static int
freadptrbufsize (FILE *fp)
{
size_t size = 0;
freadptr (fp, &size);
return size;
}
ssize_t
getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
int delim1, int delim2, FILE *stream)
{
size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */
char *read_pos; /* Where we're reading into *LINEPTR. */
ssize_t bytes_stored = -1;
char *ptr = *lineptr;
size_t size = *linesize;
bool found_delimiter;
if (!ptr)
{
size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
ptr = malloc (size);
if (!ptr)
return -1;
}
if (size < offset)
goto done;
nbytes_avail = size - offset;
read_pos = ptr + offset;
if (nbytes_avail == 0 && nmax <= size)
goto done;
/* Normalize delimiters, since memchr2 doesn't handle EOF. */
if (delim1 == EOF)
delim1 = delim2;
else if (delim2 == EOF)
delim2 = delim1;
flockfile (stream);
found_delimiter = false;
do
{
/* Here always ptr + size == read_pos + nbytes_avail.
Also nbytes_avail > 0 || size < nmax. */
int c IF_LINT (= 0);
const char *buffer;
size_t buffer_len;
buffer = freadptr (stream, &buffer_len);
if (buffer)
{
if (delim1 != EOF)
{
const char *end = memchr2 (buffer, delim1, delim2, buffer_len);
if (end)
{
buffer_len = end - buffer + 1;
found_delimiter = true;
}
}
}
else
{
c = getc (stream);
if (c == EOF)
{
/* Return partial line, if any. */
if (read_pos == ptr)
goto unlock_done;
else
break;
}
if (c == delim1 || c == delim2)
found_delimiter = true;
buffer_len = 1;
}
/* We always want at least one byte left in the buffer, since we
always (unless we get an error while reading the first byte)
NUL-terminate the line buffer. */
if (nbytes_avail < buffer_len + 1 && size < nmax)
{
/* Grow size proportionally, not linearly, to avoid O(n^2)
running time. */
size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
char *newptr;
/* Increase newsize so that it becomes
>= (read_pos - ptr) + buffer_len. */
if (newsize - (read_pos - ptr) < buffer_len + 1)
newsize = (read_pos - ptr) + buffer_len + 1;
/* Respect nmax. This handles possible integer overflow. */
if (! (size < newsize && newsize <= nmax))
newsize = nmax;
if (GETNDELIM2_MAXIMUM < newsize - offset)
{
size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
if (size == newsizemax)
goto unlock_done;
newsize = newsizemax;
}
nbytes_avail = newsize - (read_pos - ptr);
newptr = realloc (ptr, newsize);
if (!newptr)
goto unlock_done;
ptr = newptr;
size = newsize;
read_pos = size - nbytes_avail + ptr;
}
/* Here, if size < nmax, nbytes_avail >= buffer_len + 1.
If size == nmax, nbytes_avail > 0. */
if (1 < nbytes_avail)
{
size_t copy_len = nbytes_avail - 1;
if (buffer_len < copy_len)
copy_len = buffer_len;
if (buffer)
memcpy (read_pos, buffer, copy_len);
else
*read_pos = c;
read_pos += copy_len;
nbytes_avail -= copy_len;
}
/* Here still nbytes_avail > 0. */
if (buffer && freadseek (stream, buffer_len))
goto unlock_done;
}
while (!found_delimiter);
/* Done - NUL terminate and return the number of bytes read.
At this point we know that nbytes_avail >= 1. */
*read_pos = '\0';
bytes_stored = read_pos - (ptr + offset);
unlock_done:
funlockfile (stream);
done:
*lineptr = ptr;
*linesize = size;
return bytes_stored ? bytes_stored : -1;
}
int
freadseek (FILE *fp, size_t offset)
{
size_t total_buffered;
int fd;
if (offset == 0)
return 0;
/* Seek over the already read and buffered input as quickly as possible,
without doing any system calls. */
total_buffered = freadahead (fp);
/* This loop is usually executed at most twice: once for ungetc buffer (if
present) and once for the main buffer. */
while (total_buffered > 0)
{
size_t buffered;
if (freadptr (fp, &buffered) != NULL && buffered > 0)
{
size_t increment = (buffered < offset ? buffered : offset);
freadptrinc (fp, increment);
offset -= increment;
if (offset == 0)
return 0;
total_buffered -= increment;
if (total_buffered == 0)
break;
}
/* Read one byte. If we were reading from the ungetc buffer, this
switches the stream back to the main buffer. */
if (fgetc (fp) == EOF)
goto eof;
offset--;
if (offset == 0)
return 0;
total_buffered--;
}
/* Test whether the stream is seekable or not. */
fd = fileno (fp);
if (fd >= 0 && lseek (fd, 0, SEEK_CUR) >= 0)
{
/* FP refers to a regular file. fseek is most efficient in this case. */
return fseeko (fp, offset, SEEK_CUR);
}
else
{
/* FP is a non-seekable stream, possibly not even referring to a file
descriptor. Read OFFSET bytes explicitly and discard them. */
char buf[4096];
do
{
size_t count = (sizeof (buf) < offset ? sizeof (buf) : offset);
if (fread (buf, 1, count, fp) < count)
goto eof;
offset -= count;
}
while (offset > 0);
return 0;
}
eof:
/* EOF, or error before or while reading. */
if (ferror (fp))
return EOF;
else
/* Encountered EOF. */
return 0;
}
int
main (int argc, char **argv)
{
int nbytes = atoi (argv[1]);
void *buf = malloc (nbytes);
ASSERT (fread (buf, 1, nbytes, stdin) == nbytes);
if (lseek (0, 0, SEEK_CUR) == nbytes)
{
/* An unbuffered stdio, such as BeOS or on uClibc compiled without
__STDIO_BUFFERS. Or stdin is a pipe. */
size_t size;
ASSERT (freadptr (stdin, &size) == NULL);
}
else
{
/* Normal buffered stdio. */
const char stdin_contents[] =
"#!/bin/sh\n\n./test-freadptr${EXEEXT} 5 < \"$srcdir/test-freadptr.sh\" || exit 1\ncat \"$srcdir/test-freadptr.sh\" | ./test-freadptr${EXEEXT} 5 || exit 1\nexit 0\n";
const char *expected = stdin_contents + nbytes;
size_t available1;
size_t available2;
size_t available3;
/* Test normal behaviour. */
{
const char *ptr = freadptr (stdin, &available1);
ASSERT (ptr != NULL);
ASSERT (available1 != 0);
ASSERT (available1 <= strlen (expected));
ASSERT (memcmp (ptr, expected, available1) == 0);
}
/* Test behaviour after normal ungetc. */
ungetc (fgetc (stdin), stdin);
{
const char *ptr = freadptr (stdin, &available2);
if (ptr != NULL)
{
ASSERT (available2 == available1);
ASSERT (memcmp (ptr, expected, available2) == 0);
}
}
/* Test behaviour after arbitrary ungetc. */
fgetc (stdin);
ungetc ('@', stdin);
{
const char *ptr = freadptr (stdin, &available3);
if (ptr != NULL)
{
ASSERT (available3 == 1 || available3 == available1);
ASSERT (ptr[0] == '@');
if (available3 > 1)
{
ASSERT (memcmp (ptr + 1, expected + 1, available3 - 1) == 0);
}
}
}
}
return 0;
}
