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Merge pull request #33330 from poettering/copy-tweaks

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Minor tweaks to copy_bytes()
This commit is contained in:
Luca Boccassi 2024-06-15 00:12:48 +01:00 committed by GitHub
commit 67153a7bc4
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1 changed files with 29 additions and 13 deletions
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42
src/shared/copy.c
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@ -41,7 +41,12 @@
#include "user-util.h"
#include "xattr-util.h"
#define COPY_BUFFER_SIZE (16U*1024U)
/* If we copy via a userspace buffer, size it to 64K */
#define COPY_BUFFER_SIZE (64U*U64_KB)
/* If a byte progress function is specified during copying, never try to copy more than 1M, so that we can
* reasonably call the progress function still */
#define PROGRESS_STEP_SIZE (1U*U64_MB)
/* A safety net for descending recursively into file system trees to copy. On Linux PATH_MAX is 4096, which means the
* deepest valid path one can build is around 2048, which we hence use as a safety net here, to not spin endlessly in
@ -162,9 +167,9 @@ int copy_bytes_full(
void *userdata) {
_cleanup_close_ int fdf_opened = -EBADF, fdt_opened = -EBADF;
bool try_cfr = true, try_sendfile = true, try_splice = true, copied_something = false;
bool try_cfr = true, try_sendfile = true, try_splice = true;
uint64_t copied_total = 0;
int r, nonblock_pipe = -1;
size_t m = SSIZE_MAX; /* that is the maximum that sendfile and c_f_r accept */
assert(fdf >= 0);
assert(fdt >= 0);
@ -264,6 +269,7 @@ int copy_bytes_full(
for (;;) {
ssize_t n;
size_t m;
if (max_bytes <= 0)
break;
@ -272,9 +278,20 @@ int copy_bytes_full(
if (r < 0)
return r;
/* sendfile() accepts at most SSIZE_MAX-offset bytes to copy, hence let's subtract how much
* copied so far from SSIZE_MAX as maximum of what we want to copy. */
if (try_sendfile) {
assert(copied_total < SSIZE_MAX);
m = (uint64_t) SSIZE_MAX - copied_total;
} else
m = SSIZE_MAX;
if (max_bytes != UINT64_MAX && m > max_bytes)
m = max_bytes;
if (progress && m > PROGRESS_STEP_SIZE)
m = PROGRESS_STEP_SIZE;
if (copy_flags & COPY_HOLES) {
off_t c, e;
@ -342,7 +359,7 @@ int copy_bytes_full(
/* use fallback below */
} else if (n == 0) { /* likely EOF */
if (copied_something)
if (copied_total > 0)
break;
/* So, we hit EOF immediately, without having copied a single byte. This
@ -369,7 +386,7 @@ int copy_bytes_full(
/* use fallback below */
} else if (n == 0) { /* likely EOF */
if (copied_something)
if (copied_total > 0)
break;
try_sendfile = try_splice = false; /* same logic as above for copy_file_range() */
@ -432,7 +449,7 @@ int copy_bytes_full(
/* use fallback below */
} else if (n == 0) { /* likely EOF */
if (copied_something)
if (copied_total > 0)
break;
try_splice = false; /* same logic as above for copy_file_range() + sendfile() */
@ -483,6 +500,12 @@ int copy_bytes_full(
}
next:
copied_total += n;
/* Disable sendfile() in case we are getting too close to it's SSIZE_MAX-offset limit */
if (copied_total > SSIZE_MAX - COPY_BUFFER_SIZE)
try_sendfile = false;
if (progress) {
r = progress(n, userdata);
if (r < 0)
@ -493,13 +516,6 @@ int copy_bytes_full(
assert(max_bytes >= (uint64_t) n);
max_bytes -= n;
}
/* sendfile accepts at most SSIZE_MAX-offset bytes to copy, so reduce our maximum by the
* amount we already copied, but don't go below our copy buffer size, unless we are close the
* limit of bytes we are allowed to copy. */
m = MAX(MIN(COPY_BUFFER_SIZE, max_bytes), m - n);
copied_something = true;
}
if (FLAGS_SET(copy_flags, COPY_VERIFY_LINKED)) {