Imported Upstream version 0.2.6
[tabix.git] / bgzf.c
diff --git a/bgzf.c b/bgzf.c
index 216cd04527f1ad187420cf1fab781e1d72e485b8..3bea7182d0384e9e4015ba7d1c69e78d16c33da6 100644 (file)
--- a/bgzf.c
+++ b/bgzf.c
@@ -1,6 +1,7 @@
 /* The MIT License
 
    Copyright (c) 2008 Broad Institute / Massachusetts Institute of Technology
+                 2011 Attractive Chaos <attractor@live.co.uk>
 
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    THE SOFTWARE.
 */
 
-/*
-  2009-06-29 by lh3: cache recent uncompressed blocks.
-  2009-06-25 by lh3: optionally use my knetfile library to access file on a FTP.
-  2009-06-12 by lh3: support a mode string like "wu" where 'u' for uncompressed output */
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <fcntl.h>
+#include <assert.h>
 #include <sys/types.h>
-#include <sys/stat.h>
 #include "bgzf.h"
 
-#include "khash.h"
+#ifdef _USE_KNETFILE
+#include "knetfile.h"
+typedef knetFile *_bgzf_file_t;
+#define _bgzf_open(fn, mode) knet_open(fn, mode)
+#define _bgzf_dopen(fp, mode) knet_dopen(fp, mode)
+#define _bgzf_close(fp) knet_close(fp)
+#define _bgzf_fileno(fp) ((fp)->fd)
+#define _bgzf_tell(fp) knet_tell(fp)
+#define _bgzf_seek(fp, offset, whence) knet_seek(fp, offset, whence)
+#define _bgzf_read(fp, buf, len) knet_read(fp, buf, len)
+#define _bgzf_write(fp, buf, len) knet_write(fp, buf, len)
+#else // ~defined(_USE_KNETFILE)
+#if defined(_WIN32) || defined(_MSC_VER)
+#define ftello(fp) ftell(fp)
+#define fseeko(fp, offset, whence) fseek(fp, offset, whence)
+#else // ~defined(_WIN32)
+extern off_t ftello(FILE *stream);
+extern int fseeko(FILE *stream, off_t offset, int whence);
+#endif // ~defined(_WIN32)
+typedef FILE *_bgzf_file_t;
+#define _bgzf_open(fn, mode) fopen(fn, mode)
+#define _bgzf_dopen(fp, mode) fdopen(fp, mode)
+#define _bgzf_close(fp) fclose(fp)
+#define _bgzf_fileno(fp) fileno(fp)
+#define _bgzf_tell(fp) ftello(fp)
+#define _bgzf_seek(fp, offset, whence) fseeko(fp, offset, whence)
+#define _bgzf_read(fp, buf, len) fread(buf, 1, len, fp)
+#define _bgzf_write(fp, buf, len) fwrite(buf, 1, len, fp)
+#endif // ~define(_USE_KNETFILE)
+
+#define BLOCK_HEADER_LENGTH 18
+#define BLOCK_FOOTER_LENGTH 8
+
+/* BGZF/GZIP header (speciallized from RFC 1952; little endian):
+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
+ | 31|139|  8|  4|              0|  0|255|      6| 66| 67|      2|BLK_LEN|
+ +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
+*/
+static const uint8_t g_magic[19] = "\037\213\010\4\0\0\0\0\0\377\6\0\102\103\2\0\0\0";
+
+#ifdef BGZF_CACHE
 typedef struct {
        int size;
        uint8_t *block;
        int64_t end_offset;
 } cache_t;
+#include "khash.h"
 KHASH_MAP_INIT_INT64(cache, cache_t)
-
-#if defined(_WIN32) || defined(_MSC_VER)
-#define ftello(fp) ftell(fp)
-#define fseeko(fp, offset, whence) fseek(fp, offset, whence)
-#else
-extern off_t ftello(FILE *stream);
-extern int fseeko(FILE *stream, off_t offset, int whence);
 #endif
 
-typedef int8_t bgzf_byte_t;
-
-static const int DEFAULT_BLOCK_SIZE = 64 * 1024;
-static const int MAX_BLOCK_SIZE = 64 * 1024;
-
-static const int BLOCK_HEADER_LENGTH = 18;
-static const int BLOCK_FOOTER_LENGTH = 8;
-
-static const int GZIP_ID1 = 31;
-static const int GZIP_ID2 = 139;
-static const int CM_DEFLATE = 8;
-static const int FLG_FEXTRA = 4;
-static const int OS_UNKNOWN = 255;
-static const int BGZF_ID1 = 66; // 'B'
-static const int BGZF_ID2 = 67; // 'C'
-static const int BGZF_LEN = 2;
-static const int BGZF_XLEN = 6; // BGZF_LEN+4
-
-static const int GZIP_WINDOW_BITS = -15; // no zlib header
-static const int Z_DEFAULT_MEM_LEVEL = 8;
-
-
-inline
-void
-packInt16(uint8_t* buffer, uint16_t value)
-{
-    buffer[0] = value;
-    buffer[1] = value >> 8;
-}
-
-inline
-int
-unpackInt16(const uint8_t* buffer)
+static inline void packInt16(uint8_t *buffer, uint16_t value)
 {
-    return (buffer[0] | (buffer[1] << 8));
+       buffer[0] = value;
+       buffer[1] = value >> 8;
 }
 
