table of contents
explain_pwrite(3) | Library Functions Manual | explain_pwrite(3) |
NAME¶
explain_pwrite - explain pwrite(2) errorsSYNOPSIS¶
#include <libexplain/pwrite.h>DESCRIPTION¶
These functions may be used to obtain explanations for errors returned by the pwrite(2) system call.explain_pwrite¶
const char *explain_pwrite(int fildes, const void *data, size_t data_size, off_t offset); The explain_pwrite function is used to obtain an explanation of an error returned by the pwrite(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be decoded.- fildes
- The original fildes, exactly as passed to the pwrite(2) system call.
- data
- The original data, exactly as passed to the pwrite(2) system call.
- data_size
- The original data_size, exactly as passed to the pwrite(2) system call.
- offset
- The original offset, exactly as passed to the pwrite(2) system call.
- Returns:
- The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.
ssize_t result = pwrite(fildes, data, data_size, offset);
{
fprintf(stderr, "%s\n", explain_pwrite(fildes, data, data_size, offset));
exit(EXIT_FAILURE); }
explain_errno_pwrite¶
const char *explain_errno_pwrite(int errnum, int fildes, const void *data, size_t data_size, off_t offset); The explain_errno_pwrite function is used to obtain an explanation of an error returned by the pwrite(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.- errnum
- The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.
- fildes
- The original fildes, exactly as passed to the pwrite(2) system call.
- data
- The original data, exactly as passed to the pwrite(2) system call.
- data_size
- The original data_size, exactly as passed to the pwrite(2) system call.
- offset
- The original offset, exactly as passed to the pwrite(2) system call.
- Returns:
- The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.
ssize_t result = pwrite(fildes, data, data_size, offset);
{ int err = errno;
fprintf(stderr, "%s\n", explain_errno_pwrite(err, fildes, data, data_size, offset));
exit(EXIT_FAILURE); }
explain_message_pwrite¶
void explain_message_pwrite(char *message, int message_size, int fildes, const void *data, size_t data_size, off_t offset); The explain_message_pwrite function is used to obtain an explanation of an error returned by the pwrite(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. The errno global variable will be used to obtain the error value to be decoded.- message
- The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.
- message_size
- The size in bytes of the location in which to store the returned message.
- fildes
- The original fildes, exactly as passed to the pwrite(2) system call.
- data
- The original data, exactly as passed to the pwrite(2) system call.
- data_size
- The original data_size, exactly as passed to the pwrite(2) system call.
- offset
- The original offset, exactly as passed to the pwrite(2) system call.
ssize_t result = pwrite(fildes, data, data_size, offset);
{ char message[3000];explain_message_pwrite(message, sizeof(message), fildes, data, data_size, offset);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
explain_message_errno_pwrite¶
void explain_message_errno_pwrite(char *message, int message_size, int errnum, int fildes, const void *data, size_t data_size, off_t offset); The explain_message_errno_pwrite function is used to obtain an explanation of an error returned by the pwrite(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.- message
- The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.
- message_size
- The size in bytes of the location in which to store the returned message.
- errnum
- The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.
- fildes
- The original fildes, exactly as passed to the pwrite(2) system call.
- data
- The original data, exactly as passed to the pwrite(2) system call.
- data_size
- The original data_size, exactly as passed to the pwrite(2) system call.
- offset
- The original offset, exactly as passed to the pwrite(2) system call.
ssize_t result = pwrite(fildes, data, data_size, offset);
{ int err = errno; char message[3000];explain_message_errno_pwrite(message, sizeof(message), err, fildes, data, data_size, offset);
fprintf(stderr, "%s\n", message); exit(EXIT_FAILURE); }
SEE ALSO¶
- pwrite(2)
- read from or write to a file descriptor at a given offset
- explain_pwrite_or_die(3)
- read from or write to a file descriptor at a given offset and report errors