mirror of
https://github.com/kovidgoyal/kitty
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116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
/*
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* fast-file-copy.c
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* Copyright (C) 2021 Kovid Goyal <kovid at kovidgoyal.net>
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*
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* Distributed under terms of the GPL3 license.
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*/
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#if __linux__
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#define _GNU_SOURCE 1
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#endif
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#include "fast-file-copy.h"
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#if __linux__
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#define HAS_SENDFILE
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#include <sys/sendfile.h>
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#include <unistd.h>
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#endif
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static bool
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copy_with_buffer(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
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if (!fcb->buf) {
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fcb->sz = 32 * 1024;
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fcb->buf = malloc(fcb->sz);
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if (!fcb->buf) return false;
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}
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while (len) {
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ssize_t amt_read = pread(infd, fcb->buf, MIN(len, fcb->sz), in_pos);
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if (amt_read < 0) {
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if (errno == EINTR || errno == EAGAIN) continue;
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return false;
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}
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if (amt_read == 0) {
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errno = EIO;
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return false;
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}
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len -= amt_read;
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in_pos += amt_read;
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uint8_t *p = fcb->buf;
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while(amt_read) {
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ssize_t amt_written = write(outfd, p, amt_read);
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if (amt_written < 0) {
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if (errno == EINTR || errno == EAGAIN) continue;
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return false;
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}
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if (amt_written == 0) {
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errno = EIO;
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return false;
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}
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amt_read -= amt_written;
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p += amt_written;
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}
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}
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return true;
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}
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#ifdef HAS_SENDFILE
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static bool
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copy_with_sendfile(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
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unsigned num_of_consecutive_zero_returns = 128;
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while (len) {
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off_t r = in_pos;
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ssize_t n = sendfile(outfd, infd, &r, len);
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if (n < 0) {
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if (errno != EAGAIN) return false;
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if (errno == ENOSYS || errno == EPERM) return copy_with_buffer(infd, outfd, in_pos, len, fcb);
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continue;
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}
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if (n == 0) {
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// happens if input file is truncated
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if (!--num_of_consecutive_zero_returns) return false;
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continue;
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};
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num_of_consecutive_zero_returns = 128;
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in_pos += n; len -= n;
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}
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return true;
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}
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static bool
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copy_with_file_range(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
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#ifdef HAS_COPY_FILE_RANGE
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unsigned num_of_consecutive_zero_returns = 128;
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while (len) {
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off64_t r = in_pos;
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ssize_t n = copy_file_range(infd, &r, outfd, NULL, len, 0);
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if (n < 0) {
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if (errno != EAGAIN) return false;
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if (errno == ENOSYS || errno == EPERM) return copy_with_sendfile(infd, outfd, in_pos, len, fcb);
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continue;
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}
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if (n == 0) {
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// happens if input file is truncated
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if (!--num_of_consecutive_zero_returns) return false;
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continue;
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};
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num_of_consecutive_zero_returns = 128;
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in_pos += n; len -= n;
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}
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return true;
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#else
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return copy_with_sendfile(infd, outfd, in_pos, len, fcb);
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#endif
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}
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#endif
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bool
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copy_between_files(int infd, int outfd, off_t in_pos, size_t len, FastFileCopyBuffer *fcb) {
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#ifdef HAS_SENDFILE
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return copy_with_file_range(infd, outfd, in_pos, len, fcb);
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#else
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return copy_with_buffer(infd, outfd, in_pos, len, fcb);
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#endif
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return true;
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}
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