/*
- * Sherlock Library -- Fast Buffered I/O on Files
+ * UCW Library -- Fast Buffered I/O on Files
*
- * (c) 1997--2000 Martin Mares <mj@ucw.cz>
+ * (c) 1997--2007 Martin Mares <mj@ucw.cz>
+ * (c) 2007 Pavel Charvat <pchar@ucw.cz>
+ *
+ * This software may be freely distributed and used according to the terms
+ * of the GNU Lesser General Public License.
*/
#include "lib/lib.h"
#include <fcntl.h>
#include <unistd.h>
+struct fb_file {
+ struct fastbuf fb;
+ int fd; /* File descriptor */
+ int is_temp_file;
+ int keep_back_buf; /* Optimize for backwards reading */
+ sh_off_t wpos; /* Real file position */
+ uns wlen; /* Window size */
+};
+#define FB_FILE(f) ((struct fb_file *)(f)->is_fastbuf)
+#define FB_BUFFER(f) (byte *)(FB_FILE(f) + 1)
+
static int
bfd_refill(struct fastbuf *f)
{
- int l = read(f->fd, f->buffer, f->buflen);
-
- if (l < 0)
- die("Error reading %s: %m", f->name);
- f->bptr = f->buffer;
- f->bstop = f->buffer + l;
- f->pos = f->fdpos;
- f->fdpos += l;
- return l;
+ struct fb_file *F = FB_FILE(f);
+ byte *read_ptr = (f->buffer = FB_BUFFER(f));
+ uns blen = f->bufend - f->buffer, back = F->keep_back_buf ? blen >> 2 : 0, read_len = blen;
+ /* Forward or no seek */
+ if (F->wpos <= f->pos)
+ {
+ sh_off_t diff = f->pos - F->wpos;
+ /* Formula for long forward seeks (prefer lseek()) */
+ if (diff > ((sh_off_t)blen << 2))
+ {
+long_seek:
+ f->bptr = f->buffer + back;
+ f->bstop = f->buffer + blen;
+ goto seek;
+ }
+ /* Short forward seek (prefer read() to skip data )*/
+ else if ((uns)diff >= back)
+ {
+ uns skip = diff - back;
+ F->wpos += skip;
+ while (skip)
+ {
+ int l = read(F->fd, f->buffer, MIN(skip, blen));
+ if (unlikely(l <= 0))
+ if (l < 0)
+ die("Error reading %s: %m", f->name);
+ else
+ {
+ F->wpos -= skip;
+ goto eof;
+ }
+ skip -= l;
+ }
+ }
+ /* Reuse part of the previous window and append new data (also F->wpos == f->pos) */
+ else
+ {
+ uns keep = back - (uns)diff;
+ if (keep >= F->wlen)
+ back = diff + (keep = F->wlen);
+ else
+ memmove(f->buffer, f->buffer + F->wlen - keep, keep);
+ read_len -= keep;
+ read_ptr += keep;
+ }
+ f->bptr = f->buffer + back;
+ f->bstop = f->buffer + blen;
+ }
+ /* Backwards seek */
+ else
+ {
+ sh_off_t diff = F->wpos - f->pos;
+ /* Formula for long backwards seeks (keep smaller backbuffer than for shorter seeks ) */
+ if (diff > ((sh_off_t)blen << 1))
+ {
+ if ((sh_off_t)back > f->pos)
+ back = f->pos;
+ goto long_seek;
+ }
+ /* Seek into previous window (do nothing... for example brewind) */
+ else if ((uns)diff <= F->wlen)
+ {
+ f->bstop = f->buffer + F->wlen;
+ f->bptr = f->bstop - diff;
+ f->pos = F->wpos;
+ return 1;
+ }
+ back *= 3;
+ if ((sh_off_t)back > f->pos)
+ back = f->pos;
+ f->bptr = f->buffer + back;
+ read_len = blen;
+ f->bstop = f->buffer + read_len;
+ /* Reuse part of previous window */