-inline
-void
-packInt32(uint8_t* buffer, uint32_t value)
+static inline int unpackInt16(const uint8_t *buffer)
 {
-    buffer[0] = value;
-    buffer[1] = value >> 8;
-    buffer[2] = value >> 16;
-    buffer[3] = value >> 24;
+       return buffer[0] | buffer[1] << 8;
 }
 
-static inline
-int
-bgzf_min(int x, int y)
+static inline void packInt32(uint8_t *buffer, uint32_t value)
 {
-    return (x < y) ? x : y;
-}
-
-static
-void
-report_error(BGZF* fp, const char* message) {
-    fp->error = message;
-}
-
-int bgzf_check_bgzf(const char *fn)
-{
-    BGZF *fp;
-    uint8_t buf[10],magic[10]="\037\213\010\4\0\0\0\0\0\377";
-    int n;
-
-    if ((fp = bgzf_open(fn, "r")) == 0) 
-    {
-        fprintf(stderr, "[bgzf_check_bgzf] failed to open the file: %s\n",fn);
-        return -1;
-    }
-
-#ifdef _USE_KNETFILE
-    n = knet_read(fp->x.fpr, buf, 10);
-#else
-    n = fread(buf, 1, 10, fp->file);
-#endif
-    bgzf_close(fp);
-
-    if ( n!=10 ) 
-        return -1;
-
-    if ( !memcmp(magic, buf, 10) ) return 1;
-    return 0;
+       buffer[0] = value;
+       buffer[1] = value >> 8;
+       buffer[2] = value >> 16;
+       buffer[3] = value >> 24;
 }
 
 static BGZF *bgzf_read_init()
 {
        BGZF *fp;
        fp = calloc(1, sizeof(BGZF));
-    fp->uncompressed_block_size = MAX_BLOCK_SIZE;
-    fp->uncompressed_block = malloc(MAX_BLOCK_SIZE);
-    fp->compressed_block_size = MAX_BLOCK_SIZE;
-    fp->compressed_block = malloc(MAX_BLOCK_SIZE);
-       fp->cache_size = 0;
+       fp->open_mode = 'r';
+       fp->uncompressed_block = malloc(BGZF_BLOCK_SIZE);
+       fp->compressed_block = malloc(BGZF_BLOCK_SIZE);
+#ifdef BGZF_CACHE
        fp->cache = kh_init(cache);
-       return fp;
-}
-
-static
-BGZF*
-open_read(int fd)
-{
-#ifdef _USE_KNETFILE
-    knetFile *file = knet_dopen(fd, "r");
-#else
-    FILE* file = fdopen(fd, "r");
-#endif
-    BGZF* fp;
-       if (file == 0) return 0;
-       fp = bgzf_read_init();
-    fp->file_descriptor = fd;
-    fp->open_mode = 'r';
-#ifdef _USE_KNETFILE
-    fp->x.fpr = file;
-#else
-    fp->file = file;
 #endif
-    return fp;
+       return fp;
 }
 
-static
-BGZF*
-open_write(int fd, int compress_level) // compress_level==-1 for the default level
+static BGZF *bgzf_write_init(int compress_level) // compress_level==-1 for the default level
 {
-    FILE* file = fdopen(fd, "w");
-    BGZF* fp;
-       if (file == 0) return 0;
-       fp = malloc(sizeof(BGZF));
-    fp->file_descriptor = fd;
-    fp->open_mode = 'w';
-    fp->owned_file = 0;
+       BGZF *fp;
+       fp = calloc(1, sizeof(BGZF));
+       fp->open_mode = 'w';
+       fp->uncompressed_block = malloc(BGZF_BLOCK_SIZE);
+       fp->compressed_block = malloc(BGZF_BLOCK_SIZE);
        fp->compress_level = compress_level < 0? Z_DEFAULT_COMPRESSION : compress_level; // Z_DEFAULT_COMPRESSION==-1
        if (fp->compress_level > 9) fp->compress_level = Z_DEFAULT_COMPRESSION;
-#ifdef _USE_KNETFILE
-    fp->x.fpw = file;
-#else
-    fp->file = file;
-#endif
-    fp->uncompressed_block_size = DEFAULT_BLOCK_SIZE;
-    fp->uncompressed_block = NULL;
-    fp->compressed_block_size = MAX_BLOCK_SIZE;
-    fp->compressed_block = malloc(MAX_BLOCK_SIZE);
-    fp->block_address = 0;
-    fp->block_offset = 0;
-    fp->block_length = 0;
-    fp->error = NULL;
-    return fp;
+       return fp;
+}
+// get the compress level from the mode string
+static int mode2level(const char *__restrict mode)
+{
+       int i, compress_level = -1;
+       for (i = 0; mode[i]; ++i)
+               if (mode[i] >= '0' && mode[i] <= '9') break;
+       if (mode[i]) compress_level = (int)mode[i] - '0';
+       if (strchr(mode, 'u')) compress_level = 0;
+       return compress_level;
 }
 
