X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=inline;f=lib%2Ffastbuf.h;h=fadf306135ec7ebe5b490816d7ec871230234a9c;hb=b43635d10f884732f466de394596b31d3779ea7c;hp=69df9b710bc4f565a38c85b65143fdf7f84dba41;hpb=995eaf5dcd982789ccab07c5302bee5d5afea4fc;p=libucw.git

diff --git a/lib/fastbuf.h b/lib/fastbuf.h
index 69df9b71..fadf3061 100644
--- a/lib/fastbuf.h
+++ b/lib/fastbuf.h
@@ -1,7 +1,8 @@
 /*
  *	Sherlock Library -- Fast Buffered I/O
  *
- *	(c) 1997--2000 Martin Mares <mj@ucw.cz>
+ *	(c) 1997--2004 Martin Mares <mj@ucw.cz>
+ *	(c) 2004 Robert Spalek <robert@ucw.cz>
  *
  *	This software may be freely distributed and used according to the terms
  *	of the GNU Lesser General Public License.
@@ -19,7 +20,8 @@
 #include "lib/unaligned.h"
 
 /*
- *  Generic buffered I/O on a top of buffer swapping functions.
+ *  Generic buffered I/O. You supply hooks to be called for low-level operations
+ *  (swapping of buffers, seeking and closing), we do the rest.
  *
  *  Buffer layout when reading:
  *
@@ -35,52 +37,96 @@
  *
  *  When writing:
  *
- *  +----------------+---------------------------+
- *  | written data   | free space                |
- *  +----------------+---------------------------+
- *  ^                 ^                           ^
- *  buffer=bstop      bptr                        bufend
+ *  +--------+--------------+--------------------+
+ *  | unused | written data | free space         |
+ *  +--------+--------------+--------------------+
+ *  ^         ^              ^                    ^
+ *  buffer    bstop          bptr                 bufend
+ *
+ *  Dirty tricks:
+ *
+ *    - You can mix reads and writes on the same stream, but you must
+ *	call bflush() in between and remember that the file position
+ *	points after the flushed buffer which is not necessarily the same
+ *	as after the data you've read.
+ *    - The spout/refill hooks can change not only bptr and bstop, but also
+ *	the location of the buffer; fb-mem.c takes advantage of it.
+ *    - In some cases, the user of the bdirect interface can be allowed to modify
+ *	the data in the buffer to avoid unnecessary copying. If the back-end
+ *	allows such modifications, it can set can_overwrite_buffer accordingly:
+ *		*  0 if no modification is allowed,
+ *		*  1 if the user can modify the buffer on the condition that
+ *		     the modifications will be undone before calling the next
+ *		     fastbuf operation
+ *		*  2 if the user is allowed to overwrite the data in the buffer
+ *		     if bdirect_read_commit_modified() is called afterwards.
+ *		     In this case, the back-end must be prepared for trimming
+ *		     of the buffer which is done by the commit function.
  */
 
 struct fastbuf {
+  byte is_fastbuf[0];			/* Dummy field for checking of type casts */
   byte *bptr, *bstop;			/* Access pointers */
   byte *buffer, *bufend;		/* Start and end of the buffer */
   byte *name;				/* File name for error messages */
-  uns buflen;				/* Size of the buffer */
-  sh_off_t pos;				/* Position of buffer start in the file */
-  sh_off_t fdpos;			/* Current position in the non-buffered file */
-  int fd;				/* File descriptor, -1 if not a real file */
-  int is_temp_file;			/* Is a temporary file, delete on close */
-  void *lldata;				/* Data private to access functions below */
-  void *llpos;				/* ... continued ... */
+  sh_off_t pos;				/* Position of bstop in the file */
   int (*refill)(struct fastbuf *);	/* Get a buffer with new data */
   void (*spout)(struct fastbuf *);	/* Write buffer data to the file */
   void (*seek)(struct fastbuf *, sh_off_t, int);  /* Slow path for bseek(), buffer already flushed */
   void (*close)(struct fastbuf *);	/* Close the stream */
+  int (*config)(struct fastbuf *, uns, int);	/* Configure the stream */
+  int can_overwrite_buffer;		/* Can the buffer be altered? (see discussion above) 0=never, 1=temporarily, 2=permanently */
 };
 
-/* FastIO on standard files */
+/* FastIO on standard files (specify buffer size 0 to enable mmaping) */
 
-struct fastbuf *bopen(byte *name, uns mode, uns buffer);
-struct fastbuf *bopen_tmp(uns buffer);
-struct fastbuf *bfdopen(int fd, uns buffer);
-void bbcopy(struct fastbuf *f, struct fastbuf *t, uns l);
+struct fastbuf *bopen(byte *name, uns mode, uns buflen);
+struct fastbuf *bopen_tmp(uns buflen);
+struct fastbuf *bfdopen(int fd, uns buflen);
+struct fastbuf *bfdopen_shared(int fd, uns buflen);
 
