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/*
* SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <dirent.h>
#include <sys/param.h>
/* realpath logic:
* 1. prepend CWD (/)
* 2. iterate over components (search until next '/' or end of line)
* - empty, skip the component
* - if it is '.', skip the component
* - if it is '..'
* - and out_level == 0, ??? ('/..')
* - otherwise, reverse-search for '/', set out_pos to that - 1, decrement out_level
* - otherwise, add the component to output, increment out_level
*/
char * realpath(const char *file_name, char *resolved_name)
{
char * out_path = resolved_name;
if (out_path == NULL) {
/* allowed as an extension, allocate memory for the output path */
out_path = malloc(PATH_MAX);
if (out_path == NULL) {
errno = ENOMEM;
return NULL;
}
}
/* canonical path starts with / */
strlcpy(out_path, "/", PATH_MAX);
/* pointers moving over the input and output path buffers */
const char* in_ptr = file_name;
char* out_ptr = out_path + 1;
/* number of path components in the output buffer */
size_t out_depth = 0;
while (*in_ptr) {
/* "path component" is the part between two '/' path separators.
* locate the next path component in the input path:
*/
const char* end_of_path_component = strchrnul(in_ptr, '/');
size_t path_component_len = end_of_path_component - in_ptr;
if (path_component_len == 0 ||
(path_component_len == 1 && in_ptr[0] == '.')) {
/* empty path component or '.' - nothing to do */
} else if (path_component_len == 2 && in_ptr[0] == '.' && in_ptr[1] == '.') {
/* '..' - remove one path component from the output */
if (out_depth == 0) {
/* nothing to remove */
} else if (out_depth == 1) {
/* there is only one path component in output;
* remove it, but keep the leading separator
*/
out_ptr = out_path + 1;
*out_ptr = '\0';
out_depth = 0;
} else {
/* remove last path component and the separator preceding it */
char * prev_sep = strrchr(out_path, '/');
assert(prev_sep > out_path); /* this shouldn't be the leading separator */
out_ptr = prev_sep;
*out_ptr = '\0';
--out_depth;
}
} else {
/* copy path component to output; +1 is for the separator */
if (out_ptr - out_path + 1 + path_component_len > PATH_MAX - 1) {
/* output buffer insufficient */
errno = E2BIG;
goto fail;
} else {
/* add separator if necessary */
if (out_depth > 0) {
*out_ptr = '/';
++out_ptr;
}
memcpy(out_ptr, in_ptr, path_component_len);
out_ptr += path_component_len;
*out_ptr = '\0';
++out_depth;
}
}
/* move input pointer to separator right after this path component */
in_ptr += path_component_len;
if (*in_ptr != '\0') {
/* move past it unless already at the end of the input string */
++in_ptr;
}
}
return out_path;
fail:
if (resolved_name == NULL) {
/* out_path was allocated, free it */
free(out_path);
}
return NULL;
}
char * getcwd(char *buf, size_t size)
{
if (buf == NULL) {
return strdup("/");
}
strlcpy(buf, "/", size);
return buf;
}
int chdir(const char *path)
{
(void) path;
errno = ENOSYS;
return -1;
}
/* std::filesystem functions call chmod and exit with an exception if it fails,
* so not failing with ENOSYS seems a better solution.
*/
int chmod(const char *path, mode_t mode)
{
return 0;
}
/* As a workaround for libstdc++ being built with _GLIBCXX_HAVE_DIRFD,
* we have to provide at least a stub for dirfd function.
*/
int dirfd(DIR *dirp)
{
errno = ENOSYS;
return -1;
}