-BGZF*
-bgzf_open(const char* __restrict path, const char* __restrict mode)
+BGZF *bgzf_open(const char *path, const char *mode)
 {
-    BGZF* fp = NULL;
-    if (strchr(mode, 'r') || strchr(mode, 'R')) { /* The reading mode is preferred. */
-#ifdef _USE_KNETFILE
-               knetFile *file = knet_open(path, mode);
-               if (file == 0) return 0;
+       BGZF *fp = 0;
+       if (strchr(mode, 'r') || strchr(mode, 'R')) {
+               _bgzf_file_t fpr;
+               if ((fpr = _bgzf_open(path, "r")) == 0) return 0;
                fp = bgzf_read_init();
-               fp->file_descriptor = -1;
-               fp->open_mode = 'r';
-               fp->x.fpr = file;
-#else
-               int fd, oflag = O_RDONLY;
-#ifdef _WIN32
-               oflag |= O_BINARY;
-#endif
-               fd = open(path, oflag);
-               if (fd == -1) return 0;
-        fp = open_read(fd);
-#endif
-    } else if (strchr(mode, 'w') || strchr(mode, 'W')) {
-               int fd, compress_level = -1, oflag = O_WRONLY | O_CREAT | O_TRUNC;
-#ifdef _WIN32
-               oflag |= O_BINARY;
-#endif
-               fd = open(path, oflag, 0666);
-               if (fd == -1) return 0;
-               { // set compress_level
-                       int i;
-                       for (i = 0; mode[i]; ++i)
-                               if (mode[i] >= '0' && mode[i] <= '9') break;
-                       if (mode[i]) compress_level = (int)mode[i] - '0';
-                       if (strchr(mode, 'u')) compress_level = 0;
-               }
-        fp = open_write(fd, compress_level);
-    }
-    if (fp != NULL) fp->owned_file = 1;
-    return fp;
+               fp->fp = fpr;
+       } else if (strchr(mode, 'w') || strchr(mode, 'W')) {
+               FILE *fpw;
+               if ((fpw = fopen(path, "w")) == 0) return 0;
+               fp = bgzf_write_init(mode2level(mode));
+               fp->fp = fpw;
+       }
+       return fp;
 }
 
-BGZF*
-bgzf_fdopen(int fd, const char * __restrict mode)
+BGZF *bgzf_dopen(int fd, const char *mode)
 {
-       if (fd == -1) return 0;
-    if (mode[0] == 'r' || mode[0] == 'R') {
-        return open_read(fd);
-    } else if (mode[0] == 'w' || mode[0] == 'W') {
-               int i, compress_level = -1;
-               for (i = 0; mode[i]; ++i)
-                       if (mode[i] >= '0' && mode[i] <= '9') break;
-               if (mode[i]) compress_level = (int)mode[i] - '0';
-               if (strchr(mode, 'u')) compress_level = 0;
-        return open_write(fd, compress_level);
-    } else {
-        return NULL;
-    }
+       BGZF *fp = 0;
+       if (strchr(mode, 'r') || strchr(mode, 'R')) {
+               _bgzf_file_t fpr;
+               if ((fpr = _bgzf_dopen(fd, "r")) == 0) return 0;
+               fp = bgzf_read_init();
+               fp->fp = fpr;
+       } else if (strchr(mode, 'w') || strchr(mode, 'W')) {
+               FILE *fpw;
+               if ((fpw = fdopen(fd, "w")) == 0) return 0;
+               fp = bgzf_write_init(mode2level(mode));
+               fp->fp = fpw;
+       }
+       return fp;
 }
 
