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perf: direct syscall fastpath for absolute paths in zend_virtual_cwd #22722

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perf: direct syscall fastpath for absolute paths in zend_virtual_cwd #22722

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1a02d9e
perf: direct syscall fastpath for absolute paths in zend_virtual_cwd
henderkes Jul 14, 2026
f86110c
use kernel resolution for use_realpath: CWD_REALPATH
henderkes Jul 17, 2026
ab77592
remove realcache enabled check
henderkes Sep 17, 2026
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69 changes: 69 additions & 0 deletions Zend/zend_virtual_cwd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1301,6 +1301,27 @@ CWD_API int virtual_filepath(const char *path, char **filepath) /* {{{ */
}
/* }}} */

#ifndef ZEND_WIN32
/* An absolute path without dot segments doesn't need a per-thread CWD emulation */
static zend_always_inline bool virtual_path_is_direct(const char *path)
{
const char *s = path;

if (*s != '/') {
return false;
}
do {
if (s[1] == '.'
&& (s[2] == '\0' || s[2] == '/'
|| (s[2] == '.' && (s[3] == '\0' || s[3] == '/')))) {
return false;
}
s = strchr(s + 1, '/');
} while (s != NULL);
return true;
}
#endif

CWD_API FILE *virtual_fopen(const char *path, const char *mode) /* {{{ */
{
cwd_state new_state;
Expand All @@ -1310,6 +1331,12 @@ CWD_API FILE *virtual_fopen(const char *path, const char *mode) /* {{{ */
return NULL;
}

#ifndef ZEND_WIN32
if (virtual_path_is_direct(path)) {
return fopen(path, mode);
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}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, path, NULL, CWD_EXPAND)) {
CWD_STATE_FREE_ERR(&new_state);
Expand All @@ -1333,6 +1360,12 @@ CWD_API int virtual_access(const char *pathname, int mode) /* {{{ */
cwd_state new_state;
int ret;

#ifndef ZEND_WIN32
if (pathname[0] == '/') {
return access(pathname, mode);
}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, pathname, NULL, CWD_REALPATH)) {
CWD_STATE_FREE_ERR(&new_state);
Expand Down Expand Up @@ -1442,6 +1475,21 @@ CWD_API int virtual_open(const char *path, int flags, ...) /* {{{ */
cwd_state new_state;
int f;

#ifndef ZEND_WIN32
if (virtual_path_is_direct(path)) {
if (flags & O_CREAT) {
mode_t mode;
va_list arg;

va_start(arg, flags);
mode = (mode_t) va_arg(arg, int);
va_end(arg);
return open(path, flags, mode);
}
return open(path, flags);
}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, path, NULL, CWD_FILEPATH)) {
CWD_STATE_FREE_ERR(&new_state);
Expand Down Expand Up @@ -1533,6 +1581,12 @@ CWD_API int virtual_stat(const char *path, zend_stat_t *buf) /* {{{ */
cwd_state new_state;
int retval;

#ifndef ZEND_WIN32
if (path[0] == '/') {
return php_sys_stat(path, buf);
}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, path, NULL, CWD_REALPATH)) {
CWD_STATE_FREE_ERR(&new_state);
Expand All @@ -1551,6 +1605,15 @@ CWD_API int virtual_lstat(const char *path, zend_stat_t *buf) /* {{{ */
cwd_state new_state;
int retval;

#ifndef ZEND_WIN32
/* CWD_EXPAND strips '..' textually (save=0 -> no symlink lookups),
* but the kernel resolves it physically. Different file
* when a parent component is a symlink. */
if (virtual_path_is_direct(path)) {
return php_sys_lstat(path, buf);
}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, path, NULL, CWD_EXPAND)) {
CWD_STATE_FREE_ERR(&new_state);
Expand Down Expand Up @@ -1637,6 +1700,12 @@ CWD_API DIR *virtual_opendir(const char *pathname) /* {{{ */
cwd_state new_state;
DIR *retval;

#ifndef ZEND_WIN32
if (virtual_path_is_direct(pathname)) {
return opendir(pathname);
}
#endif

CWD_STATE_COPY(&new_state, &CWDG(cwd));
if (virtual_file_ex(&new_state, pathname, NULL, CWD_REALPATH)) {
CWD_STATE_FREE_ERR(&new_state);
Expand Down
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