 /* FastIO on in-memory streams */
 
 struct fastbuf *fbmem_create(unsigned blocksize);	/* Create stream and return its writing fastbuf */
 struct fastbuf *fbmem_clone_read(struct fastbuf *);	/* Create reading fastbuf */
 
+/* FastIO on memory mapped files */
+
+struct fastbuf *bopen_mm(byte *name, uns mode);
+
+/* FastI on file descriptors with limit */
+
+struct fastbuf *bopen_limited_fd(int fd, uns bufsize, uns limit);
+
+/* FastIO on static buffers */
+
+void fbbuf_init_read(struct fastbuf *f, byte *buffer, uns size, uns can_overwrite);
+void fbbuf_init_write(struct fastbuf *f, byte *buffer, uns size);
+static inline uns
+fbbuf_count_written(struct fastbuf *f)
+{
+  return f->bptr - f->bstop;
+}
+
+/* Configuring stream parameters */
+
+int bconfig(struct fastbuf *f, uns type, int data);
+
+#define BCONFIG_IS_TEMP_FILE 0
+
 /* Universal functions working on all fastbuf's */
 
 void bclose(struct fastbuf *f);
 void bflush(struct fastbuf *f);
 void bseek(struct fastbuf *f, sh_off_t pos, int whence);
 void bsetpos(struct fastbuf *f, sh_off_t pos);
+void brewind(struct fastbuf *f);
+void bskip(struct fastbuf *f, uns len);
+sh_off_t bfilesize(struct fastbuf *f);
 
 static inline sh_off_t btell(struct fastbuf *f)
 {
-  return f->pos + (f->bptr - f->buffer);
+  return f->pos + (f->bptr - f->bstop);
 }
 
 int bgetc_slow(struct fastbuf *f);
@@ -251,6 +297,7 @@ static inline void bwrite(struct fastbuf *f, void *b, uns l)
 }
 
 byte *bgets(struct fastbuf *f, byte *b, uns l);	/* Non-std */
+int bgets_nodie(struct fastbuf *f, byte *b, uns l);
 byte *bgets0(struct fastbuf *f, byte *b, uns l);
 
 static inline void
@@ -272,6 +319,21 @@ bputsn(struct fastbuf *f, byte *b)
   bputc(f, '\n');
 }
 
+void bbcopy_slow(struct fastbuf *f, struct fastbuf *t, uns l);
+static inline void
+bbcopy(struct fastbuf *f, struct fastbuf *t, uns l)
+{
+  if (f->bptr + l <= f->bstop &&
+      t->bptr + l <= t->bufend)
+    {
+      memcpy(t->bptr, f->bptr, l);
+      t->bptr += l;
+      f->bptr += l;
+    }
+  else
+    bbcopy_slow(f, t, l);
+}
+
 /* I/O on addr_int_t */
 
 #ifdef CPU_64BIT_POINTERS
@@ -284,9 +346,46 @@ bputsn(struct fastbuf *f, byte *b)
 
 /* Direct I/O on buffers */
 
-int bdirect_read_prepare(struct fastbuf *f, byte **buf);
-void bdirect_read_commit(struct fastbuf *f, byte *pos);
-int bdirect_write_prepare(struct fastbuf *f, byte **buf);
-void bdirect_write_commit(struct fastbuf *f, byte *pos);
+static inline uns
+bdirect_read_prepare(struct fastbuf *f, byte **buf)
+{
+  if (f->bptr == f->bstop && !f->refill(f))
+    return 0;
+  *buf = f->bptr;
+  return f->bstop - f->bptr;
+}
+
+static inline void
+bdirect_read_commit(struct fastbuf *f, byte *pos)
+{
+  f->bptr = pos;
+}
+
+static inline void
+bdirect_read_commit_modified(struct fastbuf *f, byte *pos)
+{
+  f->bptr = pos;
+  f->buffer = pos;	/* Avoid seeking backwards in the buffer */
+}
+
+static inline uns
+bdirect_write_prepare(struct fastbuf *f, byte **buf)
+{
+  if (f->bptr == f->bufend)
+    f->spout(f);
+  *buf = f->bptr;
+  return f->bufend - f->bptr;
+}
+
+static inline void
+bdirect_write_commit(struct fastbuf *f, byte *pos)
+{
+  f->bptr = pos;
+}
+
+/* Formatted output */
+
+int bprintf(struct fastbuf *b, byte *msg, ...);
+int vbprintf(struct fastbuf *b, byte *msg, va_list args);
 
 #endif