-static
-int
-deflate_block(BGZF* fp, int block_length)
+// Deflate the block in fp->uncompressed_block into fp->compressed_block. Also adds an extra field that stores the compressed block length.
+static int deflate_block(BGZF *fp, int block_length)
 {
-    // Deflate the block in fp->uncompressed_block into fp->compressed_block.
-    // Also adds an extra field that stores the compressed block length.
-
-    bgzf_byte_t* buffer = fp->compressed_block;
-    int buffer_size = fp->compressed_block_size;
-
-    // Init gzip header
-    buffer[0] = GZIP_ID1;
-    buffer[1] = GZIP_ID2;
-    buffer[2] = CM_DEFLATE;
-    buffer[3] = FLG_FEXTRA;
-    buffer[4] = 0; // mtime
-    buffer[5] = 0;
-    buffer[6] = 0;
-    buffer[7] = 0;
-    buffer[8] = 0;
-    buffer[9] = OS_UNKNOWN;
-    buffer[10] = BGZF_XLEN;
-    buffer[11] = 0;
-    buffer[12] = BGZF_ID1;
-    buffer[13] = BGZF_ID2;
-    buffer[14] = BGZF_LEN;
-    buffer[15] = 0;
-    buffer[16] = 0; // placeholder for block length
-    buffer[17] = 0;
-
-    // loop to retry for blocks that do not compress enough
-    int input_length = block_length;
-    int compressed_length = 0;
-    while (1) {
-        z_stream zs;
-        zs.zalloc = NULL;
-        zs.zfree = NULL;
-        zs.next_in = fp->uncompressed_block;
-        zs.avail_in = input_length;
-        zs.next_out = (void*)&buffer[BLOCK_HEADER_LENGTH];
-        zs.avail_out = buffer_size - BLOCK_HEADER_LENGTH - BLOCK_FOOTER_LENGTH;
-
-        int status = deflateInit2(&zs, fp->compress_level, Z_DEFLATED,
-                                  GZIP_WINDOW_BITS, Z_DEFAULT_MEM_LEVEL, Z_DEFAULT_STRATEGY);
-        if (status != Z_OK) {
-            report_error(fp, "deflate init failed");
-            return -1;
-        }
-        status = deflate(&zs, Z_FINISH);
-        if (status != Z_STREAM_END) {
-            deflateEnd(&zs);
-            if (status == Z_OK) {
-                // Not enough space in buffer.
-                // Can happen in the rare case the input doesn't compress enough.
-                // Reduce the amount of input until it fits.
-                input_length -= 1024;
-                if (input_length <= 0) {
-                    // should never happen
-                    report_error(fp, "input reduction failed");
-                    return -1;
-                }
-                continue;
-            }
-            report_error(fp, "deflate failed");
-            return -1;
-        }
-        status = deflateEnd(&zs);
-        if (status != Z_OK) {
-            report_error(fp, "deflate end failed");
-            return -1;
-        }
-        compressed_length = zs.total_out;
-        compressed_length += BLOCK_HEADER_LENGTH + BLOCK_FOOTER_LENGTH;
-        if (compressed_length > MAX_BLOCK_SIZE) {
-            // should never happen
-            report_error(fp, "deflate overflow");
-            return -1;
-        }
-        break;
-    }
+       uint8_t *buffer = fp->compressed_block;
+       int buffer_size = BGZF_BLOCK_SIZE;
+       int input_length = block_length;
+       int compressed_length = 0;
+       int remaining;
+       uint32_t crc;
+
+       assert(block_length <= BGZF_BLOCK_SIZE); // guaranteed by the caller
+       memcpy(buffer, g_magic, BLOCK_HEADER_LENGTH); // the last two bytes are a place holder for the length of the block
+       while (1) { // loop to retry for blocks that do not compress enough
+               int status;
+               z_stream zs;
+               zs.zalloc = NULL;
+               zs.zfree = NULL;
+               zs.next_in = fp->uncompressed_block;
+               zs.avail_in = input_length;
+               zs.next_out = (void*)&buffer[BLOCK_HEADER_LENGTH];
+               zs.avail_out = buffer_size - BLOCK_HEADER_LENGTH - BLOCK_FOOTER_LENGTH;
+               status = deflateInit2(&zs, fp->compress_level, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY); // -15 to disable zlib header/footer
+               if (status != Z_OK) {
+                       fp->errcode |= BGZF_ERR_ZLIB;
+                       return -1;
+               }
+               status = deflate(&zs, Z_FINISH);
+               if (status != Z_STREAM_END) { // not compressed enough
+                       deflateEnd(&zs); // reset the stream
+                       if (status == Z_OK) { // reduce the size and recompress
+                               input_length -= 1024;
+                               assert(input_length > 0); // logically, this should not happen
+                               continue;
+                       }
+                       fp->errcode |= BGZF_ERR_ZLIB;
+                       return -1;
+               }
+               if (deflateEnd(&zs) != Z_OK) {
+                       fp->errcode |= BGZF_ERR_ZLIB;
+                       return -1;
+               }
+               compressed_length = zs.total_out;
+               compressed_length += BLOCK_HEADER_LENGTH + BLOCK_FOOTER_LENGTH;
+               assert(compressed_length <= BGZF_BLOCK_SIZE);
+               break;
+       }
 
-    packInt16((uint8_t*)&buffer[16], compressed_length-1);
-    uint32_t crc = crc32(0L, NULL, 0L);
-    crc = crc32(crc, fp->uncompressed_block, input_length);
-    packInt32((uint8_t*)&buffer[compressed_length-8], crc);
-    packInt32((uint8_t*)&buffer[compressed_length-4], input_length);
-
-    int remaining = block_length - input_length;
-    if (remaining > 0) {
-        if (remaining > input_length) {
-            // should never happen (check so we can use memcpy)
-            report_error(fp, "remainder too large");
-            return -1;
-        }
-        memcpy(fp->uncompressed_block,
-               fp->uncompressed_block + input_length,
-               remaining);
-    }
-    fp->block_offset = remaining;
-    return compressed_length;
+       assert(compressed_length > 0);
+       packInt16((uint8_t*)&buffer[16], compressed_length - 1); // write the compressed_length; -1 to fit 2 bytes
+       crc = crc32(0L, NULL, 0L);
+       crc = crc32(crc, fp->uncompressed_block, input_length);
+       packInt32((uint8_t*)&buffer[compressed_length-8], crc);
+       packInt32((uint8_t*)&buffer[compressed_length-4], input_length);
+
+       remaining = block_length - input_length;
+       if (remaining > 0) {
+               assert(remaining <= input_length);
+               memcpy(fp->uncompressed_block, fp->uncompressed_block + input_length, remaining);
+       }
+       fp->block_offset = remaining;
+       return compressed_length;
 }
 
