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#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
const char *get_filename_ext(const char *filename) {
const char *dot = strrchr(filename, '.');
if (!dot || dot == filename) return "";
return dot + 1;
}
static int write_all(int fd, const void *buf, size_t size) {
while (size) {
ssize_t written = write(fd, buf, size);
if (written < 0) {
return -1;
}
size -= written;
buf = (const char *)buf + written;
}
return 0;
}
static int copy_file_content(int src_fd, int dst_fd) {
char buf[4096];
ssize_t readed;
while ((readed = read(src_fd, buf, sizeof(buf))) > 0) {
if (write_all(dst_fd, buf, readed) < 0) {
perror("write_all");
return -1;
}
}
if (readed < 0) {
perror("read");
return -1;
}
return 0;
}
static int copy_at(int src_dir_fd, const char *src_path, int dst_dir_fd, const char *dst_path);
static int copy_dir_content(int src_fd, int dst_fd) {
int ret = -1;
// duplicate the descriptor to prevent closedir from closing original one
src_fd = dup(src_fd);
if (src_fd < 0) {
perror("dup");
goto cleanup0;
}
DIR *src_dir = fdopendir(src_fd);
if (!src_dir) {
perror("fdopendir");
close(src_fd);
goto cleanup0;
}
for (struct dirent *ent; (errno = 0, ent = readdir(src_dir));) {
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) {
continue;
}
if (copy_at(src_fd, ent->d_name, dst_fd, ent->d_name) < 0) {
goto cleanup1;
}
}
if (errno != 0) {
perror("readdir");
goto cleanup1;
}
ret = 0;
cleanup1:
closedir(src_dir);
cleanup0:
return ret;
}
#define ERROR_NOT_A_SYMLINK (-2)
static int copy_symlink(int src_dir_fd, const char *src_path, int dst_dir_fd, const char *dst_path) {
char symlink_target[PATH_MAX];
ssize_t symlink_target_len = readlinkat(src_dir_fd, src_path, symlink_target, sizeof(symlink_target) - 1);
if (symlink_target_len >= 0) {
symlink_target[symlink_target_len] = '\0';
if (symlinkat(symlink_target, dst_dir_fd, dst_path) < 0) {
perror("symlinkat");
return -1;
}
return 0;
} else if (errno == EINVAL) {
return ERROR_NOT_A_SYMLINK;
} else {
perror("readlinkat");
return -1;
}
}
static int copy_at(int src_dir_fd, const char *src_path, int dst_dir_fd, const char *dst_path) {
int ret = copy_symlink(src_dir_fd, src_path, dst_dir_fd, dst_path);
if (ret != ERROR_NOT_A_SYMLINK) {
goto cleanup0;
}
ret = -1;
int src_fd = openat(src_dir_fd, src_path, O_NOFOLLOW | O_RDONLY);
if (src_fd < 0) {
perror("openat");
goto cleanup0;
}
struct stat stat;
if (fstat(src_fd, &stat) < 0) {
perror("fstat");
goto cleanup1;
}
int dst_oflag = O_NOFOLLOW;
if (S_ISDIR(stat.st_mode)) {
if (mkdirat(dst_dir_fd, dst_path, stat.st_mode) < 0) {
perror("mkdirat");
goto cleanup1;
}
dst_oflag |= O_RDONLY | O_DIRECTORY;
} else {
dst_oflag |= O_WRONLY | O_CREAT | O_EXCL;
}
int dst_fd = openat(dst_dir_fd, dst_path, dst_oflag, stat.st_mode);
if (dst_fd < 0) {
perror("openat");
goto cleanup1;
}
switch (stat.st_mode & S_IFMT) {
case S_IFDIR:
ret = copy_dir_content(src_fd, dst_fd);
break;
case S_IFREG:
ret = copy_file_content(src_fd, dst_fd);
break;
default:
fprintf(stderr, "copy_at: unsupported file inode type\n");
}
cleanup2:
close(dst_fd);
cleanup1:
close(src_fd);
cleanup0:
return ret;
}
void cpdir(const char *src_path, const char *dst_path) {
copy_at(AT_FDCWD, src_path, AT_FDCWD, dst_path);
}
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