src/compat/fcntl.h

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright 2015 (c) Jérémie Galarneau <jeremie.galarneau@efficios.com>
   5  *
   6  * fcntl compatibility layer.
   7  */
   8
   9 #ifndef _BABELTRACE_COMPAT_FCNTL_H
  10 #define _BABELTRACE_COMPAT_FCNTL_H
  11
  12 #include "common/common.h"
  13
  14 #ifdef BABELTRACE_HAVE_POSIX_FALLOCATE
  15
  16 #include <fcntl.h>
  17
  18 static inline
  19 int bt_posix_fallocate(int fd, off_t offset, off_t len)
  20 {
  21         return posix_fallocate(fd, offset, len);
  22 }
  23
  24 #elif defined(__MINGW32__) /* #ifdef BABELTRACE_HAVE_POSIX_FALLOCATE */
  25
  26 #include <stdlib.h>
  27 #include <windows.h>
  28 #include <fcntl.h>
  29
  30 static inline
  31 int bt_posix_fallocate(int fd, off_t offset, off_t len)
  32 {
  33         HANDLE handle;
  34         LARGE_INTEGER pos, file_pos, orig_end_offset, range_end;
  35         int ret = 0;
  36         char zero = 0;
  37         DWORD byteswritten;
  38
  39         if (offset < 0 || len <= 0) {
  40                 ret = EINVAL;
  41                 goto end;
  42         }
  43
  44         range_end.QuadPart = (__int64) offset + (__int64) len;
  45
  46         /* Get a handle from the fd */
  47         handle = (HANDLE) _get_osfhandle(fd);
  48         if (handle == INVALID_HANDLE_VALUE) {
  49                 ret = EBADF;
  50                 goto end;
  51         }
  52
  53         /* Get the file original end offset */
  54         ret = GetFileSizeEx(handle, &orig_end_offset);
  55         if (ret == 0) {
  56                 ret = EBADF;
  57                 goto end;
  58         }
  59
  60         /* Make sure we don't truncate the file */
  61         if (orig_end_offset.QuadPart >= range_end.QuadPart) {
  62                 ret = 0;
  63                 goto end;
  64         }
  65
  66         /* Get the current file pointer position */
  67         pos.QuadPart = 0;
  68         ret = SetFilePointerEx(handle, pos, &file_pos, FILE_CURRENT);
  69         if (ret == 0) {
  70                 ret = EBADF;
  71                 goto end;
  72         }
  73
  74         /* Move the file pointer to the new end offset */
  75         ret = SetFilePointerEx(handle, range_end, NULL, FILE_BEGIN);
  76         if (ret == 0) {
  77                 ret = EBADF;
  78                 goto end;
  79         }
  80
  81         /* Sets the physical file size to the current position */
  82         ret = SetEndOfFile(handle);
  83         if (ret == 0) {
  84                 ret = EINVAL;
  85                 goto restore;
  86         }
  87
  88         /*
  89          * Move the file pointer back 1 byte, and write a single 0 at the
  90          * last byte of the new end offset, the operating system will zero
  91          * fill the file.
  92          */
  93         pos.QuadPart = -1;
  94         ret = SetFilePointerEx(handle, pos, NULL, FILE_END);
  95         if (ret == 0) {
  96                 ret = EBADF;
  97                 goto end;
  98         }
  99
 100         ret = WriteFile(handle, &zero, 1, &byteswritten, NULL);
 101         if (ret == 0 || byteswritten != 1) {
 102                 ret = ENOSPC;
 103         } else {
 104                 ret = 0;
 105         }
 106
 107 restore:
 108         /* Restore the original file pointer position */
 109         if (!SetFilePointerEx(handle, file_pos, NULL, FILE_BEGIN)) {
 110                 /* We moved the file pointer but failed to restore it. */
 111                 bt_common_abort();
 112         }
 113
 114 end:
 115         return ret;
 116 }
 117
 118 #else
 119
 120 #include <sys/types.h>
 121 #include <unistd.h>
 122 #include <string.h>
 123
 124 #define BABELTRACE_FALLOCATE_BUFLEN     256
 125
 126 #ifndef min_t
 127 #define min_t(type, a, b)       \
 128         ((type) (a) < (type) (b) ? (type) (a) : (type) (b))
 129 #endif
 130
 131 static inline
 132 int bt_posix_fallocate(int fd, off_t offset, off_t len)
 133 {
 134         int ret = 0;
 135         ssize_t copy_len;
 136         char buf[BABELTRACE_FALLOCATE_BUFLEN];
 137         off_t i, file_pos, orig_end_offset, range_end;
 138
 139         if (offset < 0 || len < 0) {
 140                 ret = EINVAL;
 141                 goto end;
 142         }
 143
 144         range_end = offset + len;
 145         if (range_end < 0) {
 146                 ret = EFBIG;
 147                 goto end;
 148         }
 149
 150         file_pos = lseek(fd, 0, SEEK_CUR);
 151         if (file_pos < 0) {
 152                 ret = errno;
 153                 goto end;
 154         }
 155
 156         orig_end_offset = lseek(fd, 0, SEEK_END);
 157         if (orig_end_offset < 0) {
 158                 ret = errno;
 159                 goto end;
 160         }
 161
 162         /* Seek back to original position. */
 163         ret = lseek(fd, file_pos, SEEK_SET);
 164         if (ret) {
 165                 ret = errno;
 166                 goto end;
 167         }
 168
 169         /*
 170          * The file may not need to grow, but we want to ensure the
 171          * space has actually been reserved by the file system. First, copy
 172          * the "existing" region of the file, then grow the file if needed.
 173          */
 174         for (i = file_pos; i < min_t(off_t, range_end, orig_end_offset);
 175                         i += copy_len) {
 176                 ssize_t copy_ret;
 177
 178                 copy_len = min_t(size_t, BABELTRACE_FALLOCATE_BUFLEN,
 179                                 min_t(off_t, range_end - i,
 180                                         orig_end_offset - i));
 181                 copy_ret = pread(fd, &buf, copy_len, i);
 182                 if (copy_ret < copy_len) {
 183                         /*
 184                          * The caller must handle any EINTR.
 185                          * POSIX_FALLOCATE(3) does not mention EINTR.
 186                          * However, glibc does forward to fallocate()
 187                          * directly on Linux, which may be interrupted.
 188                          */
 189                         ret = errno;
 190                         goto end;
 191                 }
 192
 193                 copy_ret = pwrite(fd, &buf, copy_len, i);
 194                 if (copy_ret < copy_len) {
 195                         /* Same caveat as noted at pread() */
 196                         ret = errno;
 197                         goto end;
 198                 }
 199         }
 200
 201         /* Grow file, as necessary. */
 202         memset(&buf, 0, BABELTRACE_FALLOCATE_BUFLEN);
 203         for (i = orig_end_offset; i < range_end; i += copy_len) {
 204                 ssize_t write_ret;
 205
 206                 copy_len = min_t(size_t, BABELTRACE_FALLOCATE_BUFLEN,
 207                                 range_end - i);
 208                 write_ret = pwrite(fd, &buf, copy_len, i);
 209                 if (write_ret < copy_len) {
 210                         ret = errno;
 211                         goto end;
 212                 }
 213         }
 214 end:
 215         return ret;
 216 }
 217 #endif /* #else #ifdef BABELTRACE_HAVE_POSIX_FALLOCATE */
 218
 219 #endif /* _BABELTRACE_COMPAT_FCNTL_H */