-static
-int
-inflate_block(BGZF* fp, int block_length)
+// Inflate the block in fp->compressed_block into fp->uncompressed_block
+static int inflate_block(BGZF* fp, int block_length)
 {
-    // Inflate the block in fp->compressed_block into fp->uncompressed_block
-
-    z_stream zs;
-       int status;
-    zs.zalloc = NULL;
-    zs.zfree = NULL;
-    zs.next_in = fp->compressed_block + 18;
-    zs.avail_in = block_length - 16;
-    zs.next_out = fp->uncompressed_block;
-    zs.avail_out = fp->uncompressed_block_size;
-
-    status = inflateInit2(&zs, GZIP_WINDOW_BITS);
-    if (status != Z_OK) {
-        report_error(fp, "inflate init failed");
-        return -1;
-    }
-    status = inflate(&zs, Z_FINISH);
-    if (status != Z_STREAM_END) {
-        inflateEnd(&zs);
-        report_error(fp, "inflate failed");
-        return -1;
-    }
-    status = inflateEnd(&zs);
-    if (status != Z_OK) {
-        report_error(fp, "inflate failed");
-        return -1;
-    }
-    return zs.total_out;
+       z_stream zs;
+       zs.zalloc = NULL;
+       zs.zfree = NULL;
+       zs.next_in = fp->compressed_block + 18;
+       zs.avail_in = block_length - 16;
+       zs.next_out = fp->uncompressed_block;
+       zs.avail_out = BGZF_BLOCK_SIZE;
+
+       if (inflateInit2(&zs, -15) != Z_OK) {
+               fp->errcode |= BGZF_ERR_ZLIB;
+               return -1;
+       }
+       if (inflate(&zs, Z_FINISH) != Z_STREAM_END) {
+               inflateEnd(&zs);
+               fp->errcode |= BGZF_ERR_ZLIB;
+               return -1;
+       }
+       if (inflateEnd(&zs) != Z_OK) {
+               fp->errcode |= BGZF_ERR_ZLIB;
+               return -1;
+       }
+       return zs.total_out;
 }
 
-static
-int
-check_header(const bgzf_byte_t* header)
+static int check_header(const uint8_t *header)
 {
-    return (header[0] == GZIP_ID1 &&
-            header[1] == (bgzf_byte_t) GZIP_ID2 &&
-            header[2] == Z_DEFLATED &&
-            (header[3] & FLG_FEXTRA) != 0 &&
-            unpackInt16((uint8_t*)&header[10]) == BGZF_XLEN &&
-            header[12] == BGZF_ID1 &&
-            header[13] == BGZF_ID2 &&
-            unpackInt16((uint8_t*)&header[14]) == BGZF_LEN);
+       return (header[0] == 31 && header[1] == 139 && header[2] == 8 && (header[3] & 4) != 0
+                       && unpackInt16((uint8_t*)&header[10]) == 6
+                       && header[12] == 'B' && header[13] == 'C'
+                       && unpackInt16((uint8_t*)&header[14]) == 2);
 }
 
+#ifdef BGZF_CACHE
 static void free_cache(BGZF *fp)
 {
        khint_t k;
@@ -431,12 +288,8 @@ static int load_block_from_cache(BGZF *fp, int64_t block_address)
        if (fp->block_length != 0) fp->block_offset = 0;
        fp->block_address = block_address;
        fp->block_length = p->size;
-       memcpy(fp->uncompressed_block, p->block, MAX_BLOCK_SIZE);
-#ifdef _USE_KNETFILE
-       knet_seek(fp->x.fpr, p->end_offset, SEEK_SET);
-#else
-       fseeko(fp->file, p->end_offset, SEEK_SET);
-#endif
+       memcpy(fp->uncompressed_block, p->block, BGZF_BLOCK_SIZE);
+       _bgzf_seek((_bgzf_file_t)fp->fp, p->end_offset, SEEK_SET);
        return p->size;
 }
 
@@ -446,8 +299,8 @@ static void cache_block(BGZF *fp, int size)
        khint_t k;
        cache_t *p;
        khash_t(cache) *h = (khash_t(cache)*)fp->cache;
-       if (MAX_BLOCK_SIZE >= fp->cache_size) return;
-       if ((kh_size(h) + 1) * MAX_BLOCK_SIZE > fp->cache_size) {
+       if (BGZF_BLOCK_SIZE >= fp->cache_size) return;
+       if ((kh_size(h) + 1) * BGZF_BLOCK_SIZE > fp->cache_size) {
                /* A better way would be to remove the oldest block in the
                 * cache, but here we remove a random one for simplicity. This
                 * should not have a big impact on performance. */
@@ -463,201 +316,140 @@ static void cache_block(BGZF *fp, int size)
        p = &kh_val(h, k);
        p->size = fp->block_length;
        p->end_offset = fp->block_address + size;
-       p->block = malloc(MAX_BLOCK_SIZE);
-       memcpy(kh_val(h, k).block, fp->uncompressed_block, MAX_BLOCK_SIZE);
+       p->block = malloc(BGZF_BLOCK_SIZE);
+       memcpy(kh_val(h, k).block, fp->uncompressed_block, BGZF_BLOCK_SIZE);
 }
+#else
+static void free_cache(BGZF *fp) {}
+static int load_block_from_cache(BGZF *fp, int64_t block_address) {return 0;}
+static void cache_block(BGZF *fp, int size) {}
+#endif
 