+ if (F->wlen && read_len <= back + diff && read_len > back + diff - F->wlen)
+ {
+ uns keep = read_len + F->wlen - back - diff;
+ memmove(f->buffer + read_len - keep, f->buffer, keep);
+ }
+seek:
+ /* Do lseek() */
+ F->wpos = f->pos + (f->buffer - f->bptr);
+ if (sh_seek(F->fd, F->wpos, SEEK_SET) < 0)
+ die("Error seeking %s: %m", f->name);
+ }
+ /* Read (part of) buffer */
+ do
+ {
+ int l = read(F->fd, read_ptr, read_len);
+ if (unlikely(l < 0))
+ die("Error reading %s: %m", f->name);
+ if (!l)
+ if (unlikely(read_ptr < f->bptr))
+ goto eof;
+ else
+ break; /* Incomplete read because of EOF */
+ read_ptr += l;
+ read_len -= l;
+ F->wpos += l;
+ }
+ while (read_ptr <= f->bptr);
+ if (read_len)
+ f->bstop = read_ptr;
+ f->pos += f->bstop - f->bptr;
+ F->wlen = f->bstop - f->buffer;
+ return f->bstop - f->bptr;
+eof:
+ /* Seeked behind EOF */
+ f->bptr = f->bstop = f->buffer;
+ F->wlen = 0;
+ return 0;
}
static void
bfd_spout(struct fastbuf *f)
{
+ /* Do delayed lseek() if needed */
+ if (FB_FILE(f)->wpos != f->pos && sh_seek(FB_FILE(f)->fd, f->pos, SEEK_SET) < 0)
+ die("Error seeking %s: %m", f->name);
+
int l = f->bptr - f->buffer;
- char *c = f->buffer;
+ byte *c = f->buffer;
+ /* Write the buffer */
+ FB_FILE(f)->wpos = (f->pos += l);
+ FB_FILE(f)->wlen = 0;
while (l)
{
- int z = write(f->fd, c, l);
+ int z = write(FB_FILE(f)->fd, c, l);
if (z <= 0)
die("Error writing %s: %m", f->name);
- f->fdpos += z;
l -= z;
c += z;
}
- f->bptr = f->buffer;
- f->pos = f->fdpos;
+ f->bptr = f->buffer = FB_BUFFER(f);
}
-static void
+static int
bfd_seek(struct fastbuf *f, sh_off_t pos, int whence)
{
+ /* Delay the seek for the next refill() or spout() call (if whence != SEEK_END). */
sh_off_t l;
-
- if (whence == SEEK_SET && pos == f->fdpos)
- return;
-
- l = sh_seek(f->fd, pos, whence);
- if (l < 0)
- die("lseek on %s: %m", f->name);
- f->fdpos = f->pos = l;
+ switch (whence)
+ {
+ case SEEK_SET:
+ f->pos = pos;
+ return 1;
+ case SEEK_CUR:
+ l = f->pos + pos;
+ if ((pos > 0) ^ (l > f->pos))
+ return 0;
+ f->pos = l;
+ return 1;
+ case SEEK_END:
+ l = sh_seek(FB_FILE(f)->fd, pos, SEEK_END);
+ if (l < 0)
+ return 0;
+ FB_FILE(f)->wpos = f->pos = l;
+ FB_FILE(f)->wlen = 0;
+ return 1;
+ default:
+ ASSERT(0);
+ }
}
static void
bfd_close(struct fastbuf *f)
{
- close(f->fd);
- if (f->is_temp_file && unlink(f->name) < 0)
- die("unlink(%s): %m", f->name);
+ bclose_file_helper(f, FB_FILE(f)->fd, FB_FILE(f)->is_temp_file);
+ xfree(f);
}
-static struct fastbuf *
-bfdopen_internal(int fd, uns buflen, byte *name)
+static int
+bfd_config(struct fastbuf *f, uns item, int value)
{
- int namelen = strlen(name) + 1;
- struct fastbuf *b = xmalloc_zero(sizeof(struct fastbuf) + buflen + namelen);
-
- b->buflen = buflen;
- b->buffer = (char *)(b+1);
- b->bptr = b->bstop = b->buffer;
