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Hash cache: Improved work with extended file attributes #309

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merged 2 commits into from
Apr 29, 2024
Merged

Hash cache: Improved work with extended file attributes #309

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fdcb846
Define and use xattr key to store mtime of file checksum as macro
jrohel Apr 25, 2024
9cbda3c
Do not work with xattrs after finding out that they are not supported
jrohel Apr 25, 2024
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35 changes: 22 additions & 13 deletions librepo/checksum.c
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Original file line number Diff line number Diff line change
Expand Up @@ -229,19 +229,18 @@ lr_checksum_fd_compare(LrChecksumType type,

_cleanup_free_ gchar *timestamp_str = g_strdup_printf("%lli", timestamp);
const char *type_str = lr_checksum_type_to_str(type);
_cleanup_free_ gchar *timestamp_key = g_strconcat(XATTR_CHKSUM_PREFIX, "mtime", NULL);
_cleanup_free_ gchar *checksum_key = g_strconcat(XATTR_CHKSUM_PREFIX, type_str, NULL);

if (caching && timestamp != -1) {
// Load cached checksum if enabled and used
char buf[256];
ssize_t attr_size;
attr_size = FGETXATTR(fd, timestamp_key, &buf, sizeof(buf)-1);
attr_size = FGETXATTR(fd, XATTR_CHKSUM_MTIME, &buf, sizeof(buf)-1);
if (attr_size != -1) {
buf[attr_size] = 0;
// check that mtime stored in xattr is the same as timestamp
if (strcmp(timestamp_str, buf) == 0) {
g_debug("%s: Using mtime cached in xattr: [%s] %s", __func__, timestamp_key, buf);
g_debug("%s: Using mtime cached in xattr: [%s] %s", __func__, XATTR_CHKSUM_MTIME, buf);
attr_size = FGETXATTR(fd, checksum_key, &buf, sizeof(buf)-1);
if (attr_size != -1) {
buf[attr_size] = 0;
Expand All @@ -257,6 +256,10 @@ lr_checksum_fd_compare(LrChecksumType type,
// timestamp stored in xattr is different => checksums are no longer valid
lr_checksum_clear_cache(fd);
}
} else if (errno == ENOTSUP) {
// Extended attributes are not supported by the filesystem, or are disabled.
// Disable the use of extended attributes for cache.
caching = FALSE;
}
}

Expand All @@ -279,7 +282,7 @@ lr_checksum_fd_compare(LrChecksumType type,

if (caching && *matches && timestamp != -1) {
// Store timestamp and checksum as extended file attribute if caching is enabled
FSETXATTR(fd, timestamp_key, timestamp_str, strlen(timestamp_str), 0);
FSETXATTR(fd, XATTR_CHKSUM_MTIME, timestamp_str, strlen(timestamp_str), 0);
FSETXATTR(fd, checksum_key, checksum, strlen(checksum), 0);
}

Expand All @@ -294,22 +297,28 @@ lr_checksum_fd_compare(LrChecksumType type,
void
lr_checksum_clear_cache(int fd)
{
char *xattrs = NULL;
ssize_t xattrs_len;
ssize_t bytes_read;
const char *attr;
ssize_t prefix_len = strlen(XATTR_CHKSUM_PREFIX);
// Remove the extended attribute containing mtime.
if (FREMOVEXATTR(fd, XATTR_CHKSUM_MTIME) == -1) {
if (errno == ENOTSUP) {
// Extended attributes are not supported by the filesystem, or are disabled.
return;
}
}

xattrs_len = FLISTXATTR(fd, NULL, 0);
// Remove the other extended attributes used by librepo to store the file checksum.
// Librepo does not need this to work properly. Deleting the mtime attribute is sufficient.
// We're just cleaning up.
ssize_t xattrs_len = FLISTXATTR(fd, NULL, 0);
if (xattrs_len <= 0) {
return;
}
xattrs = lr_malloc(xattrs_len);
bytes_read = FLISTXATTR(fd, xattrs, xattrs_len);
char *xattrs = lr_malloc(xattrs_len);
ssize_t bytes_read = FLISTXATTR(fd, xattrs, xattrs_len);
if (bytes_read < 0) {
goto cleanup;
}
attr = xattrs;
ssize_t prefix_len = strlen(XATTR_CHKSUM_PREFIX);
const char *attr = xattrs;
while (attr < xattrs + xattrs_len) {
if (strncmp(XATTR_CHKSUM_PREFIX, attr, prefix_len) == 0) {
FREMOVEXATTR(fd, attr);
Expand Down
1 change: 1 addition & 0 deletions librepo/xattr_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
#define __LR_XATTR_INTERNAL_H__

#define XATTR_CHKSUM_PREFIX "user.Librepo.checksum."
#define XATTR_CHKSUM_MTIME XATTR_CHKSUM_PREFIX "mtime"