-int
-bgzf_read_block(BGZF* fp)
+int bgzf_read_block(BGZF *fp)
 {
-    bgzf_byte_t header[BLOCK_HEADER_LENGTH];
+       uint8_t header[BLOCK_HEADER_LENGTH], *compressed_block;
        int count, size = 0, block_length, remaining;
-#ifdef _USE_KNETFILE
-    int64_t block_address = knet_tell(fp->x.fpr);
-       if (load_block_from_cache(fp, block_address)) return 0;
-    count = knet_read(fp->x.fpr, header, sizeof(header));
-#else
-    int64_t block_address = ftello(fp->file);
+       int64_t block_address;
+       block_address = _bgzf_tell((_bgzf_file_t)fp->fp);
        if (load_block_from_cache(fp, block_address)) return 0;
-    count = fread(header, 1, sizeof(header), fp->file);
-#endif
-    if (count == 0) {
-        fp->block_length = 0;
-        return 0;
-    }
+       count = _bgzf_read(fp->fp, header, sizeof(header));
+       if (count == 0) { // no data read
+               fp->block_length = 0;
+               return 0;
+       }
+       if (count != sizeof(header) || !check_header(header)) {
+               fp->errcode |= BGZF_ERR_HEADER;
+               return -1;
+       }
        size = count;
-    if (count != sizeof(header)) {
-        report_error(fp, "read failed");
-        return -1;
-    }
-    if (!check_header(header)) {
-        report_error(fp, "invalid block header");
-        return -1;
-    }
-    block_length = unpackInt16((uint8_t*)&header[16]) + 1;
-    bgzf_byte_t* compressed_block = (bgzf_byte_t*) fp->compressed_block;
-    memcpy(compressed_block, header, BLOCK_HEADER_LENGTH);
-    remaining = block_length - BLOCK_HEADER_LENGTH;
-#ifdef _USE_KNETFILE
-    count = knet_read(fp->x.fpr, &compressed_block[BLOCK_HEADER_LENGTH], remaining);
-#else
-    count = fread(&compressed_block[BLOCK_HEADER_LENGTH], 1, remaining, fp->file);
-#endif
-    if (count != remaining) {
-        report_error(fp, "read failed");
-        return -1;
-    }
+       block_length = unpackInt16((uint8_t*)&header[16]) + 1; // +1 because when writing this number, we used "-1"
+       compressed_block = (uint8_t*)fp->compressed_block;
+       memcpy(compressed_block, header, BLOCK_HEADER_LENGTH);
+       remaining = block_length - BLOCK_HEADER_LENGTH;
+       count = _bgzf_read(fp->fp, &compressed_block[BLOCK_HEADER_LENGTH], remaining);
+       if (count != remaining) {
+               fp->errcode |= BGZF_ERR_IO;
+               return -1;
+       }
        size += count;
-    count = inflate_block(fp, block_length);
-    if (count < 0) return -1;
-    if (fp->block_length != 0) {
-        // Do not reset offset if this read follows a seek.
-        fp->block_offset = 0;
-    }
-    fp->block_address = block_address;
-    fp->block_length = count;
+       if ((count = inflate_block(fp, block_length)) < 0) return -1;
+       if (fp->block_length != 0) fp->block_offset = 0; // Do not reset offset if this read follows a seek.
+       fp->block_address = block_address;
+       fp->block_length = count;
        cache_block(fp, size);
-    return 0;
+       return 0;
 }
 
-int
-bgzf_read(BGZF* fp, void* data, int length)
+ssize_t bgzf_read(BGZF *fp, void *data, ssize_t length)
 {
-    if (length <= 0) {
-        return 0;
-    }
-    if (fp->open_mode != 'r') {
-        report_error(fp, "file not open for reading");
-        return -1;
-    }
-
-    int bytes_read = 0;
-    bgzf_byte_t* output = data;
-    while (bytes_read < length) {
-        int copy_length, available = fp->block_length - fp->block_offset;
-               bgzf_byte_t *buffer;
-        if (available <= 0) {
-            if (bgzf_read_block(fp) != 0) {
-                return -1;
-            }
-            available = fp->block_length - fp->block_offset;
-            if (available <= 0) {
-                break;
-            }
-        }
-        copy_length = bgzf_min(length-bytes_read, available);
-        buffer = fp->uncompressed_block;
-        memcpy(output, buffer + fp->block_offset, copy_length);
-        fp->block_offset += copy_length;
-        output += copy_length;
-        bytes_read += copy_length;
-    }
-    if (fp->block_offset == fp->block_length) {
-#ifdef _USE_KNETFILE
-        fp->block_address = knet_tell(fp->x.fpr);
-#else
-        fp->block_address = ftello(fp->file);
-#endif
-        fp->block_offset = 0;
-        fp->block_length = 0;
-    }
-    return bytes_read;
+       ssize_t bytes_read = 0;
+       uint8_t *output = data;
+       if (length <= 0) return 0;
+       assert(fp->open_mode == 'r');
+       while (bytes_read < length) {
+               int copy_length, available = fp->block_length - fp->block_offset;
+               uint8_t *buffer;
+               if (available <= 0) {
+                       if (bgzf_read_block(fp) != 0) return -1;
+                       available = fp->block_length - fp->block_offset;
+                       if (available <= 0) break;
+               }
+               copy_length = length - bytes_read < available? length - bytes_read : available;
+               buffer = fp->uncompressed_block;
+               memcpy(output, buffer + fp->block_offset, copy_length);
+               fp->block_offset += copy_length;
+               output += copy_length;
+               bytes_read += copy_length;
+       }
+       if (fp->block_offset == fp->block_length) {
+               fp->block_address = _bgzf_tell((_bgzf_file_t)fp->fp);
+               fp->block_offset = fp->block_length = 0;
+       }
+       return bytes_read;
 }
 