- b->bufend = b->buffer + buflen;
- b->name = b->bufend;
- strcpy(b->name, name);
- b->fd = fd;
- b->refill = bfd_refill;
- b->spout = bfd_spout;
- b->seek = bfd_seek;
- b->close = bfd_close;
- return b;
-}
+ int orig;
-struct fastbuf *
-bopen(byte *name, uns mode, uns buffer)
-{
- struct fastbuf *b;
- int fd = sh_open(name, mode, 0666);
- if (fd < 0)
- die("Unable to %s file %s: %m",
- (mode & O_CREAT) ? "create" : "open", name);
- b = bfdopen_internal(fd, buffer, name);
- if (mode & O_APPEND)
- bfd_seek(b, 0, SEEK_END);
- return b;
+ switch (item)
+ {
+ case BCONFIG_IS_TEMP_FILE:
+ orig = FB_FILE(f)->is_temp_file;
+ FB_FILE(f)->is_temp_file = value;
+ return orig;
+ case BCONFIG_KEEP_BACK_BUF:
+ orig = FB_FILE(f)->keep_back_buf;
+ FB_FILE(f)->keep_back_buf = value;
+ return orig;
+ default:
+ return -1;
+ }
}
struct fastbuf *
-bfdopen(int fd, uns buffer)
+bfdopen_internal(int fd, const char *name, uns buflen)
{
- byte x[32];
+ ASSERT(buflen);
+ int namelen = strlen(name) + 1;
+ struct fb_file *F = xmalloc_zero(sizeof(struct fb_file) + buflen + namelen);
+ struct fastbuf *f = &F->fb;
- sprintf(x, "fd%d", fd);
- return bfdopen_internal(fd, buffer, x);
+ bzero(F, sizeof(*F));
+ f->buffer = (byte *)(F+1);
+ f->bptr = f->bstop = f->buffer;
+ f->bufend = f->buffer + buflen;
+ f->name = f->bufend;
+ memcpy(f->name, name, namelen);
+ F->fd = fd;
+ f->refill = bfd_refill;
+ f->spout = bfd_spout;
+ f->seek = bfd_seek;
+ f->close = bfd_close;
+ f->config = bfd_config;
+ f->can_overwrite_buffer = 2;
+ return f;
}
-void bbcopy(struct fastbuf *f, struct fastbuf *t, uns l)
+void
+bfilesync(struct fastbuf *b)
{
- uns rf = f->bstop - f->bptr;
-
- if (!l)
- return;
- if (rf)
- {
- uns k = (rf <= l) ? rf : l;
- bwrite(t, f->bptr, k);
- f->bptr += k;
- l -= k;
- }
- while (l >= t->buflen)
- {
- t->spout(t);
- if ((uns) read(f->fd, t->buffer, t->buflen) != t->buflen)
- die("bbcopy: %s exhausted", f->name);
- f->pos = f->fdpos;
- f->fdpos += t->buflen;
- f->bstop = f->bptr = f->buffer;
- t->bptr = t->bufend;
- l -= t->buflen;
- }
- while (l)
- {
- uns k = t->bufend - t->bptr;
-
- if (!k)
- {
- t->spout(t);
- k = t->bufend - t->bptr;
- }
- if (k > l)
- k = l;
- bread(f, t->bptr, k);
- t->bptr += k;
- l -= k;
- }
+ bflush(b);
+ if (fsync(FB_FILE(b)->fd) < 0)
+ msg(L_ERROR, "fsync(%s) failed: %m", b->name);
}
#ifdef TEST
-int main(int argc, char **argv)
+int main(void)
{
struct fastbuf *f, *t;
- int c;
-
- f = bopen("/etc/profile", O_RDONLY, 16);
- t = bfdopen(1, 13);
- bbcopy(f, t, 100);
+ f = bopen_tmp(16);
+ t = bfdopen_shared(1, 13);
+ for (uns i = 0; i < 16; i++)
+ bwrite(f, "<hello>", 7);
+ bprintf(t, "%d\n", (int)btell(f));
+ brewind(f);
+ bbcopy(f, t, ~0U);
+ bprintf(t, "\n%d %d\n", (int)btell(f), (int)btell(t));
bclose(f);
bclose(t);
+ return 0;
}
#endif
projects / libucw.git / blobdiff