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a8032d1224
No need to memcpy() source buffer data when we might just process the data in place instead of accumulating it into a separate buffer. This is the case when a whole buffer would have been copied, summed, written out and then discarded right away. Also move the CRC32 processing within the loop so the data is more likely to remain in the L1 CPU cache between the CRC32 sum, SHA1 sum and the write call. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
123 lines
2.5 KiB
C
123 lines
2.5 KiB
C
/*
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* csum-file.c
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*
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* Copyright (C) 2005 Linus Torvalds
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*
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* Simple file write infrastructure for writing SHA1-summed
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* files. Useful when you write a file that you want to be
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* able to verify hasn't been messed with afterwards.
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*/
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#include "cache.h"
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#include "progress.h"
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#include "csum-file.h"
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static void sha1flush(struct sha1file *f, void *buf, unsigned int count)
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{
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for (;;) {
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int ret = xwrite(f->fd, buf, count);
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if (ret > 0) {
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f->total += ret;
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display_throughput(f->tp, f->total);
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buf = (char *) buf + ret;
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count -= ret;
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if (count)
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continue;
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return;
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}
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if (!ret)
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die("sha1 file '%s' write error. Out of diskspace", f->name);
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die("sha1 file '%s' write error (%s)", f->name, strerror(errno));
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}
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}
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int sha1close(struct sha1file *f, unsigned char *result, unsigned int flags)
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{
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int fd;
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unsigned offset = f->offset;
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if (offset) {
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SHA1_Update(&f->ctx, f->buffer, offset);
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sha1flush(f, f->buffer, offset);
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f->offset = 0;
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}
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SHA1_Final(f->buffer, &f->ctx);
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if (result)
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hashcpy(result, f->buffer);
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if (flags & (CSUM_CLOSE | CSUM_FSYNC)) {
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/* write checksum and close fd */
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sha1flush(f, f->buffer, 20);
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if (flags & CSUM_FSYNC)
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fsync_or_die(f->fd, f->name);
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if (close(f->fd))
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die("%s: sha1 file error on close (%s)",
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f->name, strerror(errno));
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fd = 0;
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} else
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fd = f->fd;
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free(f);
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return fd;
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}
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int sha1write(struct sha1file *f, void *buf, unsigned int count)
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{
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while (count) {
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unsigned offset = f->offset;
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unsigned left = sizeof(f->buffer) - offset;
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unsigned nr = count > left ? left : count;
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void *data;
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if (f->do_crc)
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f->crc32 = crc32(f->crc32, buf, nr);
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if (nr == sizeof(f->buffer)) {
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/* process full buffer directly without copy */
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data = buf;
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} else {
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memcpy(f->buffer + offset, buf, nr);
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data = f->buffer;
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}
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count -= nr;
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offset += nr;
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buf = (char *) buf + nr;
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left -= nr;
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if (!left) {
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SHA1_Update(&f->ctx, data, offset);
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sha1flush(f, data, offset);
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offset = 0;
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}
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f->offset = offset;
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}
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return 0;
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}
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struct sha1file *sha1fd(int fd, const char *name)
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{
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return sha1fd_throughput(fd, name, NULL);
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}
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struct sha1file *sha1fd_throughput(int fd, const char *name, struct progress *tp)
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{
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struct sha1file *f = xmalloc(sizeof(*f));
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f->fd = fd;
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f->offset = 0;
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f->total = 0;
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f->tp = tp;
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f->name = name;
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f->do_crc = 0;
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SHA1_Init(&f->ctx);
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return f;
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}
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void crc32_begin(struct sha1file *f)
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{
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f->crc32 = crc32(0, Z_NULL, 0);
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f->do_crc = 1;
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}
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uint32_t crc32_end(struct sha1file *f)
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{
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f->do_crc = 0;
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return f->crc32;
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}
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