-int bgzf_flush(BGZFfp)
+int bgzf_flush(BGZF *fp)
 {
-    while (fp->block_offset > 0) {
-        int count, block_length;
+       assert(fp->open_mode == 'w');
+       while (fp->block_offset > 0) {
+               int block_length;
                block_length = deflate_block(fp, fp->block_offset);
-        if (block_length < 0) return -1;
-#ifdef _USE_KNETFILE
-        count = fwrite(fp->compressed_block, 1, block_length, fp->x.fpw);
-#else
-        count = fwrite(fp->compressed_block, 1, block_length, fp->file);
-#endif
-        if (count != block_length) {
-            report_error(fp, "write failed");
-            return -1;
-        }
-        fp->block_address += block_length;
-    }
-    return 0;
+               if (block_length < 0) return -1;
+               if (fwrite(fp->compressed_block, 1, block_length, fp->fp) != block_length) {
+                       fp->errcode |= BGZF_ERR_IO; // possibly truncated file
+                       return -1;
+               }
+               fp->block_address += block_length;
+       }
+       return 0;
 }
 
-int bgzf_flush_try(BGZF *fp, int size)
+int bgzf_flush_try(BGZF *fp, ssize_t size)
 {
-       if (fp->block_offset + size > fp->uncompressed_block_size)
+       if (fp->block_offset + size > BGZF_BLOCK_SIZE)
                return bgzf_flush(fp);
        return -1;
 }
 
-int bgzf_write(BGZF* fp, const void* data, int length)
+ssize_t bgzf_write(BGZF *fp, const void *data, ssize_t length)
 {
-       const bgzf_byte_t *input = data;
-       int block_length, bytes_written;
-    if (fp->open_mode != 'w') {
-        report_error(fp, "file not open for writing");
-        return -1;
-    }
-
-    if (fp->uncompressed_block == NULL)
-        fp->uncompressed_block = malloc(fp->uncompressed_block_size);
-
-    input = data;
-    block_length = fp->uncompressed_block_size;
-    bytes_written = 0;
-    while (bytes_written < length) {
-        int copy_length = bgzf_min(block_length - fp->block_offset, length - bytes_written);
-        bgzf_byte_t* buffer = fp->uncompressed_block;
-        memcpy(buffer + fp->block_offset, input, copy_length);
-        fp->block_offset += copy_length;
-        input += copy_length;
-        bytes_written += copy_length;
-        if (fp->block_offset == block_length) {
-            if (bgzf_flush(fp) != 0) {
-                break;
-            }
-        }
-    }
-    return bytes_written;
+       const uint8_t *input = data;
+       int block_length = BGZF_BLOCK_SIZE, bytes_written;
+       assert(fp->open_mode == 'w');
+       input = data;
+       bytes_written = 0;
+       while (bytes_written < length) {
+               uint8_t* buffer = fp->uncompressed_block;
+               int copy_length = block_length - fp->block_offset < length - bytes_written? block_length - fp->block_offset : length - bytes_written;
+               memcpy(buffer + fp->block_offset, input, copy_length);
+               fp->block_offset += copy_length;
+               input += copy_length;
+               bytes_written += copy_length;
+               if (fp->block_offset == block_length && bgzf_flush(fp)) break;
+       }
+       return bytes_written;
 }
 
 int bgzf_close(BGZF* fp)
 {
-    if (fp->open_mode == 'w') {
-        if (bgzf_flush(fp) != 0) return -1;
-               { // add an empty block
-                       int count, block_length = deflate_block(fp, 0);
-#ifdef _USE_KNETFILE
-                       count = fwrite(fp->compressed_block, 1, block_length, fp->x.fpw);
-#else
-                       count = fwrite(fp->compressed_block, 1, block_length, fp->file);
-#endif
+       int ret, count, block_length;
+       if (fp == 0) return -1;
+       if (fp->open_mode == 'w') {
+               if (bgzf_flush(fp) != 0) return -1;
+               block_length = deflate_block(fp, 0); // write an empty block
+               count = fwrite(fp->compressed_block, 1, block_length, fp->fp);
+               if (fflush(fp->fp) != 0) {
+                       fp->errcode |= BGZF_ERR_IO;
+                       return -1;
                }
-#ifdef _USE_KNETFILE
-        if (fflush(fp->x.fpw) != 0) {
-#else
-        if (fflush(fp->file) != 0) {
-#endif
-            report_error(fp, "flush failed");
-            return -1;
-        }
-    }
-    if (fp->owned_file) {
-#ifdef _USE_KNETFILE
-               int ret;
-               if (fp->open_mode == 'w') ret = fclose(fp->x.fpw);
-               else ret = knet_close(fp->x.fpr);
-        if (ret != 0) return -1;
-#else
-        if (fclose(fp->file) != 0) return -1;
-#endif
-    }
-    free(fp->uncompressed_block);
-    free(fp->compressed_block);
+       }
+       ret = fp->open_mode == 'w'? fclose(fp->fp) : _bgzf_close(fp->fp);
+       if (ret != 0) return -1;
+       free(fp->uncompressed_block);
+       free(fp->compressed_block);
        free_cache(fp);
-    free(fp);
-    return 0;
+       free(fp);
+       return 0;
 }
 
