diff options
Diffstat (limited to 'erts/emulator/nifs/unix')
-rw-r--r-- | erts/emulator/nifs/unix/unix_prim_file.c | 957 |
1 files changed, 957 insertions, 0 deletions
diff --git a/erts/emulator/nifs/unix/unix_prim_file.c b/erts/emulator/nifs/unix/unix_prim_file.c new file mode 100644 index 0000000000..57c8ef62e1 --- /dev/null +++ b/erts/emulator/nifs/unix/unix_prim_file.c @@ -0,0 +1,957 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson 2017. All Rights Reserved. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * %CopyrightEnd% + */ + +#include "erl_nif.h" +#include "config.h" +#include "sys.h" + +#ifdef VALGRIND +# include <valgrind/memcheck.h> +#endif + +#include "prim_file_nif.h" + +#if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__) +#define __DARWIN__ 1 +#endif + +#if defined(__DARWIN__) || defined(HAVE_LINUX_FALLOC_H) || defined(HAVE_POSIX_FALLOCATE) +#include <fcntl.h> +#endif + +#ifdef HAVE_LINUX_FALLOC_H +#include <linux/falloc.h> +#endif + +#include <utime.h> + +/* Macros for testing file types. */ +#ifdef NO_UMASK +#define FILE_MODE 0644 +#define DIR_MODE 0755 +#else +#define FILE_MODE 0666 +#define DIR_MODE 0777 +#endif + +/* Old platforms might not have IOV_MAX defined. */ +#if !defined(IOV_MAX) && defined(UIO_MAXIOV) +#define IOV_MAX UIO_MAXIOV +#elif !defined(IOV_MAX) +#define IOV_MAX 16 +#endif + +typedef struct { + efile_data_t common; + int fd; +} efile_unix_t; + +static int has_invalid_null_termination(const ErlNifBinary *path) { + const char *null_pos, *end_pos; + + null_pos = memchr(path->data, '\0', path->size); + end_pos = (const char*)&path->data[path->size] - 1; + + if(null_pos == NULL) { + return 1; + } + + /* prim_file:internal_name2native sometimes feeds us data that is "doubly" + * NUL-terminated, so we'll accept any number of trailing NULs so long as + * they aren't interrupted by anything else. */ + while(null_pos < end_pos && (*null_pos) == '\0') { + null_pos++; + } + + return null_pos != end_pos; +} + +posix_errno_t efile_marshal_path(ErlNifEnv *env, ERL_NIF_TERM path, efile_path_t *result) { + if(!enif_inspect_binary(env, path, result)) { + return EINVAL; + } + + if(has_invalid_null_termination(result)) { + return EINVAL; + } + + return 0; +} + +ERL_NIF_TERM efile_get_handle(ErlNifEnv *env, efile_data_t *d) { + efile_unix_t *u = (efile_unix_t*)d; + + ERL_NIF_TERM result; + unsigned char *bits; + + bits = enif_make_new_binary(env, sizeof(u->fd), &result); + memcpy(bits, &u->fd, sizeof(u->fd)); + + return result; +} + +static int open_file_type_check(const efile_path_t *path, int fd) { + struct stat file_info; + int error; + +#ifndef HAVE_FSTAT + error = stat((const char*)path->data, &file_info); + (void)fd; +#else + error = fstat(fd, &file_info); + (void)path; +#endif + + if(error < 0) { + /* If we failed to stat assume success and let the next call handle the + * error. The old driver checked whether the file was to be used + * immediately in a read within the call, but the new implementation + * never does that. */ + return 1; + } else { + /* The old driver tolerated opening /dev/null despite the "no devices" + * limitation. It provided no explanation for this but we still need + * to match the behavior. We're checking through stat(2) instead of + * comparing the name to account for links. */ + struct stat null_device_info; + int is_dev_null; + + is_dev_null = (stat("/dev/null", &null_device_info) == 0); + is_dev_null &= (file_info.st_ino == null_device_info.st_ino); + is_dev_null &= (file_info.st_dev == null_device_info.st_dev); + + if(is_dev_null) { + return 1; + } + } + + if(!S_ISREG(file_info.st_mode)) { + return 0; + } + + return 1; +} + +posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes, + ErlNifResourceType *nif_type, efile_data_t **d) { + + int flags, fd; + + flags = 0; + + if(modes & EFILE_MODE_READ && !