/*
* Analogous to back_line(), but deals with "raw lines".
* {{ This is supposed to be more efficient than back_line(). }}
*/
off_t
back_raw_line(off_t curr_pos, char **linep, int *line_lenp)
{
int n;
int c;
off_t new_pos;
if (curr_pos == -1 || curr_pos <= ch_zero() || ch_seek(curr_pos - 1))
return (-1);
n = size_linebuf;
linebuf[--n] = '\0';
for (;;) {
c = ch_back_get();
if (c == '\n' || ABORT_SIGS()) {
/*
* This is the newline ending the previous line.
* We have hit the beginning of the line.
*/
new_pos = ch_tell() + 1;
break;
}
if (c == EOI) {
/*
* We have hit the beginning of the file.
* This must be the first line in the file.
* This must, of course, be the beginning of the line.
*/
new_pos = ch_zero();
break;
}
if (n <= 0) {
int old_size_linebuf = size_linebuf;
char *fm;
char *to;
if (expand_linebuf()) {
/*
* Overflowed the input buffer.
* Pretend the line ended here.
*/
new_pos = ch_tell() + 1;
break;
}
/*
* Shift the data to the end of the new linebuf.
*/
for (fm = linebuf + old_size_linebuf - 1,
to = linebuf + size_linebuf - 1;
fm >= linebuf; fm--, to--)
*to = *fm;
n = size_linebuf - old_size_linebuf;
}
linebuf[--n] = c;
}
if (linep != NULL)
*linep = &linebuf[n];
if (line_lenp != NULL)
*line_lenp = size_linebuf - 1 - n;
return (new_pos);
}
/*
* Get the next line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the NEXT line. The line obtained is the line starting at curr_pos.
*/
off_t
forw_line(off_t curr_pos)
{
off_t new_pos;
int c;
if (curr_pos == NULL_POSITION || ch_seek(curr_pos))
return (NULL_POSITION);
c = ch_forw_get();
if (c == EOI)
return (NULL_POSITION);
prewind();
for (;;) {
if (sigs)
return (NULL_POSITION);
if (c == '\n' || c == EOI) {
/*
* End of the line.
*/
new_pos = ch_tell();
break;
}
/*
* Append the char to the line and get the next char.
*/
if (pappend(c)) {
/*
* The char won't fit in the line; the line
* is too long to print in the screen width.
* End the line here.
*/
new_pos = ch_tell() - 1;
break;
}
c = ch_forw_get();
}
(void) pappend('\0');
if (squeeze && *line == '\0') {
/*
* This line is blank.
* Skip down to the last contiguous blank line
* and pretend it is the one which we are returning.
*/
while ((c = ch_forw_get()) == '\n')
if (sigs)
return (NULL_POSITION);
if (c != EOI)
(void) ch_back_get();
new_pos = ch_tell();
}
return (new_pos);
}
/*
* Analogous to back_line(), but deals with "raw lines".
* {{ This is supposed to be more efficient than back_line(). }}
*/
off_t
back_raw_line(off_t curr_pos)
{
char *p;
int c;
off_t new_pos;
if (curr_pos == NULL_POSITION || curr_pos <= (off_t)0 ||
ch_seek(curr_pos-1))
return (NULL_POSITION);
p = &linebuf[sizeof(linebuf)];
*--p = '\0';
for (;;) {
c = ch_back_get();
if (c == '\n') {
/*
* This is the newline ending the previous line.
* We have hit the beginning of the line.
*/
new_pos = ch_tell() + 1;
break;
}
if (c == EOI) {
/*
* We have hit the beginning of the file.
* This must be the first line in the file.
* This must, of course, be the beginning of the line.
*/
new_pos = (off_t)0;
break;
}
if (p <= linebuf) {
/*
* Overflowed the input buffer.
* Pretend the line ended here.
*/
new_pos = ch_tell() + 1;
break;
}
*--p = c;
}
line = p;
return (new_pos);
}
/*
* Get the previous line.
* A "current" position is passed and a "new" position is returned.
* The current position is the position of the first character of
* a line. The new position is the position of the first character
* of the PREVIOUS line. The line obtained is the one starting at new_pos.
*/
off_t
back_line(off_t curr_pos)
{
off_t new_pos, begin_new_pos;
int c;
if (curr_pos == NULL_POSITION || curr_pos <= (off_t)0 ||
ch_seek(curr_pos-1))
return (NULL_POSITION);
if (squeeze) {
/*
* Find out if the "current" line was blank.
*/
(void) ch_forw_get(); /* Skip the newline */
c = ch_forw_get(); /* First char of "current" line */
(void) ch_back_get(); /* Restore our position */
(void) ch_back_get();
if (c == '\n') {
/*
* The "current" line was blank.
* Skip over any preceeding blank lines,
* since we skipped them in forw_line().
*/
while ((c = ch_back_get()) == '\n')
if (sigs)
return (NULL_POSITION);
if (c == EOI)
return (NULL_POSITION);
(void) ch_forw_get();
}
}
/*
* Scan backwards until we hit the beginning of the line.
*/
for (;;) {
if (sigs)
return (NULL_POSITION);
c = ch_back_get();
if (c == '\n') {
/*
* This is the newline ending the previous line.
* We have hit the beginning of the line.
*/
new_pos = ch_tell() + 1;
break;
}
if (c == EOI) {
/*
* We have hit the beginning of the file.
* This must be the first line in the file.
* This must, of course, be the beginning of the line.
*/
new_pos = ch_tell();
break;
}
}
/*
* Now scan forwards from the beginning of this line.
* We keep discarding "printable lines" (based on screen width)
* until we reach the curr_pos.
*
* {{ This algorithm is pretty inefficient if the lines
* are much longer than the screen width,
* but I don't know of any better way. }}
*/
if (ch_seek(new_pos))
return (NULL_POSITION);
loop:
begin_new_pos = new_pos;
prewind();
do {
c = ch_forw_get();
if (c == EOI || sigs)
return (NULL_POSITION);
new_pos++;
if (c == '\n')
break;
if (pappend(c)) {
/*
* Got a full printable line, but we haven't
* reached our curr_pos yet. Discard the line
* and start a new one.
*/
(void) pappend('\0');
(void) ch_back_get();
new_pos--;
goto loop;
}
} while (new_pos < curr_pos);
(void) pappend('\0');
return (begin_new_pos);
}
