pread_write.c 5.4 KB

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  1. /* vi: set sw=4 ts=4:
  2. *
  3. * Copyright (C) 2002 by Erik Andersen <andersen@uclibc.org>
  4. * Based in part on the files
  5. * ./sysdeps/unix/sysv/linux/pwrite.c,
  6. * ./sysdeps/unix/sysv/linux/pread.c,
  7. * sysdeps/posix/pread.c
  8. * sysdeps/posix/pwrite.c
  9. * from GNU libc 2.2.5, but reworked considerably...
  10. *
  11. * This program is free software; you can redistribute it and/or modify it
  12. * under the terms of the GNU Library General Public License as published by
  13. * the Free Software Foundation; either version 2 of the License, or (at your
  14. * option) any later version.
  15. *
  16. * This program is distributed in the hope that it will be useful, but WITHOUT
  17. * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18. * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
  19. * for more details.
  20. *
  21. * You should have received a copy of the GNU Library General Public License
  22. * along with this program; if not, write to the Free Software Foundation,
  23. * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  24. */
  25. #define _GNU_SOURCE
  26. #define _LARGEFILE64_SOURCE
  27. #include <features.h>
  28. #undef __OPTIMIZE__
  29. /* We absolutely do _NOT_ want interfaces silently
  30. * * * renamed under us or very bad things will happen... */
  31. #ifdef __USE_FILE_OFFSET64
  32. # undef __USE_FILE_OFFSET64
  33. #endif
  34. #include <errno.h>
  35. #include <sys/types.h>
  36. #include <sys/syscall.h>
  37. #include <unistd.h>
  38. #if ! defined __UCLIBC_HAS_LFS__
  39. #define off64_t off_t
  40. #endif
  41. #ifdef __NR_pread
  42. #define __NR___syscall_pread __NR_pread
  43. static inline _syscall4(ssize_t, __syscall_pread, int, fd,
  44. void *, buf, size_t, count, off64_t, offset);
  45. ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)
  46. {
  47. return(__syscall_pread(fd, buf, count, (off64_t)offset));
  48. }
  49. weak_alias (__libc_pread, pread)
  50. #if defined __UCLIBC_HAS_LFS__
  51. ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)
  52. {
  53. return(__syscall_pread(fd, buf, count, offset));
  54. }
  55. weak_alias (__libc_pread64, pread64)
  56. #endif /* __UCLIBC_HAS_LFS__ */
  57. #endif /* __NR_pread */
  58. #ifdef __NR_pwrite
  59. #define __NR___syscall_pwrite __NR_pwrite
  60. static inline _syscall4(ssize_t, __syscall_pwrite, int, fd,
  61. const void *, buf, size_t, count, off64_t, offset);
  62. ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)
  63. {
  64. return(__syscall_pwrite(fd, buf, count, (off64_t)offset));
  65. }
  66. weak_alias (__libc_pwrite, pwrite)
  67. #if defined __UCLIBC_HAS_LFS__
  68. ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)
  69. {
  70. return(__syscall_pwrite(fd, buf, count, offset));
  71. }
  72. weak_alias (__libc_pwrite64, pwrite64)
  73. #endif /* __UCLIBC_HAS_LFS__ */
  74. #endif /* __NR_pwrite */
  75. #if ! defined __NR_pread || ! defined __NR_pwrite
  76. static ssize_t __fake_pread_write(int fd, void *buf,
  77. size_t count, off_t offset, int do_pwrite)
  78. {
  79. int save_errno;
  80. ssize_t result;
  81. off_t old_offset;
  82. /* Since we must not change the file pointer preserve the
  83. * value so that we can restore it later. */
  84. if ((old_offset=__lseek(fd, 0, SEEK_CUR)) == (off_t) -1)
  85. return -1;
  86. /* Set to wanted position. */
  87. if (__lseek (fd, offset, SEEK_SET) == (off_t) -1)
  88. return -1;
  89. if (do_pwrite==1) {
  90. /* Write the data. */
  91. result = write(fd, buf, count);
  92. } else {
  93. /* Read the data. */
  94. result = read(fd, buf, count);
  95. }
  96. /* Now we have to restore the position. If this fails we
  97. * have to return this as an error. */
  98. save_errno = errno;
  99. if (__lseek(fd, old_offset, SEEK_SET) == (off_t) -1)
  100. {
  101. if (result == -1)
  102. __set_errno(save_errno);
  103. return -1;
  104. }
  105. __set_errno(save_errno);
  106. return(result);
  107. }
  108. #if defined __UCLIBC_HAS_LFS__
  109. static ssize_t __fake_pread_write64(int fd, void *buf,
  110. size_t count, off64_t offset, int do_pwrite)
  111. {
  112. int save_errno;
  113. ssize_t result;
  114. off64_t old_offset;
  115. /* Since we must not change the file pointer preserve the
  116. * value so that we can restore it later. */
  117. if ((old_offset=__lseek64(fd, 0, SEEK_CUR)) == (off64_t) -1)
  118. return -1;
  119. /* Set to wanted position. */
  120. if (__lseek64(fd, offset, SEEK_SET) == (off64_t) -1)
  121. return -1;
  122. if (do_pwrite==1) {
  123. /* Write the data. */
  124. result = write(fd, buf, count);
  125. } else {
  126. /* Read the data. */
  127. result = read(fd, buf, count);
  128. }
  129. /* Now we have to restore the position. */
  130. save_errno = errno;
  131. if (__lseek64 (fd, old_offset, SEEK_SET) == (off64_t) -1) {
  132. if (result == -1)
  133. __set_errno (save_errno);
  134. return -1;
  135. }
  136. __set_errno (save_errno);
  137. return result;
  138. }
  139. #endif /* __UCLIBC_HAS_LFS__ */
  140. #endif /* ! defined __NR_pread || ! defined __NR_pwrite */
  141. #ifndef __NR_pread
  142. ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)
  143. {
  144. return(__fake_pread_write(fd, buf, count, offset, 0));
  145. }
  146. weak_alias (__libc_pread, pread)
  147. #if defined __UCLIBC_HAS_LFS__
  148. ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)
  149. {
  150. return(__fake_pread_write64(fd, buf, count, offset, 0));
  151. }
  152. weak_alias (__libc_pread64, pread64)
  153. #endif /* __UCLIBC_HAS_LFS__ */
  154. #endif /* ! __NR_pread */
  155. #ifndef __NR_pwrite
  156. ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)
  157. {
  158. return(__fake_pread_write(fd, buf, count, offset, 1));
  159. }
  160. weak_alias (__libc_pwrite, pwrite)
  161. #if defined __UCLIBC_HAS_LFS__
  162. ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)
  163. {
  164. return(__fake_pread_write64(fd, (void*)buf, count, offset, 1));
  165. }
  166. weak_alias (__libc_pwrite64, pwrite64)
  167. #endif /* __UCLIBC_HAS_LFS__ */
  168. #endif /* ! __NR_pwrite */