#if __APPLE__

Expand Down
20 changes: 7 additions & 13 deletions tests/test_checksum.c
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Original file line number Diff line number Diff line change
Expand Up @@ -102,7 +102,6 @@ START_TEST(test_cached_checksum_matches)
struct stat st;
char buf[256];
GError *tmp_err = NULL;
gchar *timestamp_key = g_strconcat(XATTR_CHKSUM_PREFIX, "mtime", NULL);
gchar *checksum_key = g_strconcat(XATTR_CHKSUM_PREFIX, "sha256", NULL);
gchar *mtime_str = NULL;

Expand All @@ -113,7 +112,7 @@ START_TEST(test_cached_checksum_matches)
fclose(f);

// Assert no cached checksum exists
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf)-1);
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached timestamp should not exists
attr_ret = GETXATTR(filename, checksum_key, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached checksum should not exists
Expand Down Expand Up @@ -155,7 +154,7 @@ START_TEST(test_cached_checksum_matches)
timestamp *= 1000000000; //convert sec timestamp to nanosec timestamp
timestamp += st.st_mtim.tv_nsec;
mtime_str = g_strdup_printf("%lli", timestamp);
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf)-1);
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf)-1);
ck_assert(attr_ret != -1);
buf[attr_ret] = 0;
ck_assert_str_eq(buf, mtime_str);
Expand All @@ -176,7 +175,6 @@ START_TEST(test_cached_checksum_matches)

exit_label:
lr_free(filename);
lr_free(timestamp_key);
lr_free(checksum_key);
lr_free(mtime_str);
}
Expand All @@ -192,7 +190,6 @@ START_TEST(test_cached_checksum_value)
static char *expected = "d78931fcf2660108eec0d6674ecb4e02401b5256a6b5ee82527766ef6d198c67";
char buf[256];
GError *tmp_err = NULL;
gchar *timestamp_key = g_strconcat(XATTR_CHKSUM_PREFIX, "mtime", NULL);
gchar *checksum_key = g_strconcat(XATTR_CHKSUM_PREFIX, "sha256", NULL);
gchar *mtime_str = NULL;
gchar *calculated = NULL;
Expand All @@ -204,7 +201,7 @@ START_TEST(test_cached_checksum_value)
fclose(f);

// Assert no cached checksum exists
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf)-1);
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached timestamp should not exists
attr_ret = GETXATTR(filename, checksum_key, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached checksum should not exists
Expand All @@ -229,14 +226,13 @@ START_TEST(test_cached_checksum_value)
// Assert no cached checksum exists
// This assumes issue #235 is unresolved. Once it is, this code
// should fail and the test will need updated.
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf)-1);
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached timestamp should not exists
attr_ret = GETXATTR(filename, checksum_key, &buf, sizeof(buf)-1);
ck_assert(attr_ret == -1); // Cached checksum should not exists

lr_free(calculated);
g_free(filename);
g_free(timestamp_key);
g_free(checksum_key);
lr_free(mtime_str);
}
Expand All @@ -249,7 +245,6 @@ START_TEST(test_cached_checksum_clear)
ssize_t attr_ret;
char *filename;
char buf[256];
gchar *timestamp_key = g_strconcat(XATTR_CHKSUM_PREFIX, "mtime", NULL);
gchar *checksum_key = g_strconcat(XATTR_CHKSUM_PREFIX, "sha256", NULL);
const char *other_key = "user.Other.Attribute";
const char *value = "some value";
Expand All @@ -262,7 +257,7 @@ START_TEST(test_cached_checksum_clear)
// set extended attributes
fd = open(filename, O_RDONLY);
ck_assert_int_ge(fd, 0);
attr_ret = FSETXATTR(fd, timestamp_key, value, strlen(value), 0);
attr_ret = FSETXATTR(fd, XATTR_CHKSUM_MTIME, value, strlen(value), 0);
if (attr_ret == -1) {
if (errno == ENOTSUP) {
goto cleanup;
Expand All @@ -275,7 +270,7 @@ START_TEST(test_cached_checksum_clear)
ck_assert(attr_ret != -1);

// verify that xattrs are set
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf));
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf));
ck_assert(attr_ret != -1);
attr_ret = GETXATTR(filename, checksum_key, &buf, sizeof(buf));
ck_assert(attr_ret != -1);
Expand All @@ -285,7 +280,7 @@ START_TEST(test_cached_checksum_clear)
lr_checksum_clear_cache(fd);

// verify that checksum xattrs are removed
attr_ret = GETXATTR(filename, timestamp_key, &buf, sizeof(buf));
attr_ret = GETXATTR(filename, XATTR_CHKSUM_MTIME, &buf, sizeof(buf));
ck_assert(attr_ret == -1);
attr_ret = GETXATTR(filename, checksum_key, &buf, sizeof(buf));
ck_assert(attr_ret == -1);
Expand All @@ -295,7 +290,6 @@ START_TEST(test_cached_checksum_clear)
cleanup:
close(fd);
g_free(filename);
g_free(timestamp_key);
g_free(checksum_key);
}
END_TEST
Expand Down
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