105 lines
1.9 KiB
C++
105 lines
1.9 KiB
C++
#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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struct __DIR
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{
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int fd { -1 };
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size_t entry_count { 0 };
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size_t entry_index { 0 };
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size_t entries_size { 0 };
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dirent* entries { nullptr };
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static constexpr size_t default_entries_size { 128 };
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};
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int closedir(DIR* dirp)
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{
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if (dirp == nullptr || dirp->fd == -1)
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{
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errno = EBADF;
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return -1;
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}
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close(dirp->fd);
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free(dirp);
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return 0;
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}
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int dirfd(DIR* dirp)
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{
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if (dirp == nullptr || dirp->fd == -1)
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{
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errno = EINVAL;
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return -1;
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}
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return dirp->fd;
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}
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DIR* fdopendir(int fd)
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{
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DIR* dirp = static_cast<DIR*>(malloc(sizeof(DIR)));
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if (dirp == nullptr)
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return nullptr;
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dirp->entries = static_cast<dirent*>(malloc(DIR::default_entries_size * sizeof(dirent)));
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dirp->entries_size = DIR::default_entries_size;
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if (dirp->entries == nullptr)
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{
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free(dirp);
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return nullptr;
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}
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dirp->fd = fd;
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dirp->entry_count = 0;
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dirp->entry_index = 0;
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return dirp;
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}
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DIR* opendir(const char* dirname)
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{
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int fd = open(dirname, O_RDONLY);
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if (fd == -1)
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return nullptr;
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return fdopendir(fd);
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}
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struct dirent* readdir(DIR* dirp)
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{
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if (dirp == nullptr || dirp->fd == -1)
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{
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errno = EBADF;
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return nullptr;
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}
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dirp->entry_index++;
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if (dirp->entry_index < dirp->entry_count)
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return &dirp->entries[dirp->entry_index];
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readdir_do_syscall:
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long entry_count = syscall(SYS_READ_DIR, dirp->fd, dirp->entries, dirp->entries_size);
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if (entry_count == -1 && errno == ENOBUFS)
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{
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const size_t new_entries_size = dirp->entries_size * 2;
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dirent* new_entries = static_cast<dirent*>(malloc(new_entries_size * sizeof(dirent)));
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if (new_entries == nullptr)
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return nullptr;
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dirp->entries = new_entries;
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dirp->entries_size = new_entries_size;
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goto readdir_do_syscall;
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}
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if (entry_count <= 0)
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return nullptr;
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dirp->entry_count = entry_count;
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dirp->entry_index = 0;
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return &dirp->entries[0];
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}
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