 void bgzf_set_cache_size(BGZF *fp, int cache_size)
@@ -670,17 +462,10 @@ int bgzf_check_EOF(BGZF *fp)
        static uint8_t magic[28] = "\037\213\010\4\0\0\0\0\0\377\6\0\102\103\2\0\033\0\3\0\0\0\0\0\0\0\0\0";
        uint8_t buf[28];
        off_t offset;
-#ifdef _USE_KNETFILE
-       offset = knet_tell(fp->x.fpr);
-       if (knet_seek(fp->x.fpr, -28, SEEK_END) != 0) return -1;
-       knet_read(fp->x.fpr, buf, 28);
-       knet_seek(fp->x.fpr, offset, SEEK_SET);
-#else
-       offset = ftello(fp->file);
-       if (fseeko(fp->file, -28, SEEK_END) != 0) return -1;
-       fread(buf, 1, 28, fp->file);
-       fseeko(fp->file, offset, SEEK_SET);
-#endif
+       offset = _bgzf_tell((_bgzf_file_t)fp->fp);
+       if (_bgzf_seek(fp->fp, -28, SEEK_END) < 0) return 0;
+       _bgzf_read(fp->fp, buf, 28);
+       _bgzf_seek(fp->fp, offset, SEEK_SET);
        return (memcmp(magic, buf, 28) == 0)? 1 : 0;
 }
 
@@ -689,26 +474,82 @@ int64_t bgzf_seek(BGZF* fp, int64_t pos, int where)
        int block_offset;
        int64_t block_address;
 
-    if (fp->open_mode != 'r') {
-        report_error(fp, "file not open for read");
-        return -1;
-    }
-    if (where != SEEK_SET) {
-        report_error(fp, "unimplemented seek option");
-        return -1;
+       if (fp->open_mode != 'r' || where != SEEK_SET) {
+               fp->errcode |= BGZF_ERR_MISUSE;
+               return -1;
+       }
+       block_offset = pos & 0xFFFF;
+       block_address = pos >> 16;
+       if (_bgzf_seek(fp->fp, block_address, SEEK_SET) < 0) {
+               fp->errcode |= BGZF_ERR_IO;
+               return -1;
+       }
+       fp->block_length = 0;  // indicates current block has not been loaded
+       fp->block_address = block_address;
+       fp->block_offset = block_offset;
+       return 0;
+}
+
+int bgzf_is_bgzf(const char *fn)
+{
+       uint8_t buf[16];
+       int n;
+       _bgzf_file_t fp;
+       if ((fp = _bgzf_open(fn, "r")) == 0) return 0;
+       n = _bgzf_read(fp, buf, 16);
+       _bgzf_close(fp);
+       if (n != 16) return 0;
+       return memcmp(g_magic, buf, 16) == 0? 1 : 0;
+}
+
+int bgzf_getc(BGZF *fp)
+{
+       int c;
+       if (fp->block_offset >= fp->block_length) {
+               if (bgzf_read_block(fp) != 0) return -2; /* error */
+               if (fp->block_length == 0) return -1; /* end-of-file */
+       }
+       c = ((unsigned char*)fp->uncompressed_block)[fp->block_offset++];
+    if (fp->block_offset == fp->block_length) {
+        fp->block_address = _bgzf_tell((_bgzf_file_t)fp->fp);
+        fp->block_offset = 0;
+        fp->block_length = 0;
     }
-    block_offset = pos & 0xFFFF;
-    block_address = (pos >> 16) & 0xFFFFFFFFFFFFLL;
-#ifdef _USE_KNETFILE
-    if (knet_seek(fp->x.fpr, block_address, SEEK_SET) != 0) {
-#else
-    if (fseeko(fp->file, block_address, SEEK_SET) != 0) {
+       return c;
+}
+
+#ifndef kroundup32
+#define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))
 #endif
-        report_error(fp, "seek failed");
-        return -1;
-    }
-    fp->block_length = 0;  // indicates current block is not loaded
-    fp->block_address = block_address;
-    fp->block_offset = block_offset;
-    return 0;
+
+int bgzf_getline(BGZF *fp, int delim, kstring_t *str)
+{
+       int l, state = 0;
+       unsigned char *buf = (unsigned char*)fp->uncompressed_block;
+       str->l = 0;
+       do {
+               if (fp->block_offset >= fp->block_length) {
+                       if (bgzf_read_block(fp) != 0) { state = -2; break; }
+                       if (fp->block_length == 0) { state = -1; break; }
+               }
+               for (l = fp->block_offset; l < fp->block_length && buf[l] != delim; ++l);
+               if (l < fp->block_length) state = 1;
+               l -= fp->block_offset;
+               if (str->l + l + 1 >= str->m) {
+                       str->m = str->l + l + 2;
+                       kroundup32(str->m);
+                       str->s = (char*)realloc(str->s, str->m);
+               }
+               memcpy(str->s + str->l, buf + fp->block_offset, l);
+               str->l += l;
+               fp->block_offset += l + 1;
+               if (fp->block_offset >= fp->block_length) {
+                       fp->block_address = _bgzf_tell((_bgzf_file_t)fp->fp);
+                       fp->block_offset = 0;
+                       fp->block_length = 0;
+               } 
+       } while (state == 0);
+       if (str->l == 0 && state < 0) return state;
+       str->s[str->l] = 0;
+       return str->l;
 }