(modes & EFILE_MODE_WRITE)) { + flags |= O_RDONLY; + } else if(modes & EFILE_MODE_WRITE && !(modes & EFILE_MODE_READ)) { + if(!(modes & EFILE_MODE_NO_TRUNCATE)) { + flags |= O_TRUNC; + } + + flags |= O_WRONLY | O_CREAT; + } else if(modes & EFILE_MODE_READ_WRITE) { + flags |= O_RDWR | O_CREAT; + } else { + return EINVAL; + } + + if(modes & EFILE_MODE_APPEND) { + flags &= ~O_TRUNC; + flags |= O_APPEND; + } + + if(modes & EFILE_MODE_EXCLUSIVE) { + flags |= O_EXCL; + } + + if(modes & EFILE_MODE_SYNC) { +#ifndef O_SYNC + return ENOTSUP; +#else + flags |= O_SYNC; +#endif + } + + do { + fd = open((const char*)path->data, flags, FILE_MODE); + } while(fd == -1 && errno == EINTR); + + if(fd != -1) { + efile_unix_t *u; + + if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) && !open_file_type_check(path, fd)) { + close(fd); + + /* This is blatantly incorrect, but we're documented as returning + * this for everything that isn't a file. */ + return EISDIR; + } + + u = (efile_unix_t*)enif_alloc_resource(nif_type, sizeof(efile_unix_t)); + u->fd = fd; + + EFILE_INIT_RESOURCE(&u->common, modes); + (*d) = &u->common; + + return 0; + } + + (*d) = NULL; + return errno; +} + +int efile_close(efile_data_t *d) { + efile_unix_t *u = (efile_unix_t*)d; + int fd; + + ASSERT(erts_atomic32_read_nob(&d->state) == EFILE_STATE_CLOSED); + ASSERT(u->fd != -1); + + fd = u->fd; + u->fd = -1; + + /* close(2) either always closes (*BSD, Linux) or leaves the fd in an + * undefined state (POSIX 2008, Solaris), so we must not retry on EINTR. */ + + if(close(fd) < 0) { + u->common.posix_errno = errno; + return 0; + } + + return 1; +} + +static void shift_iov(SysIOVec **iov, int *iovlen, ssize_t shift) { + SysIOVec *head_vec = (*iov); + + ASSERT(shift >= 0); + + while(shift > 0) { + ASSERT(head_vec < &(*iov)[*iovlen]); + + if(shift < head_vec->iov_len) { + head_vec->iov_base = (char*)head_vec->iov_base + shift; + head_vec->iov_len -= shift; + break; + } else { + shift -= head_vec->iov_len; + head_vec++; + } + } + + (*iovlen) -= head_vec - (*iov); + (*iov) = head_vec; +} + +Sint64 efile_readv(efile_data_t *d, SysIOVec *iov, int iovlen) { + efile_unix_t *u = (efile_unix_t*)d; + + Sint64 bytes_read; + ssize_t result; + + bytes_read = 0; + + do { + int use_fallback = 0; + + if(iovlen < 1) { + result = 0; + break; + } + + /* writev(2) implies readv(2) */ +#ifdef HAVE_WRITEV + result = readv(u->fd, iov, MIN(IOV_MAX, iovlen)); + + /* Fall back to using read(2) if readv(2) reports that the combined + * size of iov is greater than SSIZE_T_MAX. */ + use_fallback = (result < 0 && errno == EINVAL); +#else + use_fallback = 1; +#endif + + if(use_fallback) { + result = read(u->fd, iov->iov_base, iov->iov_len); + } + + if(result > 0) { + shift_iov(&iov, &iovlen, result); + bytes_read += result; + } + } while(result > 0 || (result < 0 && errno == EINTR)); + + u->common.posix_errno = errno; + + if(result == 0 && bytes_read > 0) { + return bytes_read; + } + + return result; +} + +Sint64 efile_writev(efile_data_t *d, SysIOVec *iov, int iovlen) { + efile_unix_t *u = (efile_unix_t*)d; + + Sint64 bytes_written; + ssize_t result; + + bytes_written = 0; + + do { + int use_fallback = 0; + + if(iovlen < 1) { + result = 0; + break; + } + +#ifdef HAVE_WRITEV + result = writev(u->fd, iov, MIN(IOV_MAX, iovlen)); + + /* Fall back to using write(2) if writev(2) reports that the combined + * size of iov is greater than SSIZE_T_MAX. */ + use_fallback = (result < 0 && errno == EINVAL); +#else + use_fallback = 1; +#endif + + if(use_fallback) { + result = write(u->fd, iov->iov_base, iov->iov_len); + } + + if(result > 0) { + shift_iov(&iov, &iovlen, result); + bytes_written += result; + } + } while(result > 0 || (result < 0 && errno == EINTR)); + + u->common.posix_errno = errno; + + if(result == 0 && bytes_written > 0) { + return bytes_written; + } + + return result; +} + +Sint64 efile_preadv(efile_data_t *d, Sint64 offset, SysIOVec *iov, int iovlen) { + efile_unix_t *u = (efile_unix_t*)d; + + Uint64 bytes_read; + Sint64 result; + +#if !defined(HAVE_PREADV) && !defined(HAVE_PREAD) + /* This function is documented as leaving the file position undefined, but + * the old driver always reset it so there's probably code in the wild that + * relies on this behavior. */ + off_t original_position = lseek(u->fd, 0, SEEK_CUR); + + if(original_position < 0 || lseek(u->fd, offset, SEEK_SET) < 0) { + u->common.posix_errno = errno; + return -1; + } +#endif + + bytes_read = 0; + + do { + if(iovlen < 1) { + result = 0; + break; + } + +#if defined(HAVE_PREADV) + result = preadv(u->fd, iov, MIN(IOV_MAX, iovlen), offset); +#elif defined(HAVE_PREAD) + result = pread(u->fd, iov->iov_base, iov->iov_len, offset); +#else + result = read(u->fd, iov->iov_base, iov->iov_len); +#endif + + if(result > 0) { + shift_iov(&iov, &iovlen, result); + bytes_read += result; + offset += result; + } + } while(result > 0 || (result < 0 && errno == EINTR)); + + u->common.posix_errno = errno; + +#if !defined(HAVE_PREADV) && !defined(HAVE_PREAD) + if(result >= 0) { + if(lseek(u->fd, original_position, SEEK_SET) < 0) { + u->common.posix_errno = errno; + return -1; + } + } +#endif + + if(result == 0 && bytes_read > 0) { + return bytes_read; + } + + return result; +} + +Sint64 efile_pwritev(efile_data_t *d, Sint64 offset, SysIOVec *iov, int iovlen) { + efile_unix_t *u = (efile_unix_t*)d; + + Sint64 bytes_written; + ssize_t result; + +#if !defined(HAVE_PWRITEV) && !defined(HAVE_PWRITE) + off_t original_position = lseek(u->fd, 0, SEEK_CUR); + + if(original_position < 0 || lseek(u->fd, offset, SEEK_SET) < 0) { + u->common.posix_errno = errno; + return -1; + } +#endif + + bytes_written = 0; + + do { + if(iovlen < 1) { + result = 0; + break; + } + +#if defined(HAVE_PWRITEV) + result = pwritev(u->fd, iov, MIN(IOV_MAX, iovlen), offset); +#elif defined(HAVE_PWRITE) + result = pwrite(u->fd, iov->iov_base, iov->iov_len, offset); +#else + result = write(u->fd, iov->iov_base, iov->iov_len); +#endif + + if(result > 0) { + shift_iov(&iov, &iovlen, result); + bytes_written += result; + offset += result; + } + } while(result > 0 || (result < 0 && errno == EINTR)); + + u->common.posix_errno = errno; + +#if !defined(HAVE_PWRITEV) && !defined(HAVE_PWRITE) + if(result >= 0) { + if(lseek(u->fd, original_position, SEEK_SET) < 0) { + u->common.posix_errno = errno; + return -1; + } + } +#endif + + if(result == 0 && bytes_written > 0) { + return bytes_written; + } + + return result; +} + +int efile_seek(efile_data_t *d, enum efile_seek_t seek, Sint64 offset, Sint64 *new_position) { + efile_unix_t *u = (efile_unix_t*)d; + off_t result; + int whence; + + switch(seek) { + case EFILE_SEEK_BOF: whence = SEEK_SET; break; + case EFILE_SEEK_CUR: whence = SEEK_CUR; break; + case EFILE_SEEK_EOF: whence = SEEK_END; break; + default: ERTS_INTERNAL_ERROR("Invalid seek parameter"); + } + + result = lseek(u->fd, offset, whence); + + /* + * The man page for lseek (on SunOs 5) says: + * + * "if fildes is a remote file descriptor and offset is negative, lseek() + * returns the file pointer even if it is negative." + */ + if(result < 0 && errno == 0) { + errno = EINVAL; + } + + if(result < 0) { + u->common.posix_errno = errno; + return 0; + } + + (*new_position) = result; + + return 1; +} + +int efile_sync(efile_data_t *d, int data_only) { + efile_unix_t *u = (efile_unix_t*)d; + +#if defined(HAVE_FDATASYNC) && !defined(__DARWIN__) + if(data_only) { + if(fdatasync(u->fd) < 0) { + u->common.posix_errno = errno; + return 0; + } + + return 1; + } +#endif + +#if defined(__DARWIN__) && defined(F_FULLFSYNC) + if(fcntl(u->fd, F_FULLFSYNC) < 0) { +#else + if(fsync(u->fd) < 0) { +#endif + u->common.posix_errno = errno; + return 0; + } + + return 1; +} + +int efile_advise(efile_data_t *d, Sint64 offset, Sint64 length, enum efile_advise_t advise) { + efile_unix_t *u = (efile_unix_t*)d; +#ifdef HAVE_POSIX_FADVISE + int p_advise; + + switch(advise) { + case EFILE_ADVISE_NORMAL: p_advise = POSIX_FADV_NORMAL; break; + case EFILE_ADVISE_RANDOM: p_advise = POSIX_FADV_RANDOM; break; + case EFILE_ADVISE_SEQUENTIAL: p_advise = POSIX_FADV_SEQUENTIAL; break; + case EFILE_ADVISE_WILL_NEED: p_advise = POSIX_FADV_WILLNEED; break; + case EFILE_ADVISE_DONT_NEED: p_advise = POSIX_FADV_DONTNEED; break; + case EFILE_ADVISE_NO_REUSE: p_advise = POSIX_FADV_NOREUSE; break; + default: + u->common.posix_errno = EINVAL; + return 0; + } + + if(posix_fadvise(u->fd, offset, length, p_advise) < 0) { + u->common.posix_errno = errno; + return 0; + } + + return 1; +#else + /* We'll pretend to support this syscall as it's only a recommendation even + * on systems that do support it. */ + return 1; +#endif +} + +int efile_allocate(efile_data_t *d, Sint64 offset, Sint64 length) { + efile_unix_t *u = (efile_unix_t*)d; + int ret = -1; + + /* We prefer OS-specific methods, but fall back to posix_fallocate on + * failure. It's unclear whether this has any practical benefit on + * modern systems, but the old driver did it. */ + +#if defined(HAVE_FALLOCATE) + /* Linux-specific */ + do { + ret = fallocate(u->fd, FALLOC_FL_KEEP_SIZE, offset, length); + } while(ret < 0 && errno == EINTR); +#elif defined(F_PREALLOCATE) + /* Mac-specific */ + fstore_t fs = {}; + + fs.fst_flags = F_ALLOCATECONTIG; + fs.fst_posmode = F_VOLPOSMODE; + fs.fst_offset = offset; + fs.fst_length = length; + + ret = fcntl(u->fd, F_PREALLOCATE, &fs); + if(ret < 0) { + fs.fst_flags = F_ALLOCATEALL; + ret = fcntl(u->fd, F_PREALLOCATE, &fs); + } +#elif !defined(HAVE_POSIX_FALLOCATE) + u->common.posix_errno = ENOTSUP; + return 0; +#endif + +#ifdef HAVE_POSIX_FALLOCATE + if(ret < 0) { + do { + ret = posix_fallocate(u->fd, offset, length); + + /* On Linux and Solaris for example, posix_fallocate() returns a + * positive error number on error and it does not set errno. On + * FreeBSD however (9.0 at least), it returns -1 on error and it + * sets errno. */ + if (ret > 0) { + errno = ret; + ret = -1; + } + } while(ret < 0 && errno == EINTR); + } +#endif + + if(ret < 0) { + u->common.posix_errno = errno; + return 0; + } + + return 1; +} + +int efile_truncate(efile_data_t *d) { + efile_unix_t *u = (efile_unix_t*)d; + off_t offset; + + offset = lseek(u->fd, 0, SEEK_CUR); + + if(offset < 0) { + u->common.posix_errno = errno; + return 0; + } + + if(ftruncate(u->fd, offset) < 0) { + u->common.posix_errno = errno; + return 0; + } + + return 1; +} + +posix_errno_t efile_read_info(const efile_path_t *path, int follow_links, efile_fileinfo_t *result) { + struct stat data; + + if(follow_links) { + if(stat((const char*)path->data, &data) < 0) { + return errno; + } + } else { + if(lstat((const char*)path->data, &data) < 0) { + return errno; + } + } + + if(S_ISCHR(data.st_mode) || S_ISBLK(data.st_mode)) { + result->type = EFILE_FILETYPE_DEVICE; + } else if(S_ISDIR(data.st_mode)) { + result->type = EFILE_FILETYPE_DIRECTORY; + } else if(S_ISREG(data.st_mode)) { + result->type = EFILE_FILETYPE_REGULAR; + } else if(S_ISLNK(data.st_mode)) { + result->type = EFILE_FILETYPE_SYMLINK; + } else { + result->type = EFILE_FILETYPE_OTHER; + } + + result->a_time = (Sint64)data.st_atime; + result->m_time = (Sint64)data.st_mtime; + result->c_time = (Sint64)data.st_ctime; + result->size = data.st_size; + + result->major_device = data.st_dev; + result->minor_device = data.st_rdev; + result->links = data.st_nlink; + result->inode = data.st_ino; + result->mode = data.st_mode; + result->uid = data.st_uid; + result->gid = data.st_gid; + +#ifndef NO_ACCESS + result->access = EFILE_ACCESS_NONE; + + if(access((const char*)path->data, R_OK) == 0) { + result->access |= EFILE_ACCESS_READ; + } + if(access((const char*)path->data, W_OK) == 0) { + result->access |= EFILE_ACCESS_WRITE; + } +#else + /* Just look at read/write access for owner. */ + result->access = ((data.st_mode >> 6) & 07) >> 1; +#endif + + return 0; +} + +posix_errno_t efile_set_permissions(const efile_path_t *path, Uint32 permissions) { + const mode_t MUTABLE_MODES = (S_ISUID | S_ISGID | S_IRWXU | S_IRWXG | S_IRWXO); + mode_t new_modes = permissions & MUTABLE_MODES; + + if(chmod((const char*)path->data, new_modes) < 0) { + new_modes &= ~(S_ISUID | S_ISGID); + + if (chmod((const char*)path->data, new_modes) < 0) { + return errno; + } + } + + return 0; +} + +posix_errno_t efile_set_owner(const efile_path_t *path, Uint32 owner, Uint32 group) { + if(chown((const char*)path->data, owner, group) < 0) { + return errno; + } + + return 0; +} + +posix_errno_t efile_set_time(const efile_path_t *path, Sint64 a_time, Sint64 m_time, Sint64 c_time) { + struct utimbuf tval; + + tval.actime = (time_t)a_time; + tval.modtime = (time_t)m_time; + + (void)c_time; + + if(utime((const char*)path->data, &tval) < 0) { + return errno; + } + + return 0; +} + +posix_errno_t efile_read_link(ErlNifEnv *env, const efile_path_t *path, ERL_NIF_TERM *result) { + ErlNifBinary result_bin; + + if(!enif_alloc_binary(256, &result_bin)) { + return ENOMEM; + } + + for(;;) { + ssize_t bytes_copied; + + bytes_copied = readlink((const char*)path->data, (char*)result_bin.data, + result_bin.size); + + if(bytes_copied <= 0) { + posix_errno_t saved_errno = errno; + enif_release_binary(&result_bin); + return saved_errno; + } else if(bytes_copied < result_bin.size) { + if(!enif_realloc_binary(&result_bin, bytes_copied)) { + enif_release_binary(&result_bin); + return ENOMEM; + } + + (*result) = enif_make_binary(env, &result_bin); + + return 0; + } + + /* The result didn't fit into the buffer, so we'll try again with a + * larger one. */ + + if(!enif_realloc_binary(&result_bin, result_bin.size * 2)) { + enif_release_binary(&result_bin); + return ENOMEM; + } + } +} + +static int is_ignored_name(int name_length, const char *name) { + if(name_length == 1 && name[0] == '.') { + return 1; + } else if(name_length == 2 && memcmp(name, "..", 2) == 0) { + return 1; + } + + return 0; +} + +posix_errno_t efile_list_dir(ErlNifEnv *env, const efile_path_t *path, ERL_NIF_TERM *result) { + ERL_NIF_TERM list_head; + + struct dirent *dir_entry; + DIR *dir_stream; + + dir_stream = opendir((const char*)path->data); + if(dir_stream == NULL) { + posix_errno_t saved_errno = errno; + *result = enif_make_list(env, 0); + return saved_errno; + } + + list_head = enif_make_list(env, 0); + dir_entry = readdir(dir_stream); + + while(dir_entry != NULL) { + int name_length = strlen(dir_entry->d_name); + + if(!is_ignored_name(name_length, dir_entry->d_name)) { + unsigned