FpRead
Read data from file descriptor
Declaration
Source position: bunxh.inc line 85
function FpRead(fd: cint; buf: pChar; nbytes: TSize) : TsSize;
function FpRead(fd: cint; var buf; nbytes: TSize) : TsSize;
Description
FpdRead reads at most nbytes bytes from the file descriptor fd, and stores them in buf.
The function returns the number of bytes actually read, or -1 if an error occurred. No checking on the length of buf is done.
Errors
Extended error information can be retrieved using fpGetErrno .
See also
| Name | Description |
|---|---|
| FpClose | Close file descriptor |
| FpFTruncate | Truncate file on certain size. |
| FpLSeek | Set file pointer position. |
| FpOpen | Open file and return file descriptor |
| FpWrite | Write data to file descriptor |
Example
Program Example20;
{ Program to demonstrate the fdRead and fdTruncate functions. }
Uses BaseUnix;
Const Data : string[10] = '1234567890';
Var FD : cint;
l : longint;
begin
FD:=fpOpen('test.dat',o_wronly or o_creat,&666);
if fd>0 then
begin
{ Fill file with data }
for l:=1 to 10 do
if fpWrite (FD,Data[1],10)<>10 then
begin
writeln ('Error when writing !');
halt(1);
end;
fpClose(FD);
FD:=fpOpen('test.dat',o_rdonly);
{ Read data again }
If FD>0 then
begin
For l:=1 to 5 do
if fpRead (FD,Data[1],10)<>10 then
begin
Writeln ('Error when Reading !');
Halt(2);
end;
fpClose(FD);
{ Truncating file at 60 bytes }
{ For truncating, file must be open or write }
FD:=fpOpen('test.dat',o_wronly,&666);
if FD>0 then
begin
if fpfTruncate(FD,60)<>0 then
Writeln('Error when truncating !');
fpClose (FD);
end;
end;
end;
end.