[PATCH 0.9.33 1/7] Revert "pread/pwrite: backport fix"

[Natanael Copa]

This backport breaks x86_64 badly.

This reverts commit 342a3d861fde5651ee53486addbacddcec6a0a58.

Signed-off-by: Natanael Copa <ncopa at alpinelinux.org>
---
 libc/sysdeps/linux/common/pread_write.c | 143 +++++++++++++++++++++++++++-----
 1 file changed, 124 insertions(+), 19 deletions(-)

diff --git a/libc/sysdeps/linux/common/pread_write.c b/libc/sysdeps/linux/common/pread_write.c
index baf8691..88e6957 100644
--- a/libc/sysdeps/linux/common/pread_write.c
+++ b/libc/sysdeps/linux/common/pread_write.c
@@ -17,7 +17,6 @@
 #include <unistd.h>
 #include <stdint.h>
 #include <endian.h>
-#include <sysdep-cancel.h>
 
 extern __typeof(pread) __libc_pread;
 extern __typeof(pwrite) __libc_pwrite;
@@ -28,17 +27,15 @@ extern __typeof(pwrite64) __libc_pwrite64;
 
 #include <bits/kernel_types.h>
 
-# define __NR___syscall_pread __NR_pread64
+#ifdef __NR_pread
+
+# define __NR___syscall_pread __NR_pread
 static __inline__ _syscall5(ssize_t, __syscall_pread, int, fd, void *, buf,
 		size_t, count, off_t, offset_hi, off_t, offset_lo)
 
 ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)
 {
-	int oldtype = LIBC_CANCEL_ASYNC ();
-	int result = __syscall_pread(fd, buf, count, __LONG_LONG_PAIR(offset >> 31, offset));
-	LIBC_CANCEL_RESET (oldtype);
-	return result;
-
+	return __syscall_pread(fd, buf, count, __LONG_LONG_PAIR(offset >> 31, offset));
 }
 weak_alias(__libc_pread,pread)
 
@@ -47,24 +44,22 @@ ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)
 {
 	uint32_t low = offset & 0xffffffff;
 	uint32_t high = offset >> 32;
-	int oldtype = LIBC_CANCEL_ASYNC ();
-	int result = __syscall_pread(fd, buf, count, __LONG_LONG_PAIR(high, low));
-	LIBC_CANCEL_RESET (oldtype);
-	return result;
+	return __syscall_pread(fd, buf, count, __LONG_LONG_PAIR(high, low));
 }
 weak_alias(__libc_pread64,pread64)
 # endif /* __UCLIBC_HAS_LFS__  */
 
-# define __NR___syscall_pwrite __NR_pwrite64
+#endif /* __NR_pread */
+
+#ifdef __NR_pwrite
+
+# define __NR___syscall_pwrite __NR_pwrite
 static __inline__ _syscall5(ssize_t, __syscall_pwrite, int, fd, const void *, buf,
 		size_t, count, off_t, offset_hi, off_t, offset_lo)
 
 ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)
 {
-	int oldtype = LIBC_CANCEL_ASYNC ();
-	int result = __syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR(offset >> 31, offset));
-	LIBC_CANCEL_RESET (oldtype);
-	return result;
+	return __syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR(offset >> 31, offset));
 }
 weak_alias(__libc_pwrite,pwrite)
 
@@ -73,10 +68,120 @@ ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)
 {
 	uint32_t low = offset & 0xffffffff;
 	uint32_t high = offset >> 32;
-	int oldtype = LIBC_CANCEL_ASYNC ();
-	int result = __syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR(high, low));
-	LIBC_CANCEL_RESET (oldtype);
+	return __syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR(high, low));
+}
+weak_alias(__libc_pwrite64,pwrite64)
+# endif /* __UCLIBC_HAS_LFS__  */
+#endif /* __NR_pwrite */
+
+#if ! defined __NR_pread || ! defined __NR_pwrite
+
+static ssize_t __fake_pread_write(int fd, void *buf,
+		size_t count, off_t offset, int do_pwrite)
+{
+	int save_errno;
+	ssize_t result;
+	off_t old_offset;
+
+	/* Since we must not change the file pointer preserve the
+	 * value so that we can restore it later.  */
+	if ((old_offset=lseek(fd, 0, SEEK_CUR)) == (off_t) -1)
+		return -1;
+
+	/* Set to wanted position.  */
+	if (lseek(fd, offset, SEEK_SET) == (off_t) -1)
+		return -1;
+
+	if (do_pwrite == 1) {
+		/* Write the data.  */
+		result = write(fd, buf, count);
+	} else {
+		/* Read the data.  */
+		result = read(fd, buf, count);
+	}
+
+	/* Now we have to restore the position.  If this fails we
+	 * have to return this as an error.  */
+	save_errno = errno;
+	if (lseek(fd, old_offset, SEEK_SET) == (off_t) -1)
+	{
+		if (result == -1)
+			__set_errno(save_errno);
+		return -1;
+	}
+	__set_errno(save_errno);
+	return(result);
+}
+
+# ifdef __UCLIBC_HAS_LFS__
+
+static ssize_t __fake_pread_write64(int fd, void *buf,
+		size_t count, off64_t offset, int do_pwrite)
+{
+	int save_errno;
+	ssize_t result;
+	off64_t old_offset;
+
+	/* Since we must not change the file pointer preserve the
+	 * value so that we can restore it later.  */
+	if ((old_offset=lseek64(fd, 0, SEEK_CUR)) == (off64_t) -1)
+		return -1;
+
+	/* Set to wanted position.  */
+	if (lseek64(fd, offset, SEEK_SET) == (off64_t) -1)
+		return -1;
+
+	if (do_pwrite == 1) {
+		/* Write the data.  */
+		result = write(fd, buf, count);
+	} else {
+		/* Read the data.  */
+		result = read(fd, buf, count);
+	}
+
+	/* Now we have to restore the position. */
+	save_errno = errno;
+	if (lseek64(fd, old_offset, SEEK_SET) == (off64_t) -1) {
+		if (result == -1)
+			__set_errno (save_errno);
+		return -1;
+	}
+	__set_errno (save_errno);
 	return result;
 }
+# endif /* __UCLIBC_HAS_LFS__  */
+#endif /*  ! defined __NR_pread || ! defined __NR_pwrite */
+
+#ifndef __NR_pread
+ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)
+{
+	return __fake_pread_write(fd, buf, count, offset, 0);
+}
+weak_alias(__libc_pread,pread)
+
+# ifdef __UCLIBC_HAS_LFS__
+ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)
+{
+	return __fake_pread_write64(fd, buf, count, offset, 0);
+}
+weak_alias(__libc_pread64,pread64)
+# endif /* __UCLIBC_HAS_LFS__  */
+#endif /* ! __NR_pread */
+
+#ifndef __NR_pwrite
+ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)
+{
+	/* we won't actually be modifying the buffer,
+	 *just cast it to get rid of warnings */
+	return __fake_pread_write(fd, (void*)buf, count, offset, 1);
+}
+weak_alias(__libc_pwrite,pwrite)
+
+# ifdef __UCLIBC_HAS_LFS__
+ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)
+{
+	return __fake_pread_write64(fd, (void*)buf, count, offset, 1);
+}
 weak_alias(__libc_pwrite64,pwrite64)
 # endif /* __UCLIBC_HAS_LFS__  */
+#endif /* ! __NR_pwrite */
-- 
1.7.12