char *name_bytes; + ERL_NIF_TERM name_term; + + name_bytes = enif_make_new_binary(env, name_length, &name_term); + sys_memcpy(name_bytes, dir_entry->d_name, name_length); + + list_head = enif_make_list_cell(env, name_term, list_head); + } + + dir_entry = readdir(dir_stream); + } + + (*result) = list_head; + closedir(dir_stream); + + return 0; +} + +posix_errno_t efile_rename(const efile_path_t *old_path, const efile_path_t *new_path) { + if(rename((const char*)old_path->data, (const char*)new_path->data) < 0) { + if(errno == ENOTEMPTY) { + return EEXIST; + } + + if(strcmp((const char*)old_path->data, "/") == 0) { + /* Alpha reports renaming / as EBUSY and Linux reports it as EACCES + * instead of EINVAL.*/ + return EINVAL; + } + + return errno; + } + + return 0; +} + +posix_errno_t efile_make_hard_link(const efile_path_t *existing_path, const efile_path_t *new_path) { + if(link((const char*)existing_path->data, (const char*)new_path->data) < 0) { + return errno; + } + + return 0; +} + +posix_errno_t efile_make_soft_link(const efile_path_t *existing_path, const efile_path_t *new_path) { + if(symlink((const char*)existing_path->data, (const char*)new_path->data) < 0) { + return errno; + } + + return 0; +} + +posix_errno_t efile_make_dir(const efile_path_t *path) { +#ifdef NO_MKDIR_MODE + if(mkdir((const char*)path->data) < 0) { +#else + if(mkdir((const char*)path->data, DIR_MODE) < 0) { +#endif + return errno; + } + + return 0; +} + +posix_errno_t efile_del_file(const efile_path_t *path) { + if(unlink((const char*)path->data) < 0) { + /* Linux sets the wrong error code. */ + if(errno == EISDIR) { + return EPERM; + } + + return errno; + } + + return 0; +} + +posix_errno_t efile_del_dir(const efile_path_t *path) { + if(rmdir((const char*)path->data) < 0) { + posix_errno_t saved_errno = errno; + + if(saved_errno == ENOTEMPTY) { + saved_errno = EEXIST; + } + + /* The error code might be wrong if we're trying to delete the current + * directory. */ + if(saved_errno == EEXIST) { + struct stat path_stat, cwd_stat; + int has_stat; + + has_stat = (stat((const char*)path->data, &path_stat) == 0); + has_stat &= (stat(".", &cwd_stat) == 0); + + if(has_stat && path_stat.st_ino == cwd_stat.st_ino) { + if(path_stat.st_dev == cwd_stat.st_dev) { + return EINVAL; + } + } + } + + return saved_errno; + } + + return 0; +} + +posix_errno_t efile_set_cwd(const efile_path_t *path) { + if(chdir((const char*)path->data) < 0) { + return errno; + } + + return 0; +} + +posix_errno_t efile_get_device_cwd(ErlNifEnv *env, int device_index, ERL_NIF_TERM *result) { + (void)device_index; + (void)result; + (void)env; + + return ENOTSUP; +} + +posix_errno_t efile_get_cwd(ErlNifEnv *env, ERL_NIF_TERM *result) { + ErlNifBinary result_bin; + size_t bytes_copied; + + if(!enif_alloc_binary(256, &result_bin)) { + return ENOMEM; + } + + while(getcwd((char*)result_bin.data, result_bin.size) == NULL) { + posix_errno_t saved_errno = errno; + + if(saved_errno != ERANGE) { + enif_release_binary(&result_bin); + return saved_errno; + } else { + if(!enif_realloc_binary(&result_bin, result_bin.size * 2)) { + enif_release_binary(&result_bin); + return ENOMEM; + } + } + } + + /* getcwd(2) guarantees null-termination. */ + bytes_copied = strlen((const char*)result_bin.data); + + if(!enif_realloc_binary(&result_bin, bytes_copied)) { + enif_release_binary(&result_bin); + return ENOMEM; + } + + (*result) = enif_make_binary(env, &result_bin); + + return 0; +} + +posix_errno_t efile_altname(ErlNifEnv *env, const efile_path_t *path, ERL_NIF_TERM *result) { + (void)path; + (void)result; + + return ENOTSUP; +} |