well-behaved gzip files, avoiding forks. */
+ if (ENABLE_FEATURE_SEAMLESS_GZ && ENABLE_DESKTOP && BB_MMU) {
+ uint16_t magic;
+ fd = open(fname, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ xread(fd, &magic, 2);
+
+ if (magic == GZIP_MAGIC) {
+ image = NULL;
+ xmalloc_unpack_gz(NULL, fd, &image, maxsz_p);
+ close(fd);
+ if (image)
+ return image;
+ }
+
+ close(fd);
+ }
+
fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
if (fd < 0)
return NULL;
diff --git a/include/bb_archive.h b/include/bb_archive.h
index b82cfd8..618a632 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -217,6 +217,7 @@ int FAST_FUNC check_signature16(transformer_aux_data_t
*aux, int src_fd, unsigne
IF_DESKTOP(long long) int inflate_unzip(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
IF_DESKTOP(long long) int unpack_Z_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
IF_DESKTOP(long long) int unpack_gz_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
+void xmalloc_unpack_gz(transformer_aux_data_t *aux, int src_fd, char **outptr,
size_t *maxsz_p) FAST_FUNC;
IF_DESKTOP(long long) int unpack_bz2_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
IF_DESKTOP(long long) int unpack_lzma_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
IF_DESKTOP(long long) int unpack_xz_stream(transformer_aux_data_t *aux, int
src_fd, int dst_fd) FAST_FUNC;
--
1.8.3.1
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