.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32 .\" .\" Standard preamble: .\" ======================================================================== .de Sh \" Subsection heading .br .if t .Sp .ne 5 .PP \fB\\$1\fR .PP .. .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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They are used to provide quick read access to files; the \s-1QIO\s0 routines use buffering adapted to the block size of the device, similar to stdio, but with a more convenient syntax for reading newline-terminated lines. \s-1QIO\s0 is short for \*(L"Quick I/O\*(R" (a bit of a misnomer, as \s-1QIO\s0 provides read-only access to files only). .PP The \s-1QIOSTATE\s0 structure returned by \fBQIOopen\fR and \fBQIOfdopen\fR is the analog to stdio's \s-1FILE\s0 structure and should be treated as a black box by all users of these routines. Only the above \s-1API\s0 should be used. .PP \&\fBQIOopen\fR opens the given file for reading. For regular files, if your system provides that information and the size is reasonable, \s-1QIO\s0 will use the block size of the underlying file system as its buffer size; otherwise, it will default to a buffer of 8 \s-1KB\s0. Returns a pointer to use for subsequent calls, or \s-1NULL\s0 on error. \fBQIOfdopen\fR performs the same operation except on an already-open file descriptor (\fIfd\fR must designate a file open for reading). .PP \&\fBQIOclose\fR closes the open file and releases any resources used by the \&\s-1QIOSTATE\s0 structure. The \s-1QIOSTATE\s0 pointer should not be used again after it has been passed to this function. .PP \&\fBQIOread\fR reads the next newline-terminated line in the file and returns a pointer to it, with the trailing newline replaced by nul. The returned pointer is a pointer into a buffer in the \s-1QIOSTATE\s0 object and therefore will remain valid until \fBQIOclose\fR is called on that object. If \s-1EOF\s0 is reached, an error occurs, or if the line is longer than the buffer size, \&\s-1NULL\s0 is returned instead. To distinguish between the error cases, use \&\fBQIOerror\fR and \fBQIOtoolong\fR. .PP \&\fBQIOfileno\fR returns the descriptor of the open file. .PP \&\fBQIOlength\fR returns the length in bytes of the last line returned by \&\fBQIOread\fR. Its return value is only defined after a successful call to \&\fBQIOread\fR. .PP \&\fBQIOrewind\fR sets the read pointer back to the beginning of the file and reads the first block of the file in anticipation of future reads. It returns 0 if successful and \-1 on error. .PP \&\fBQIOtell\fR returns the current value of the read pointer (the \fIlseek\fR\|(2) offset at which the next line will start). .PP \&\fBQIOerror\fR returns true if there was an error in the last call to \&\fBQIOread\fR, false otherwise. \fBQIOtoolong\fR returns true if there was an error and the error was that the line was too long. If \fBQIOread\fR returns \&\s-1NULL\s0, these functions should be called to determine what happened. If \&\fBQIOread\fR returned \s-1NULL\s0 and \fBQIOerror\fR is false, \s-1EOF\s0 was reached. Note that if \fBQIOtoolong\fR returns true, the next call to \fBQIOread\fR will try to read the remainder of the line and will likely return a partial line; users of this library should in general treat long lines as fatal errors. .SH "EXAMPLES" .IX Header "EXAMPLES" This block of code opens \fI/etc/motd\fR and reads it a line at a time, printing out each line preceeded by its offset in the file. .PP .Vb 3 \& QIOSTATE *qp; \& off_t offset; \& char *p; .Ve .PP .Vb 12 \& qp = QIOopen("/etc/motd"); \& if (qp == NULL) { \& perror("Open error"); \& exit(1); \& } \& for (p = QIOread(qp); p != NULL; p = QIOread(qp)) \& printf("%ld: %s\en", (unsigned long) QIOtell(qp), p); \& if (QIOerror(qp)) { \& perror("Read error"); \& exit(1); \& } \& QIOclose(qp); .Ve .SH "HISTORY" .IX Header "HISTORY" Written by Rich \f(CW$alz\fR for InterNetNews. Updated by Russ Allbery . .PP $Id: qio.3 7880 2008-06-16 20:37:13Z iulius $